A hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoirs and related devices

Abstract

The present application belongs to the field of petroleum and natural gas engineering, and discloses a hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir and related devices, obtains modeling parameters required for modeling; uses the modeling parameters to establish a three-dimensional fracture penetration numerical simulation model; uses the three-dimensional fracture penetration numerical simulation model to calculate critical mechanical parameters and critical bedding quantity of the target coalbed section roof rock and floor rock; according to the actual mechanical parameters and bedding quantity of the critical mechanical parameters and critical bedding quantity of the target coalbed section roof rock and floor rock, judges whether the target coalbed section needs to be subjected to fracture height control; when the target coalbed section needs to be subjected to fracture height control, uses the three-dimensional fracture penetration numerical simulation model to perform fracturing form simulation, obtains fracturing construction parameters when the fracture height meets the requirements and uses the fracturing construction parameters as the final fracturing construction parameters. The present application can realize effective control of the fracture height of the target coalbed section and improve the production effect of single well after fracturing.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil and gas engineering, and particularly relates to a hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir and a related device. BACKGROUND

[0002] The deep coalbed methane reservoir has a burial depth generally exceeding 2000 meters, and is an important component of unconventional oil and gas resources. The geological resources of deep coal rock gas with a burial depth exceeding 2000 meters amount to 40.71 trillion m 3 With a substantial reduction in effective development blocks of shallow coalbed methane, the deep coalbed methane reservoir will be the main battlefield for development of major gas fields in the future. Vigorous development of the deep coalbed methane reservoir can not only effectively solve the current energy shortage problem, but is also crucial for energy security.

[0003] The deep coalbed methane reservoir has a thickness generally not exceeding 6 meters, and the reservoir thickness is small and the network of cleavage and fissure is widely developed, which are typical characteristics of the deep coalbed methane reservoir. Development of the deep coalbed methane reservoir must rely on large-scale limited-volume fracturing technology to form an effective support fracture network in the reservoir, and ultimately achieve economic benefit mining. However, in the fracturing process, the typical characteristics of the deep coalbed methane reservoir make it difficult to control the fracture propagation trajectory, and the fracture height is difficult to control within the target coalbed section, which seriously affects the fracturing development effect and restricts vigorous development of the deep coalbed methane reservoir. How to regulate and control the fracturing parameters and effectively control the fracture height has become a technical bottleneck problem restricting economic benefit development of the deep coalbed methane reservoir. SUMMARY

[0004] In order to solve the technical bottleneck problem that the limited-volume fracturing of the deep coalbed methane reservoir is difficult to control the fracture height, the present application aims to provide a hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir and a related device. Based on the present application, the fracturing process of the deep coalbed methane reservoir can be simulated, the pump injection program can be optimized, and the critical reservoir parameters can be determined as the target, so as to ultimately achieve effective control of the fracture height of the target coalbed section and improve the production effect of a single well after fracturing.

[0005] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0006] A hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir, comprising the following processes:

[0007] Obtaining modeling parameters required for modeling;

[0008] Using the modeling parameters, a three-dimensional fracture penetration numerical simulation model is established based on a fracturing module of a petrel software platform;

[0009] The critical mechanical parameters and the critical bedding quantity of the roof rock above the target coal seam section and the critical mechanical parameters and the critical bedding quantity of the floor rock below the target coal seam section are calculated by using the three-dimensional fracture penetrating strata numerical simulation model;

[0010] According to the calculated critical mechanical parameters and the critical bedding quantity of the roof rock, the calculated critical mechanical parameters and the critical bedding quantity of the floor rock, and the actual mechanical parameters and the actual bedding quantity of the roof rock and the actual mechanical parameters and the actual bedding quantity of the floor rock, it is judged whether the target coal seam section needs to be controlled in fracture height;

[0011] When the target coal seam section needs to be controlled in fracture height, the fracture pattern simulation is carried out by using the three-dimensional fracture penetrating strata numerical simulation model, the fracturing construction parameters when the fracture height meets the requirements are obtained, and the fracturing construction parameters at this time are taken as the final fracturing construction parameters.

[0012] Preferably, the modeling parameters required for modeling include:

[0013] The number and the distribution angle of cleavages of the target coal seam section;

[0014] The lithology and the number of beddings of the roof rock above the target coal seam section and the floor rock below the target coal seam section;

[0015] The mechanical property parameters, the ground stress property parameters, the basic physical property parameters, the vertical fracture toughness index and the horizontal fracture toughness index of the roof rock, the target coal seam section and the floor rock.

