Fracturing construction displacement design method considering stress shadow effect

Abstract

The invention belongs to the field of oil and gas field development, and particularly relates to a fracturing construction displacement design method considering a stress shadow effect. The problem of how to effectively avoid the adverse effect of the stress shadow effect on hydraulic fracturing when the multi-cluster perforation fracturing technology is used in the unconventional oil and gas reservoir development process is solved. According to the technical scheme, a geologic model and a natural fracture distribution model are established according to reservoir parameters and engineering parameters of a research block, different fracturing construction displacements are set through Kinetix fracturing production software, the hydraulic fracturing process is simulated, the stress shadow volume after hydraulic fracturing is calculated through a three-dimensional fracturing numerical simulator, and the reservoir parameters and the engineering parameters of the research block are calculated. And drawing a relation curve of the fracturing construction displacement and the stress shadow volume, wherein the fracturing construction displacement corresponding to the maximum stress shadow volume is the optimal fracturing construction displacement. The method has the advantages that the actual application effect is good, the generalizability is high, the adverse effect of the stress shadow effect on hydraulic fracturing is effectively avoided, and technical support is provided for development and production of unconventional oil and gas reservoirs.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas field development, and particularly relates to a fracturing construction displacement design method taking stress shadow effect into consideration. Background Art

[0002] At present, the development of unconventional oil and gas reservoirs often requires the deployment of horizontal wells and large-scale hydraulic fracturing to form a complex hydraulic fracture network, so as to achieve the purpose of improving reservoir permeability and increasing oil and gas recovery. In this process, the expansion morphology of hydraulic fractures is an important factor affecting the effect of reservoir transformation. At present, the most common hydraulic fracturing technology in the exploitation of unconventional oil and gas reservoirs is multi-cluster perforation fracturing technology. However, in the process of using this technology, due to the opening and expansion of hydraulic fractures, the stress field around the hydraulic fractures will change, resulting in an obvious stress shadow effect. When the distances between different clusters are often close, due to the influence of the stress shadow effect, it is easy to cause the hydraulic fractures to be difficult to open and expand, directly affecting the width, morphology, extension direction and fracturing pressure of the fractures, and then directly affecting the production, recovery rate and economic benefits of the horizontal well fracturing design. In the process of hydraulic fracturing, a reasonable fracturing construction displacement can affect the stress changes around the hydraulic fractures to a certain extent, which is conducive to the opening, extension and expansion of hydraulic fractures, and finally forms an effective hydraulic fracture network to maximize the transformation of the reservoir. Therefore, it is necessary to study the law of ground stress changes during multi-cluster perforation fracturing in horizontal wells to optimize the fracturing construction displacement. After extensive research, the patent number 202111470445.2, "A Cluster Spacing Optimization Method Considering Stress Shadow Effect", simulates the hydraulic fracturing process through sequential geological models, estimates the stress shadow generated during the hydraulic fracturing process, and evaluates the most effective cluster spacing based on the size of the stress shadow volume. This scheme only considers the effect of cluster spacing on ground stress changes during hydraulic fracturing, and does not consider other factors, such as the effect of pumping fluid volume, pumping pressure, etc. on ground stress changes; the article "Study on the Extension Law of Multiple Fractures in Hydraulic Fracturing at Different Injection Rates" takes homogeneous cement slurry specimens as the research object, and optimizes the appropriate injection rate by comparing the fracturing crack morphology generated by hydraulic fracturing at different injection rates. However, this study does not consider the influence of the heterogeneity of actual reservoir rocks on the crack morphology. Summary of the invention

[0003] The purpose of the present invention is to reduce the adverse effect of the stress shadow effect generated when using multi-cluster perforation fracturing technology for hydraulic fracturing on the construction of a complex hydraulic fracture network. The present invention adopts a numerical simulation method and uses full three-dimensional fracturing numerical simulation software to simulate the hydraulic fracturing process under different fracturing construction displacements. By comparing and analyzing the changes in the ground stress field before and after fracturing, the stress shadow volume under different fracturing construction displacements is obtained and the optimal fracturing construction displacement is obtained by comparative analysis. This method is simple to calculate and has strong scalability.

[0004] To achieve the above object, the present invention provides a method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the method comprising the following steps:

[0005] S100, obtaining reservoir parameters of the study block;

[0006] S200, obtaining production well parameters of the study block;

[0007] S300, based on the collected reservoir parameters and engineering parameters of the study block, gradually import the well location data, well trajectory data, logging data, and geostress data of the study block into the petroleum software, complete the establishment of the structural model, attribute model, and geostress model of the shale gas well, and form the geological model of the study block by the structural model, the attribute model, and the geostress model;

[0008] S400, establishing a natural fracture distribution model based on the collected reservoir parameters of the study block and in combination with a geological model of the study block;

[0009] S500, based on the collected engineering parameters of the production wells in the research block, as well as the geological model and the natural fracture distribution model, different fracturing operation displacements are set, and the Kinetix fracturing production software is used to simulate the hydraulic fracturing process and generate hydraulic fractures; S600, the stress field values ​​of the hydraulic fractures before and after fracturing are calculated using a full three-dimensional fracturing numerical simulator;

[0010] S700, calculating the volume of the region where the difference in stress field values ​​before and after hydraulic fracture fracturing exceeds a preset stress difference, that is, the stress shadow volume;

[0011] S800, drawing a relationship curve between different fracturing operation displacements and stress shadow volumes, and the fracturing operation displacement corresponding to the maximum stress shadow volume is the fracturing operation displacement.

