Method and device for evaluating the feasibility of geothermal modification construction using oilfield old wells

Abstract

The present disclosure relates to the technical field of geothermal development and petroleum engineering, and particularly relates to a method and device for evaluating the construction feasibility of geothermal reconstruction using old oil wells. The method for evaluating the construction feasibility of geothermal reconstruction using old oil wells comprises: determining construction feasibility evaluation parameters of geothermal reconstruction of old oil wells, and determining the construction feasibility evaluation result of geothermal reconstruction of old oil wells based on the evaluation result determined by the construction feasibility evaluation parameters. The construction feasibility evaluation parameters comprise evaluation parameters of reconstruction pump chamber adaptability, evaluation parameters of casing apparent status, evaluation parameters of casing residual service capacity, evaluation parameters of cementing quality and evaluation parameters of wellbore pressure stabilization sealing capacity.

Description

Technical Field

[0001] This disclosure relates to the fields of geothermal development and petroleum engineering technology, and in particular to a method and apparatus for assessing the feasibility of geothermal retrofitting using old oilfield wells. Background Technology

[0002] The oilfield has a large number of old wells, a wide geographical distribution, and complex and diverse well conditions. Although some old wells in the oilfield have relatively good geothermal resources, they have problems such as unsuitable size, damaged wellbore integrity, and insufficient remaining service life, making it impossible to carry out renovation construction or posing high construction risks. Summary of the Invention

[0003] This disclosure provides a method and apparatus for assessing the feasibility of geothermal retrofitting using old oilfield wells, in order to solve problems existing in related technologies.

[0004] Firstly, this disclosure provides a feasibility assessment method for geothermal stimulation using old oilfield wells, including:

[0005] The feasibility assessment parameters for geothermal stimulation of old wells in oilfields are determined. These parameters include assessment parameters for the compatibility of the stimulation pump room, assessment parameters for the current appearance of the casing, assessment parameters for the remaining service capacity of the casing, assessment parameters for cementing quality, and assessment parameters for the wellbore pressure stabilization and sealing capacity.

[0006] The evaluation results of the modified pump room adaptability are determined based on the evaluation parameters of the modified pump room adaptability, the evaluation results of the casing apparent status are determined based on the evaluation parameters of the casing apparent status, the evaluation results of the casing remaining service capacity are determined based on the evaluation parameters of the casing remaining service capacity, the evaluation results of the cementing quality are determined based on the evaluation parameters of the cementing quality, and the evaluation results of the wellbore pressure stabilization and sealing capacity are determined based on the evaluation parameters of the wellbore pressure stabilization and sealing capacity.

[0007] Based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity, the feasibility assessment results of geothermal modification of the old wells in the oilfield are determined.

[0008] In some embodiments, the assessment results for determining the feasibility of geothermal stimulation of the old oilfield well based on the assessment results of the adaptability of the modified pump chamber, the assessment results of the apparent condition of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity include:

[0009] If the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing all fail to meet the "not recommended" criteria, then the first stage score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing.

[0010] If the first-stage integral equals the preset first-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield is determined to be "not recommended" based on the first-stage integral.

[0011] In some embodiments, the method further includes:

[0012] If the first stage integral is greater than the preset first stage integral, then after performing wellhead rectification, well cleaning, retrieval or casing repair on the old wells in the oilfield in sequence, the evaluation results of the cementing quality and the evaluation results of the wellbore pressure stabilization and sealing capacity are determined.

[0013] In some embodiments, the method further includes:

[0014] If the first stage score is greater than the preset first stage score and the cementing quality assessment result does not meet the "not recommended" requirement, then the second stage score is determined based on the assessment results of the modified pump room adaptability, the assessment results of the casing appearance status, the assessment results of the casing remaining service capacity, and the assessment results of the cementing quality.

[0015] If the second-stage integral is less than or equal to the preset second-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield will be determined as "not recommended" based on the second-stage integral.

[0016] In some embodiments, the method further includes:

[0017] If the second-stage integral is greater than the preset second-stage integral, then the old well in the oilfield will be sealed with cement plugs to plug the original producing layer and pressure tested in the wellbore in sequence to obtain the evaluation result of the wellbore's pressure stabilization and sealing capacity.

[0018] If the assessment result of the wellbore pressure stabilization and sealing capability does not meet the "not recommended" requirement, then a comprehensive score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capability.

[0019] According to the preset evaluation rules, the feasibility evaluation result of geothermal renovation of the old wells in the oilfield is determined based on the comprehensive score.

[0020] In some embodiments, the method further includes:

[0021] If the assessment result of the apparent condition of the casing meets the condition of "cannot be accurately assessed based on existing data", then after well cleaning, fishing, or casing repair of the old well in the oilfield, the assessment result of the apparent condition of the casing is determined; if the assessment result of the apparent condition of the casing does not meet the condition of "not recommended", then the first stage integration step is performed based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent condition of the casing, and the assessment result of the remaining service capacity of the casing; and / or,

[0022] If the assessment result of the remaining service capacity of the casing meets the condition of "cannot be accurately assessed based on existing data", then after performing well cleaning, fishing or casing repair and logging on the old well in the oilfield, the assessment result of the remaining service capacity of the casing is determined; if the assessment result of the remaining service capacity of the casing does not meet the condition of "not recommended", then the first stage integration step is performed based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent status of the casing and the assessment result of the remaining service capacity of the casing.

[0023] Secondly, this disclosure provides a feasibility assessment device for geothermal stimulation using old oilfield wells, comprising:

[0024] The determination module is used to determine the feasibility assessment parameters for geothermal renovation of old wells in oilfields. The feasibility assessment parameters include the assessment parameters for the adaptability of the renovation pump room, the assessment parameters for the current appearance of the casing, the assessment parameters for the remaining service capacity of the casing, the assessment parameters for the cementing quality, and the assessment parameters for the wellbore pressure stabilization and sealing capacity.

[0025] The processing module is used to determine the assessment result of the adaptability of the modified pump room based on the assessment parameters of the adaptability of the modified pump room, the assessment result of the apparent status of the casing based on the assessment parameters of the apparent status of the casing, the assessment result of the remaining service capacity of the casing based on the assessment parameters of the remaining service capacity of the casing, the assessment result of the cementing quality based on the assessment parameters of the cementing quality, and the assessment result of the wellbore pressure stabilization and sealing capacity based on the assessment parameters of the wellbore pressure stabilization and sealing capacity.

[0026] The processing module is also used to determine the feasibility assessment results for geothermal stimulation of the old wells in the oilfield based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity.

[0027] Thirdly, this disclosure provides a computer device including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the foregoing aspects.

[0028] Fourthly, this disclosure provides a computer-readable storage medium having a computer program stored thereon that, when executed by a processor, implements the steps of the methods described in the above aspects.

[0029] Fifthly, this disclosure provides a computer program product, including a computer program / instructions that, when executed by a processor, implement the steps of the methods described in the foregoing aspects.

[0030] This disclosure provides a method and apparatus for assessing the feasibility of geothermal stimulation of old oilfield wells. The method determines feasibility assessment parameters for geothermal stimulation of old oilfield wells, including parameters for assessing the compatibility of the stimulated pump chamber, the current appearance of the casing, the remaining service capacity of the casing, the cementing quality, and the wellbore pressure stabilization and sealing capacity. The method determines the assessment results based on the parameters for pump chamber compatibility, the current appearance of the casing, and the remaining service capacity of the casing, and then proceeds based on the parameters for assessing cementing quality. The quality assessment parameters determine the cementing quality assessment results, and the wellbore pressure stabilization and sealing capacity assessment parameters determine the wellbore pressure stabilization and sealing capacity assessment results. Based on the assessment results of pump room adaptability, casing appearance status, casing remaining service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity, the feasibility assessment results for geothermal stimulation of old oilfield wells are determined. This approach can effectively classify and assess old oilfield wells, which are numerous, geographically distributed, and have complex and diverse well conditions, identify engineering construction risks in advance, and select suitable old oilfield wells for geothermal stimulation construction according to their specific conditions. Attached Figure Description

[0031] The present disclosure will be described in more detail below based on embodiments and with reference to the accompanying drawings:

[0032] Figure 1 A flowchart illustrating a feasibility assessment method for geothermal retrofitting using old oilfield wells, provided in an embodiment of this disclosure, is shown.

