CN109887614B - Hydraulic fracture analysis method and device - Google Patents
Hydraulic fracture analysis method and device Download PDFInfo
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- CN109887614B CN109887614B CN201910058833.6A CN201910058833A CN109887614B CN 109887614 B CN109887614 B CN 109887614B CN 201910058833 A CN201910058833 A CN 201910058833A CN 109887614 B CN109887614 B CN 109887614B
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Abstract
The invention relates to a hydraulic fracture analysis method and a hydraulic fracture analysis device, and belongs to the technical field of shale gas development. The method comprises the following steps: obtaining the distribution range of natural fractures in each of a plurality of regions of a shale gas reservoir in a shale gas field; acquiring the stress difference of each area; hydraulically fracturing the shale gas reservoir to form hydraulic fractures in each zone; acquiring the distribution range of hydraulic fractures in each region; acquiring the overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on the designated surface, and the area of the first orthographic projection of the hydraulic fractures in each region on the designated surface; determining the communication degree of the hydraulic fractures in each region to the natural fractures according to a first preset formula; and generating a first corresponding relation table of the stress difference and the communication degree according to a first preset formula. The present invention provides a way to analyze hydraulic fractures based on their communication with natural fractures. The method is used for analyzing the hydraulic fracture in the shale gas reservoir.
Description
Technical Field
The invention relates to the technical field of shale gas development, in particular to a hydraulic fracture analysis method and device.
Background
The shale gas is natural gas existing in a shale reservoir in a free state and an adsorption state, has no natural energy, and can obtain commercial yield only by hydraulic fracturing in the development process of the shale gas reservoir.
The shale reservoir stratum widely develops natural fractures, and in the hydraulic fracturing process, the hydraulic fractures can communicate or expand the natural fractures to form a complex fracture network, so that the shale gas reservoir stratum is fully improved, and natural gas existing in shale can be transported through the hydraulic fractures.
Although hydraulic fracturing techniques have been developed more thoroughly, there is no clear way to analyze hydraulic fractures based on their communication with natural fractures.
Disclosure of Invention
The application provides a hydraulic fracture analysis method and device. The problem that the related art does not have a clear mode for analyzing the hydraulic fractures according to the communication degree of the hydraulic fractures to the natural fractures can be solved, and the technical scheme is as follows:
in one aspect, a hydraulic fracture analysis method is provided, the method comprising:
obtaining the distribution range of natural fractures in each of a plurality of regions of a shale gas reservoir in a shale gas field;
acquiring the stress difference of each region;
hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each of the zones;
acquiring the distribution range of hydraulic fractures in each region;
acquiring the overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on a designated plane and the area of the first orthographic projection of the hydraulic fractures in each region on the designated plane, wherein the designated plane is parallel to the horizontal plane;
determining the communication degree of the hydraulic fracture in each region to the natural fracture according to a first preset formula, wherein the first preset formula is as follows:
wherein the D1 is the overlapping area, the D2 is the area of the first orthographic projection, and the G1 is the degree of communication;
and generating a first corresponding relation table of the stress difference and the communication degree according to the first preset formula, wherein the first corresponding relation table comprises the corresponding relation of the stress difference and the communication degree of each region.
Optionally, the shale gas field further comprises a plurality of gas wells, the plurality of gas wells penetrate through the plurality of regions in a one-to-one correspondence, each gas well comprises a horizontal gas well, the first orthographic projection of the hydraulic fracture in each region on the designated surface comprises a first sub orthographic projection and a second sub orthographic projection, the first sub orthographic projection and the second sub orthographic projection are positioned on two sides of a reference surface penetrating through a horizontal gas well in each gas well corresponding to the region, and the reference surface is perpendicular to the designated surface, and the method further comprises:
acquiring the area of a first sub orthographic projection and the area of a second sub orthographic projection of the hydraulic fracture in each region on the designated surface;
determining the symmetry coefficient of the hydraulic fracture in each area on two sides of the gas well according to a second preset formula, wherein the second preset formula is as follows:
wherein the G2 is the symmetry coefficient, the D21 is the area of the first orthographic projection, and the D22 is the area of the second orthographic projection;
and generating a second corresponding relation table of the stress difference and the symmetry coefficient, wherein the second corresponding relation table comprises the corresponding relation of the stress difference and the symmetry coefficient of each region.
Optionally, the method further comprises:
acquiring the average trend of the natural fracture of each region;
and generating a third corresponding relation table of the average trend and the communication degree of the natural fractures, wherein the third corresponding relation table comprises the average trend and the communication degree of the natural fractures of each region.
Optionally, the method further comprises:
judging whether the hydraulic fractures in each area are symmetrical on two sides of the gas well according to whether the symmetry coefficient is within a preset coefficient range, wherein the preset coefficient range is as follows: 0.8< G2< 1.2;
obtaining a symmetrical judgment result of whether the hydraulic fractures in each area are symmetrical on two sides of the gas well;
and updating the second corresponding relation table so that the second corresponding relation table further comprises the corresponding relation between the stress difference of each region and the symmetry judgment result.
Optionally, the shale gas reservoir is located in a shale gas field, the shale gas field further includes multiple gas wells, the multiple regions and the multiple gas wells correspond one to one, each gas well passes through its corresponding region, and the obtaining a distribution range of natural fractures in each of the multiple regions of the shale gas reservoir includes:
acquiring a three-dimensional data volume of the shale gas reservoir;
carrying out ant body tracking on the three-dimensional data body to obtain the distribution range and the response intensity of a plurality of ant bodies in each region;
determining the number of natural cracks in the distribution range of each ant body in each region according to a designated corresponding relation table, wherein the designated corresponding relation table comprises the corresponding relation between the response intensity of the ant bodies and the number of the natural cracks, and the number is positively correlated with the response intensity;
acquiring imaging logging fracture interpretation data of each gas well, wherein the imaging logging fracture interpretation data comprise a trend range and an inclination angle range of a natural fracture in each gas well;
and randomly assigning the trend range and the dip angle range of the natural fractures in each gas well to a plurality of natural fractures in the region of each gas well to obtain the distribution range of the natural fractures in each region.
Optionally, the preset correspondence table includes:
the ant body is corresponding to 4000 natural cracks when the response intensity of the ant body is less than 0.4, is corresponding to 8300 natural cracks when the response intensity of the ant body is more than 0.4 and less than or equal to 0.65, is corresponding to 6400 natural cracks when the response intensity of the ant body is more than 0.65 and less than or equal to 0.8, and is corresponding to 11500 natural cracks when the response intensity of the ant body is more than 0.8.
Optionally, the obtaining a three-dimensional data volume of the shale gas reservoir includes:
performing three-dimensional earthquake on the shale gas reservoir;
collecting three-dimensional seismic data generated by the shale gas reservoir in a three-dimensional seismic process;
interpreting the three-dimensional seismic data to obtain the three-dimensional data volume.
Optionally, the hydraulic fracturing of the shale gas reservoir comprises:
performing hydraulic fracturing on the shale gas reservoir and acquiring microseism monitoring data generated by the shale gas reservoir;
the acquiring of the distribution range of the hydraulic fractures in each region comprises the following steps:
interpreting the microseismic inspection data to obtain a distribution range of hydraulic fractures for each of the zones.
