Fractured horizontal well crack water exploration numerical simulation method

Abstract

The invention discloses a fractured horizontal well crack water exploration numerical simulation method. The method comprises the steps that a crack and a water injection well corresponding to a target fractured horizontal well are determined; establishing an oil reservoir geologic model corresponding to the target fractured horizontal well on-site scale, and distinguishing formation water components and injection water components of the water injection well in the oil reservoir geologic model by giving different definitions; based on the different definitions, a historical fitting result is simulated through numerical values, and a source water injection well and a source crack of production water of the target fractured horizontal well are determined; the problem that effective water plugging measures cannot be specifically formulated due to the fact that the existing horizontal well numerical simulation water exploration technology cannot comprehensively and accurately recognize the water outlet crack condition is effectively solved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of water plugging in oilfield development, and particularly to a numerical simulation method for finding water in fractures of fractured horizontal wells. Background Art

[0002] The statements in this section only provide background information related to the present disclosure and do not constitute prior art.

[0003] Horizontal well fracturing technology is a new type of oil and gas production technology developed in the United States in the late 1980s. It is mainly applied to the exploitation of unconventional oil and gas resources such as shale gas, coalbed methane, and tight oil and gas, and can also be used for the stimulation and transformation of conventional oil and gas resources. It has been widely applied and developed in countries and regions such as the United States, Canada, and China, and is an advanced technology in the current oil and gas production field. Horizontal well fracturing technology can effectively transform reservoirs with low permeability, ultra-low permeability, or natural fractures, improving the recoverable degree of oil and gas; it can reduce the number of surface wells, lower drilling costs and environmental impacts; it can increase the single-well production and cumulative production, and extend the production life of oil and gas wells; it can utilize various staged fracturing technologies to achieve refined management and optimized design of the horizontal well section.

[0004] However, if necessary reservoir management is not carried out after production, the production performance and stability of oil and gas wells will be affected. For example, when the fracturing fractures interact and connect with the injected water, problems such as rapid water cut increase and large production decline often occur after production, and the development effect is affected. Therefore, it is necessary to develop horizontal well water finding technology.

[0005] Horizontal well water finding technology refers to the technology of using different methods and tools for testing and analysis during the production process of horizontal wells to determine the location and degree of the water-producing intervals. Horizontal well water finding technology mainly includes dynamic verification water finding method technology, mechanical water finding technology, isotope labeling water finding technology, crawler conveying method for measuring the liquid production profile of horizontal wells, intelligent staged water finding technology, and numerical simulation technology, etc.

[0006] However, among the current water finding technologies, the disadvantage of the dynamic verification water finding method technology is the long test cycle. The disadvantage of the mechanical water finding technology is that it cannot carry out staged production and cannot perform reservoir transformation measures such as fracturing, and there are risks of wellbore collapse and sand production. The disadvantage of the isotope labeling water finding technology is that radioactive isotopes need to be prepared and used. Although the impact on personnel and the environment is very small, safety and protection measures still need to be noted. The disadvantage of the crawler conveying method for measuring the liquid production profile of horizontal wells is the complex on-site construction process and high cost. The crawler has high requirements for the wellbore, is prone to downhole jamming, and the measured data cannot fully reflect the normal production state. The disadvantage of the intelligent staged water finding technology is that it requires the use of intelligent water finding pipe strings, with high costs, and there may be situations of pipe string failure or malfunction.

[0007] The existing numerical simulation technology for finding water in fractures of hydraulically fractured horizontal wells is too simplistic. Regarding the technology for identifying the location of water coming out of fractures, after numerical simulation history fitting, the location of water-producing fractures is determined only by the water saturation distribution of each layer. It is not clear which direction the water produced by the horizontal well comes from, and it is also unclear what proportion of water output from each well entering the fracture of the horizontal well.

[0008] Therefore, due to the long cycle, high cost, proneness to accidents and safety risks, inaccurate test data and other problems of current water-finding technical means, it is urgent to propose a new water-finding method that combines geological, reservoir and engineering conditions to comprehensively and accurately identify water-producing cracks in order to formulate effective water-blocking measures.