[0012] In the further described method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the reservoir parameters include well logging data, stratification data, geostress data, and natural fracture data.

[0013] In the further described method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the logging data at least includes permeability data, saturation data, and porosity data.

[0014] Further, in the method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the geostress data at least include the maximum horizontal principal stress, the minimum horizontal principal stress, the vertical stress, the Young's modulus, the Poisson's ratio and the direction of the horizontal principal stress.

[0015] In the further described method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the natural fracture data at least include fracture length, direction and spacing.

[0016] Further described is a method for designing the displacement of a fracturing operation taking into account the stress shadow effect, wherein the engineering parameters include well location data, well trajectory data, wellbore structure data, perforation data, fracturing segmentation and clustering data, proppant data, and fracturing fluid data.

[0017] In the further described method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the well trajectory data at least includes depth measurement, azimuth angle and well inclination angle.

[0018] In the further described method for designing the displacement of a fracturing operation taking into account the stress shadow effect, the wellbore structure data at least includes the casing lowering depth, casing size, and casing inner diameter.

[0019] In the further described method for designing the displacement of a fracturing operation considering the stress shadow effect, the distribution of natural fractures in the described natural fracture distribution model follows a normal distribution, wherein the normal distribution is:

[0020]

[0021] In the formula, x is a random variable; μ is the mean, which is the center position of the distribution and a dimensionless quantity; σ is the standard deviation, which is the width of the distribution, σ 2 is the standard deviation; e is the base of natural logarithm, approximately equal to 2.71828; π is the circumference of a circle, approximately equal to 3.14159;

[0022] Further, a method for designing the displacement of a fracturing operation considering the stress shadow effect is described, and the calculation method of the stress shadow volume is as follows:

[0023] |SS m |≥ΔS

[0024] Where, S is the ground stress before hydraulic fracturing, in MPa; S m is the ground stress after hydraulic fracturing, in MPa; ΔS is the stress difference threshold, in MPa.

[0025] Compared with the prior art, the present invention has the following beneficial effects: (1) It has a wide range of applications and can be used for tight sandstone reservoirs, shale reservoirs and other oil and gas reservoirs that require hydraulic fracturing; (2) The hydraulic fracturing construction displacement design method can study the hydraulic fracturing construction displacement design problems under different geological conditions, including different structures, ground stress differences, natural fracture development degrees and different cluster spacings; (3) The method is easy to promote and has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the attached picture:

[0027] Figure 1 is the technical roadmap for this approach.

[0028] Figure 2 This is the result of studying the block structure model using this method.

[0029] Figure 3 This is the result of studying the block attribute model using this method.

[0030] Figure 4 This is the result of the ground stress model of the studied area using this method.

[0031] Figure 5 This is the result of the natural fracture distribution model in the study area using this method.

[0032] Figure 6 This is the simulation result of hydraulic fracturing fractures in the block studied by this method.

[0033] Figure 7 This is the volume simulation result of block stress shadow studied by this method. Figure 8 This is the relationship curve between different fracturing operation displacement and stress shadow volume of the simulation results of this method. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the embodiments and accompanying drawings;

[0035] The present invention provides a method for designing the displacement of a hydraulic fracturing operation taking into account the stress shadow effect. Figure 1 is the technical roadmap of this method, which includes the following steps:

[0036] First, obtain reservoir parameters from the XX gas field, including well logging data, stratification data, geostress data, and natural fracture data;

[0037] Second, obtain reservoir parameters from the XX gas field, including well location data, well trajectory data, wellbore structure data, perforation data, fracturing segmentation and clustering data, proppant data, and fracturing fluid data;

[0038] Third, a reservoir structure model is established based on logging data and stratification data, such as Figure 2 As shown;

[0039] Fourth, a reservoir attribute model is established based on well logging data and reservoir structure model, such as Figure 3 As shown;

[0040] Fifth, a reservoir stress model is established based on the geostress data and reservoir structure model, such as Figure 4 As shown;

[0041] Sixth, according to the normal distribution law of natural fracture data, the natural fracture distribution model results are established, such as Figure 5 As shown, the natural fracture data are shown below;

[0042] Table 1:

[0043] Crack properties Length, m Direction, ° Spacing, m average value 20 127 30 Standard Deviation 10 20 10