Optionally, the obtaining a stress difference of each of the regions includes:
acquiring overburden pressure of each area;
acquiring the formation pore pressure of each region;
acquiring the horizontal maximum principal stress of each region according to a third preset formula, wherein the third preset formula is as follows:
the sigmaHFor the horizontal maximum principal stress of each of said regions, said EhorzIs the anisotropic horizontal static Young's modulus, said EvertIs an anisotropic perpendicular static Young's modulusAmount v saidvertFor the anisotropic vertical static Poisson's ratio, said vhorzIs the anisotropic horizontal static Poisson's ratio, the epsilonHThe strain coefficient of the structure in the direction of the maximum principal stress, the epsilonhIs the minimum principal stress direction strain coefficient, the σvFor overburden pressure of each of the zones and the PpFormation pore pressure for each of the zones;
acquiring the horizontal minimum principal stress of each region according to a fourth preset formula, wherein the fourth preset formula is as follows:
the sigmahA horizontal minimum principal stress for each of said regions;
obtaining the stress difference of each region according to a fifth preset formula, wherein the fifth preset formula is as follows: t1 ═ σH-σhAnd the T1 is the stress difference of each region.
In another aspect, a hydraulic fracture analysis device is provided, the hydraulic fracture analysis device comprising:
the system comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining the distribution range of natural fractures in each of a plurality of areas of a shale gas reservoir in a shale gas field;
the second acquisition module is used for acquiring the stress difference of each region;
a fracturing module for hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each of the zones;
the third acquisition module is used for acquiring the distribution range of the hydraulic fractures in each region;
a fourth acquisition module, configured to acquire an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture in each of the regions on a designated plane, and an area of a first orthographic projection of the hydraulic fracture in each of the regions on the designated plane, where the designated plane is parallel to a horizontal plane;
a first determination module for determining hydraulic fracture pairs in each of the zones according to a first preset formulaThe communication degree of the natural fracture is as follows:
wherein the D1 is the overlapping area, the D2 is the area of the first orthographic projection, and the G1 is the degree of communication;
the first generating module is configured to generate a first correspondence table of the stress difference and the communication degree according to the first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each of the regions.
The technical scheme provided by the application can at least comprise the following beneficial effects: after the distribution range and the stress difference of the natural fractures in each area in the shale gas reservoir are obtained, hydraulic fracturing is performed on the shale gas reservoir and the distribution range of the hydraulic fractures in each area is obtained. The overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on the designated face and the area of the first orthographic projection of the hydraulic fractures in each region on the designated face are then obtained. And determining the proportion of the overlapping area to the area of the first orthographic projection according to a first preset formula so as to obtain the communication degree of the hydraulic fracture in each region to the natural fracture. The communication may be in a size that reflects the communication of hydraulic fractures with natural fractures. And then generating a first corresponding relation table of the stress difference and the communication degree according to the first preset formula. The hydraulic fractures are analyzed according to the communication degree of the hydraulic fractures to the natural fractures under different stress differences.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments will be briefly described below, it being apparent that the drawings in the following description are only some embodiments of the invention, and that other drawings may be derived from those drawings by a person skilled in the art without inventive effort.
FIG. 1 is a flow chart of a hydraulic fracture analysis method according to an embodiment of the present invention;
FIG. 2 is a flow chart of another hydraulic fracture analysis method provided by an embodiment of the invention;
FIG. 3 is a flowchart of a method for obtaining a three-dimensional data volume of a shale gas reservoir according to an embodiment of the present invention;
FIG. 4 is a schematic diagram showing the distribution of natural fracture trends in a gas well;
fig. 5 is a flowchart of a method for obtaining a stress difference of each region according to an embodiment of the present invention;
FIG. 6 illustrates orthographic distribution plots of hydraulic fractures and natural fractures on a given face in a region of a shale gas reservoir;
FIG. 7 illustrates orthographic distribution plots of hydraulic fractures and natural fractures on a given face in another region of a shale gas reservoir;
FIG. 8 is a orthographic projection diagram of a hydraulic fracture in a region and a horizontal segment of a gas well in the gas well corresponding to the region on a designated surface according to another embodiment of the invention;
FIG. 9 is a orthographic projection diagram of a hydraulic fracture in another area and a horizontal segment of a gas well in the gas well corresponding to the area on a designated surface, according to an embodiment of the invention;
FIG. 10 is a flow chart of yet another hydraulic fracture analysis method provided by an embodiment of the present invention;
FIG. 11 shows orthographic distribution plots of hydraulic fractures and natural fractures on a given face in yet another region of a shale gas reservoir;
FIG. 12 shows orthographic distribution plots of hydraulic fractures and natural fractures on a given face in yet another region of a shale gas reservoir;
FIG. 13 is a flow chart of yet another hydraulic fracture analysis method provided by an embodiment of the present invention;
FIG. 14 is a schematic structural diagram of a hydraulic fracture analysis apparatus according to an embodiment of the present invention;
FIG. 15 is a schematic structural diagram of another hydraulic fracture analysis apparatus provided in an embodiment of the present invention;
fig. 16 is a schematic structural diagram of a first obtaining module according to an embodiment of the present invention;
fig. 17 is a schematic structural diagram of a second obtaining module according to an embodiment of the present invention;
FIG. 18 is a schematic structural diagram of another hydraulic fracture analysis apparatus provided in an embodiment of the present invention;
fig. 19 is a schematic structural diagram of another hydraulic fracture analysis apparatus according to an embodiment of the present invention.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, and it is apparent that the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Shale gas fields typically include multiple shale gas reservoirs in which natural fractures exist. And shale gas is distributed in these natural fractures. But shale gas is not readily extracted from natural fractures. Hydraulic fracturing of shale gas reservoirs is therefore required. After hydraulic fracturing is carried out on a certain shale gas reservoir, hydraulic fractures can be formed in the shale gas reservoir, and the hydraulic fractures can be communicated with natural fractures, so that shale gas located in the natural fractures can be transported through the hydraulic fractures. So that the shale gas can be easily exploited.
Fig. 1 is a flow chart of a hydraulic fracture analysis method according to an embodiment of the present invention, and as shown in fig. 1, the hydraulic fracture analysis method may include:
And 102, acquiring the stress difference of each area.
And 104, acquiring the distribution range of the hydraulic fractures in each area.
And 105, acquiring the overlapping area of the orthographic projections of the hydraulic fracture and the natural fracture in each area on the designated surface, and the area of the first orthographic projection of the hydraulic fracture in each area on the designated surface, wherein the designated surface is parallel to the horizontal plane.
And 106, determining the communication degree of the hydraulic fractures in each area to the natural fractures according to a first preset formula.
Wherein, the first preset formula is as follows:
d1 is the overlapping area, D2 is the area of the first orthographic projection, and G1 is the communication degree.
In summary, in the hydraulic fracture analysis method provided by the embodiment of the present invention, after the distribution range and the stress difference of the natural fractures in each region in the shale gas reservoir are obtained, the shale gas reservoir is subjected to hydraulic fracturing, and the distribution range of the hydraulic fractures in each region is obtained. The overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on the designated face and the area of the first orthographic projection of the hydraulic fractures in each region on the designated face are then obtained. And determining the proportion of the overlapping area to the area of the first orthographic projection according to a first preset formula so as to obtain the communication degree of the hydraulic fracture in each region to the natural fracture. The communication may be in a size that reflects the communication of hydraulic fractures with natural fractures. And then generating a first corresponding relation table of the stress difference and the communication degree according to the first preset formula. The hydraulic fractures are analyzed according to the communication degree of the hydraulic fractures to the natural fractures under different stress differences.
It should be noted that, a shale gas field generally includes a plurality of shale gas reservoirs, and after obtaining a first correspondence table of stress differences and communication degrees of a plurality of regions in one shale gas reservoir of the shale gas field and stress differences of a plurality of regions in another shale gas reservoir of the shale gas field, a worker may refer to the first correspondence table to predict communication degrees corresponding to the stress differences of different regions in the another shale gas reservoir.