[0016] Preferably, the number and the distribution angle of cleavages of the target coal seam section are determined by well logging interpretation data combined with drilling coring, including: the number of cleavages is counted according to the number of cleavages per unit area on the core end surface, and the distribution angle of cleavages is counted according to the angle between the cleavages and the maximum horizontal principal stress to count the distribution direction of the cleavages;

[0017] For the roof rock and the floor rock, when the lithology is mudstone or shale, the actual number of beddings needs to be counted; when the lithology is sandstone, the number of beddings is zero;

[0018] The mechanical property parameters include Young's modulus, Poisson's ratio, tensile strength, compressive strength and friction coefficient;

[0019] The vertical fracture toughness index and the horizontal fracture toughness index are calculated by the mechanical property parameters;

[0020] The ground stress property parameters include the maximum horizontal principal stress, the minimum horizontal principal stress and the vertical principal stress;

[0021] The basic physical property parameters include porosity and permeability.

[0022] Preferably, the vertical fracture toughness index KICvertical = 0.005 + 0.155 x K1 - 0.00312 x K2 + 0.0148 x E, with units of MPa.m. 0.5 ;

[0023] The horizontal fracture toughness index KIChorizontal = 0.6 x KICvertical.

[0024] Wherein, K1 is the tensile strength, K2 is the compressive strength, and E is the Young's modulus.

[0025] Preferably, the three-dimensional crack penetration numerical simulation model is used to calculate the critical mechanical parameters and critical bedding quantity of the roof rock above the target coal seam section and the critical mechanical parameters and critical bedding quantity of the floor rock below the target coal seam section, including:

[0026] When the lithology of the roof rock is sandstone or limestone, a first penetration simulation control parameter is set, and then a crack penetration shear slip control module in the fracturing module is enabled to perform crack propagation simulation, in the simulation process, it is judged whether the crack will penetrate the roof rock, and then the first penetration simulation control parameter is continuously adjusted until the crack height does not penetrate the roof rock, at which time the critical mechanical parameters of the roof rock are determined;

[0027] When the lithology of the floor rock is sandstone or limestone, a first penetration simulation control parameter is set, and then a crack penetration shear slip control module is enabled to perform crack propagation simulation, in the simulation process, it is judged whether the crack will penetrate the floor rock, and then the first penetration simulation control parameter is continuously adjusted until the crack height does not penetrate the floor rock, at which time the critical mechanical parameters of the floor rock are determined;

[0028] Wherein, the first penetration simulation control parameter includes the minimum horizontal principal stress, friction coefficient and tensile strength of the rock, and the critical mechanical parameter includes the critical minimum horizontal principal stress, critical rock friction coefficient and critical rock tensile strength;

[0029] When the lithology of the roof rock is shale, a second penetration simulation control parameter is set, and then a crack penetration offset control module in the fracturing module is enabled to perform crack propagation simulation, in the simulation process, it is judged whether the crack will penetrate the roof rock, and then the second penetration simulation control parameter is continuously adjusted until the crack height does not penetrate the roof rock, at which time the critical bedding quantity of the roof rock is determined;

[0030] When the lithology of the floor rock is shale, a second layer-penetration simulation control parameter is set, and then a crack layer-penetration deviation control module in the fracturing module is enabled to perform crack propagation simulation, in which it is determined whether the crack will penetrate the floor rock, and then the second layer-penetration simulation control parameter is continuously adjusted until the crack height will not penetrate the floor rock, at which time the critical bedding number of the floor rock is determined.

[0031] When the lithology of the roof rock is mudstone, a second layer-penetration simulation control parameter is set, and then a crack layer-penetration deviation control module in the fracturing module is enabled to perform crack propagation simulation, in which it is determined whether the crack will penetrate the roof rock, and then the second layer-penetration simulation control parameter is continuously adjusted until the crack height will not penetrate the roof rock, at which time the critical bedding number of the roof rock is determined.

[0032] When the lithology of the floor rock is mudstone, a second layer-penetration simulation control parameter is set, and then a crack layer-penetration deviation control module in the fracturing module is enabled to perform crack propagation simulation, in which it is determined whether the crack will penetrate the floor rock, and then the second layer-penetration simulation control parameter is continuously adjusted until the crack height will not penetrate the floor rock, at which time the critical bedding number of the floor rock is determined.

[0033] The second layer-penetration simulation control parameter includes a deviation amount and a bedding number.

[0034] Preferably, according to the calculated critical mechanical parameters and critical bedding number of the roof rock, the calculated critical mechanical parameters and critical bedding number of the floor rock, and the actual mechanical parameters and bedding number of the roof rock and the actual mechanical parameters and bedding number of the floor rock, it is determined whether the crack height needs to be controlled in the target coal seam section, including:

[0035] When the lithology of the roof rock is shale or mudstone, if the actual bedding number in the roof rock is greater than or equal to the calculated critical bedding number of the roof rock, it is indicated that the crack height will not penetrate the layer when the target coal seam section is subjected to hydraulic fracturing, and it is determined that the crack height does not need to be controlled at this time; if the actual bedding number in the roof rock is less than the calculated critical bedding number, it is indicated that the crack height will penetrate the layer when the target coal seam section is subjected to hydraulic fracturing, and it is determined that the crack height needs to be controlled at this time.

