Quantitative evaluation method for CO2 volume fracturing energizing efficiency of shale oil horizontal well

Abstract

The invention provides a shale oil horizontal well CO2 volume fracturing energization efficiency quantitative evaluation method. The shale oil horizontal well CO2 volume fracturing energization efficiency quantitative evaluation method comprises the steps that the underground liquid amount of a CO2 test well and the underground liquid amount of a comparison well are obtained; according to the reservoir geologic model where the shale oil horizontal well is located, the single-well CO2 optimal injection rate of the CO2 test well is determined; the geological model of the reservoir where the shale oil horizontal well is located is pre-constructed through reservoir section basic parameters of the CO2 test well and horizontal well production dynamic parameters; and calculating the CO2 volume fracturing energizing efficiency of the shale oil horizontal well according to the underground liquid amount of the CO2 test well, the underground liquid amount of the comparison well and the single-well CO2 injection amount of the CO2 test well. According to the mine field scale calculation method for the CO2 volume fracturing energization efficiency, quantitative evaluation of the mine field scale CO2 energization efficiency is achieved, the method is simple, feasible and high in operability, the method is also suitable for calculation of fracturing fluid imbibition volumes of other unconventional reservoirs, and reliable support is provided for improvement and optimization of the volume fracturing technology.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum and natural gas engineering, and relates to a quantitative evaluation method for CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells. Background Art

[0002] The key to the efficient development of shale oil and gas is to inject large-scale, high-displacement water-based fracturing fluid into the formation to form a complex fracture network. Under the current volume fracturing technology mode, the average single well fluid consumption is large, and the oil-seeking and fluid-discharging cycle is long, which seriously affects the oil production rate and the energy replenishment method is single, and it is difficult to stabilize production. The reservoir has not been effectively and fully utilized. In order to further improve the recovery rate, it is urgent to explore new injection media to increase production. Among them, carbon dioxide (CO2) has unique advantages such as low viscosity and easy injection, high diffusion coefficient, strong solubility, obvious energy enhancement effect, and water resource saving. It is an important direction for shale oil production. Continental shale oil usually has low pressure and strong heterogeneity. Supplementing formation energy is an important means to increase the production of a single well. Among them, energy enhancement efficiency is the core indicator for evaluating the CO2 energy enhancement effect. However, the seepage law of CO2 entering the formation is extremely complex, and it is extremely difficult to quantitatively evaluate the energy enhancement efficiency of CO2 injected into the formation. Compared with the main fracturing fluid, what is the energy enhancement efficiency of CO2? How much fracturing fluid can be replaced by CO2 to achieve the same energy enhancement effect, thereby saving water resources. At present, quantitative characterization is urgently needed on site to further optimize fracturing construction parameters and guide on-site construction. At present, domestic and foreign scholars have conducted some research on the energy enhancement effect of CO2, mainly in the following categories:

[0003] (1) Zhang Kuangsheng (Zhang Kuangsheng, Bai Xiaohu, Liu Shun, et al. Effect and parameter optimization of CO2 injection in tight oil reservoirs [J]. Science and Technology Engineering, 2020, 20(26): 10752-10758). In order to study the effect of CO2 injection in tight oil reservoirs, the influence of CO2 on the reservoir pore structure is analyzed, and the changes in crude oil volume coefficient and saturation pressure after CO2 injection are analyzed by phase calculation. The finite difference method and the three-dimensional finite element method are used to establish a three-dimensional dynamic geostress and reservoir bidirectional coupling model, analyze the change law of reservoir permeability and the pressure distribution characteristics near the bottom of the well, and evaluate the effect of CO2 injection.

[0004] (2) Liu Yincang et al. (Liu Yincang, Qiu Wei, Song Yongfang et al. A composite fracturing method for continental shale oil reservoirs, patent number: CN202110332966.5) This method first uses acid to pretreat the reservoir; liquid carbon dioxide is injected into the pretreated reservoir, and then acidic gel fluid is used to create main fractures, and slick water is used to open and expand micro-cracks and branch fracture systems. The use of pre-liquid CO2 is mainly used to increase formation energy and improve the post-fracturing return rate.