[0009] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may contain information that does not constitute prior art. Summary of the invention

[0010] In view of this, the present invention provides a numerical simulation method for finding water in fractures of fractured horizontal wells to solve the problem that the existing horizontal well numerical simulation water finding technology cannot comprehensively and accurately identify the water fracture conditions, and thus cannot formulate effective water blocking measures in a targeted manner.

[0011] In order to achieve the above-mentioned object of the invention, the numerical simulation method for finding water in fractures of a hydraulically fractured horizontal well is characterized by comprising:

[0012] Determine the fractures and water injection wells corresponding to the target fracturing horizontal well;

[0013] Establishing a reservoir geological model corresponding to the field scale of the target fracturing horizontal well, and distinguishing the formation water components and the injection water components of the water injection well in the reservoir geological model by giving different definitions;

[0014] Based on the different definitions, the source injection wells and source fractures of the water produced by the target fractured horizontal well are determined using the historical matching results of numerical simulation.

[0015] In the present disclosure and possible embodiments, the different definitions include:

[0016] Different numbers are respectively assigned to the formation water components and the injected water components of each of the injection wells.

[0017] In the present disclosure and possible embodiments, the method for establishing a reservoir geological model corresponding to the field scale of the target fractured horizontal well includes:

[0018] Determine the simulation area;

[0019] The determined method includes taking the target fractured horizontal well and the surrounding oil and water wells as the center, and expanding outward by the scale of an injection-production well spacing as the simulation area.

[0020] In the present disclosure and possible embodiments, the method for establishing the reservoir geological model further includes:

[0021] Determine the simulation layer;

[0022] The determined method includes, according to the subdivision situation of each well layer level of the oil and water wells, and according to the layer subordination relationship, determining the smallest common sedimentary unit between wells as the simulation layer.

[0023] In the present disclosure and possible embodiments, the method for establishing the reservoir geological model further includes:

[0024] Initialize the oil saturation, water saturation, and gas saturation;

[0025] Use the saturation obtained from drilling cores for the initialization, and the sum of the oil saturation, the water saturation, and the gas saturation is equal to 1.

[0026] In the present disclosure and possible embodiments, the method for establishing the reservoir geological model further includes:

[0027] Establish the reservoir geological model using CMG software according to the well point layer data and reservoir data.

[0028] In the present disclosure and possible embodiments, the well point layer data includes:

[0029] The top depth of the layer sandstone, the thickness of the layer sandstone, the effective thickness, porosity, permeability, oil saturation, and perforation time.

[0030] In the present disclosure and possible embodiments, the reservoir data includes:

[0031] PVT data, relative permeability data, oil viscosity, original oil-gas ratio, and rock compressibility.

[0032] In the present disclosure and possible embodiments, the method for numerical simulation history matching includes:

[0033] Adopt the method of fixing the liquid production of the oil well and the injection volume of the injection well to perform the history matching on the daily oil production and water cut of the oil well, and perform the history matching on the injection pressure of the injection well until the history matching reaches the set compliance rate.

[0034] In the present disclosure and possible embodiments, the set compliance rate reaches more than 95%.

[0035] In the present disclosure and possible embodiments, the history matching is performed by adjusting the permeability, relative permeability curve, formation coefficient, and skin factor.

[0036] In the present disclosure and possible embodiments, the method for determining the source injection well and the source fracture includes:

[0037] The numerical simulation history matching results include the formation water content in the produced water and / or the injection water content of each injection well;

[0038] Determine the source injection well using the formation water content and / or the injection water content of the injection well, and determine the source fracture through the source injection well.