[0036] When the lithology of the floor rock is shale or mudstone, if the actual bedding number in the floor rock is greater than or equal to the calculated critical bedding number of the floor rock, it is indicated that the crack height will not penetrate the layer when the target coal seam section is subjected to hydraulic fracturing, and it is determined that the crack height does not need to be controlled at this time; if the actual bedding number in the floor rock is less than the calculated critical bedding number, it is indicated that the crack height will penetrate the layer when the target coal seam section is subjected to hydraulic fracturing, and it is determined that the crack height needs to be controlled at this time.

[0037] When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock ≥ the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock ≥ the calculated critical tensile strength of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is not needed at this time; if the actual rock friction coefficient of the roof rock ≤ the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is not needed at this time;

[0038] When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock ≥ the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock ≥ the calculated critical tensile strength of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is not needed at this time; if the actual rock friction coefficient of the roof rock ≤ the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is not needed at this time;

[0039] When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock < the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock < the calculated critical tensile strength of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is needed at this time; if the actual rock friction coefficient of the roof rock > the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is needed at this time;

[0040] When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock < the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock < the calculated critical tensile strength of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is needed at this time; if the actual rock friction coefficient of the roof rock > the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is judged that the fracture height control is needed at this time.

[0041] Preferably, when the target coal seam section needs to be controlled in fracture height, a three-dimensional fracture penetration numerical simulation model is used for fracturing mode simulation to obtain the fracturing construction parameters when the fracture height meets the requirements, and the fracturing construction parameters at this time are taken as the final fracturing construction parameters, including:

[0042] When the target coal seam section needs to control the fracture height, the three-dimensional fracture penetration numerical simulation model is used for fracture morphology simulation, and the fracture construction parameters are continuously adjusted until the fracture result shows that the fracture height meets the requirements, and the fracture construction parameters at this time are taken as the final fracture construction parameters.

[0043] The fracture construction parameters include the fracture fluid discharge, the fracture fluid viscosity, the sand ratio and the total liquid volume.

[0044] When the fracture height is less than 1 / 4 of the thickness of the roof rock or the floor rock horizon, it indicates that the fracture height meets the requirements.

[0045] The application also provides a hydraulic fracturing optimization design system for controlling the fracture height of a deep coalbed methane reservoir, which is used to realize the hydraulic fracturing optimization design method for controlling the fracture height of the deep coalbed methane reservoir.

[0046] The data acquisition module is used to acquire modeling parameters required for modeling.

[0047] The modeling module is used to establish a three-dimensional fracture penetration numerical simulation model based on the petrel software platform fracture module by using the modeling parameters.

[0048] The calculation module is used to calculate the critical mechanical parameters and the critical bedding quantity of the roof rock above the target coal seam section and the critical mechanical parameters and the critical bedding quantity of the floor rock below the target coal seam section by using the three-dimensional fracture penetration numerical simulation model.

[0049] The judgment module is used to judge whether the target coal seam section needs to control the fracture height according to the calculated critical mechanical parameters and critical bedding quantity of the roof rock, the calculated critical mechanical parameters and critical bedding quantity of the floor rock, and the actual mechanical parameters and bedding quantity of the roof rock and the actual mechanical parameters and bedding quantity of the floor rock.

[0050] The optimization module is used to use the three-dimensional fracture penetration numerical simulation model for fracture morphology simulation when the target coal seam section needs to control the fracture height, and obtain the fracture construction parameters when the fracture height meets the requirements, and take the fracture construction parameters at this time as the final fracture construction parameters.

[0051] The application also provides an electronic device, which comprises:

[0052] One or more processors;

[0053] A storage device having one or more programs stored thereon;

[0054] The one or more programs, when executed by the one or more processors, cause the one or more processors to implement the method for optimizing design of hydraulic fracturing for controlling fracture height of deep coalbed methane reservoirs as described above.

[0055] The application further provides a storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for optimizing design of hydraulic fracturing for controlling fracture height of deep coalbed methane reservoirs as described above.

[0056] The application has the following beneficial effects:

[0057] The principle of the method for optimizing design of hydraulic fracturing for controlling fracture height of deep coalbed methane reservoirs is as follows: for deep coalbed methane reservoirs, since the properties of the top and bottom plate rocks (i.e. the top plate rock and the bottom plate rock) are indefinite, when the fractures expand along the vertical direction, the fracture height may be affected by the shear slip between the layers, and the fracture height may also be affected by the deviation caused by the fracture contacting the bedding. The application combines the two sets of fracture height expansion criteria, first judges the lithology, then selects the fracture layer-penetrating control criterion to identify whether the reservoir will occur layer penetration under specific stratum property parameters, and then optimizes the fracturing process parameters accordingly, so as to finally control the fracture height in the target coalbed section. The application can restore the expansion form of the fractures in the height direction during the limit volume fracturing of the deep coalbed methane reservoir; can analyze whether the fractures will occur layer penetration under different top and bottom plate rock properties; can optimize the pumping program, and effectively control the height of the fractures in the target coalbed section, and improve the fracturing effect of a single well. BRIEF DESCRIPTION OF DRAWINGS

[0058] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description.