[0005] (3) Shen Yiding et al. (Shen Yiding, Qiu Liewei, Yang Xiaowu et al. A CO2-enhanced acidic clean fracturing fluid and its preparation method, patent number: CN201610320618.5). This method dissolves a water-soluble polyether nonionic surfactant, a long-chain tertiary ammonium salt cationic surfactant and potassium chloride in water to form a composite emulsion base liquid; liquid CO2 is added to the above emulsion and stirred evenly to obtain an acidic clean fracturing fluid. The CO2-enhanced fracturing fluid can not only improve the flowback capacity; but also the liquid CO2 can interact with the low-viscosity composite emulsion to form a high-viscosity gel. The acidic clean fracturing fluid and the CO2 foam fracturing fluid work together to improve the recovery efficiency.

[0006] In summary, method (1) uses numerical simulation to analyze the changes in formation pressure corresponding to different CO2 injection amounts and evaluate the energy enhancement effect. This method has a large error in establishing an ideal numerical simulation, and it only stays at the change in formation pressure. It cannot answer the specific energy enhancement multiple of CO2 compared to fracturing fluid at the mine scale, and cannot specify the field optimization design. Methods (2) and (3) apply the CO2 energy enhancement effect to shale oil volume fracturing. The CO2 mine injection amount relies on experience, and no relevant basis has been established. Therefore, it is still impossible to effectively evaluate the energy enhancement efficiency of CO2 volume fracturing at the mine scale. Summary of the invention

[0007] In view of the problems existing in the prior art, the present invention provides a method for quantitatively evaluating the CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells, thereby solving the technical problem in the prior art that it is impossible to quantitatively and effectively evaluate the CO2 volume fracturing energy enhancement efficiency at the mine scale.

[0008] The present invention is achieved through the following technical solutions:

[0009] A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells, comprising the following steps:

[0010] Obtain the amount of liquid entering the ground from the CO2 test well and the comparison well;

[0011] Determine the optimal CO2 injection rate for a single well of the CO2 test well based on the reservoir geological model of the shale oil horizontal well;

[0012] Calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well according to the amount of liquid injected into the ground of the CO2 test well, the amount of liquid injected into the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well;

[0013] The reservoir geological model where the shale oil horizontal well is located is pre-constructed based on the basic parameters of the reservoir section of the CO2 test well and the horizontal well production dynamic parameters.

[0014] Preferably, the construction of the reservoir geological model where the shale oil horizontal well is located includes the following process:

[0015] S21: Obtaining the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well;

[0016] S22: constructing an initial geological model according to the basic parameters of the reservoir section of the CO2 test well;

[0017] S23: using the initial geological model to obtain the distribution of reservoir permeability field, porosity field, oil saturation field and formation pressure field of the horizontal well;

[0018] S24: The initial geological model is simulated and corrected in combination with the reservoir permeability field, porosity field, oil saturation field, formation pressure field distribution and horizontal well production dynamic parameters to complete the establishment of the reservoir geological model where the shale oil horizontal well is located.

[0019] Preferably, the basic parameters of the reservoir section of the CO2 test well include target reservoir burial depth, target reservoir thickness, permeability, porosity, oil saturation, reservoir temperature, reservoir pressure and crude oil viscosity;

[0020] The horizontal well production dynamic parameters include the daily liquid production, daily oil production and daily water production of a single horizontal well in the first year.

[0021] Preferably, the process of simulating and correcting the initial geological model is specifically as follows:

[0022] Importing the hydraulic fracture parameters of the horizontal well into the initial geological model, fitting the daily liquid production, daily oil production and daily water production in the first year according to the actual production working system of the horizontal well, if the relative errors of the fitted daily liquid production, daily oil production and daily water production in the first year are not more than 5% compared with the daily liquid production, daily oil production and daily water production of the single horizontal well in the first year, respectively, then the established initial geological model meets the use requirements;

[0023] On the contrary, the initial geological model is corrected by adjusting the basic parameters of the reservoir section until the fitted daily liquid production, daily oil production and daily water production in the first year are compared with the daily liquid production, daily oil production and daily water production of the horizontal well in the first year, and the relative errors are no more than 5%, thereby completing the establishment of the geological model.