[0039] The present disclosure has the following beneficial effects:

[0040] The numerical simulation method for finding water in fractures of a fractured horizontal well in the present disclosure, by giving different definitions (numbers) to the formation water components and the injection water components of the injection well respectively, is used to distinguish the composition of the produced water entering the fractured horizontal well. The components of this composition are formation water and / or the injection water of which injection well or which several injection wells, and how much is the entry amount of each component in the composition. Thus, according to the entering components and component amounts, it is possible to judge the injection well source of the main water components of the produced water of this fractured horizontal well, as well as the fracture source affected by the main water components, that is, through the "multiple types of water component definition technology" proposed by the method of the present disclosure, it is possible to clearly judge the water output ratio and water inflow direction of each injection well entering the fractures of this fractured horizontal well, so that the water-producing fracture situation can be quickly, safely, comprehensively, and accurately identified. Further, according to the judgment result, it is possible to guide the subsequent water shutoff operation and provide technical guarantee for formulating effective water shutoff measures. Description of the Drawings

[0041] Through the following description of the embodiments of the present disclosure with reference to the drawings, the above and other objects, features, and advantages of the present disclosure are clearer. In the drawings:

[0042] Figure 1 is the flowchart of the numerical simulation method for finding water in fractures of a fractured horizontal well in an embodiment of the present disclosure;

[0043] Figure 2 is the distribution diagram of water component H20_1 in the No. 1 oil layer in an embodiment of the present disclosure;

[0044] Figure 3 is the distribution diagram of water component H20_4 in the No. 2 oil layer in an embodiment of the present disclosure;

[0045] Figure 4 is the distribution diagram of water component H20_4 in the No. 3 oil layer in an embodiment of the present disclosure. Detailed Embodiments

[0046] The present disclosure will be described based on embodiments. However, it should be noted that the present disclosure is not limited to these embodiments. In the following detailed description of the present disclosure, some specific details are described in detail. However, those skilled in the art can also fully understand the present disclosure for the parts not described in detail.

[0047] In addition, those of ordinary skill in the art should understand that the provided drawings are only for illustrating the purposes, features, and advantages of the present disclosure, and the drawings are not actually drawn to scale. At the same time, unless the context clearly requires otherwise, the words such as "including", "comprising", etc. throughout the specification and claims should be interpreted as having the meaning of including rather than exclusive or exhaustive; that is, the meaning of "including but not limited to".

[0048] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the following further describes the present invention in detail according to the drawings and by way of examples.

[0049] Specifically, taking a certain fractured horizontal well FRC-1 as an example, the numerical simulation method for finding water in fractures of the fractured horizontal well of the present disclosure will be described in detail. Figure 1 is the flowchart of the numerical simulation method for finding water in fractures of the fractured horizontal well in the embodiment of the present disclosure; as Figure 1 shown, the method includes the following steps:

[0050] Step S10: Determine the fractures and injection wells corresponding to the target fractured horizontal well; specifically as follows:

[0051] According to the data obtained on-site in the target area, determine the basic situation of the target fractured horizontal well; the basic situation includes:

[0052] 1. The number of oil layers penetrated and perforated by the high-water-cut target fractured horizontal well determined to have a dominant water flow channel;

[0053] 2. The number of fractures of the target fractured horizontal well, and number the artificial fractures in sequence from the root to the toe of the horizontal layer section of the horizontal well according to the number of fractures;

[0054] 3. The distribution and number of oil and water wells (oil wells and injection wells) around the target fractured horizontal well, and record the number of injection wells among them.

[0055] Further, in this embodiment, the fractured horizontal well FRC-1 is a high-water-cut fractured horizontal well with a dominant water flow channel. The fractured horizontal well FRC-1 penetrates and perforates 5 oil layers (PI2, PI41, PI42, PI51, and PI52); The FRC-1 well has 7 perforation sections and is all fractured. From the root to the toe direction, the artificial fracture numbers are successively ①, ②, ③, ④,

[0056] ⑤, ⑥, and ⑦; There are 4 injection wells (INJ-1, INJ-2, INJ-3, INJ-4) and 2 production wells (PRO-1 and PRO-2) distributed around Well FRC-1.