[0044] Seventh, set different fracturing operation displacements to 8m 3 / min、10m 3 / min、12m 3 / min、14m 3 / min、16m 3 / min、18m 3 / min、20m 3 / min、22m 3 / min、24m 3 / min, the number of fracturing segments is 18, the cluster spacing is 20-30m, and the fracturing scale is 1800m 3 / segment, the amount of sand added is 200t / segment, and the hydraulic fracturing process considering the superposition of three-dimensional stress shadows is simulated by using Kinetix fracturing production software to produce hydraulic fractures. Figure 6 As shown;

[0045] Eighth, the stress field values ​​before and after hydraulic fracture fracturing are calculated using a full three-dimensional fracturing numerical simulator;

[0046] Ninth, use the calculator to screen the area volume where the difference in stress field values ​​before and after hydraulic fracturing exceeds 5MPa, that is, the stress shadow volume. The results are as follows Figure 7 As shown;

[0047] Tenth, draw the relationship curve between different fracturing operation displacement and stress shadow volume, such as Figure 8 As shown;

[0048] Compared with the prior art, the present invention has the following beneficial effects: (1) It has a wide range of applications and can be used in tight sandstone reservoirs, shale reservoirs and other oil and gas reservoirs that require hydraulic fracturing; (2) The hydraulic fracturing construction displacement design method can study the hydraulic fracturing construction displacement design problems under different geological conditions, including different structures, ground stress differences, natural fracture development degrees and different cluster spacings; (3) The calculation method is easy to promote and has low cost.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for designing the displacement of fracturing operation considering the stress shadow effect. It is characterized in that The method comprises the following steps: S100, obtaining reservoir parameters of a research block; S200, obtaining production well parameters of the study block; S300, based on the collected reservoir parameters and engineering parameters of the research block, gradually import the well location data, well trajectory data, logging data, and geostress data of tight gas and shale gas into the petroleum software, complete the establishment of the structural model, attribute model, and geostress model of the shale gas well, and form the geological model of the tight gas and shale gas wells by the structural model, the attribute model, and the geostress model; S400, establishing a natural fracture distribution model based on the collected reservoir parameters of the research block and in combination with the geological models of the tight gas and shale gas wells; S500, based on the collected engineering parameters of the production wells in the research block, as well as the geological model and the natural fracture distribution model, different fracturing operation displacements are set, and the Kinetix fracturing production software is used to simulate the hydraulic fracturing process and generate hydraulic fractures; S600, the stress field values ​​of the hydraulic fractures before and after fracturing are calculated using a full three-dimensional fracturing numerical simulator; S700, calculating the volume of the region where the difference in stress field values ​​before and after hydraulic fracture fracturing exceeds a preset stress difference, that is, the stress shadow volume; S800, drawing a relationship curve between different fracturing operation displacements and stress shadow volumes, and the fracturing operation displacement corresponding to the maximum stress shadow volume is the fracturing operation displacement.

2. A method for designing the displacement of a hydraulic fracturing operation taking into account the stress shadow effect according to claim 1, It is characterized in that The reservoir parameters include well logging data, stratification data, geostress data, and natural fracture data.

3. A method for designing the displacement of a hydraulic fracturing operation taking into account the stress shadow effect according to claim 1, It is characterized in that The logging data at least includes permeability data, saturation data, and porosity data.

4. A method for designing the displacement of a hydraulic fracturing operation considering the stress shadow effect according to claim 1, It is characterized in that The geostress data at least include the maximum horizontal principal stress, the minimum horizontal principal stress, the vertical stress, the Young's modulus, the Poisson's ratio and the direction of the maximum horizontal principal stress.

5. A method for designing the displacement of a hydraulic fracturing operation considering the stress shadow effect according to claim 1, It is characterized in that The natural fracture data at least include fracture length, direction and spacing.

6. A method for designing the displacement of a hydraulic fracturing operation considering the stress shadow effect according to claim 1, It is characterized in that The engineering parameters include well location data, well trajectory data, wellbore structure data, perforation data, fracturing segmentation and clustering data, proppant data, and fracturing fluid data.

7. A method for designing displacement of hydraulic fracturing considering stress shadow effect according to claim 1, It is characterized in that The well trajectory data at least include depth, azimuth and well inclination.

8. A method for designing displacement of hydraulic fracturing considering stress shadow effect according to claim 1, It is characterized in that The wellbore structure data at least include casing lowering depth, casing size, and casing inner diameter.

9. A method for designing displacement of hydraulic fracturing considering stress shadow effect according to claim 1, It is characterized in that The distribution of natural fractures in the natural fracture distribution model follows normal distribution.

10. A method for designing the displacement of a hydraulic fracturing operation considering the stress shadow effect according to claim 1, It is characterized in that The calculation method of the stress shadow volume is as follows: |S-S m |≥ΔS Where, S is the ground stress before hydraulic fracturing, in MPa; S m is the ground stress after hydraulic fracturing, in MPa; ΔS is the stress difference threshold, in MPa.

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