[0024] Preferably, the process of determining the single-well CO2 injection rate of the CO2 test well based on the reservoir geological model of the shale oil horizontal well is specifically as follows: according to the reservoir geological model of the shale oil horizontal well, the correlation between different CO2 injection rates and the area of ​​the oil-water two-phase mixed region is obtained; when the area of ​​the mixed region no longer changes with the CO2 injection rate, the single-stage CO2 optimal injection rate is obtained; based on the single-stage CO2 optimal injection rate and combined with the actual number of injection stages in the mine, the single-well optimal CO2 injection rate of the CO2 test well is determined.

[0025] Preferably, the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is calculated according to the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well and the single-well CO2 injection amount of the CO2 test well, specifically: the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are obtained, and when the relative errors of the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are no more than 5%, the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is calculated according to the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well and the single-well CO2 injection amount of the CO2 test well; specifically:

[0026]

[0027] Where: Ep is the energy efficiency, times; V T is the amount of liquid entering the ground in the comparison well, m 3 ; V O is the amount of liquid entering the ground in the CO2 test well, m 3 ; V C is the CO2 injection volume of the CO2 test well, m 3 .

[0028] Preferably, the horizontal well geological parameters include the horizontal section length of the horizontal well and the oil layer drilling rate parameter;

[0029] The horizontal well volume fracturing transformation parameters include the number of fracturing stages, the number of fracturing clusters, the amount of liquid entering the ground, the amount of sand added, the construction displacement, and the wellbore pressure in the first thirty days.

[0030] A quantitative evaluation system for CO2 volume fracturing efficiency of shale oil horizontal wells, comprising:

[0031] Parameter acquisition unit: The parameter acquisition unit is used to obtain the amount of liquid entering the ground in the CO2 test well and the comparison well;

[0032] The first data processing unit: The first data processing unit is used to determine the optimal CO2 injection rate of a single well of the CO2 test well according to the reservoir geological model of the shale oil horizontal well; the reservoir geological model of the shale oil horizontal well is pre-constructed by the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well;

[0033] Second data processing unit: The second data processing unit is used to calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well based on the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well.

[0034] A terminal device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above method when executing the computer program.

[0035] A computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0036] Compared with the prior art, the present invention has the following beneficial technical effects:

[0037] The present invention discloses a quantitative evaluation method for CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells. The method determines the optimal CO2 injection volume of a single well of a CO2 test well based on a reservoir geological model of the shale oil horizontal well. Combined with the amount of liquid entering the ground of the CO2 test well and the comparison well, the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is quantitatively obtained, and a mine-scale calculation method for the CO2 volume fracturing energy enhancement efficiency is formed, which solves the problem of quantitatively evaluating the CO2 energy enhancement efficiency at the mine-scale. The method is simple, feasible, and highly operable, and is also applicable to the calculation of the imbibition volume of fracturing fluid in other unconventional reservoirs, providing reliable support for the improvement and optimization of volume fracturing technology.

[0038] Furthermore, the reservoir geological model of the established shale oil horizontal wells was simulated and corrected using the horizontal well hydraulic fracture parameters and horizontal well production dynamic parameters, which effectively improved the accuracy of the model and the accuracy of the quantitative evaluation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 It is a schematic flow chart of a quantitative evaluation method for CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells in the present invention;

[0041] Figure 2 It is a structural schematic diagram of a quantitative evaluation system for CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells in the present invention;

[0042] Figure 3 This is a flow chart for calculating the CO2 volume fracturing efficiency of shale oil horizontal wells in Example 3 of the present invention;