In the method for analyzing the hydraulic fracture provided by the embodiment of the invention, the hydraulic fracture can be analyzed according to different parameters under different conditions. The following describes a way of analyzing hydraulic fractures according to the communication degree of the hydraulic fractures to natural fractures under different stress differences and a way of analyzing hydraulic fractures according to the symmetry degree of the hydraulic fractures on two sides of a gas well under different stress differences.
Fig. 2 is a flow chart of another hydraulic fracture analysis method provided in an embodiment of the present invention, and as shown in fig. 2, the hydraulic fracture analysis method may include:
The shale gas reservoir is located in a shale gas field, the shale gas field further comprises a plurality of gas wells, and the plurality of gas wells penetrate through the plurality of areas in a one-to-one correspondence mode.
Optionally, as shown in fig. 3, step 201 may include:
and 2011, acquiring a three-dimensional data volume of the shale gas reservoir.
For example, in step 2011, a three-dimensional earthquake may be performed on the shale gas reservoir (the three-dimensional earthquake refers to an earthquake generated by placing and starting an artificial seismic source on the stratum where the shale gas reservoir is located). Then, three-dimensional seismic data generated by the shale gas reservoir in the three-dimensional seismic process can be collected, and the three-dimensional seismic data comprises three-dimensional seismic waves generated by the shale gas reservoir in the three-dimensional seismic process. The three-dimensional seismic data may then be interpreted to obtain a three-dimensional data volume that includes a distribution of the shale gas reservoir in three-dimensional space. The three-dimensional seismic data can be input into three-dimensional seismic wave interpretation software (such as GeoFrame or LandMark), so that the three-dimensional seismic wave interpretation software interprets the three-dimensional seismic data to obtain a three-dimensional data volume.
Ant body tracing is a bionic algorithm for simulating an ant colony to search food, and the bionic algorithm can extract the distribution range and response intensity of a fault plane (such as an ant body) from a three-dimensional data body.
As in step 2012, the three-dimensional data volume may be input into a three-dimensional geological model software (e.g., Petrel), so that the three-dimensional geological model software processes the three-dimensional data volume by using an ant tracking algorithm to obtain a distribution range and a response strength of a plurality of ant bodies in each region of the shale gas reservoir.
In the appointed corresponding relation table, the ant bodies have different numbers of corresponding natural cracks in different response strength ranges.
Optionally, in the specified correspondence table, 4000 natural cracks are corresponded when the response strength of the ant body is less than 0.4. The ant body corresponds to 8300 natural cracks when the response strength of the ant body is greater than 0.4 and less than or equal to 0.65. And 6400 natural cracks are formed when the response loudness of the ant body is greater than 0.65 and less than or equal to 0.8. When the response strength of the ant body is more than 0.8, the ant body corresponds to 11500 natural cracks.
And step 2014, acquiring imaging logging fracture interpretation data of each gas well.
The imaging logging fracture interpretation data comprise the trend range and the dip angle range of the natural fracture in each gas well.
Optionally, in step 2014, an imaging log may be performed on each gas well using the logging tool to obtain imaging log data of each gas well, where the imaging log data includes a borehole wall image of the gas well. The imaging log data for each gas well may then be input into an imaging log interpretation software (e.g., techlog) and the imaging log interpretation software may be caused to interpret the imaging log data to obtain imaging log fracture interpretation data for each gas well.
It should be noted that the orientation of a natural fracture in a gas well may refer to the azimuth of the natural fracture in the gas well. For example, fig. 4 is a schematic distribution diagram of the natural fracture strike in a gas well, and the schematic distribution diagram includes a circle with an azimuth marked and four sectors located in the circle. The starting angle to the ending angle of each fan shape represents the trend range of the natural fracture, and the radius of each fan shape can reflect the number of the natural fractures in the trend range. And 0 degrees represents the true north direction, 90 degrees represents the true east direction, 180 degrees represents the true south direction, and 270 degrees represents the true west direction. The natural fractures in the gas well run in a range including: a range of 35 degrees to 55 degrees, a range of 120 degrees to 140 degrees, a range of 215 degrees to 235 degrees, and a range of 300 degrees to 330 degrees.
It should be noted that, when the trend of a certain natural crack is obtained, if one end of the natural crack is used as a starting end and the other end is used as a ending end, the trend of the natural crack is oriented to the true north. If the other end of the natural crack is taken as a starting end and the other end is taken as a final section, the trend of the natural crack faces the south. That is, the natural fractures are oriented toward true north and south with the same essential meaning.
Since the 35 degree to 55 degree trend range and the 215 degree to 235 degree trend range in fig. 4 are symmetrical, the 120 degree to 140 degree trend range and the 300 degree to 330 degree trend range are symmetrical. Thus, the range of 35 degrees to 55 degrees is synonymous with the range of 215 degrees to 235 degrees, and the range of 120 degrees to 150 degrees and the range of 300 degrees to 330 degrees. In addition, as can be seen from fig. 4, the number of natural fractures with a strike ranging from 35 degrees to 55 degrees accounts for one third of the number of natural fractures in the well, and the number of natural fractures with a strike ranging from 120 degrees to 150 degrees accounts for two thirds of the number of natural fractures in the well.
Additionally, the dip angle of a natural fracture in a gas well refers to the angle of the natural fracture in the gas well from the horizontal.
When the random assignment is carried out on the plurality of natural fractures in the area of the gas well, the trends of the plurality of natural fractures can be randomly assigned within the trend range of the natural fractures in the gas well. And the trends of the natural fractures with different proportions can be specified according to the trend ranges with different proportions.
Alternatively, if the distribution of natural fractures in a gas well is shown in fig. 4, the orientation of one third of the natural fractures in the area of the gas well may be randomly assigned within the orientation range of 35 degrees to 55 degrees, and the orientation of the other two thirds of the natural fractures in the area of the gas well may be randomly assigned within the orientation range of 120 degrees to 140 degrees.
In addition, if the inclination angle range of the natural fracture in a certain gas well is 5 degrees to 10 degrees, the inclination angle of the natural fracture in the area where the gas well is located can be randomly assigned within the inclination angle range of 5 degrees to 10 degrees.
As shown in fig. 5, step 202 may include:
at step 2021, overburden pressure is obtained for each zone.
The shale gas reservoir is located in a shale gas field, the shale gas field further comprises a plurality of drill platforms, the plurality of drill platforms correspond to the plurality of gas wells one by one, and each drill platform is located on the corresponding gas well.
For example, in step 2021, density log data for each gas well may be obtained by a density logging tool.
The densitometry data may then be interpreted by densitometry data interpretation software (e.g., Forward) to obtain an average initial rock density, a first density fitting parameter, and a second density fitting parameter between each region in the shale gas reservoir and the surface.
And then, acquiring the depth and the vertical depth of the area corresponding to the gas well in the shale gas reservoir. Wherein depth refers to the length that extends from the surface of the shale gas field to the zone along the direction of extension of the gas well, and vertical depth refers to the distance from the zone to the surface in a direction perpendicular to the horizontal plane. It should be noted that the gas well includes a vertical section gas well and a horizontal section gas well which are connected, the vertical section gas well extends to the shale gas reservoir, and the horizontal section gas well is located in the shale gas reservoir. The extending direction of the gas well at the vertical well section is vertical to the horizontal plane, and the extending direction of the gas well at the horizontal well section is parallel to the horizontal plane. When the density logging is carried out on the gas well, only the density logging is carried out on the gas well at the straight well section in the gas well, and at the moment, the depth and the vertical depth of the area corresponding to the gas well are the same.