[0033] Figure 2 A basic flowchart of a construction feasibility assessment method for geothermal renovation using old oilfield wells, provided by an embodiment of this disclosure, is shown.

[0034] Figure 3This is a schematic diagram of a construction feasibility assessment device for geothermal retrofitting using old oilfield wells, provided as an embodiment of this disclosure. Detailed Implementation

[0035] To enable those skilled in the art to better understand the technical solutions of this disclosure, and to fully understand and implement the process of how this disclosure applies technical means to solve technical problems and achieve corresponding technical effects, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, not all embodiments. The embodiments of this disclosure and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this disclosure. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort should fall within the protection scope of this disclosure.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this disclosure described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0038] As oilfield development enters its mid-to-late stages, a large number of old oilfield wells without oil and gas development benefits often face closure and sealing. Sealing wells requires strict adherence to relevant disposal standards, which consumes considerable manpower, material resources, and financial resources. However, on the other hand, some old oilfield wells, due to the good geothermal resources and energy and heat demand in their respective blocks, possess the prerequisites and advantages for geothermal development. If these old oilfield wells can be converted into geothermal wells, the following benefits will be brought: (1) Saving geothermal resource development costs. Converting idle old oilfield wells into geothermal wells eliminates the costs of geological exploration and resource evaluation before drilling, shortens the construction cycle, and saves drilling fees, land occupation fees, and other construction costs. It is estimated that the cost is only 1 / 3 to 1 / 2 of that of drilling new geothermal wells. (2) Revitalizing old oilfield well resources and realizing asset preservation and appreciation. Converting old oilfield wells into geothermal wells turns "waste" into treasure, avoids asset idleness, and adds new clean heating benefit points. (3) To contribute to the construction of a green and low-carbon oilfield.

[0039] However, the oilfield has a large number of old wells, a wide geographical distribution, and complex and diverse well conditions. Although some old wells in the oilfield have relatively good geothermal resources, they have problems such as unsuitable size, damaged wellbore integrity, and insufficient remaining service life, making it impossible to carry out renovation construction or posing high construction risks.

[0040] Based on this, this disclosure provides a feasibility assessment method for geothermal transformation of old oilfield wells. This method is universally applicable, as it can identify the risks of geothermal development of old oilfield wells in advance, improving the success rate of construction. Furthermore, it can classify and screen numerous old oilfield wells from an engineering perspective, quickly identifying which wells are suitable for geothermal resource development and reuse, thus eliminating redundant work. Using this feasibility assessment method, oilfield companies can comprehensively plan and rationally allocate their old oilfield well assets.

[0041] Example 1

[0042] This disclosure proposes a feasibility assessment method for geothermal transformation of old oilfield wells. From an engineering perspective, it assesses the geothermal (water intake and reinjection) transformation of old oilfield wells, identifies which old oilfield wells are suitable for geothermal resource development using the water intake and reinjection method, improves the success rate of construction, and reduces risks.

[0043] This disclosure embodiment considers five fundamental engineering conditions affecting the renovation of old wells in oilfields, evaluates these five conditions sequentially, and synthesizes them into a final feasibility assessment result. This feasibility assessment result can be expressed as:

[0044] B={b1,b2,b3,b4,b5} (1)

[0045] Among them, B represents the feasibility assessment result of geothermal renovation of old wells in the oilfield, which is determined by the assessment results of five basic engineering conditions; b1 represents the assessment result of the adaptability of the renovation pump room; b2 represents the assessment result of the current appearance of the casing; b3 represents the assessment result of the remaining service capacity of the casing; b4 represents the assessment result of the cementing quality; and b5 represents the assessment result of the wellbore pressure stabilization and sealing capacity.

[0046] For example, the adaptability of the modified pump room is evaluated to obtain the evaluation result. The adaptability of the modified pump room is determined by two sub-evaluation indicators: the adaptability of the surface casing to the modified pump room and the adaptability of the technical casing to the modified pump room. The evaluation result of the modified pump room adaptability can be expressed as:

[0047] b1={b 11 ,b 12} (2)

[0048] Among them, b 11 This indicates the assessment results of the compatibility of the surface casing with the pump chamber. 12 This indicates the assessment results regarding the compatibility of the pump room with the modified casing.

[0049] For example, the assessment method for the compatibility of surface casing retrofit pump chambers can be:

[0050] Scenario 1: If the diameter of the surface casing is ≥339.7mm, the depth of the surface casing is ≥300m, and the cement return distance of the remaining casing sections to the ground is ≥300m, then the evaluation result of the compatibility of the surface casing with the pump room is "excellent".

[0051] Scenario 2: Except for Scenario 1, if the diameter of the surface casing is ≥301.6mm, the depth of the surface casing is ≥200m, and the cement return distance of the remaining casing sections is ≥200m from the ground, then the assessment result of the compatibility of the surface casing with the pump room is "medium".

[0052] Scenario 3: Except for scenarios 1 and 2, if the diameter of the surface casing is ≥273.1mm, the depth of the surface casing is ≥150m, and the cement return distance of the remaining casing sections to the ground is ≥150m, then the assessment result of the compatibility of the surface casing with the pump room is "cautious".

[0053] Scenario 4: If the diameter of the surface casing is <273.1mm, or the depth of the surface casing is <150m, or the cement return distance of the remaining casing sections is <150m from the ground, then the assessment result of the compatibility of the surface casing with the pump room is "not recommended".

[0054] For example, the assessment method for the compatibility of technical casing retrofit pump chambers can be:

[0055] Scenario 1: If the diameter of the technical casing is ≥244.5mm and the distance from the well cement return of the oil layer casing to the ground is ≥300m, then the assessment result of the adaptability of the technical casing to the pump room is "medium".

[0056] Scenario 2: If 177.8mm < technical casing diameter ≤ 244.5mm, and the cement return distance of the oil layer casing to the ground is ≥ 200m, then the assessment result of the adaptability of the technical casing to the pump room is "cautious".

[0057] Scenario 3: If the diameter of the technical casing is ≤177.8mm, or the distance from the well cement return point of the oil layer casing to the ground is <200m, then the assessment result of the compatibility of the technical casing with the pump room is "not recommended".

[0058] Based on this, when evaluating the adaptability of the modified pump chamber in this embodiment, the adaptability of the surface sleeve modified pump chamber and the adaptability of the technical sleeve modified pump chamber are evaluated sequentially, and the following situations are considered:

[0059] 1. If the assessment result of the surface casing modification pump room adaptability is "excellent" or "medium", then the technical casing modification pump room adaptability will not be further assessed, and the modification pump room adaptability will be "excellent" or "medium".

[0060] 2. If the assessment result of the surface casing modification pump room adaptability is "cautious", then the assessment result of the technical casing modification pump room adaptability needs to be continued. If the assessment result of the technical casing modification pump room adaptability is "neutral", the assessment result of the modification pump room adaptability is "neutral". If the assessment result of the technical casing modification pump room adaptability is "cautious" or "not recommended", then the assessment result of the modification pump room adaptability is "cautious".

[0061] 3. If the assessment result of the surface casing modification pump room adaptability is "not recommended", then the technical casing modification pump room adaptability needs to be further assessed. The final assessment result of the modification pump room adaptability is equivalent to the assessment result of the technical casing modification pump room adaptability.

[0062] For example, the apparent condition of the casing is assessed to obtain the assessment result. The apparent condition of the casing is determined by two sub-assessment indicators: casing damage and casing passability. The assessment result of the apparent condition of the casing can be expressed as:

[0063] b2={b 21 ,b 22} (3)

[0064] Among them, b 21 This indicates the assessment result of the hedging loss situation, b 22 This indicates the assessment result of the casing's passability.

[0065] For example, the assessment method for hedging losses can be:

[0066] If no casing bending, cracking, or misalignment occurs in the casing section above and 100m below the target reservoir, the assessment result of the casing damage is "excellent".

[0067] If the casing section above the target reservoir and the casing section 100m below the target reservoir have slight casing bends that do not affect the passage of the drill string, but there are no cracks, breaks, or other issues, then the assessment result for the casing damage is "medium".