[0043] Figure 4The actual daily liquid production, daily oil production, and daily water production of a shale oil horizontal well in Example 3 of the present invention;

[0044] Figure 5 This is a fitting diagram of the actual daily liquid production of a shale oil horizontal well in Example 3 of the present invention;

[0045] Figure 6 This is a fitting diagram of the actual daily oil production of a shale oil horizontal well in Example 3 of the present invention;

[0046] Figure 7 This is a fitting diagram of the actual daily water production of a shale oil horizontal well in Example 3 of the present invention;

[0047] Figure 8 This is a correlation diagram between the single-stage CO2 injection amount and the miscible area in Example 3 of the present invention;

[0048] Fig. 9 A comparison chart of geology and fracturing parameters between a shale oil test well and a comparison well in Example 3 of the present invention;

[0049] Fig.10 This is a comparison chart of the pressure of the shale oil test well and the comparison well in Example 3 of the present invention. DETAILED DESCRIPTION

[0050] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0051] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0052] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible sub-ranges and individual values ​​within the range (including integers and fractions).

[0053] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0054] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0055] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0056] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0057] Example 1

[0058] like Figure 1 As shown, the present invention provides a method for quantitatively evaluating the efficiency of CO2 volume fracturing energy enhancement in shale oil horizontal wells, comprising the following steps:

[0059] S1: Obtain the amount of liquid entering the ground from the CO2 test well and the comparison well;

[0060] S2: Determine the optimal CO2 injection rate for a single well of the CO2 test well according to the reservoir geological model of the shale oil horizontal well; the reservoir geological model of the shale oil horizontal well is pre-constructed according to the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well;

[0061] The construction of the reservoir geological model of the shale oil horizontal well includes the following processes:

[0062] S21: Obtaining the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well;

[0063] The basic parameters of the reservoir section of the CO2 test well include target reservoir burial depth, target reservoir thickness, permeability, porosity, oil saturation, reservoir temperature, reservoir pressure and crude oil viscosity;

[0064] The horizontal well production dynamic parameters include the daily liquid production, daily oil production and daily water production of a single horizontal well in the first year.

[0065] S22: constructing an initial geological model according to the basic parameters of the reservoir section of the CO2 test well;

[0066] S23: using the initial geological model to obtain the distribution of reservoir permeability field, porosity field, oil saturation field and formation pressure field of the horizontal well;

[0067] S24: The initial geological model is simulated and corrected in combination with the reservoir permeability field, porosity field, oil saturation field, formation pressure field distribution and horizontal well production dynamic parameters to complete the establishment of the reservoir geological model where the shale oil horizontal well is located.

[0068] The process of simulating and correcting the initial geological model is specifically as follows:

[0069] Importing the hydraulic fracture parameters of the horizontal well into the initial geological model, fitting the daily liquid production, daily oil production and daily water production in the first year according to the actual production working system of the horizontal well, if the relative errors of the fitted daily liquid production, daily oil production and daily water production in the first year are not more than 5% compared with the daily liquid production, daily oil production and daily water production of the single horizontal well in the first year, respectively, then the established initial geological model meets the use requirements;

[0070] On the contrary, the initial geological model is corrected by adjusting the basic parameters of the reservoir section until the fitted daily liquid production, daily oil production and daily water production in the first year are compared with the daily liquid production, daily oil production and daily water production of the horizontal well in the first year, and the relative errors are no more than 5%, thereby completing the establishment of the geological model.

[0071] Here, the relative error is calculated as follows:

[0072]

[0073] Where ω1 is the relative error between the daily liquid production, daily oil production and daily water production in the first year and the daily liquid production, daily oil production and daily water production of a single horizontal well in the first year.

[0074] In the relative error judgment process, the relative errors of daily liquid production, daily oil production and daily water production in the first year must be no more than 5% to improve the model accuracy.