Then, the height from the drill floor of the drill floor corresponding to the gas well corresponding to each area to the ground can be obtained.
Thereafter, overburden pressure for each zone may be calculated according to a sixth predetermined formula. The sixth preset formula may be:
wherein σvFor overburden pressure, p, of each zonesurFor the average initial rock density, A, between each region and the ground0The first density fitting parameter is set, alpha is the second density fitting parameter, z is the depth from each area to the ground, TVD is the vertical depth from each area to the ground, AG is the height from the drill floor of the drill floor corresponding to the gas well corresponding to each area to the ground, and g is the gravity acceleration.
Exemplarily at ρsur2650kg/m3、A0Is 0.04. Alpha is 0.99, Z and TVD are both 1400m, AG is 6m, and gravity acceleration g is 9.8m/s2Then, σ can be calculated according to a sixth preset formulavIs 40 MPa. At rhosur2650kg/m3、A00.04, alpha 0.99, Z and TVD 1800m, AG 6m, and g 9.8m/s gravity acceleration2Then, σ can be calculated according to a sixth preset formulavIs 49 MPa.
2022, obtaining formation pore pressure for each zone.
Wherein, the third preset formula is:
σHfor the horizontal maximum principal stress, E, of each zonehorzAs the anisotropic horizontal static Young's modulus, EvertIs an anisotropic perpendicular direction static Young's modulus, vvertIs the anisotropic vertical static Poisson's ratio, vhorzIs the anisotropic horizontal static Poisson's ratio, epsilonHThe structural strain coefficient, epsilon, in the direction of maximum principal stresshIs the minimum principal stress direction strain coefficient, sigmavOverburden pressure for each zone and PpThe formation pore pressure for each zone.
In step 2023, the three-dimensional data volume of the shale gas reservoir acquired in step 2011 may be analyzed by a three-dimensional geological model software to obtain an anisotropic horizontal static young modulus, an anisotropic vertical static poisson ratio, an anisotropic horizontal static poisson ratio, a maximum principal stress direction structural strain coefficient, and a minimum principal stress direction strain coefficient in the shale gas reservoir.
Illustratively, in step 2023, if EhorzIs 25GPa and EvertIs 23GPa and vvertIs 0.25 vhorzIs 0.27, PpIs 15MPa, epsilonHIs 0.89 epsilonhIs 0.93 and σvIs 40MWhen Pa, sigma can be calculated according to a third preset formulaHIs 37 MPa. If EhorzIs 25GPa and EvertIs 23GPa and vvertIs 0.25 vhorzIs 0.27, PpIs 15MPa, epsilonHIs 0.89 epsilonhIs 0.93 and σvAt 49MPa, sigma can be calculated according to a third preset formulaHIs 47 MPa.
Wherein, the fourth preset formula is:
σhthe horizontal minimum principal stress for each region.
Illustratively, in step 2024, if EhorzIs 25GPa and EvertIs 23GPa and vvertIs 0.25 vhorzIs 0.27, PpIs 15MPa, epsilonHIs 0.89 epsilonhIs 0.93 and σvWhen the pressure is 40MPa, the sigma can be calculated according to a fourth preset formulahIs 26 MPa. If EhorzIs 25GPa and EvertIs 23GPa and vvertIs 0.25 vhorzIs 0.27, PpIs 15MPa, epsilonHIs 0.89 epsilonhIs 0.93 and σvAt 49MPa, sigma can be calculated according to a fourth preset formulahIs 27 MPa.
Wherein, the fifth preset formula is: t1 ═ σH-σhAnd T1 is the stress difference for each region.
Illustratively, in step 2025, if σ isHIs 37MPa and sigmahAt 26MPa, T1 can be calculated to be 11MPa according to the fifth predetermined formula. If σHIs 47MPa and sigmahAt 27MPa, T1 can be calculated to be 20MPa according to the fifth predetermined formula.
The shale gas reservoir is hydraulically fractured 203 to form hydraulic fractures in each zone.
It should be noted that when hydraulic fracturing is performed on a shale gas reservoir, the shale gas reservoir may undergo a micro-earthquake. And in step 203, when the shale gas reservoir is subjected to hydraulic fracturing, the micro earthquake generated by the shale gas reservoir can be monitored so as to obtain the micro earthquake monitoring data generated by the shale gas reservoir.
And step 204, acquiring the distribution range of the hydraulic fractures in each area.
In step 204, the microseismic monitoring data may be interpreted to obtain a distribution range of hydraulic fractures for each zone. Illustratively, in step 204, the microseismic survey data may be input into microseismic wave interpretation software (e.g., InSite) that interprets the microseismic survey data to obtain the distribution range of the hydraulic fracture of each region.
And step 205, acquiring the overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each area on the designated surface, and the area of the first orthographic projection of the hydraulic fractures in each area on the designated surface, wherein the designated surface is parallel to the horizontal plane.
For example, fig. 6 shows orthographic distribution patterns of hydraulic fractures and natural fractures on a designated face in a region of a shale gas reservoir, wherein the natural fractures L11 and the hydraulic fractures L21 in the region overlap, the natural fractures are rectangular, and the hydraulic fractures L21 are circular, as shown in fig. 6. Fig. 7 shows orthographic distribution patterns of hydraulic fractures and natural fractures on a given face in another region of the shale gas reservoir, where natural fractures L12 and hydraulic fractures L22 overlap, as shown in fig. 7.
And step 206, determining the communication degree of the hydraulic fractures in each area to the natural fractures according to a first preset formula.
Wherein, the first preset formula is as follows:
wherein D1 is the overlapping area, D2 is the area of the first orthographic projection, and G1 is the communication degree.
It should be noted that, in step 206, the overlapping area of the natural fracture L11 and the hydraulic fracture L21 in fig. 6 may be obtained first, so as to obtain the overlapping area of the natural fracture L11 and the hydraulic fracture L21And the area of the first orthographic projection of the hydraulic fracture L21. If the overlap area D1 of the natural fracture L11 and the hydraulic fracture L21 is 100m2The area D2 of the first orthographic projection of the hydraulic fracture L21 is 400m2Then, according to a first predetermined formula, the communication G1 of the hydraulic fracture to the natural fracture in the area shown in fig. 6 can be calculated to be 0.25.
In addition, in step 206, the overlapping area of the natural fracture L12 and the hydraulic fracture L22 in fig. 7 and the area of the first orthographic projection of the hydraulic fracture L22 may also be obtained first. If the overlap area D1 of the natural fracture L12 and the hydraulic fracture L22 is 30m2The area D2 of the first orthographic projection of the hydraulic fracture L22 is 300m2Then, according to a first predetermined formula, the communication G1 of the hydraulic fracture to the natural fracture in the area shown in fig. 7 can be calculated to be 0.1.
Step 207, generating a first corresponding relation table of the stress difference and the communication degree according to a first preset formula, wherein the first corresponding relation table includes a corresponding relation of the stress difference and the communication degree of each region.
In step 207, if the stress difference of the region shown in fig. 6 is 20MPa, the stress difference of the region shown in fig. 7 is 11 MPa. Then a first correspondence table may be generated as follows:
first corresponding relation table
| Difference in stress | Degree of communication |
| 11 | 0.1 |
| 20 | 0.25 |
In the first mapping table, when the stress difference of the region in the shale gas reservoir is 11MPa, the communication degree is 0.1, and when the stress difference of the region in the shale gas reservoir is 20MPa, the communication degree is 0.25.