[0057] Step S20: Establish a reservoir geological model and give different definitions to the formation water components and the injected water components of the injection wells; specifically as follows:

[0058] 1. Establish a reservoir geological model at the field scale corresponding to the target fractured horizontal well, and select the simulation horizons for numerical simulation. The selection method is as follows:

[0059] (1) Determine the simulation area. The selected simulation area must include the water exploration well group. To reduce the influence of the boundary on the injection-production balance of the target water exploration well group, the simulation area should be expanded by one injection-production well spacing on the basis of the target water exploration well group.

[0060] (2) Determine the simulation horizons. Specifically, according to the subdivision of each well's small horizons and the subordinate relationship of the small horizons, determine the smallest common sedimentary unit between wells as the simulation horizon, and number them in order from top to bottom.

[0061] (3) Initialize the oil, water, and gas saturations. When dealing with saturations, use the saturations obtained from drilling cores. Oil saturation + water saturation + gas saturation = 1.

[0062] (4) Finally, establish a CMG software reservoir geological model based on the well point small horizon data, including data such as the top depth of the small horizon sandstone, the thickness of the small horizon sandstone, effective thickness, porosity, permeability, oil saturation, and perforation time.

[0063] Furthermore, in this embodiment, to reduce the influence of the boundary on the injection-production balance of the water exploration well group, the simulation area should be expanded by one injection-production well spacing on the basis of the water exploration well group, and establish an actual field geological model with a size of 800 m × 1050 m (X - Y), covering the horizontal well and other production wells and injection wells.

[0064] According to the corresponding relationship between the oil and water layers of the oil and water wells, their respective perforation conditions and fracturing conditions are shown in Table 1:

[0065] Table 1 Perforated horizons and fracturing conditions of the well group

[0066] Pound sign Well type Perforated interval Fracturing situation FRC-1 Horizontal well PI2, PI41, PI42, PI51, PI52 Fracturing PRO-1 Oil well PI2, PI41, PI42, PI52 Fracturing PRO-2 Oil well PI2, PI41, PI42, PI51, PI52 / INJ-1 Water injection well PI2, PI41, PI42, PI51 / INJ-2 Water injection well PI2, PI41 Fracturing INJ-3 Water injection well PI2, PI41, PI51 / INJ-4 Water injection well PI2, PI41, PI42, PI51, PI52 Fracturing

[0067] Combined with Table 1, select PI2, PI41, PI42, PI51, and PI52 as the simulation horizons. The simulation horizons are numbered in sequence as 1, 2, 3, 4, and 5, that is, divided into the 1st oil layer (PI2), the 2nd oil layer (PI41), the 3rd oil layer (PI42), the 4th oil layer (PI51), and the 5th oil layer (PI52).

[0068] Statistically analyze the data of each small layer of the well points, including the top depth of the small layer sandstone, the thickness of the small layer sandstone, effective thickness, porosity, permeability, oil saturation, perforation time, etc.; statistically analyze the reservoir data, including PVT data, relative permeability data, oil viscosity, original oil-gas ratio, rock compressibility, etc.; import the above data into the reservoir geological model of the CMG software according to the set requirements and formats in this field.

[0069] 2. In the reservoir geological model, distinguish the formation water components and the injected water components of the injection wells by giving different definitions; specifically as follows:

[0070] In the reservoir geological model, according to the number of injection wells determined in Step 1, define the number of different types of water components other than the formation water components, that is, define the injected water qualities of different injection wells as different components, and distinguish them from the formation water. Each injection well is separately defined with a water component. Preferably, the definition method is to give numbers respectively, that is, different numbers are assigned to the formation water and the injected water of each injection well for distinction.

[0071] Furthermore, in this embodiment, the injected water qualities of different injection wells are defined as different components and distinguished from the formation water. In this example, the water component definition (number) of the formation water is H20, and the water component names of the injected water of the other 4 injection wells are defined (numbered) as follows:

[0072] The injected water component definition (number) of injection well INJ-1 is H20_1;

[0073] The injected water component definition (number) of injection well INJ-2 is H20_2;

[0074] The injected water component definition (number) of injection well INJ-3 is H20_3;

[0075] The injected water component definition (number) of injection well INJ-4 is H20_4.