[0075] In addition, the process of determining the single-well CO2 injection rate of the CO2 test well based on the reservoir geological model of the shale oil horizontal well is specifically as follows: according to the reservoir geological model of the shale oil horizontal well, the correlation between different CO2 injection rates and the area of ​​the oil-water two-phase miscible region is obtained; when the area of ​​the miscible region no longer changes with the CO2 injection rate, the single-stage CO2 optimal injection rate is obtained; based on the single-stage CO2 optimal injection rate and combined with the actual number of injection stages in the mine, the single-well CO2 optimal injection rate of the CO2 test well is determined.

[0076] S3: Calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well according to the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well.

[0077] Specifically, the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are obtained. When the relative error of the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well is not greater than 5%, the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is calculated by the amount of liquid injected into the ground of the CO2 test well, the amount of liquid injected into the ground of the comparison well, and the single-well CO2 injection amount of the CO2 test well. Specifically,

[0078]

[0079] Where: Ep is the energy efficiency, times; V T is the amount of liquid entering the ground in the comparison well, m 3 ; V O is the amount of liquid entering the ground in the CO2 test well, m 3 ; V C is the CO2 injection volume of the CO2 test well, m 3 .

[0080] Here, the larger the value of CO2 volume fracturing energy enhancement efficiency is, the better the energy enhancement effect is.

[0081] When the relative errors of the horizontal well geological parameters and the horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are greater than 5%, the comparison well is reselected so that the relative errors of the horizontal well geological parameters and the horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are no more than 5%.

[0082] Here, the relative error is calculated as follows:

[0083]

[0084] Where ω2 is the relative error between the horizontal well geological parameters of the CO2 test well and the reference well and the horizontal well volume fracturing transformation parameters.

[0085] The horizontal well geological parameters include the horizontal section length of the horizontal well and the oil layer drilling rate parameter;

[0086] The horizontal well volume fracturing transformation parameters include the number of fracturing stages, the number of fracturing clusters, the amount of liquid entering the ground, the amount of sand added, the construction displacement, and the wellbore pressure in the first thirty days.

[0087] Among them, in the relative error judgment process, the horizontal section length of the horizontal well, the oil layer drilling rate parameters, the number of fracturing stages, the number of fracturing clusters, the amount of liquid entering the ground, the amount of sand added, the construction displacement and the wellbore pressure in the first thirty days must not be greater than 5% to ensure the similarity of the reservoir geology of the two horizontal wells.

[0088] The purpose of the present invention is to provide a quantitative characterization method for the energy enhancement efficiency of CO2 volume fracturing in shale oil horizontal wells. For different types of reservoirs, the downhole rock samples of the shale oil reservoir section are first processed into standard rock samples, and the physical property parameters of the rock samples such as porosity, permeability, and oil saturation are tested, and the basic parameters such as the target reservoir and horizontal well production dynamics are obtained at the same time. Secondly, a shale oil geological model is established based on the basic parameters of the target reservoir, and a numerical simulation of the pre-CO2 energy enhancement effect is carried out to optimize the single-stage CO2 injection amount. Finally, the geological parameters, volume fracturing transformation parameters, and pressure change data of the horizontal wells on the same platform of the target reservoir shale oil are collected, and the energy enhancement efficiency is quantitatively calculated. The larger the value, the higher the energy enhancement effect, thereby achieving the purpose of characterizing the energy enhancement efficiency of CO2 volume fracturing in shale horizontal wells. The present invention proposes a quantitative characterization method for the energy enhancement efficiency of CO2 volume fracturing in shale oil horizontal wells, forming a mine-scale calculation method for the energy enhancement efficiency of CO2 volume fracturing. The core of the present invention is to solve the problem of CO2 energy enhancement efficiency at the mine scale, that is, how much fracturing fluid can be replaced by CO2 to achieve the same energy enhancement effect. The mine further optimizes the CO2 injection amount to achieve the purpose of saving water resources. Compared with the previous method of characterizing the imbibition volume of fracturing fluid by experiments or numerical simulations, which only stays at the experimental scale, the calculation method and accuracy are greatly improved. The calculation method is simple and feasible, with strong operability. It is also applicable to the calculation of the imbibition volume of fracturing fluid in other unconventional reservoirs, and provides reliable support for the improvement and optimization of volume fracturing technology.