And step 208, acquiring the area of the first sub orthographic projection and the area of the second sub orthographic projection of the hydraulic fracture in each region on the designated surface.
The first orthographic projection of the hydraulic fracture in each area on the designated surface comprises a first sub orthographic projection and a second sub orthographic projection, the first sub orthographic projection and the second sub orthographic projection are located on two sides of a reference surface of a horizontal section of the gas well penetrating through the corresponding gas well in each area, and the reference surface is perpendicular to the designated surface.
For example, fig. 8 is an orthographic projection diagram of a hydraulic fracture in a region and a horizontal gas well in a gas well corresponding to the region on a designated surface, as shown in fig. 8, wherein the hydraulic fractures L23 in the region are located on two sides of a reference plane (the reference plane is a plane which passes through the horizontal gas well Y11 and is perpendicular to the paper surface, and is not shown in fig. 8) of the horizontal gas well Y11 in the gas well corresponding to the region. The first orthographic projection of the hydraulic fracture L23 on the designated plane comprises a first sub orthographic projection and a second sub orthographic projection, wherein the first sub orthographic projection is located on one side of the reference plane, and the second sub orthographic projection is located on the other side of the reference plane.
Fig. 9 is an orthographic projection diagram of a hydraulic fracture in a further area and a horizontal gas well in a gas well corresponding to the area on a designated surface, wherein the hydraulic fracture L24 in the area is located on two sides of a reference surface (not shown in fig. 9) passing through the horizontal gas well Y12 in the gas well corresponding to the area, according to the embodiment of the invention. The first orthographic projection of the hydraulic fracture L24 on the designated plane comprises a first sub orthographic projection and a second sub orthographic projection, wherein the first sub orthographic projection is located on one side of the reference plane, and the second sub orthographic projection is located on the other side of the reference plane.
And 209, determining the symmetry coefficient of the hydraulic fracture in each area on two sides of the gas well according to a second preset formula.
Wherein the second predetermined formula is:
g2 is the symmetry coefficient, D21 is the area of the first orthographic projection, and D22 is the area of the second orthographic projection.
In step 209, a first sub-forward projection area and a second sub-forward projection area of the hydraulic fracture L23 in fig. 8 may be obtained. Illustratively, if the first sub-orthographic projection area of the hydraulic fracture L23 is 270m2The second sub-forward projection area is 300m2Then the symmetry coefficient G2 for the hydraulic fracture in the area shown in fig. 8 on both sides of the gas well may be calculated to be 0.9 according to a second predetermined formula.
In addition, in step 208, the first sub-forward projection area and the second sub-forward projection area of the hydraulic fracture L24 in fig. 9 may also be obtained first. If the first sub-orthographic projection area of the hydraulic fracture L24 is 50m2The second sub-forward projection area is 250m2Then the symmetry coefficient G2 of the hydraulic fracture in the area shown in fig. 9 on both sides of the gas well may be calculated to be 0.2 according to a second predetermined formula.
Step 210, generating a second corresponding relation table of the stress difference and the symmetry coefficient, wherein the second corresponding relation table comprises the corresponding relation of the stress difference and the symmetry coefficient of each area.
In step 210, if the stress difference of the region shown in fig. 8 is 13MPa, the stress difference of the region shown in fig. 9 is 23 MPa. Then a second correspondence table may be generated as follows:
second corresponding relation table
| Difference in stress | Coefficient of symmetry |
| 3 | 0.9 |
| 23 | 0.1 |
In the second correspondence table, when the stress difference of the region in the shale gas reservoir is 13MPa, the symmetry coefficient is 0.2, and when the stress difference of the region in the shale gas reservoir is 23MPa, the symmetry coefficient is 0.1.
In the above embodiment, after the distribution range and the stress difference of the natural fractures in each region in the shale gas reservoir are obtained, the shale gas reservoir is subjected to hydraulic fracturing, and the distribution range of the hydraulic fractures in each region is obtained. The trends of the natural fractures in the well are randomly specified within the trend range of the natural fractures, the area of a first orthographic projection and the area of a second orthographic projection of the hydraulic fractures in each area on a specified surface can be obtained, the symmetry coefficient of the hydraulic fractures in each area on two sides of the gas well is determined according to a second preset formula, and then a second corresponding relation table of stress difference and the symmetry coefficient is generated. The effect of analyzing the hydraulic fracture according to the symmetry of the hydraulic fracture on two sides of the gas well under different stress differences is achieved.
In addition, after a second corresponding relation table of stress differences and symmetry coefficients of a plurality of regions in one shale gas reservoir of the shale gas field and stress differences of a plurality of regions in another shale gas reservoir of the shale gas field are obtained, a worker can predict the symmetry coefficients corresponding to the stress differences of different regions in the another shale gas reservoir by referring to the second corresponding relation table.
The following describes a manner of analyzing hydraulic fractures according to the communication degree of the hydraulic fractures with respect to natural fractures when the average directions of the natural fractures are different.
Fig. 10 is a flowchart of another hydraulic fracture analysis method according to an embodiment of the present invention, and as shown in fig. 10, the hydraulic fracture analysis method may include:
And step 1002, acquiring the stress difference of each area.
And 1003, performing hydraulic fracturing on the shale gas reservoir to form hydraulic fractures in each area.
And 1004, acquiring the distribution range of the hydraulic fractures in each area.
And step 1006, determining the communication degree of the hydraulic fracture in each area to the natural fracture according to a first preset formula.
It should be noted that, as for the specific implementation process of step 1001 to step 1007, reference may be made to the specific implementation process of step 201 to step 207 in the foregoing embodiment.
The average orientation of a natural fracture in a region is the average of the orientations of a plurality of natural fractures located in the region.
Illustratively, fig. 11 shows orthographic distribution diagrams of hydraulic fractures and natural fractures on a designated face in yet another region in the shale gas reservoir, as shown in fig. 11, the natural fractures L15 and the hydraulic fractures L25 in the region overlap, and the average trend of the natural fractures L15 is 71 degrees. Fig. 12 shows orthographic distribution diagrams of hydraulic fractures and natural fractures on a designated face in yet another region in a shale gas reservoir, as shown in fig. 12, where natural fractures L16 and hydraulic fractures L26 overlap and the average strike-out of natural fractures L16 is 25 degrees.
And 1009, generating a third correspondence table of the average trend and the communication degree of the natural fractures, wherein the third correspondence table comprises the average trend and the communication degree of the natural fractures of each region.
In step 1009, if the communication rate of the hydraulic fractures to the natural fractures in the region shown in fig. 11 is 0.3, and the communication rate of the hydraulic fractures to the natural fractures in the region shown in fig. 12 is 0.1, a third correspondence table may be generated as follows:
third correspondence table
| Mean trend direction | Degree of communication |
| 71 | 0.3 |
| 25 | 0.1 |
In the third correspondence table, when the average trend of natural fractures in the area of the shale gas reservoir is 71 degrees, the communication degree is 0.3, and when the average trend of natural fractures in the area of the shale gas reservoir is 25 degrees, the communication degree is 0.1.
In the above embodiment, after obtaining the distribution range of the natural fractures in each zone in the shale gas reservoir, performing hydraulic fracturing on the shale gas reservoir, and obtaining the distribution range of the hydraulic fractures in each zone. And obtaining the average trend of the natural cracks of each area, and generating a second corresponding relation table of the stress difference and the symmetry coefficient. The hydraulic fracture effect can be analyzed according to the communication degree of the hydraulic fracture to the natural fracture under the condition that the average trend of the natural fracture is different.