[0076] Step S30: Use the numerical simulation history matching results to determine the source injection well and the source fracture of the production water of the target fractured horizontal well; specifically as follows:

[0077] 1. According to the production history information, conduct numerical simulation history matching, specifically as follows:

[0078] Determine the matching index according to the collection status of the production history data and the target accuracy requirements of the project research.

[0079] The matching index is mainly based on the production rate and injection pressure indicators. The production rate matching index is mainly the daily water production and daily oil production fitting the fixed production liquid volume, and the injection pressure matching index is mainly the injection pressure curve fitting the fixed injection volume.

[0080] The above fitting indexes are consistent with the changing trend of the actual production curve data, and the average error of the data points is less than ±5%.

[0081] Furthermore, in this embodiment, the production and injection dynamic data of horizontal wells and other oil and water wells are statistically analyzed. Historical fitting is carried out by adjusting main parameters such as permeability, relative permeability curve, formation factor, skin factor, etc. The fitting process mainly involves setting the liquid production of oil wells and the injection volume of water wells. Historical fitting is performed on the daily oil production and water cut of oil wells, and the injection pressure of water wells is fitted. The fitting results show that the fitting of daily oil production, water cut and injection pressure is good, and the coincidence rate reaches more than 95%.

[0082] 2. According to the historical fitting results, determine the water injection well and the source fracture of the production water of the target fractured horizontal well; the specific determination method is as follows:

[0083] After completing the historical fitting that meets the error accuracy, the distribution of different water components and the proportion of the production of various water components in the production water of the fractured horizontal well in the total water production are obtained. Determine which water injection well the main water components come from, that is, trace back to the source of the water injection well, and the position (number) of the fracture affected by the main water components, that is, trace back to the specific fracture source. Then, based on the source of the water injection well and the fracture source, clearly judge the proportion of the water production volume and the water inflow direction of each water injection well entering the fracture of the fractured horizontal well, so as to comprehensively and accurately identify the water-producing fracture situation. Then, according to the above judgment results, guide the subsequent water shutoff and plugging, and provide technical support for formulating effective water shutoff measures.

[0084] Furthermore, in this embodiment, after historical fitting, the proportion of the production of different water components in the total water production and the distribution of different water components are obtained, as specifically shown in Table 2 and Figure 2 - 4 as follows:

[0085] Table 2 Results of the source and water production proportion of different water components in the produced water of Well FRC-1

[0086] Source Water component name <![CDATA[Daily water production (m 3 / d)]]> Water production ratio (%) Formation water <![CDATA[H20]]> 2.158 19.09 INJ-1 <![CDATA[H20_1]]> 2.333 20.64 INJ-2 <![CDATA[H20_2]]> 0 0.00 INJ-3 <![CDATA[H20_3]]> 0.316 2.79 INJ-4 <![CDATA[H20_4]]> 6.499 57.48

[0087] The daily water production of different water components in the produced water of Well FRC-1 is statistically analyzed, and the proportion of the water production of each component is calculated. From the analysis results in Table 2, it can be seen that among the water components of the produced water of Well FRC-1, the production of H20_4 is the largest, followed by H20_1 and H20 components. Therefore, the produced water of Well FRC-1 mainly comes from water injection well INJ-4, water injection well INJ-1 and formation water, and water injection well INJ-4 has the highest proportion.

[0088] From the water component distribution map ( Figure 2 - Figure 4)It can be seen that the main channeling fractures of injection well INJ-4 are the ②, ③, and ④ fractures in the No. 2 and No. 3 oil layers, and the main channeling fracture of injection well INJ-1 is the ⑦ fracture in the No. 1 oil layer.

[0089] According to the above judgment results, the plugging measures formulated are as follows: plug the ⑦ fracture in the No. 1 oil layer; plug the ②, ③, and ④ fractures in the No. 2 oil layer; plug the ②, ③, and ④ fractures in the No. 3 oil layer.