[0068] If the casing section above the target reservoir and the casing section 100m below it have slight casing bending that does not affect the passage of the drill string, and there is casing rupture that can be repaired by methods such as cementing, but there is no casing misalignment, then the assessment result of the casing damage is "cautious".

[0069] If there is severe casing bending affecting drill passage in the casing section above and 100m below the target reservoir, or severe casing rupture that cannot be repaired, or casing misalignment, the assessment result for casing damage is "not recommended".

[0070] For example, the method for assessing cannula passability can be:

[0071] If no dust blockage or falling objects are found in the casing section above the target reservoir and the casing section 100m below it, the casing passability assessment result is "excellent".

[0072] If there is dust blockage or falling debris in the casing section above and 100m below the target reservoir, the casing passability assessment result is "cautious".

[0073] Based on this, when assessing the apparent condition of the casing, the embodiments of this disclosure evaluate the casing damage and the casing passability in sequence, and divide them into the following situations:

[0074] 1. If the assessment result of the casing loss is "excellent", then the casing passability will continue to be assessed. If the assessment result of the casing passability is "excellent", then the current appearance of the casing is "excellent"; if the assessment result of the casing passability is "cautious", then the current appearance of the casing is "medium".

[0075] 2. If the assessment result of the casing loss is "medium", then the casing passability will continue to be assessed. If the assessment result of the casing passability is "excellent", then the assessment result of the casing appearance status is "medium"; if the assessment result of the casing passability is "cautious", then the assessment result of the casing appearance status is "cautious".

[0076] 3. If the assessment result of the casing loss situation is "cautious", then continue to assess the casing passability. If the assessment result of the casing passability is "excellent", then the assessment result of the casing appearance status is "cautious"; if the assessment result of the casing passability is "cautious", then the assessment result of the casing appearance status is "not recommended".

[0077] 4. If the assessment result of the casing damage is "not recommended", then the casing passability will not be further assessed, and the assessment result of the casing appearance status will be "not recommended".

[0078] For example, the remaining service capacity of the casing is assessed to obtain the assessment result. The assessment method for the remaining service capacity of the casing is as follows:

[0079] Consider the maximum casing pressure under operating conditions. Ignoring dynamic fluid level issues and assuming a uniform temperature field distribution, the maximum casing pressure under operating conditions is calculated based on geothermal water overflowing to the wellhead. The formula for calculating the maximum casing pressure is as follows:

[0080] p imax =0.00981ρ m h f (4)

[0081] Where, p imax Indicates the maximum casing internal pressure, MPa; ρ m This indicates the density of geothermal water, in g / cm³. 3 h f The depth of the bottom boundary of the geothermal reservoir is indicated in meters (m).

[0082] Consider the maximum external casing pressure under operating conditions. The formula for calculating the maximum external casing pressure is as follows:

[0083] p omax =h f G0 (5)

[0084] Where, p omax G0 represents the maximum external pressure of the casing, in MPa; G0 represents the pressure gradient of the overlying strata, in MPa / m.

[0085] Consider the effective pressure of the casing under operating conditions. The formula for calculating the effective pressure of the casing is as follows:

[0086] p e =|p imax -p omax | (6)

[0087] Considering the critical wall thickness for safe service of the casing under operating conditions, the formula for calculating the critical wall thickness for safe service of the casing is as follows:

[0088]

[0089] Among them, t cr The critical wall thickness for safe service of the casing is indicated in mm; S represents the rated pressure safety factor of the casing, ranging from 1 to 1.1; K o The overpressure coefficient of the casing is 1.1; D represents the nominal diameter of the casing in mm; k t This represents the casing wall thickness deviation coefficient, with a value of 0.875; f ymn β represents the minimum yield strength of the casing material, in MPa; β represents the attenuation correction value at the casing thread, ranging from 1.5 to 2 mm.

[0090] Consider the remaining life of the casing. The formula for calculating the remaining life of the casing is as follows:

[0091]

[0092] Among them, T r Indicates the remaining life of the casing, a; t cmin V represents the minimum wall thickness of the casing under current conditions, in mm; kd This indicates the corrosion rate of the casing under geothermal extraction operation conditions, expressed in mm / a.

[0093] For geothermal wells undergoing renovation in oilfields, data on the corrosion rate of casing under geothermal extraction conditions may be lacking. In such cases, the minimum wall thickness of the casing under current conditions can be determined in the following ways: 1. Obtain the casing corrosion rate through indoor simulation tests or wellhead stripping; 2. Propose an estimate based on casing monitoring data from geothermal wells operating in the same block; 3. Propose an estimate based on historical operating data or relevant literature.

[0094] The minimum wall thickness of the casing under current conditions can be estimated using the following formula:

[0095] t cmin =t g -T o ·V ky (9)

[0096] Among them, t g Indicates the nominal wall thickness of the casing, in mm; T o Indicates the age of old wells in the oil field, a; V ky This indicates the corrosion rate under oil and gas extraction conditions, expressed in mm / a.

[0097] The nominal casing wall thickness, well age, and corrosion rate under oil and gas extraction conditions can be determined using, but is not limited to, data from drilling design, well structure design, well history, and logging of old oil wells. In some cases, the corrosion rate under oil and gas extraction conditions may not be directly available; however, it can be calculated using the following formula:

[0098]

[0099] Among them, V ky Δt represents the corrosion rate under oil and gas extraction conditions, Δt represents the change in casing wall thickness between two tests (mm), and ΔT represents the interval between two tests (a).

[0100] Based on this, when assessing the remaining service life of the casing in this embodiment, the remaining service life of the casing is first calculated according to the above formulas (4) to (10), and T is used as the basis for the calculation. r Indicates. If T r If the remaining service capacity of the casing is ≥20a, the assessment result is "excellent"; if 15a≤T r If the service life is less than 20 years, the assessment result of the remaining service life of the casing is "medium"; if 10 years ≤ T r If the service life is less than 15 years, the assessment result for the remaining service capacity of the casing is "cautious"; if T r If the service life is less than 10 years, the assessment result for the remaining service capacity of the casing is "not recommended".

[0101] For example, the cementing quality is evaluated to obtain the evaluation results. Cementing quality is determined by two sub-evaluation indicators: cement return height and interlayer isolation. The evaluation results of cementing quality can be expressed as:

[0102] b4={b 41 ,b 42} (11)

[0103] Among them, b 41 Indicates cement return to high level, b 42 Indicates interlayer isolation.

[0104] For example, the assessment method for cement backfill height can be:

[0105] For casing sections that are in direct contact with the target reservoir, if the cement return height is ≥50m above the top boundary of the reservoir, the assessment result of the cement return height is "excellent".

[0106] For casing sections that are in direct contact with the target reservoir, if the cement return height reaches 30-50m above the top boundary of the reservoir, the assessment result of the cement return height is "medium".

[0107] For casing sections that are in direct contact with the target reservoir, if the cement return to the top of the reservoir less than 30m above the top boundary, but there is room for secondary cementing, the assessment result for the cement return height is "cautious"; otherwise, the assessment result for the cement return height is "not recommended".

[0108] For example, the evaluation method for interlayer isolation can be:

[0109] First, the casing is cleaned to ensure it does not interfere with the insertion and normal operation of the measuring instruments. Then, the interlayer sealing of the cement sheath in the target reservoir section is evaluated according to SY / T6592.

[0110] If the cement ring interlayer seal is assessed as "non-transferable", then the assessment result of the interlayer seal is "excellent".

[0111] If the interlayer seal of the cement ring is assessed as "highly likely to not cross-link", then the assessment result of the interlayer seal is "medium".

[0112] If the interlayer seal assessment of the cement ring is "highly likely to be compromised" or "compromised", but can be remedied by measures such as cement squeezing, then the assessment result of the interlayer seal is "cautious"; otherwise, the assessment result of the interlayer seal is "not recommended".

[0113] Based on this, the embodiments of this disclosure evaluate cement return height and interlayer sealing in sequence when assessing cementing quality, and divide the evaluation into the following cases:

[0114] 1. If the assessment result of cement return is "not recommended", then the interlayer isolation will not be assessed further, and the assessment result of cementing quality will be "not recommended".