In addition, after a third corresponding relation table of the average trend of the natural fractures of the multiple regions in one shale gas reservoir of the shale gas field and the communication degree of the hydraulic fractures to the natural fractures and the average trend of the natural fractures of the multiple regions in another shale gas reservoir of the shale gas field are obtained, a worker can refer to the third corresponding relation table to predict the communication degree corresponding to the average trend of the natural fractures of different regions in the another shale gas reservoir.
The process of analyzing hydraulic fractures according to the symmetric determination results of hydraulic fractures on two sides of a gas well under different stress differences is described below.
Fig. 13 is a flowchart of a hydraulic fracture analysis method according to another embodiment of the present invention, and as shown in fig. 13, the hydraulic fracture analysis method may include:
And step 1302, acquiring the stress difference of each area.
And 1303, performing hydraulic fracturing on the shale gas reservoir to form hydraulic fractures in each area.
And 1304, acquiring the distribution range of the hydraulic fractures in each area.
And 1306, determining the communication degree of the hydraulic fractures in each area to the natural fractures according to a first preset formula.
And 1309, determining the symmetry coefficient of the hydraulic fracture in each area on two sides of the gas well according to a second preset formula.
It should be noted that, the specific implementation process of step 1301 to step 1310 may refer to the specific implementation process of step 201 to step 210 in the above embodiment.
And 1311, judging whether the hydraulic fractures in each area are symmetrical on two sides of the gas well according to whether the symmetry coefficient is within a preset coefficient range.
Wherein, the preset coefficient range is as follows: 0.8< G2< 1.2. For example, in step 1311, it may be determined that the symmetry coefficient 0.9 of the hydraulic fracture on both sides of the gas well in the region shown in fig. 8 is within the preset coefficient range, that is, the hydraulic fracture in the region shown in fig. 8 is symmetric on both sides of the gas well. In step 1311, it may also be determined that the symmetry coefficient 0.2 of the hydraulic fractures in the area shown in fig. 9 on both sides of the gas well is outside the preset coefficient range, that is, the hydraulic fractures in the area shown in fig. 9 are asymmetric on both sides of the gas well.
And 1312, acquiring a symmetrical judgment result of whether the hydraulic fractures in each area are symmetrical on two sides of the gas well.
In step 1312, it may be obtained that the symmetry determination result of the hydraulic fracture in the region shown in fig. 8 is symmetric. And it can be obtained that the symmetry determination result of the hydraulic fracture in the region shown in fig. 9 is asymmetric.
For example, the second mapping table updated in step 1313 may be as follows:
updated second corresponding relation table
| Difference in stress | Coefficient of symmetry | Result of symmetry determination |
| 3 | 0.9 | Symmetry |
| 23 | 0.1 | Asymmetry |
In the above-described embodiment, the area of the first sub-orthographic projection of the hydraulic fracture on the designated plane (the area of the first sub-orthographic projection of the hydraulic fracture L23 in fig. 8 as in the above-described embodiment) and the area of the second sub-orthographic projection (the area of the second sub-orthographic projection of the hydraulic fracture L23 in fig. 8 as in the above-described embodiment) in each region are obtained. And determining the symmetry coefficient of the hydraulic fracture in each area on two sides of the gas well according to a second preset formula, and generating a second corresponding relation table of the stress difference and the symmetry coefficient. And judging whether the hydraulic fractures in each area are symmetrical on two sides of the gas well according to whether the symmetry coefficient is within the preset coefficient range. And obtaining a symmetrical judgment result of whether the hydraulic fractures in each area are symmetrical on two sides of the gas well. And then updating the second corresponding relation table so that the second corresponding relation table also comprises the corresponding relation between the stress difference of each area and the symmetry judgment result. The effect of analyzing the hydraulic fractures according to the symmetric judgment results of the hydraulic fractures on the two sides of the gas well under different stress differences is achieved.
In addition, after obtaining the updated second correspondence table of the stress differences and the symmetry coefficients of the multiple regions in one shale gas reservoir of the shale gas field and the stress differences of the multiple regions in another shale gas reservoir of the shale gas field, the worker may refer to the updated second correspondence table to predict the symmetry determination results corresponding to the stress differences of the different regions in the another shale gas reservoir.
In summary, in the hydraulic fracture analysis method provided by the embodiment of the present invention, after the distribution range and the stress difference of the natural fractures in each region in the shale gas reservoir are obtained, the shale gas reservoir is subjected to hydraulic fracturing, and the distribution range of the hydraulic fractures in each region is obtained. Then, the overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on the designated surface and the area of the first orthographic projection of the hydraulic fractures in each region on the designated surface are obtained. And determining the proportion of the overlapping area to the area of the first orthographic projection according to a first preset formula so as to obtain the communication degree of the hydraulic fracture in each region to the natural fracture. The communication may be in a size that reflects the communication of hydraulic fractures with natural fractures. And then generating a first corresponding relation table of the stress difference and the communication degree according to the first preset formula. The hydraulic fractures are analyzed according to the communication degree of the hydraulic fractures to the natural fractures under different stress differences.
Fig. 14 is a schematic structural diagram of a hydraulic fracture analysis apparatus according to an embodiment of the present invention, and as shown in fig. 14, the hydraulic fracture analysis apparatus 140 may include:
a first obtaining module 1401 is configured to obtain a distribution range of natural fractures in each of a plurality of regions of a shale gas reservoir in a shale gas field.
A second obtaining module 1402, configured to obtain a stress difference of each region.
A fracturing module 1403 for hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each zone.
A third obtaining module 1404, configured to obtain a distribution range of hydraulic fractures in each zone.
A fourth obtaining module 1405, configured to obtain an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture on the designated plane in each region, and an area of a first orthographic projection of the hydraulic fracture on the designated plane in each region, wherein the designated plane is parallel to the horizontal plane.
A first determining module 1406 is configured to determine a communication degree of the hydraulic fractures in each zone with the natural fractures according to a first preset formula.
Wherein, the first preset formula is as follows:
d1 is the overlapping area, D2 is the area of the first orthographic projection, and G1 is the communication degree.
The first generating module 1407 is configured to generate a first correspondence table of the stress difference and the communication degree according to a first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each area.
In summary, in the hydraulic fracture analysis apparatus provided in the embodiment of the present invention, after the first obtaining module and the second obtaining module obtain the distribution range and the stress difference of the natural fractures in each region in the shale gas reservoir, the fracturing module performs hydraulic fracturing on the shale gas reservoir and obtains the distribution range of the hydraulic fractures in each region. Then, the third acquisition module acquires the overlapping area of the orthographic projections of the hydraulic fracture and the natural fracture in each area on the designated surface, and the fourth acquisition module acquires the area of the first orthographic projection of the hydraulic fracture in each area on the designated surface. The first determining module determines the proportion of the overlapping area to the area of the first orthographic projection according to a first preset formula so as to obtain the communication degree of the hydraulic fractures in each region to the natural fractures. The communication may be in a size that reflects the communication of hydraulic fractures with natural fractures. And then the first generating module generates a first corresponding relation table of the stress difference and the communication degree according to the first preset formula. The hydraulic fractures are analyzed according to the communication degree of the hydraulic fractures to the natural fractures under different stress differences.
Fig. 15 is a schematic structural diagram of another hydraulic fracture analysis apparatus according to an embodiment of the present invention, and as shown in fig. 15, the hydraulic fracture analysis apparatus 150 may include:
the first obtaining module 1501 is configured to obtain a distribution range of natural fractures in each of a plurality of regions of a shale gas reservoir in a shale gas field.