[0059] Figure 1 Fig. 1 is a diagram of a three-dimensional fracture layer-penetrating numerical simulation model established by using the fracturing module of the petrel software platform in the embodiments of the application;

[0060] Fig. 2 (a) is a diagram of the longitudinal profile of the fractures before optimization in the embodiments of the application; and Fig. 2 (b) is a diagram of the longitudinal profile of the fractures after optimization in the embodiments of the application.

[0061] In the figures, 1 represents the target coalbed section, 2 represents the top plate rock, and 3 represents the bottom plate rock. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the application more clear, the following will combine the drawings in the embodiments of the application to clearly and completely describe the technical solutions in the embodiments of the application.

[0063] The application discloses a hydraulic fracturing optimization design method for controlling fracture height of a deep coalbed gas reservoir.

[0064] Step (1), the number and distribution angle of cleavages of a target coalbed section are determined by well logging interpretation data in combination with drilling coring, and the lithology and bedding number B of roof rock of the upper part of the deep coalbed gas reservoir coalbed section (i.e. the target coalbed section) and floor rock of the lower part of the deep coalbed gas reservoir coalbed section are determined. e-true Specifically, the number of cleavages of the deep coalbed gas reservoir coalbed section is counted according to the number of cleavages per unit area on the core end face, and the distribution angle of the cleavages is counted according to the included angle between the cleavages and the maximum horizontal principal stress to count the distribution direction of the cleavages. The lithology of the roof rock of the upper part of the target coalbed section and the floor rock of the lower part is determined, and if the lithology is mudstone or shale, the actual bedding number B of the roof rock and the floor rock is counted. e-true If the lithology is sandstone, the influence of the bedding is not considered, and the actual bedding number of the roof rock and the floor rock is not counted.

[0065] Step (2), the mechanical property parameters, the ground stress property parameters and the basic physical property parameters of the roof rock, the target coalbed section and the floor rock are measured by drilling coring in combination with indoor true triaxial compression experiments and steady-state displacement experiments; wherein the mechanical property parameters include the Young's modulus E, the Poisson's ratio v, the tensile strength K1, the compressive strength K2 and the friction coefficient μ of the rock; the ground stress property parameters include the maximum horizontal principal stress SH, the minimum horizontal principal stress Sh and the vertical principal stress SV; and the basic physical property parameters include the porosity and the permeability k of the rock. φ

[0066] Step (3), a three-dimensional fracture penetration numerical simulation model is established by using a fracturing module of a petrel software platform in combination with the parameters collected in steps (1) and (2); specifically, before the three-dimensional fracture penetration numerical simulation model is established, firstly, the KIC parameters (i.e. fracture toughness indexes) of the vertical fracture toughness and the horizontal fracture toughness of the three horizons of the roof rock, the target coalbed section and the floor rock of the model are calculated according to the rock mechanical parameters, and the calculation formulae of the vertical fracture toughness KIC parameter and the horizontal fracture toughness KIC parameter are as follows:

[0067] KIC vertical = 0.005 + 0.155 * K1 - 0.00312 * K2 + 0.0148 * E, unit: MPa.m 0.5

[0068] KIC horizontal = 0.6 * KIC vertical

[0069] ​Step (4), set the through-layer simulation control parameters of the roof rock and the floor rock by the fracture through-layer offset control module (OFFSET) and the fracture through-layer shear slip control module (Shear Slip) in the fracturing module of the petrel software platform, continuously adjust the control parameters for through-layer fracturing simulation until the critical mechanical parameters and the critical bedding number B of the roof rock and the floor rock (i.e. the roof rock and the floor rock) are determined e-critical Specifically:

[0070] When the lithology of the roof rock (or the floor rock) is sandstone or limestone, set the through-layer simulation control parameters, the through-layer simulation control parameters including the minimum horizontal principal stress of the rock, the friction coefficient of the rock, and the tensile strength of the rock, then enable the fracture through-layer shear slip control module (Shear Slip) to perform fracture propagation simulation, determine whether the fracture will penetrate the roof rock (or the floor rock), then continuously adjust the through-layer simulation control parameters until the fracture height will not penetrate the roof rock (or the floor rock), at this time, the critical mechanical parameters when the lithology of the roof rock (or the floor rock) is sandstone or limestone are determined, the critical mechanical parameters including the critical minimum horizontal principal stress Sh- critical , the critical rock friction coefficient μ- critical , and the critical rock tensile strength K1- critical ;

[0071] When the lithology of the roof rock (or the floor rock) is shale, set the through-layer simulation control parameters, the through-layer simulation control parameters including the offset amount offset and the bedding number, wherein the offset amount offset is set to a fixed value of 5.5 cm, then enable the fracture through-layer offset control module (OFFSET) to perform fracture propagation simulation, determine whether the fracture will penetrate the roof rock (or the floor rock), then continuously adjust the through-layer simulation control parameters until the fracture height will not penetrate the roof rock (or the floor rock), at this time, the critical bedding number B e-critical of the roof rock (or the floor rock) when the lithology of the roof rock (or the floor rock) is shale is determined.