[0090] It can be seen from the description of this embodiment that the method of the present disclosure combines geological, reservoir, and engineering conditions. On the basis of establishing a geological model and history matching, a new numerical simulation method is adopted to comprehensively and accurately identify the water-producing positions of fractures. Compared with the existing technical achievements, the numerical simulation method for finding water in fractures of a fractured horizontal well in the present disclosure proposes a "multi-type water component definition technology", defines the injection water quality of different injection wells as different components, distinguishes them from formation water, defines a water component for each injection well, and differentiates them with numbers. After history matching, the distribution of different water components, as well as the proportion of the production of various water components in the produced water of the horizontal well to the total water production, are obtained, the production well of the main water component is determined, and the fracture positions affected by the production of the main water component are determined, clearly judging the proportion of the water production from each injection well entering the fractures of the fractured horizontal well and the water inflow direction, achieving the purpose of comprehensively and accurately identifying the water-producing fracture conditions. Moreover, this method has a short cycle, low cost, no potential safety hazards, and accurate and reliable data.

[0091] The above-described embodiments are only used to illustrate the implementation manners of the present disclosure, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present disclosure. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present disclosure, several deformations, equivalent replacements, improvements, etc. can be made, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the patent of the present disclosure shall be subject to the appended claims.

Claims

1. A numerical simulation method for finding water in fractures of a fractured horizontal well, characterized in that, Including: Determine the fractures and injection wells corresponding to the target fractured horizontal well; Establish a reservoir geological model at the field scale corresponding to the target fractured horizontal well, and distinguish the formation water components and the injection water components of the injection wells in the reservoir geological model by giving different definitions; Based on the different definitions, use the numerical simulation history matching results to determine the source injection well and the source fracture of the production water of the target fractured horizontal well.

2. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 1, characterized in that: The ways of the different definitions include: Assign different numbers to the formation water components and the injection water components of each injection well; and / or, The method for establishing a reservoir geological model at the field scale corresponding to the target fractured horizontal well includes: Determine the simulation area; The determining method includes taking the target fractured horizontal well and the oil and water wells around it as the center, and expanding outward by a scale of an injection-production well spacing as the simulation area.

3. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 2, characterized in that The method for establishing the reservoir geological model further includes: Determine the simulation layer; The determining method includes, according to the subdivision situation of each well layer level of the oil and water wells, and according to the layer membership relationship, determining the smallest sedimentary unit common between wells as the simulation layer.

4. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 3, characterized in that The method for establishing the reservoir geological model further includes: Initialize the oil saturation, water saturation and gas saturation; Use the saturation obtained from drilling cores for the initialization, and the sum of the oil saturation, the water saturation and the gas saturation is equal to 1.

5. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 4, characterized in that, The method for establishing the reservoir geological model further includes: Establish the reservoir geological model using CMG software according to the well point layer data and reservoir data.

6. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 5, wherein The well point layer data includes: Top depth of the sandstone of the layer, thickness of the sandstone of the layer, effective thickness, porosity, permeability, oil saturation and perforation time.

7. The numerical simulation method for water finding in fractures of a fractured horizontal well according to claim 5, wherein The reservoir data includes: PVT data, relative permeability data, oil viscosity, original oil-gas ratio and rock compressibility.

8. The numerical simulation method for water finding in fractures of a fractured horizontal well according to any one of claims 1-7, characterized in that, The method for numerical simulation history matching includes: Adopt the method of fixing the liquid production of the oil well and the injection volume of the injection well, perform the history matching on the daily oil production and water cut of the oil well, and perform the history matching on the injection pressure of the injection well until the history matching reaches the set compliance rate.

9. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 8, characterized in that: The set compliance rate reaches more than 95%; and / or, Perform the history matching by adjusting the permeability, relative permeability curve, formation coefficient and skin factor.

10. The numerical simulation method for finding water in fractures of a fractured horizontal well according to claim 9, wherein, The method for determining the source injection well and the source fracture includes: The numerical simulation history matching results include the formation water content and / or the injection water content of each injection well in the production water; Use the formation water content and / or the injection water content of the injection well to determine the source injection well, and determine the source fracture through the source injection well.

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