[0115] 2. If the cement return assessment result is "Excellent", then the interlayer sealing needs to be further assessed. The assessment result of cementing quality is equivalent to the assessment result of interlayer sealing.

[0116] 3. If the assessment result for cement return is "Medium", then the interlayer sealing needs to be further assessed. If the assessment result for interlayer sealing is "Excellent", then the assessment result for cementing quality is "Medium"; if the assessment result for interlayer sealing is "Medium", then the assessment result for cementing quality is "Cautious"; if the assessment result for interlayer sealing is "Cautious" or "Not Recommended", then the assessment result for cementing quality is "Not Recommended".

[0117] 4. If the cementing quality assessment result is "cautious," then it is necessary to continue with b. 42 An assessment will be conducted. If the assessment result for interlayer sealing is "excellent" or "moderate", the assessment result for cementing quality will be "cautious"; if the assessment result for interlayer sealing is "cautious" or "not recommended", the assessment result for cementing quality will be "not recommended".

[0118] For example, the wellbore's pressure-stabilizing and sealing capability is evaluated to obtain the evaluation result. The evaluation method for the wellbore's pressure-stabilizing and sealing capability can be:

[0119] First, cement plugs are driven into the bottom boundary of the target reservoir to seal the oil and gas producing layer.

[0120] For the well section above the bottom boundary of the target reservoir, pressure testing is conducted using clean water as the medium. The wellhead pressure is ≥6MPa during the test and is stabilized for 30 minutes. If the pressure drop during this period is ≤0.5MPa, the evaluation result of the wellbore pressure stabilization and sealing capability is "excellent".

[0121] For the well section above the bottom boundary of the target reservoir, pressure testing is conducted using clean water as the medium. The wellhead pressure is ≥6MPa during the test and is maintained for 30 minutes. If the pressure drop is ≤1.0MPa and the pressure stabilization and sealing capacity of the wellbore is assessed as “medium”.

[0122] For the well section above the bottom boundary of the target reservoir, pressure testing is conducted using clean water as the medium. The wellhead pressure is ≥6MPa during the test and is stabilized for 30 minutes. If the pressure drop is ≤1.5MPa and 1.0MPa < 1.0MPa during the test, the assessment result of the wellbore pressure stabilization and sealing capability is "cautious".

[0123] For pressure testing of the well section above the bottom boundary of the target reservoir, clean water medium should be used. The wellhead pressure should be ≥6MPa during the test and stabilized for 30 minutes. If the pressure drop during the test is >1.5MPa, the assessment result of the wellbore pressure stabilization and sealing capacity is "not recommended".

[0124] Based on this, when evaluating the basic conditions for the renovation of old wells in the oilfield, the embodiments of this disclosure first evaluate the compatibility of the renovation pump room, the current appearance of the casing, the remaining service capacity of the casing, the cementing quality, and the wellbore pressure stabilization and sealing capacity in sequence.

[0125] First, it should be noted that if the evaluation result of any of the above sub-items (b1, b2, b3, b4, b5) is "not recommended", then the subsequent sub-items will not be evaluated. The overall evaluation result of the basic engineering conditions for the renovation of old oilfield wells is "not recommended", that is, based on the existing basic conditions for the renovation of old oilfield wells, it is not recommended to renovate them into geothermal wells.

[0126] Secondly, if none of the above sub-items (b1, b2, b3, b4, b5) are rated as "not recommended", then the evaluation results of each sub-item need to be scored. A sub-item is rated as "excellent" with 5 points, "medium" with 3 points, and "cautious" with 0 points. Finally, the scores of the five sub-items are added together to calculate the comprehensive score of the basic conditions for the renovation of old wells in the oilfield.

[0127] Table 1 shows the preset evaluation rules for the feasibility assessment of geothermal transformation of old oilfield wells provided in the embodiments of this disclosure. As shown in Table 1, if the total score after summing is >20 points, the feasibility assessment result for geothermal transformation of old oilfield wells is "Excellent"; if the total score after summing is >15 points, the feasibility assessment result for geothermal transformation of old oilfield wells is "Medium"; if the total score after summing is >10 points, the feasibility assessment result for geothermal transformation of old oilfield wells is "Cautious"; if the total score after summing is ≤10 points, the feasibility assessment result for geothermal transformation of old oilfield wells is "Not Recommended".

[0128] Table 1. Pre-set assessment rules for the feasibility assessment of geothermal restoration using old oilfield wells.

[0129] Comprehensive score >20 >15 >10 ≤10 excellent middle careful Not recommended

[0130] Figure 1 This document illustrates a flowchart of a feasibility assessment method for geothermal retrofitting using old oilfield wells, as provided in an embodiment of this disclosure. Figure 1 As shown, the specific implementation of this embodiment of the disclosure consists of the following steps:

[0131] Step 1: Assess the compatibility of the pump room for retrofitting old wells in the oilfield.

[0132] Based on, but not limited to, data such as the design, drilling, logging, and well history of the old wells in the oilfield to be evaluated, we can obtain information on the number of times the wells were drilled, the number of casing layers, the depth of each casing layer, the outer diameter of each casing layer, and the cement return height of each casing layer.

[0133] The method proposed in this disclosure is used to evaluate the compatibility of the pump chamber for refurbishment of an old oilfield well. If the evaluation result is "not recommended," no further evaluation is needed, and the overall evaluation result for the old oilfield well is "not recommended," meaning that refurbishment of the geothermal well is not recommended. If the evaluation result is "excellent," "moderate," or "cautious," then the next step is to evaluate the current appearance of the well casing.

[0134] Step 2: Assess the current condition of the casing of old wells in the oilfield.

[0135] Based on, but not limited to, well repair and well history data of old wells in the oilfield to be evaluated, it can be determined whether there are casing bends, cracks, misalignments, or other issues downhole, as well as whether there is dust blockage or fallen debris.

[0136] The method proposed in this disclosure is used to assess the current condition of the casing of an old oilfield well. If the assessment result is "not recommended," no further assessment is needed, and the overall assessment result for the old oilfield well is "not recommended," meaning that geothermal well stimulation construction is not recommended. If the assessment result is "excellent," "moderate," or "cautious," then the next step is to assess the current condition of the well casing.

[0137] In particular, if the apparent condition of the casing cannot be clearly determined based on the existing data, this assessment should be skipped and the next step should be to assess the remaining service life of the casing in the old wells of the oilfield.

[0138] Step 3: Assess the remaining service life of the casing in old oil wells.

[0139] By using, but not limited to, relevant geological data from old wells in the oil field, the bottom vertical depth of the target thermal reservoir and the pressure gradient of the overlying strata can be determined, and the density of geothermal water can be estimated.

[0140] The minimum yield strength of the casing material can be found through relevant data such as drilling design and well structure design of old wells in the oil field.

[0141] The corrosion rate of casing under geothermal extraction conditions can be obtained through methods including, but not limited to, indoor simulation tests or wellhead plate methods, estimation based on casing monitoring data of geothermal wells operating in the same block, and estimation based on historical operating data or relevant literature.

[0142] The nominal wall thickness of the casing, the age of the old well, and the corrosion rate under oil and gas extraction conditions can be obtained from relevant data such as drilling design, well structure design, well history, and logging of old wells in the oilfield. In particular, in some cases, the corrosion rate under oil and gas extraction conditions may not be directly available, but it can be calculated according to the above formula (10).

[0143] After obtaining the required data, the remaining service life of the casing of old oilfield wells is calculated and evaluated using the method proposed in this embodiment. If the evaluation result is "not recommended," no further evaluation is required, and the overall evaluation result for the old oilfield well is "not recommended," meaning that geothermal well modification is not recommended. If the evaluation result is "excellent," "moderate," or "cautious," then proceed to the next step.

[0144] In particular, if the remaining service life of the casing of old wells in the oilfield cannot be clearly calculated based on existing data, this assessment should be skipped.

[0145] Step 4: Calculate the scores for the first three evaluation indicators.

[0146] If the first-stage score for the first three indicators is 0, meaning the evaluation results for the first three indicators are all "cautious," then even if the evaluation results for the last two indicators are both "excellent," the overall evaluation score will still be ≤10 points, and the overall evaluation result will be "not recommended." Therefore, it can be stipulated that if the first-stage score for the first three indicators is 0, then there is no need to evaluate the last two indicators, and the overall evaluation result will be "not recommended."