[0089] Example 2

[0090] In addition, if Figure 2 As shown, the present invention also provides a quantitative evaluation system for CO2 volume fracturing energy enhancement efficiency of shale oil horizontal wells, comprising:

[0091] Parameter acquisition unit: The parameter acquisition unit is used to obtain the amount of liquid entering the ground in the CO2 test well and the comparison well;

[0092] The first data processing unit: The first data processing unit is used to determine the optimal CO2 injection rate of a single well of the CO2 test well according to the reservoir geological model of the shale oil horizontal well;

[0093] Second data processing unit: The second data processing unit is used to calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well based on the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well.

[0094] Example 3

[0095] like Figure 3 To further illustrate the technical solution of the present invention, the following examples are provided:

[0096] A certain test well H1 was treated with volume fracturing. The horizontal section length was 1920m, the oil layer drilling rate was 85.0%, a total of 24 fracturing sections, and a total fracturing fluid volume of 32740m 3 , describing the specific implementation process of the present invention.

[0097] This example provides a quantitative characterization method for the efficiency of CO2 volume fracturing in shale oil horizontal wells, as follows:

[0098] S1: Process the downhole rock samples of the shale oil reservoir section into standard rock samples to obtain the basic reservoir parameters and horizontal well production dynamic parameters of the shale oil reservoir section; specifically including the following contents:

[0099] S11: rock sample processing, specifically obtaining the downhole core of the reservoir where the CO2 test well H1 is located or the horizontal well in the same layer of the same block, making the rock of the reservoir section into a standard rock sample with a diameter of 2.5 cm and a length of 5 cm, and placing the standard rock sample in a 100°C oven to dry to constant weight;

[0100] S12: testing the physical property parameters of the rock sample, specifically using a porosity meter with helium as the working medium to test the porosity of the rock sample after drying in step S11; using a helium porosity automatic meter and an ultra-low permeability meter to test the porosity of the rock sample after drying in step S11 to be 6.5% and the permeability to be 0.15 mD, respectively, to provide a basis for collecting basic reservoir parameters;

[0101] In addition, the basic reservoir parameters include target reservoir burial depth, reservoir thickness, permeability, porosity, oil saturation, reservoir temperature, reservoir pressure, crude oil viscosity and other basic parameters, see Table 1.

[0102] Table 1 Basic parameters of the reservoir where the CO2 test well H1 is located

[0103]

[0104]

[0105] The dynamic production parameters of horizontal wells include basic parameters such as the actual daily liquid production, actual daily oil production, and actual daily water production of a single horizontal well in the first year.

[0106] S2: Establish a shale oil geological model based on basic reservoir parameters and horizontal well production dynamic parameters, conduct numerical simulation of CO2 energy enhancement effect, and optimize the single-stage CO2 injection volume; specifically include the following contents:

[0107] S21: Establishment of geological model, specifically, based on the basic reservoir parameters, using the reservoir numerical simulation software Eclipse to establish the reservoir geological model of the horizontal well, and obtain the distribution of the reservoir permeability field, porosity field, oil saturation field, formation pressure field, etc.

[0108] S22: Correction of geological model, specifically, importing the hydraulic fracture parameters of the horizontal well into the geological model of step S21, combining the actual production data of the horizontal well, fitting the first year's daily liquid production, daily oil production, daily water production and other indicators according to the actual production work system of the horizontal well, see Figures 4 to 7 The relative errors are all less than 5%, which verifies the correctness of the model, effectively improves the model accuracy, and further carries out numerical simulation of the pre-CO2 energy enhancement effect.