[0072] When the lithology of the roof rock (or the floor rock) is mudstone, set the through-layer simulation control parameters, the through-layer simulation control parameters including the offset amount offset and the bedding number, wherein the offset amount offset is set to a fixed value of 2.5 cm, then enable the fracture through-layer offset control module (OFFSET) to perform fracture propagation simulation, determine whether the fracture will penetrate the roof rock (or the floor rock), then continuously adjust the through-layer simulation control parameters until the fracture height will not penetrate the roof rock (or the floor rock), at this time, the critical bedding number B e-critical of the roof rock (or the floor rock) when the lithology of the roof rock (or the floor rock) is shale is determined.

[0073] Step (5), compare the critical mechanical parameters and the critical bedding number of the roof and floor rock determined in step (4) with the actual mechanical parameters and the actual bedding number of the roof and floor rock of the target coal seam section, to determine whether the fracture height needs to be controlled; specifically, when the lithology of the actual roof (or floor) rock of the target coal seam section is shale or mudstone, if the actual bedding number of the roof (or floor) rock exceeds the critical bedding number of the roof (or floor) rock determined in step (4), it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus there is no need to perform the fracturing optimization design; if the actual bedding number of the roof (or floor) rock does not exceed the critical bedding number of the roof (or floor) rock determined in step (4), it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus the fracturing optimization design is needed.

[0074] When the lithology of the actual roof (or floor) rock of the target coal seam section is sandstone or limestone, if the actual minimum horizontal principal stress of the roof (or floor) rock exceeds the critical minimum horizontal principal stress Sh- critical of the roof (or floor) rock determined in step (4), or if the actual rock tensile strength of the roof (or floor) rock exceeds the critical rock tensile strength K1- critical of the roof (or floor) rock determined in step (4), it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus there is no need to perform the fracturing optimization design. If the actual rock friction coefficient of the roof (or floor) rock is less than the critical rock friction coefficient μ- critical of the roof (or floor) rock determined in step (4), it indicates that the fracture height will also not penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus there is also no need to perform the fracturing optimization design.

[0075] When the lithology of the actual roof (or floor) rock of the target coal seam section is sandstone or limestone, if the actual minimum horizontal principal stress of the roof (or floor) rock does not exceed the critical minimum horizontal principal stress Sh- critical of the roof (or floor) rock determined in step (4), or if the actual rock tensile strength of the roof (or floor) rock does not exceed the critical rock tensile strength K1- critical of the roof (or floor) rock determined in step (4), it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus the fracturing optimization design is needed. If the actual rock friction coefficient of the roof (or floor) rock is greater than the critical rock friction coefficient μ- critical of the roof (or floor) rock determined in step (4), it indicates that the fracture height will also penetrate the layer during the hydraulic fracturing of the target coal seam section, and thus the fracturing optimization design is needed.

[0076] Step (6), for the target coal seam section which needs to be fractured height controlled, the three-dimensional fracture penetration numerical simulation model is used to simulate the fracturing form, and the four fracturing construction parameters of fracturing fluid discharge, fracturing fluid viscosity, sand ratio and total liquid volume are continuously adjusted until the fracturing result shows that the fracture height meets the requirements; specifically, the fracturing construction parameters are continuously adjusted, and the height H of the hydraulic fracture penetrating the roof rock (or floor rock) is calculated and simulated, when the fracture height H is less than 1 / 4 of the thickness of the roof rock (or floor rock) horizon, it can be considered that the fracture height is effectively controlled, and the fracturing construction parameters at this time are the final fracturing construction parameters obtained by optimization design.

[0077] The fracturing construction parameters optimized by the above step (6) of the application are used to design the pump injection program table, and then the field fracturing construction is carried out.

[0078] Embodiment

[0079] The deep coalbed methane resource reserves in a certain area of an oilfield are rich, the reservoir burial depth is more than 2000m, the main development horizon is No. 8 coal series, however, the field fracturing result shows that the fracture height cannot be effectively controlled, and the single well effect after fracturing is poor, therefore, the pump injection program of 10-32-56 well in a certain area is optimized and designed by using the above technical scheme of the application, and the specific steps are as follows:

[0080] Step (1), the target coal seam section of 10-32-56 well in a certain area is determined to have limestone as the roof rock and mudstone as the floor rock through well logging interpretation data combined with drilling core, and the actual number of floor mudstone layering is 10.