[0147] In particular, if it is impossible to accurately assess any of the first three items due to limited information, skip this step.

[0148] Step 5: Carry out wellhead rectification.

[0149] Make necessary modifications based on the wellhead condition to prepare for subsequent assessment work. Wellhead modification measures may include, but are not limited to, gas cutting to open the well, replacing the wellhead, and replacing the blowout preventer, depending on the specific circumstances.

[0150] Step 6: Perform well cleaning, retrieval, or casing repair work.

[0151] To carry out well cleaning, retrieval, or casing repair work.

[0152] Specifically, if Step 2 is skipped due to insufficient existing data, this step is required to determine the current appearance of the casing. If the final assessment of the current appearance of the casing is "not recommended", then no further assessment is needed. The overall assessment of the old wells in the oilfield is "not recommended", meaning that geothermal well modification construction is not recommended.

[0153] Step 7: Conduct well logging and cementing quality assessment.

[0154] Depending on the actual situation, but not limited to acoustic amplitude (CBL) logging technology, variable density (VDL) logging technology, sector cement bond (SBT, RIB) logging technology, ultrasonic imaging logging technology (IBC) technology, etc., can be used to determine the quality of cement bond outside the pipe, and the cementing quality can be evaluated according to the methods proposed above.

[0155] Specifically, if Step 3 is skipped due to insufficient existing data, this step is necessary to obtain the relevant data required for assessing the remaining service life of the casing in old oilfield wells. This can be achieved using, but is not limited to, logging data such as casing string geometry (diameter and wall thickness) obtained through methods including, but not limited to, 40-arm caliper imaging and electromagnetic flaw detection logging. The logging data should reflect variations in casing diameter and wall thickness at multiple points along the same cross-section throughout the well, as well as data on casing cracks and corrosion pits. Then, the remaining service life of the casing in the old oilfield well is assessed using the methods described above. If the final assessment result for the remaining service life of the casing is "not recommended," no further assessment is necessary, and the overall assessment result for the old oilfield well is "not recommended," meaning that geothermal well stimulation construction is not recommended.

[0156] Step 8: Calculate the scores for the first four evaluation indicators.

[0157] If the combined score of the first four indicators is ≤5, then even if the evaluation result of the latter indicator is "excellent", the overall evaluation score will still be ≤10, and the overall evaluation result will be "not recommended". Therefore, it can be stipulated that if the combined score of the first four indicators is ≤5, then there is no need to evaluate the latter indicator, and the overall evaluation result will be "not recommended".

[0158] Step 9: Seal the original layer with a cement plug.

[0159] The purpose of this step is to seal the original production layer and prevent oil and gas from leaking out.

[0160] Step 10: Wellbore pressure test.

[0161] This step assesses the wellbore's pressure-stabilizing and sealing capabilities, following the methods described above.

[0162] Step 11: Calculate the final score and give the final evaluation result of the old wells in the oil field.

[0163] Example 2

[0164] Based on the above embodiments, this disclosure provides a method for assessing the feasibility of geothermal retrofitting using old oilfield wells. Figure 2 This disclosure presents a basic flowchart illustrating a feasibility assessment method for geothermal retrofitting using old oilfield wells, as provided in an embodiment of the present disclosure. Figure 2 As shown, a feasibility assessment method for geothermal retrofitting using old oilfield wells includes:

[0165] S201 determines the feasibility assessment parameters for geothermal stimulation of old wells in the oilfield. The feasibility assessment parameters include the assessment parameters for the compatibility of the stimulation pump room, the assessment parameters for the current appearance of the casing, the assessment parameters for the remaining service capacity of the casing, the assessment parameters for the cementing quality, and the assessment parameters for the wellbore pressure stabilization and sealing capacity.

[0166] S202, the evaluation results of the adaptability of the modified pump room are determined based on the evaluation parameters of the pump room adaptability, the evaluation results of the casing apparent status are determined based on the evaluation parameters of the casing apparent status, the evaluation results of the casing remaining service capacity are determined based on the evaluation parameters of the casing remaining service capacity, the evaluation results of the cementing quality are determined based on the evaluation parameters of the cementing quality, and the evaluation results of the wellbore pressure stabilization and sealing capacity are determined based on the evaluation parameters of the wellbore pressure stabilization and sealing capacity.

[0167] S203, based on the assessment results of the adaptability of the modified pump room, the assessment results of the current appearance of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality and the assessment results of the wellbore pressure stabilization and sealing capacity, determines the feasibility assessment results of geothermal modification of old wells in the oilfield.

[0168] Specifically, firstly, the embodiments of this disclosure can determine the feasibility assessment parameters for geothermal stimulation of old oilfield wells. For example, these feasibility assessment parameters may include assessment parameters for the adaptability of the stimulation pump chamber, assessment parameters for the apparent condition of the casing, assessment parameters for the remaining service capacity of the casing, assessment parameters for cementing quality, and assessment parameters for the wellbore's pressure stabilization and sealing capacity.

[0169] The adaptability of the modified pump chamber is evaluated using the evaluation parameters for pump chamber adaptability, and the evaluation results are obtained. The apparent condition of the casing is evaluated using the evaluation parameters for casing apparent condition, and the evaluation results are obtained. The remaining service capacity of the casing is evaluated using the evaluation parameters for casing remaining service capacity, and the evaluation results are obtained. The cementing quality is evaluated using the evaluation parameters for cementing quality, and the evaluation results are obtained. The wellbore pressure stabilization and sealing capacity is evaluated using the evaluation parameters for wellbore pressure stabilization and sealing capacity, and the evaluation results are obtained.

[0170] For example, the evaluation parameters for the adaptability of the modified pump room may include evaluation parameters for the adaptability of the modified pump room for the surface casing and evaluation parameters for the adaptability of the modified pump room for the technical casing; wherein, the evaluation parameters for the adaptability of the modified pump room for the surface casing may include the diameter of the surface casing, the depth of the surface casing, and the distance from the surface to the cement return point of the remaining casing sections; the evaluation parameters for the adaptability of the modified pump room for the technical casing may include the diameter of the technical casing and the distance from the surface to the surface to the cement return point of the oil layer casing.

[0171] The assessment parameters for the apparent condition of the casing can include parameters for assessing casing damage and parameters for assessing casing passability. The parameters for assessing casing damage can include whether the target casing section has experienced bending, rupture, or misalignment, and whether such bending, rupture, or misalignment can be repaired. The parameters for assessing casing passability can include whether the target casing section has experienced dust blockage or debris. Here, the target casing section can be the casing section above the target reservoir and the casing section 100m below it.

[0172] The parameters for assessing the remaining service capacity of the casing can include the maximum internal pressure of the casing, the maximum external pressure of the casing, the effective pressure of the casing, the critical wall thickness for safe service of the casing strength, and the remaining service life of the casing. These parameters can be calculated using formulas (4) to (10) mentioned above.

[0173] Cementing quality assessment parameters may include cement return height and interlayer sealing. The assessment methods for cement return height and interlayer sealing are described above and will not be repeated here.

[0174] The evaluation parameters for wellbore pressure stabilization and sealing capability can include wellbore pressure stabilization and sealing capability itself. The evaluation method for wellbore pressure stabilization and sealing capability is described above and will not be repeated here.

[0175] The relevant content regarding the assessment methods for pump room adaptability, casing appearance status, casing remaining service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity can be found in the previous text and will not be repeated here.

[0176] Then, based on the assessment results of the adaptability of the modified pump room, the assessment results of the current appearance of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality and the assessment results of the wellbore pressure stabilization and sealing capacity, the feasibility assessment results of geothermal modification of old wells in the oilfield were determined.

[0177] As can be seen from the preceding text, the results of the construction feasibility assessment can be expressed as follows:

[0178] B={b1,b2,b3,b4,b5} (1)

[0179] Among them, B represents the feasibility assessment result of geothermal renovation of old wells in the oilfield, which is determined by the assessment results of five basic engineering conditions; b1 represents the assessment result of the adaptability of the renovation pump room; b2 represents the assessment result of the current appearance of the casing; b3 represents the assessment result of the remaining service capacity of the casing; b4 represents the assessment result of the cementing quality; and b5 represents the assessment result of the wellbore pressure stabilization and sealing capacity.