A second obtaining module 1502 is configured to obtain a stress difference of each region.
A fracturing module 1503 for hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each zone.
A third obtaining module 1504 for obtaining the distribution range of hydraulic fractures in each area.
A fourth obtaining module 1505 for obtaining an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture in each region on a designated plane, and an area of a first orthographic projection of the hydraulic fracture in each region on the designated plane, wherein the designated plane is parallel to the horizontal plane.
The first determining module 1506 is configured to determine a communication of the hydraulic fractures in each zone to the natural fractures according to a first predetermined formula.
The first generating module 1507 is configured to generate a first correspondence table of the stress difference and the communication degree according to a first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each region.
A fifth obtaining module 1508, configured to obtain an area of the first sub-orthographic projection and an area of the second sub-orthographic projection of the hydraulic fracture on the designated plane in each of the regions.
A second determining module 1509 configured to determine the symmetry coefficient of the hydraulic fractures in each zone on both sides of the gas well according to a second preset formula.
The second generating module 1510 is configured to generate a second correspondence table of the stress difference and the symmetry coefficient, where the second correspondence table includes a correspondence between the stress difference and the symmetry coefficient of each region.
Alternatively, as shown in fig. 16, the first obtaining module 1501 may include:
a first obtaining unit 15011, configured to obtain a three-dimensional data volume of the shale gas reservoir.
A tracking unit 15012, configured to perform ant body tracking on the three-dimensional data body to obtain a distribution range and response strength of multiple ant bodies in each area.
A determining unit 15013, configured to determine the number of natural cracks in the distribution range of each ant body in each area according to a designated correspondence table, where the designated correspondence table includes a correspondence between the response strength of the ant body and the number of natural cracks, and the number of natural cracks is positively correlated to the response strength.
A second acquisition unit 15014 for acquiring imaged log fracture interpretation data for each gas well.
And an assigning unit 15015, configured to randomly assign the strike range and the dip angle range of the natural fractures in each gas well to a plurality of natural fractures in the area where each gas well is located, so as to obtain the distribution range of the natural fractures in each area.
Optionally, as shown in fig. 17, the second obtaining module 1502 may include:
a third acquisition unit 15021 acquires overburden pressure for each zone.
A fourth acquiring unit 15022, configured to acquire the formation pore pressure of each zone.
A fifth obtaining unit 15023, configured to obtain a horizontal maximum principal stress of each region according to a third preset formula.
A sixth obtaining unit 15024, configured to obtain the horizontal minimum principal stress of each region according to a fourth preset formula.
A seventh acquiring unit 15025, configured to acquire the stress difference of each region according to a fifth preset formula.
Fig. 18 is a schematic structural diagram of another hydraulic fracture analysis apparatus according to an embodiment of the present invention, and as shown in fig. 17, the hydraulic fracture analysis apparatus 180 may include:
a first obtaining module 1801 is configured to obtain a distribution range of natural fractures within each of a plurality of regions of a shale gas reservoir in a shale gas field.
A second obtaining module 1802 is used for obtaining the stress difference of each area.
A fracturing module 1803 for hydraulic fracturing of the shale gas reservoir to form hydraulic fractures within each zone.
A third obtaining module 1804, configured to obtain a distribution range of the hydraulic fractures in each of the regions.
A fourth obtaining module 1805, configured to obtain an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture in each region on the designated plane, and an area of a first orthographic projection of the hydraulic fracture in each region on the designated plane, wherein the designated plane is parallel to the horizontal plane.
A first determining module 1806, configured to determine, according to a first preset formula, a communication degree of the hydraulic fractures in each region with the natural fractures.
The first generating module 1807 is configured to generate a first correspondence table of the stress difference and the communication degree according to a first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each area.
A sixth obtaining module 1808, configured to obtain an average strike of natural fractures for each region.
A third generating module 1809, configured to generate a third correspondence table of the average strike and the communication degree of the natural fractures, where the third correspondence table includes the average strike and the communication degree of the natural fractures of each region.
Fig. 19 is a schematic structural diagram of another hydraulic fracture analysis apparatus according to an embodiment of the present invention, and as shown in fig. 19, the hydraulic fracture analysis apparatus 190 may include:
the first obtaining module 1901 is configured to obtain a distribution range of natural fractures within each of a plurality of regions of a shale gas reservoir in a shale gas field.
A second obtaining module 1902, configured to obtain a stress difference of each region.
A fracturing module 1903 to hydraulically fracture the shale gas reservoir to form hydraulic fractures within each zone.
A third obtaining module 1904, configured to obtain a distribution range of hydraulic fractures in each zone.
A fourth obtaining module 1905, configured to obtain an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture in each region on the designated plane, and an area of a first orthographic projection of the hydraulic fracture in each region on the designated plane, wherein the designated plane is parallel to the horizontal plane.
A first determining module 1906, configured to determine a communication degree of the hydraulic fractures in each zone with the natural fractures according to a first preset formula.
The first generating module 1907 is configured to generate a first correspondence table of the stress difference and the communication degree according to a first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each region.
A fifth acquiring module 1908, configured to acquire an area of the first sub-orthographic projection and an area of the second sub-orthographic projection of the hydraulic fracture on the designated plane in each region.
A second determining module 1909, configured to determine the symmetry coefficient of the hydraulic fractures in each region on both sides of the gas well according to a second preset formula.
A second generating module 1910, configured to generate a second correspondence table of the stress difference and the symmetry coefficient, where the second correspondence table includes a correspondence between the stress difference and the symmetry coefficient of each region.
And a judging module 1911, configured to judge whether the hydraulic fractures in each area are symmetric on two sides of the gas well according to whether the symmetry coefficient is within a preset coefficient range.
And a seventh obtaining module 1912, configured to obtain a symmetric determination result of whether the hydraulic fractures in each region are symmetric on two sides of the gas well.
An updating module 1913, configured to update the second mapping table, so that the second mapping table further includes a mapping between the stress difference of each region and the symmetry determination result.
In summary, in the hydraulic fracture analysis apparatus provided in the embodiment of the present invention, after the first obtaining module and the second obtaining module obtain the distribution range and the stress difference of the natural fractures in each region in the shale gas reservoir, the fracturing module performs hydraulic fracturing on the shale gas reservoir and obtains the distribution range of the hydraulic fractures in each region. Then, the third acquisition module acquires the overlapping area of the orthographic projections of the hydraulic fracture and the natural fracture in each area on the designated surface, and the fourth acquisition module acquires the area of the first orthographic projection of the hydraulic fracture in each area on the designated surface. The first determining module determines the proportion of the overlapping area to the area of the first orthographic projection according to a first preset formula so as to obtain the communication degree of the hydraulic fractures in each region to the natural fractures. The communication may be in a size that reflects the communication of hydraulic fractures with natural fractures. And then the first generating module generates a first corresponding relation table of the stress difference and the communication degree according to the first preset formula. The hydraulic fractures are analyzed according to the communication degree of the hydraulic fractures to the natural fractures under different stress differences.