[0081] Step (2), the mechanical property parameters, stress characteristic parameters and basic physical property parameters of the roof rock, target coal seam section and floor rock are measured by using drilling core combined with indoor true triaxial compression experiment and steady-state displacement experiment, and the specific parameters are shown in Table 1:

[0082] Table 1

[0083]

[0084] Step (3), a three-dimensional fracture penetration numerical simulation model is established by using the fracturing module of the petrel software platform, as shown in the following formula: Figure 1

[0085] ​Step (4), for the well 10-32-56, since the roof rock is limestone, a fracture cross-formation shear slip control module (Shear Slip) is enabled for fracture propagation simulation to determine whether the fracture will cross the roof rock, then the cross-formation simulation control parameters are continuously adjusted until the fracture height will not cross the roof rock, and finally the critical mechanical parameters of the roof rock are determined, in which the critical minimum horizontal principal stress Sh- critical = 46 MPa, the critical rock friction coefficient μ- critical = 0.63, and the critical rock tensile strength K1- critical = 25.3 MPa.

[0086] Since the floor rock of the well 10-32-56 is mudstone, a fracture cross-formation offset control module (OFFSET) is enabled for fracture propagation simulation to determine whether the fracture will cross the floor rock, then the cross-formation simulation control parameters are continuously adjusted until the fracture height will not cross the floor rock, and finally the critical bedding number B e-critical = 30 is determined.

[0087] Step (5), the critical parameters determined in step (4) are compared with the actual values, and the results show that since the actual bedding number of the floor rock is less than the critical bedding number, the floor rock will cross, and the minimum horizontal principal stress and the tensile strength of the roof rock are also less than the critical parameters, so the roof rock will also cross, and therefore it is necessary to optimize the design of the fracturing pumping program.

[0088] Step (6), for the target coal seam section of the well 10-32-56, a three-dimensional fracture cross-formation numerical simulation model is used to simulate the fracturing pattern, then the fracturing fluid discharge, the fracturing fluid viscosity, the sand ratio and the total liquid volume are continuously adjusted until the fracturing result shows that the fracture height H crossing the roof rock (or the floor rock) is less than 1 / 4 of the thickness of the roof rock (or the floor rock). The finally optimized pumping parameters are: the fracturing fluid discharge is 16 m 3 / min, the fracturing fluid viscosity is 15 mPa·s-45 mPa·s, the sand ratio is 0.7, and the total liquid volume is 1943 m 3 . The comparison of the fracture patterns before and after optimization is shown in FIG. 2(a) and FIG. 2(b), and it can be seen from FIG. 2(b) that after optimization, the fracture height is basically controlled within the coal seam section.

[0089] The fracturing construction parameters optimized in step (6) are used to design the pumping program table, and then the field fracturing construction is carried out, and finally the post-fracturing production effect is compared with that of the adjacent well without optimization as shown in Table 2.

[0090] Table 2

[0091]

[0092] As shown in Table 2, compared with the non-optimized adjacent well (i.e., well 147), the cumulative gas production of the single well (i.e., well 10-32-56) is greatly improved.

[0093] The application also provides a system of a hydraulic fracturing optimization design method for controlling fracture height of a deep coalbed gas reservoir.

[0094] The data acquisition module is configured to acquire modeling parameters required for modeling.

[0095] The modeling module is configured to establish a three-dimensional fracture penetration numerical simulation model based on a fracturing module of a petrel software platform by using the modeling parameters.

[0096] The calculation module is configured to calculate critical mechanical parameters and critical bedding numbers of roof rock above a target coalbed section and critical mechanical parameters and critical bedding numbers of floor rock below the target coalbed section by using the three-dimensional fracture penetration numerical simulation model.

[0097] The judgment module is configured to judge whether the target coalbed section needs to be controlled in fracture height according to the calculated critical mechanical parameters and critical bedding numbers of the roof rock, the calculated critical mechanical parameters and critical bedding numbers of the floor rock, and actual mechanical parameters and bedding numbers of the roof rock and actual mechanical parameters and bedding numbers of the floor rock.

[0098] The optimization module is configured to perform fracturing mode simulation by using the three-dimensional fracture penetration numerical simulation model when the target coalbed section needs to be controlled in fracture height, to obtain fracturing construction parameters when the fracture height meets the requirements, and to take the fracturing construction parameters at this time as the final fracturing construction parameters.

[0099] The application also provides corresponding electronic devices and computer readable storage media for implementing the scheme provided by the application.

[0100] The device includes a memory and a processor, the memory is configured to store instructions or codes, and the processor is configured to execute the instructions or codes to enable the device to perform the hydraulic fracturing optimization design method for controlling fracture height of a deep coalbed gas reservoir.

[0101] The storage medium stores a computer program, and the computer program is executed by the processor to implement the hydraulic fracturing optimization design method for controlling fracture height of a deep coalbed gas reservoir.

[0102] The application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Moreover, the application can take the form of a computer program product implemented on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and so on) containing computer usable program code.

[0103] Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0104] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or replaced by the same, without departing from the spirit and scope of the present application. Any modification or equivalent replacement, which should be covered within the protection scope of the claims of the present application.