[0180] If the evaluation result of any of the above sub-items (b1, b2, b3, b4, b5) is "not recommended", then the subsequent sub-items will not be evaluated. The overall evaluation result of the basic engineering conditions for the renovation of old oilfield wells is "not recommended", that is, based on the existing basic conditions for the renovation of old oilfield wells, it is not recommended to renovate them into geothermal wells.

[0181] Secondly, if none of the above sub-items (b1, b2, b3, b4, b5) are rated as "not recommended", then the evaluation results of each sub-item need to be scored. A sub-item is rated as "excellent" with 5 points, "medium" with 3 points, and "cautious" with 0 points. Finally, the scores of the five sub-items are added together to calculate the comprehensive score of the basic conditions for the renovation of old wells in the oilfield.

[0182] As shown in Table 1, if the total score is greater than 20 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "excellent"; if the total score is greater than 15 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "medium"; if the total score is greater than 10 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "cautious"; and if the total score is less than or equal to 10 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "not recommended".

[0183] This disclosed embodiment examines five key engineering fundamental conditions affecting geothermal retrofitting of old wells in oilfields (including pump room compatibility, current casing appearance, remaining casing service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity). The evaluation result for each condition is categorized into four levels: "Excellent," "Medium," "Cautious," and "Not Recommended," with corresponding scores. Finally, by summarizing the evaluation results of these five fundamental conditions, the feasibility assessment result for geothermal retrofitting of old wells in oilfields is obtained.

[0184] According to the technical solution of this disclosure, feasibility assessment parameters for geothermal stimulation of old oilfield wells are determined. These parameters include assessment parameters for pump room compatibility, casing appearance status, casing remaining service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity. The assessment results are determined based on the pump room compatibility parameters, casing appearance status, casing remaining service capacity, and cementing quality. The well quality assessment results, based on the assessment parameters of the wellbore pressure stabilization and sealing capacity, determine the assessment results of the wellbore pressure stabilization and sealing capacity; based on the assessment results of the adaptability of the modified pump room, the assessment results of the current status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity, the feasibility assessment results of geothermal transformation of old oilfield wells are determined. This approach effectively classifies and assesses old oilfield wells, given their large number, wide geographical distribution, and complex and diverse well conditions, allowing for early identification of engineering construction risks and the selection of suitable old oilfield wells for geothermal transformation based on their specific conditions.

[0185] Example 3

[0186] Based on the above embodiments, and based on the assessment results of the pump room adaptability, the current condition of the casing, the remaining service capacity of the casing, the cementing quality, and the wellbore pressure stabilization and sealing capacity, the feasibility assessment results for geothermal stimulation of old wells in the oilfield are determined, including:

[0187] If the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing all fail to meet the "not recommended" criteria, then the first stage score will be determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing.

[0188] If the first-stage integral equals the preset first-stage integral, then according to the preset evaluation rules, the feasibility assessment result for geothermal transformation of old wells in the oilfield will be determined as "not recommended" based on the first-stage integral.

[0189] Specifically, the preset first-stage score can be set according to the actual situation. In this embodiment, the preset first-stage score is set to 0.

[0190] This disclosure embodiment can sequentially determine the assessment results of pump room adaptability, casing appearance status, casing remaining service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity. If any of the preceding assessment results meets the "not recommended" standard, then there is no need to determine the subsequent assessment results; the feasibility assessment result for geothermal stimulation of old oilfield wells can be directly determined as "not recommended." For example, if the pump room adaptability assessment result meets the "not recommended" standard, then there is no need to determine the subsequent assessment results of casing appearance status, casing remaining service capacity, cementing quality, and wellbore pressure stabilization and sealing capacity; the feasibility assessment result for geothermal stimulation of old oilfield wells can be directly determined as "not recommended."

[0191] If the assessment results for pump room adaptability, casing appearance status, and remaining casing service capacity all fail to meet the "not recommended" criteria, the first-stage score can be determined based on these assessment results. If the first-stage score is 0, meaning the assessment results for the first three indicators are all "cautious," then even if the assessment results for the latter two indicators (i.e., cementing quality and wellbore pressure stabilization and sealing capacity) are both "excellent," the overall assessment score (i.e., the feasibility assessment result for geothermal stimulation of old oilfield wells) will still be ≤10 points, and the overall assessment result will be "not recommended." Therefore, it can be stipulated that if the first-stage score for the first three indicators is 0, then the assessment of the latter two indicators is unnecessary, and the overall assessment result will be "not recommended."

[0192] Example 4

[0193] Based on the above embodiments, the method may further include:

[0194] If the first-stage integral is greater than the preset first-stage integral, then after the old wells in the oilfield are successively modified at the wellhead, and after well cleaning, fishing or casing repair, the assessment results of cementing quality and wellbore pressure stabilization and sealing capacity are determined.

[0195] Specifically, if the first-stage score is greater than 0, the old wells in the oilfield can be subjected to wellhead rectification, well cleaning, fishing, or casing repair in sequence. Then, the assessment results of cementing quality and wellbore pressure stabilization and sealing capacity can be determined to assess the feasibility of geothermal transformation of the old wells in the oilfield.

[0196] The determination of the cementing quality assessment results and the wellbore pressure stabilization and sealing capability assessment results can be found in the previous text, and will not be repeated here.

[0197] Example 5

[0198] Based on the above embodiments, the method further includes:

[0199] If the first-stage score is greater than the preset first-stage score and the cementing quality assessment result does not meet the "not recommended" requirement, then the second-stage score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the current status of the casing, the assessment results of the remaining service capacity of the casing, and the assessment results of the cementing quality.

[0200] If the second-stage integral is less than or equal to the preset second-stage integral, then according to the preset evaluation rules, the feasibility assessment result for geothermal transformation of old wells in the oilfield will be determined as "not recommended" based on the second-stage integral.

[0201] Specifically, if the first-stage integral is greater than the preset first-stage integral, and the cementing quality assessment result is "not recommended", then the feasibility assessment result for geothermal stimulation of old wells in the oilfield will be directly determined to be "not recommended".

[0202] If the cementing quality assessment result does not meet the "not recommended" standard, that is, if the cementing quality assessment result meets the "excellent", "medium" or "cautious" standard, then the second stage score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the current appearance of the casing, the assessment results of the remaining service capacity of the casing, and the assessment results of the cementing quality.

[0203] The preset second-stage score can be set according to the actual situation. In this embodiment, the preset second-stage score is set to 5 points.

[0204] If the second-stage score is ≤5 points and the cementing quality assessment result does not meet the "not recommended" standard, then even if the assessment result of the last indicator (i.e., the assessment result of the wellbore pressure stabilization and sealing capacity) is "excellent," the overall assessment score will still be ≤10 points, and the overall assessment result will be "not recommended." Therefore, it can be stipulated that, according to the preset assessment rules shown in Table 1, the feasibility assessment result of geothermal stimulation of old wells in the oilfield will be determined as "not recommended."

[0205] Example 6

[0206] Based on the above embodiments, the method may further include:

[0207] If the second-stage integral is greater than the preset second-stage integral, the old wells in the oilfield will be sealed with cement plugs to plug the original producing layer and pressure tested in the wellbore in sequence to obtain the evaluation results of the wellbore's pressure stabilization and sealing capacity.

[0208] If the assessment results of the wellbore pressure stabilization and sealing capacity do not meet the "not recommended" criteria, then the comprehensive score shall be determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the current appearance of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity.

[0209] According to the preset evaluation rules, the feasibility evaluation results for geothermal renovation of old wells in the oilfield are determined based on the comprehensive score.

[0210] Specifically, if the score in the second stage is greater than 5 points, cement plugs are sequentially used to seal the original formation and pressure test the wellbore of the old oilfield well to obtain the evaluation results of the wellbore's pressure stabilization and sealing capabilities.

[0211] If the assessment result of the wellbore's pressure stabilization and sealing capacity is "not recommended", then the feasibility assessment result of geothermal transformation of old wells in the oilfield will be directly determined to be "not recommended".