It should be noted that, the method embodiment provided in the embodiment of the present invention can be mutually referred to with a corresponding apparatus embodiment, and the embodiment of the present disclosure does not limit this. The sequence of the steps of the method embodiments provided by the embodiments of the present invention can be appropriately adjusted, and the steps can be correspondingly increased or decreased according to the situation, and any method that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention, and therefore, the detailed description thereof shall not be repeated.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
Claims (10)
1. A hydraulic fracture analysis method, comprising:
obtaining the distribution range of natural fractures in each of a plurality of regions of a shale gas reservoir in a shale gas field;
acquiring the stress difference of each region;
hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each of the zones;
acquiring the distribution range of hydraulic fractures in each region;
acquiring the overlapping area of the orthographic projections of the hydraulic fractures and the natural fractures in each region on a designated plane and the area of the first orthographic projection of the hydraulic fractures in each region on the designated plane, wherein the designated plane is parallel to the horizontal plane;
determining the communication degree of the hydraulic fracture in each region to the natural fracture according to a first preset formula, wherein the first preset formula is as follows:
wherein the D1 is the overlapping area, the D2 is the area of the first orthographic projection, and the G1 is the degree of communication;
and generating a first corresponding relation table of the stress difference and the communication degree according to the first preset formula, wherein the first corresponding relation table comprises the corresponding relation of the stress difference and the communication degree of each region.
2. The method of claim 1, wherein the shale gas field further comprises a plurality of gas wells which pass through the plurality of zones in a one-to-one correspondence, each gas well comprising a horizontal gas well, wherein the first orthographic projection of the hydraulic fracture in each zone on the given surface comprises a first sub orthographic projection and a second sub orthographic projection, the first sub orthographic projection and the second sub orthographic projection being located on two sides of a reference surface passing through a horizontal gas well in each gas well in the corresponding zone, the reference surface being perpendicular to the given surface, the method further comprising:
acquiring the area of a first sub orthographic projection and the area of a second sub orthographic projection of the hydraulic fracture in each region on the designated surface;
determining the symmetry coefficient of the hydraulic fracture in each area on two sides of the gas well according to a second preset formula, wherein the second preset formula is as follows:
wherein the G2 is the symmetry coefficient, the D21 is the area of the first sub-orthographic projection, and the D22 is the area of the second sub-orthographic projection;
and generating a second corresponding relation table of the stress difference and the symmetry coefficient, wherein the second corresponding relation table comprises the corresponding relation of the stress difference and the symmetry coefficient of each region.
3. The method of claim 1, further comprising:
acquiring the average trend of the natural fracture of each region;
and generating a third corresponding relation table of the average trend and the communication degree of the natural fractures, wherein the third corresponding relation table comprises the average trend and the communication degree of the natural fractures of each region.
4. The method of claim 2, further comprising:
judging whether the hydraulic fractures in each area are symmetrical on two sides of the gas well according to whether the symmetry coefficient is within a preset coefficient range, wherein the preset coefficient range is as follows: 0.8< G2< 1.2;
obtaining a symmetrical judgment result of whether the hydraulic fractures in each area are symmetrical on two sides of the gas well;
and updating the second corresponding relation table so that the second corresponding relation table further comprises the corresponding relation between the stress difference of each region and the symmetry judgment result.
5. The method of claim 1, wherein the shale gas reservoir is located in a shale gas field, the shale gas field further comprises a plurality of gas wells, the plurality of zones and the plurality of gas wells are in one-to-one correspondence, each gas well passes through its corresponding zone, and the obtaining of the distribution range of natural fractures in each of the plurality of zones of the shale gas reservoir comprises:
acquiring a three-dimensional data volume of the shale gas reservoir;
carrying out ant body tracking on the three-dimensional data body to obtain the distribution range and the response intensity of a plurality of ant bodies in each region;
determining the number of natural cracks in the distribution range of each ant body in each region according to a designated corresponding relation table, wherein the designated corresponding relation table comprises the corresponding relation between the response intensity of the ant bodies and the number of the natural cracks, and the number is positively correlated with the response intensity;
acquiring imaging logging fracture interpretation data of each gas well, wherein the imaging logging fracture interpretation data comprise a trend range and an inclination angle range of a natural fracture in each gas well;
and randomly assigning the trend range and the dip angle range of the natural fractures in each gas well to a plurality of natural fractures in the region of each gas well to obtain the distribution range of the natural fractures in each region.
6. The method according to claim 5, wherein the preset correspondence table comprises:
the ant body is corresponding to 4000 natural cracks when the response intensity of the ant body is less than 0.4, is corresponding to 8300 natural cracks when the response intensity of the ant body is more than 0.4 and less than or equal to 0.65, is corresponding to 6400 natural cracks when the response intensity of the ant body is more than 0.65 and less than or equal to 0.8, and is corresponding to 11500 natural cracks when the response intensity of the ant body is more than 0.8.
7. The method of claim 5, wherein the obtaining the three-dimensional data volume of the shale gas reservoir comprises:
performing three-dimensional earthquake on the shale gas reservoir;
collecting three-dimensional seismic data generated by the shale gas reservoir in a three-dimensional seismic process;
interpreting the three-dimensional seismic data to obtain the three-dimensional data volume.
8. The method of claim 1, wherein the hydraulic fracturing of the shale gas reservoir comprises:
performing hydraulic fracturing on the shale gas reservoir and acquiring microseism monitoring data generated by the shale gas reservoir;
the acquiring of the distribution range of the hydraulic fractures in each region comprises the following steps:
interpreting the microseismic monitoring data to obtain a distribution range of hydraulic fractures for each of the zones.
9. The method of claim 1, wherein said obtaining a stress difference for each of said regions comprises:
acquiring overburden pressure of each area;
acquiring the formation pore pressure of each region;
acquiring the horizontal maximum principal stress of each region according to a third preset formula, wherein the third preset formula is as follows:
the sigmaHFor the horizontal maximum principal stress of each of said regions, said EhorzIs the anisotropic horizontal static Young's modulus, said EvertIs the anisotropic perpendicular static Young's modulus, said vvertFor the anisotropic vertical static Poisson's ratio, said vhorzIs the anisotropic horizontal static Poisson's ratio, the epsilonHThe strain coefficient of the structure in the direction of the maximum principal stress, the epsilonhIs the minimum principal stress direction strain coefficient, the σvFor overburden pressure of each of the zones and the PpFormation pore pressure for each of the zones;
acquiring the horizontal minimum principal stress of each region according to a fourth preset formula, wherein the fourth preset formula is as follows:
the sigmahA horizontal minimum principal stress for each of said regions;
obtaining the stress difference of each region according to a fifth preset formula, wherein the fifth preset formula is as follows: t1 ═ σH-σhAnd the T1 is the stress difference of each region.
10. A hydraulic fracture analysis device, comprising:
the system comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining the distribution range of natural fractures in each of a plurality of areas of a shale gas reservoir in a shale gas field;
the second acquisition module is used for acquiring the stress difference of each region;
a fracturing module for hydraulically fracturing the shale gas reservoir to form hydraulic fractures within each of the zones;
the third acquisition module is used for acquiring the distribution range of the hydraulic fractures in each region;
a fourth acquisition module, configured to acquire an overlapping area of orthographic projections of the hydraulic fracture and the natural fracture in each of the regions on a designated plane, and an area of a first orthographic projection of the hydraulic fracture in each of the regions on the designated plane, where the designated plane is parallel to a horizontal plane;
the first determining module is used for determining the communication degree of the hydraulic fractures in each region to the natural fractures according to a first preset formula, wherein the first preset formula is as follows:
wherein the D1 is the overlapping area, the D2 is the area of the first orthographic projection, and the G1 is the degree of communication;
the first generating module is configured to generate a first correspondence table of the stress difference and the communication degree according to the first preset formula, where the first correspondence table includes a correspondence between the stress difference and the communication degree of each of the regions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910058833.6A CN109887614B (en) | 2019-01-22 | 2019-01-22 | Hydraulic fracture analysis method and device |
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