Claims

1. A method of hydraulic fracturing optimization design for controlling fracture height in deep coalbed methane reservoirs, characterized by, The method comprises the following steps: obtaining modeling parameters required for modeling; establishing a three-dimensional fracture penetration numerical simulation model based on a fracturing module of a petrel software platform by using the modeling parameters; calculating critical mechanical parameters and critical bedding quantity of the roof rock above the target coal seam section and critical mechanical parameters and critical bedding quantity of the floor rock below the target coal seam section by using the three-dimensional fracture penetration numerical simulation model; specifically, when the lithology of the roof rock is sandstone or limestone, a first penetration simulation control parameter is set, and then a fracture penetration shear slip control module in the fracturing module is enabled to perform fracture propagation simulation; in the simulation process, it is determined whether the fracture will penetrate the roof rock, and then the first penetration simulation control parameter is continuously adjusted until the fracture height does not penetrate the roof rock, at which time the critical mechanical parameters of the roof rock are determined; when the lithology of the floor rock is sandstone or limestone, a first penetration simulation control parameter is set, and then the fracture penetration shear slip control module is enabled to perform fracture propagation simulation; in the simulation process, it is determined whether the fracture will penetrate the floor rock, and then the first penetration simulation control parameter is continuously adjusted until the fracture height does not penetrate the floor rock, at which time the critical mechanical parameters of the floor rock are determined; wherein the first penetration simulation control parameter comprises the minimum horizontal principal stress, the friction coefficient and the tensile strength of the rock, and the critical mechanical parameters comprise the critical minimum horizontal principal stress, the critical rock friction coefficient and the critical rock tensile strength; when the lithology of the roof rock is shale or mudstone, a second penetration simulation control parameter is set, and then a fracture penetration offset control module in the fracturing module is enabled to perform fracture propagation simulation; in the simulation process, it is determined whether the fracture will penetrate the roof rock, and then the second penetration simulation control parameter is continuously adjusted until the fracture height does not penetrate the roof rock, at which time the critical bedding quantity of the roof rock is determined; when the lithology of the floor rock is shale or mudstone, a second penetration simulation control parameter is set, and then the fracture penetration offset control module in the fracturing module is enabled to perform fracture propagation simulation; in the simulation process, it is determined whether the fracture will penetrate the floor rock, and then the second penetration simulation control parameter is continuously adjusted until the fracture height does not penetrate the floor rock, at which time the critical bedding quantity of the floor rock is determined; wherein the second penetration simulation control parameter comprises the offset amount and the bedding quantity; judging whether the target coal seam section needs to be controlled in terms of fracture height according to the calculated critical mechanical parameters and critical bedding quantity of the roof rock, the calculated critical mechanical parameters and critical bedding quantity of the floor rock, and the actual mechanical parameters and bedding quantity of the roof rock and the actual mechanical parameters and bedding quantity of the floor rock; when the target coal seam section needs to be controlled in terms of fracture height, performing fracturing mode simulation by using the three-dimensional fracture penetration numerical simulation model to obtain fracturing construction parameters under which the fracture height meets the requirements, and taking the fracturing construction parameters at this time as the final fracturing construction parameters.

2. The method of claim 1, wherein, The modeling parameters required for modeling include: the number and distribution angle of cleats of the target coal seam section; Lithology and bedding number of the roof rock above the target coal seam section and the floor rock below the target coal seam section; Mechanical property parameters, geo-stress property parameters, basic physical property parameters, vertical fracture toughness index and horizontal fracture toughness index of the roof rock, the target coal seam section and the floor rock.

3. The hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir according to claim 2, characterized in that: The number and distribution angle of cleats of the target coal seam section are determined by well logging interpretation data combined with drilling coring, including: the number of cleats is counted according to the number of cleats per unit area on the core end face, and the distribution angle of cleats is counted according to the angle between the cleats and the maximum horizontal principal stress to count the distribution direction of cleats; For the roof rock and the floor rock, when the lithology is mudstone or shale, the actual bedding number needs to be counted; when the lithology is sandstone, the bedding number is zero; The mechanical property parameters include Young's modulus, Poisson's ratio, tensile strength, compressive strength and friction coefficient; The vertical fracture toughness index and the horizontal fracture toughness index are calculated from the mechanical property parameters; The geo-stress property parameters include the maximum horizontal principal stress, the minimum horizontal principal stress and the vertical principal stress; The basic physical property parameters include porosity and permeability.

4. The hydraulic fracturing optimization design method for controlling fracture height of deep coalbed methane reservoir according to claim 2 or 3, characterized in that: The vertical fracture toughness indicator KICvertical = 0.005 + 0.155 x K1- 0.00312 x K2+ 0.0148 x E, in MPa.m 0.5 ; The horizontal fracture toughness index KIC horizontal = 0.6 × KIC vertical; Wherein, K1 is the tensile strength, K2 is the compressive strength, and E is the Young's modulus.