[0212] If the assessment result of the wellbore pressure stabilization and sealing capability does not meet the "not recommended" standard, that is, the assessment result of the cementing quality meets the "excellent", "medium" or "cautious" standard, then the comprehensive score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the current appearance of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality and the assessment results of the wellbore pressure stabilization and sealing capability.

[0213] Here, the comprehensive score is the overall comprehensive score for the feasibility assessment of geothermal renovation of old wells in the oilfield. The feasibility assessment result of geothermal renovation of old wells in the oilfield can be determined based on the comprehensive score according to the preset assessment rules shown in Table 1.

[0214] If the comprehensive score is greater than 20 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "excellent"; if the comprehensive score is greater than 15 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "medium"; if the comprehensive score is greater than 10 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "cautious"; if the comprehensive score is less than or equal to 10 points, the feasibility assessment result for geothermal renovation of old wells in the oilfield is "not recommended".

[0215] Example 7

[0216] Based on the above embodiments, the method may further include:

[0217] If the assessment result of the apparent status of the casing meets the condition that "accurate assessment is not possible based on existing data", then the assessment result of the apparent status of the casing is determined after well cleaning, fishing or casing repair of old wells in the oilfield; if the assessment result of the apparent status of the casing does not meet the condition that "not recommended", then the first stage of integration is determined by the assessment results based on the adaptability of the modified pump room, the assessment results of the apparent status of the casing and the assessment results of the remaining service capacity of the casing.

[0218] If the assessment result of the remaining service capacity of the casing meets the condition that "it cannot be accurately assessed based on existing data", then the assessment result of the remaining service capacity of the casing is determined after well cleaning, fishing or casing repair, and logging of the old well in the oilfield. If the assessment result of the remaining service capacity of the casing does not meet the condition of "not recommended", then the first stage of integration is determined by the assessment results based on the adaptability of the modified pump room, the assessment results of the current appearance of the casing, and the assessment results of the remaining service capacity of the casing.

[0219] Specifically, if the assessment result of the casing's apparent condition is "unable to be accurately assessed based on existing data," then skip the following steps: Figure 1 Step 2, as shown, involves performing well cleaning, retrieval, or casing repair on old wells in the oilfield. After these procedures, the assessment result of the current appearance of the casing is determined. If the assessment result of the current appearance of the casing meets the "not recommended" standard, then the feasibility assessment result for geothermal stimulation of the old well in the oilfield is determined to be "not recommended." If the assessment result of the current appearance of the casing does not meet the "not recommended" standard, then the first stage integration step is determined based on the assessment results of the compatibility of the stimulation pump chamber, the assessment results of the current appearance of the casing, and the assessment results of the remaining service capacity of the casing.

[0220] If the assessment result of the remaining service capacity of the casing is "unable to be accurately assessed based on existing data", skip as follows: Figure 1 Step 3, as shown, involves performing well cleaning, retrieval, or casing repair on old wells in the oilfield, as well as logging. After these procedures, the remaining service capacity of the casing is assessed. If the assessment result for the remaining service capacity of the casing meets the "not recommended" standard, then the feasibility assessment result for geothermal stimulation of the old well in the oilfield is determined to be "not recommended." If the assessment result for the remaining service capacity of the casing does not meet the "not recommended" standard, then the first stage integration step is performed based on the assessment results of the compatibility with the stimulated pump chamber, the assessment results of the current appearance of the casing, and the assessment results of the remaining service capacity of the casing.

[0221] The foregoing mainly describes the solutions provided by the embodiments of this disclosure. It is understood that, in order to achieve the above functions, the electronic device includes hardware structures and / or software modules corresponding to the execution of each function. Those skilled in the art should readily recognize that, based on the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein, this disclosure can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this disclosure.

[0222] This disclosure embodiment can divide the electronic device into functional units according to the above method example. For example, each function can be divided into a separate functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this disclosure embodiment is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0223] By dividing each function into corresponding functional modules, this disclosure provides a feasibility assessment device for geothermal transformation using old oilfield wells. Figure 3 This is a schematic diagram of a construction feasibility assessment device for geothermal retrofitting using old oilfield wells, provided as an embodiment of this disclosure. Figure 3 As shown, the device 300 includes:

[0224] The determination module 301 is used to determine the feasibility assessment parameters for geothermal renovation of old wells in oilfields. The feasibility assessment parameters include the assessment parameters for the adaptability of the renovation pump room, the assessment parameters for the current appearance of the casing, the assessment parameters for the remaining service capacity of the casing, the assessment parameters for the cementing quality, and the assessment parameters for the wellbore pressure stabilization and sealing capacity.

[0225] The processing module 302 is used to determine the evaluation result of the adaptability of the modified pump room based on the evaluation parameters of the adaptability of the modified pump room, the evaluation result of the apparent status of the casing based on the evaluation parameters of the apparent status of the casing, the evaluation result of the remaining service capacity of the casing based on the evaluation parameters of the remaining service capacity of the casing, the evaluation result of the cementing quality based on the evaluation parameters of the cementing quality, and the evaluation result of the wellbore pressure stabilization and sealing capacity based on the evaluation parameters of the wellbore pressure stabilization and sealing capacity.

[0226] The processing module 302 is also used to determine the feasibility assessment results of geothermal renovation of the old well in the oilfield based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality and the assessment results of the wellbore pressure stabilization and sealing capacity.

[0227] In some embodiments, the processing module 302 is further configured to determine a first-stage integral based on the assessment results of the modified pump room adaptability, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing if the assessment results of the modified pump room adaptability, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing all do not meet the "not recommended" requirement.

[0228] If the first-stage integral equals the preset first-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield is determined to be "not recommended" based on the first-stage integral.

[0229] In some embodiments, the processing module 302 is further configured to determine the evaluation results of the cementing quality and the evaluation results of the wellbore pressure stabilization and sealing capacity after sequentially performing wellhead rectification, well cleaning, fishing, or casing repair on the old wells in the oilfield if the first stage integral is greater than the preset first stage integral and the evaluation result of the apparent status of the casing meets the "caution" requirement.

[0230] In some embodiments, the processing module 302 is further configured to determine a second stage score based on the assessment results of the modified pump room adaptability, the assessment results of the casing apparent status, the assessment results of the casing remaining service capacity, and the assessment results of the cementing quality if the first stage score is greater than the preset first stage score and the cementing quality assessment result does not meet the "not recommended" requirement.

[0231] If the second-stage integral is less than or equal to the preset second-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield will be determined as "not recommended" based on the second-stage integral.

[0232] In some embodiments, the processing module 302 is further configured to, if the second stage integral is greater than the preset second stage integral, sequentially perform cement plug sealing of the original producing layer and wellbore pressure test on the old oil well to obtain the evaluation result of the wellbore pressure stabilization and sealing capability;

[0233] If the assessment result of the wellbore pressure stabilization and sealing capability does not meet the "not recommended" requirement, then a comprehensive score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capability.

[0234] According to the preset evaluation rules, the feasibility evaluation result of geothermal renovation of the old wells in the oilfield is determined based on the comprehensive score.

[0235] In some embodiments, the processing module 302 is further configured to determine the assessment result of the apparent status of the casing after performing well cleaning, fishing, or casing repair on the old well in the oilfield if the assessment result of the apparent status of the casing meets the condition of "cannot be accurately assessed based on existing data"; if the assessment result of the apparent status of the casing does not meet the condition of "not recommended", the step of determining the first stage integral based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent status of the casing, and the assessment result of the remaining service capacity of the casing is executed.

[0236] The processing module 302 is further configured to determine the assessment result of the remaining service capacity of the casing after performing well cleaning, fishing, or casing repair and logging on the old well in the oilfield if the assessment result of the remaining service capacity of the casing meets the condition of "cannot be accurately assessed based on existing data"; if the assessment result of the remaining service capacity of the casing does not meet the condition of "not recommended", the module executes the step of determining the first stage integral based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent status of the casing and the assessment result of the remaining service capacity of the casing.

[0237] Based on the above embodiments, this embodiment provides a computer device, including a memory, a processor, and a computer program stored in the memory, wherein the processor executes the computer program to implement the steps of the method described in the above embodiments.

[0238] In some embodiments of this example, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the method described in the above embodiments.