[0109] S23: Optimization of single-stage CO2 injection rate. Specifically, based on the correction of the reservoir geological model where the horizontal well is located, numerical simulation of the energy enhancement effect of different CO2 injection rates is carried out, and the correlation between different CO2 injection rates and the area of ​​the oil-water two-phase miscible region is obtained according to the geological model. Figure 8 When the area of ​​the miscible region does not change with the CO2 injection rate, the energy enhancement effect is the best, and the optimal CO2 injection rate for a single stage is determined.

[0110] S3: Collect the geological parameters of horizontal wells in the shale oil reservoir section, the volume fracturing transformation parameters and the pressure change data during the well blocking stage, and quantitatively calculate the energy enhancement efficiency, including the following contents:

[0111] Among them, the horizontal well geological parameters include the horizontal section length and oil layer drilling rate parameters of the CO2 test well and the comparison well on the same platform. The relative error of the geological parameters of the CO2 test well and the comparison well is required to be less than 5% to ensure the geological similarity of the reservoirs where the two horizontal wells are located. Fig. 9 .

[0112] The parameters of horizontal well volume fracturing reconstruction include the number of fracturing stages, number of fracturing clusters, amount of fluid injected into the ground, amount of sand added, and construction displacement (such as Fig. 9 ) and other parameters, and collected the wellbore pressure data for the first thirty days (such as Fig.10 As shown in the figure, the relative error between the CO2 test well and the comparison well parameters is required to be less than 5% to ensure the similarity of the horizontal well reservoir transformation parameters of the two wells;

[0113] Energy enhancement efficiency calculation, specifically, under the condition that the horizontal well geological parameters and reservoir transformation parameters are similar, the CO2 injection volume of the single well of the test well is calculated according to step S2. The test well preferably has ten sections of pre-injection of CO2, and the total volume of the single well V C 3000m 3 , the amount of liquid entering the test well in step S3 is V O 24300m 3 Compared with the same platform, the amount of liquid entering the well V T 35682m 3 , using the following formula to calculate the energy enhancement efficiency of the test well is 3.8 times.

[0114]

[0115] Where: Ep is the energy efficiency, times; V T is the amount of liquid entering the ground in the comparison well, m 3 ; V O is the amount of liquid entering the ground in the CO2 test well, m 3 ; V C is the CO2 injection volume of the CO2 test well, m 3 .

[0116] A schematic diagram of a terminal device provided in an embodiment of the present invention. The terminal device of this embodiment includes: a processor, a memory, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps in the above-mentioned method embodiments are implemented. Alternatively, when the processor executes the computer program, the functions of the modules / units in the above-mentioned device embodiments are implemented.

[0117] The computer program may be divided into one or more modules / units, and the one or more modules / units are stored in the memory and executed by the processor to accomplish the present invention.

[0118] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0119] The processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.

[0120] The memory may be used to store the computer programs and / or modules, and the processor implements various functions of the terminal device by running or executing the computer programs and / or modules stored in the memory and calling the data stored in the memory.

[0121] If the module / unit integrated in the terminal device is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electric carrier signal, telecommunication signal and software distribution medium. It should be noted that the content contained in the computer-readable medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable media do not include electric carrier signals and telecommunication signals.

[0122] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells, characterized in that: The following steps are involved: Obtain the amount of liquid entering the ground from the CO2 test well and the comparison well; Determine the optimal CO2 injection rate for a single well of the CO2 test well based on the reservoir geological model of the shale oil horizontal well; Calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well according to the amount of liquid injected into the ground of the CO2 test well, the amount of liquid injected into the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well; The reservoir geological model where the shale oil horizontal well is located is pre-constructed based on the basic parameters of the reservoir section of the CO2 test well and the horizontal well production dynamic parameters.

2. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells according to claim 1, characterized in that: The construction of the reservoir geological model of the shale oil horizontal well includes the following processes: S21: Obtaining the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well; S22: constructing an initial geological model according to the basic parameters of the reservoir section of the CO2 test well; S23: using the initial geological model to obtain the distribution of reservoir permeability field, porosity field, oil saturation field and formation pressure field of the horizontal well; S24: The initial geological model is simulated and corrected in combination with the reservoir permeability field, porosity field, oil saturation field, formation pressure field distribution and horizontal well production dynamic parameters to complete the establishment of the reservoir geological model where the shale oil horizontal well is located.

3. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells according to claim 2, characterized in that: The basic parameters of the reservoir section of the CO2 test well include target reservoir burial depth, target reservoir thickness, permeability, porosity, oil saturation, reservoir temperature, reservoir pressure and crude oil viscosity; The horizontal well production dynamic parameters include the daily liquid production, daily oil production and daily water production of a single horizontal well in the first year.

4. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells according to claim 2, characterized in that: The process of simulating and correcting the initial geological model is specifically as follows: Importing the hydraulic fracture parameters of the horizontal well into the initial geological model, fitting the daily liquid production, daily oil production and daily water production in the first year according to the actual production working system of the horizontal well, if the relative errors of the fitted daily liquid production, daily oil production and daily water production in the first year are not more than 5% compared with the daily liquid production, daily oil production and daily water production of the single horizontal well in the first year, respectively, then the established initial geological model meets the use requirements; On the contrary, the initial geological model is corrected by adjusting the basic parameters of the reservoir section until the fitted daily liquid production, daily oil production and daily water production in the first year are compared with the daily liquid production, daily oil production and daily water production of the horizontal well in the first year, and the relative errors are no more than 5%, thereby completing the establishment of the geological model.

5. The method for quantitatively evaluating the efficiency of CO2 volume fracturing in shale oil horizontal wells according to claim 1, characterized in that: The process of determining the single-well CO2 injection rate of the CO2 test well according to the reservoir geological model of the shale oil horizontal well is specifically as follows: according to the reservoir geological model of the shale oil horizontal well, the correlation between different CO2 injection rates and the area of ​​the oil-water two-phase miscible region is obtained; when the area of ​​the miscible region no longer changes with the CO2 injection rate, the single-stage CO2 optimal injection rate is obtained; based on the single-stage CO2 optimal injection rate and combined with the actual number of injection stages in the mine, the single-well CO2 optimal injection rate of the CO2 test well is determined.

6. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells according to claim 1, characterized in that: The CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is calculated according to the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well, specifically: obtaining the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well, when the relative errors of the horizontal well geological parameters and horizontal well volume fracturing transformation parameters of the CO2 test well and the comparison well are no more than 5%, the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well is calculated according to the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well; specifically: Where: Ep is the energy efficiency, times; V T is the amount of liquid entering the ground in the comparison well, m 3 ; V O is the amount of liquid entering the ground in the CO2 test well, m 3 ; V C is the CO2 injection volume of the CO2 test well, m 3 .

7. A quantitative evaluation method for CO2 volume fracturing efficiency of shale oil horizontal wells according to claim 6, characterized in that: The horizontal well geological parameters include the horizontal section length of the horizontal well and the oil layer drilling rate parameter; The horizontal well volume fracturing transformation parameters include the number of fracturing stages, the number of fracturing clusters, the amount of liquid entering the ground, the amount of sand added, the construction displacement, and the wellbore pressure in the first thirty days.

8. A quantitative evaluation system for CO2 volume fracturing efficiency of shale oil horizontal wells, characterized in that: include: Parameter acquisition unit: The parameter acquisition unit is used to obtain the amount of liquid entering the ground in the CO2 test well and the comparison well; The first data processing unit: The first data processing unit is used to determine the optimal CO2 injection rate of a single well of the CO2 test well according to the reservoir geological model of the shale oil horizontal well; the reservoir geological model of the shale oil horizontal well is pre-constructed by the basic parameters of the reservoir section of the CO2 test well and the production dynamic parameters of the horizontal well; Second data processing unit: The second data processing unit is used to calculate the CO2 volume fracturing energy enhancement efficiency of the shale oil horizontal well based on the amount of liquid entering the ground of the CO2 test well, the amount of liquid entering the ground of the comparison well, and the single-well CO2 injection volume of the CO2 test well.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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