5. The method of claim 1, wherein, According to the calculated critical mechanical parameters and critical bedding number of the roof rock, the calculated critical mechanical parameters and critical bedding number of the floor rock, and the actual mechanical parameters and bedding number of the roof rock and the actual mechanical parameters and bedding number of the floor rock, it is judged whether the target coal seam section needs to control the fracture height, including: When the lithology of the roof rock is shale or mudstone, if the actual bedding number in the roof rock is ≥ the calculated critical bedding number of the roof rock, it indicates that the fracture height will not penetrate the layer when the target coal seam section is fractured by hydraulic fracturing, and it is judged that fracture height control is not needed at this time; if the actual bedding number in the roof rock is < the calculated critical bedding number, it indicates that the fracture height will penetrate the layer when the target coal seam section is fractured by hydraulic fracturing, and it is judged that fracture height control is needed at this time; When the lithology of the floor rock is shale or mudstone, if the actual bedding number in the floor rock is ≥ the calculated critical bedding number of the floor rock, it indicates that the fracture height will not penetrate the layer when the target coal seam section is fractured by hydraulic fracturing, and it is judged that fracture height control is not needed at this time; if the actual bedding number in the floor rock is < the calculated critical bedding number, it indicates that the fracture height will penetrate the layer when the target coal seam section is fractured by hydraulic fracturing, and it is judged that fracture height control is needed at this time; When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock is greater than or equal to the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock is greater than or equal to the calculated critical tensile strength of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that there is no need to control the fracture height at this time; if the actual rock friction coefficient of the roof rock is less than or equal to the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that there is no need to control the fracture height at this time; When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock is greater than or equal to the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock is greater than or equal to the calculated critical tensile strength of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that there is no need to control the fracture height at this time; if the actual rock friction coefficient of the roof rock is less than or equal to the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will not penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that there is no need to control the fracture height at this time; When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock is less than the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock is less than the calculated critical tensile strength of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that the fracture height needs to be controlled at this time; if the actual rock friction coefficient of the roof rock is greater than the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that the fracture height needs to be controlled at this time; When the lithology of the roof rock is sandstone or limestone, if the actual minimum horizontal principal stress of the roof rock is less than the calculated critical minimum horizontal principal stress of the roof rock, or the actual tensile strength of the roof rock is less than the calculated critical tensile strength of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that the fracture height needs to be controlled at this time; if the actual rock friction coefficient of the roof rock is greater than the calculated critical rock friction coefficient of the roof rock, it indicates that the fracture height will penetrate the layer during the hydraulic fracturing of the target coal seam section, and it is determined that the fracture height needs to be controlled at this time.

6. The method of claim 1, wherein, When the target coal seam section needs to control the fracture height, the three-dimensional fracture penetration numerical simulation model is used for fracturing mode simulation, and the fracturing construction parameters when the fracture height meets the requirements are obtained, which are taken as the final fracturing construction parameters, including: When the target coal seam section needs to control the fracture height, the three-dimensional fracture penetration numerical simulation model is used for fracturing mode simulation, and the fracturing construction parameters when the fracture height meets the requirements are obtained, which are taken as the final fracturing construction parameters, including: The fracturing construction parameters include fracturing fluid discharge, fracturing fluid viscosity, sand ratio and total liquid volume. When the crack height is less than 1 / 4 of the thickness of the roof rock or floor rock, it indicates that the crack height meets the requirements.

7. A hydraulic fracturing optimization design system for controlling fracture height in deep coalbed methane reservoirs, characterized by, The method for controlling the crack height of a deep coalbed methane reservoir by hydraulic fracturing optimization design according to any one of claims 1-6 comprises: a data acquisition module for acquiring modeling parameters required for modeling; a modeling module for establishing a three-dimensional crack-through strata numerical simulation model based on a fracturing module of a petrel software platform by using the modeling parameters; a calculation module for calculating critical mechanical parameters and critical bedding quantities of roof rock above a target coal seam section and critical mechanical parameters and critical bedding quantities of floor rock below the target coal seam section by using the three-dimensional crack-through strata numerical simulation model; a judgment module for judging whether the target coal seam section needs to be controlled in crack height according to the calculated critical mechanical parameters and critical bedding quantities of the roof rock, the calculated critical mechanical parameters and critical bedding quantities of the floor rock, and actual mechanical parameters and bedding quantities of the roof rock and actual mechanical parameters and bedding quantities of the floor rock; an optimization module for, when the target coal seam section needs to be controlled in crack height, performing fracturing mode simulation by using the three-dimensional crack-through strata numerical simulation model to obtain fracturing construction parameters when the crack height meets the requirements, and taking the fracturing construction parameters at this time as the final fracturing construction parameters.

8. An electronic device, comprising: comprise: one or more processors; a storage device having one or more programs stored thereon; when the one or more programs are executed by the one or more processors, the one or more processors implement the method for controlling the crack height of a deep coalbed methane reservoir by hydraulic fracturing optimization design according to any one of claims 1-6.

9. A storage medium, characterized by a computer program is stored thereon, wherein the computer program is executed by a processor to implement the method for controlling the crack height of a deep coalbed methane reservoir by hydraulic fracturing optimization design according to any one of claims 1-6.

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