[0239] In some embodiments of this example, a computer program product is provided, including a computer program / instructions, which, when executed by a processor, implements the steps of the method described in the above embodiments.

[0240] The processor may include, but is not limited to, one or more processors or microprocessors. Each processor may be implemented as an Application Specific Integrated Circuit (ASIC), Digital Signal Processor (DSP), Digital Signal Processing Device (DSPD), Programmable Logic Device (PLD), Field Programmable Gate Array (FPGA), controller, microcontroller, microprocessor, or other electronic component, for executing the methods in the above embodiments.

[0241] Computer-readable storage media can be implemented by any type of volatile or non-volatile storage device or a combination thereof. Computer-readable storage media may include, but are not limited to, random access memory (RAM), read-only memory (ROM), flash memory, EPROM memory, EEPROM memory, registers, and computer storage media (e.g., hard disks, floppy disks, solid-state drives, removable disks, CD-ROMs, DVD-ROMs, Blu-ray discs, etc.).

[0242] Computer-readable storage media may also store at least one computer-executable program / instruction, such as computer-readable instructions. Computer-readable storage media include, but are not limited to, volatile memory and / or non-volatile memory. Volatile memory may include, for example, random access memory (RAM) and / or cache memory. Computer-readable storage media may include, for example, read-only memory (ROM), hard disk, flash memory, etc. For example, a non-transitory computer-readable storage medium may be connected to a computing device such as a computer, and then, when the computing device executes the computer-readable instructions stored on the computer-readable storage medium, the various methods described above can be performed.

[0243] In addition, the computer device may include (but is not limited to) a data bus, an input / output (I / O) bus, a display, and input / output devices (e.g., keyboard, mouse, speakers, etc.).

[0244] The processor can communicate with external devices via the I / O bus through wired or wireless networks.

[0245] In one embodiment, the at least one computer-executable instruction may also be compiled into or comprise a software product / computer program product, wherein one or more computer-executable instructions are executed by a processor to perform the steps of the various functions and / or methods in the embodiments described herein.

[0246] In the embodiments provided in this disclosure, it should be understood that the disclosed apparatus and methods can also be implemented in other ways. The apparatus embodiments described above are merely illustrative; for example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0247] It should be noted that, in this disclosure, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element limited by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0248] While the embodiments disclosed herein are as described above, the foregoing content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art to which this disclosure pertains may make any modifications and changes in form and detail of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this disclosure shall still be determined by the scope defined in the appended claims.

Claims

1. A method for assessing the feasibility of geothermal retrofitting using old oilfield wells, characterized in that, include: The feasibility assessment parameters for geothermal stimulation of old wells in oilfields are determined. These parameters include assessment parameters for the compatibility of the stimulation pump room, assessment parameters for the current appearance of the casing, assessment parameters for the remaining service capacity of the casing, assessment parameters for cementing quality, and assessment parameters for the wellbore pressure stabilization and sealing capacity. The evaluation results of the modified pump room adaptability are determined based on the evaluation parameters of the modified pump room adaptability, the evaluation results of the casing apparent status are determined based on the evaluation parameters of the casing apparent status, the evaluation results of the casing remaining service capacity are determined based on the evaluation parameters of the casing remaining service capacity, the evaluation results of the cementing quality are determined based on the evaluation parameters of the cementing quality, and the evaluation results of the wellbore pressure stabilization and sealing capacity are determined based on the evaluation parameters of the wellbore pressure stabilization and sealing capacity. Based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity, the feasibility assessment results of geothermal modification of the old wells in the oilfield are determined.

2. The method according to claim 1, characterized in that, The assessment results based on the evaluation results of the adaptability of the modified pump chamber, the evaluation results of the apparent status of the casing, the evaluation results of the remaining service capacity of the casing, the evaluation results of the cementing quality, and the evaluation results of the wellbore pressure stabilization and sealing capacity determine the feasibility assessment results of geothermal stimulation of the old wells in the oilfield, including: If the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing all fail to meet the "not recommended" criteria, then the first stage score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, and the assessment results of the remaining service capacity of the casing. If the first-stage integral is less than or equal to the preset first-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield will be determined as "not recommended" based on the first-stage integral.

3. The method according to claim 2, characterized in that, The method further includes: If the first stage integral is greater than the preset first stage integral, then after performing wellhead rectification, well cleaning, retrieval or casing repair on the old wells in the oilfield in sequence, the evaluation results of the cementing quality and the evaluation results of the wellbore pressure stabilization and sealing capacity are determined.

4. The method according to claim 2, characterized in that, The method further includes: If the first stage score is greater than the preset first stage score and the cementing quality assessment result does not meet the "not recommended" requirement, then the second stage score is determined based on the assessment results of the modified pump room adaptability, the assessment results of the casing appearance status, the assessment results of the casing remaining service capacity, and the assessment results of the cementing quality. If the second-stage integral is less than or equal to the preset second-stage integral, then according to the preset evaluation rules, the feasibility assessment result of geothermal transformation of the old wells in the oilfield will be determined as "not recommended" based on the second-stage integral.

5. The method according to claim 4, characterized in that, The method further includes: If the second-stage integral is greater than the preset second-stage integral, then the old well in the oilfield will be sealed with cement plugs to plug the original producing layer and pressure tested in the wellbore in sequence to obtain the evaluation result of the wellbore's pressure stabilization and sealing capacity. If the assessment result of the wellbore pressure stabilization and sealing capability does not meet the "not recommended" requirement, then a comprehensive score is determined based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capability. According to the preset evaluation rules, the feasibility evaluation result of geothermal renovation of the old wells in the oilfield is determined based on the comprehensive score.

6. The method according to any one of claims 2 to 5, characterized in that, The method further includes: If the assessment result of the apparent condition of the casing meets the condition of "cannot be accurately assessed based on existing data", then after well cleaning, fishing, or casing repair of the old well in the oilfield, the assessment result of the apparent condition of the casing is determined; if the assessment result of the apparent condition of the casing does not meet the condition of "not recommended", then the step of determining the first stage integration is performed based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent condition of the casing, and the assessment result of the remaining service capacity of the casing; and / or, If the assessment result of the remaining service capacity of the casing meets the condition of "cannot be accurately assessed based on existing data", then after performing well cleaning, fishing or casing repair and logging on the old well in the oilfield, the assessment result of the remaining service capacity of the casing is determined; if the assessment result of the remaining service capacity of the casing does not meet the condition of "not recommended", then the first stage integration step is performed based on the assessment result of the adaptability of the modified pump room, the assessment result of the apparent status of the casing and the assessment result of the remaining service capacity of the casing.

7. A feasibility assessment device for geothermal retrofitting of old oilfield wells, characterized in that, include: The determination module is used to determine the feasibility assessment parameters for geothermal renovation of old wells in oilfields. The feasibility assessment parameters include the assessment parameters for the adaptability of the renovation pump room, the assessment parameters for the current appearance of the casing, the assessment parameters for the remaining service capacity of the casing, the assessment parameters for the cementing quality, and the assessment parameters for the wellbore pressure stabilization and sealing capacity. The processing module is used to determine the assessment result of the adaptability of the modified pump room based on the assessment parameters of the adaptability of the modified pump room, the assessment result of the apparent status of the casing based on the assessment parameters of the apparent status of the casing, the assessment result of the remaining service capacity of the casing based on the assessment parameters of the remaining service capacity of the casing, the assessment result of the cementing quality based on the assessment parameters of the cementing quality, and the assessment result of the wellbore pressure stabilization and sealing capacity based on the assessment parameters of the wellbore pressure stabilization and sealing capacity. The processing module is also used to determine the feasibility assessment results for geothermal stimulation of the old wells in the oilfield based on the assessment results of the adaptability of the modified pump room, the assessment results of the apparent status of the casing, the assessment results of the remaining service capacity of the casing, the assessment results of the cementing quality, and the assessment results of the wellbore pressure stabilization and sealing capacity.

8. A computer device, comprising a memory, a processor, and a computer program stored in the memory, characterized in that, The processor executes the computer program to implement the steps of the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product comprising a computer program / instructions, characterized in that, When executed by a processor, the computer program implements the steps of the method according to any one of claims 1 to 6.

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