CN-121997104-A - Shale gas development geological stability evaluation method

CN121997104ACN 121997104 ACN121997104 ACN 121997104ACN-121997104-A

Abstract

The invention discloses a shale gas development geological stability evaluation method which comprises the steps of collecting geological structure data and seismic monitoring data of a shale gas development area, dividing a space division map of the shale gas development area into a plurality of grid cells, determining the minimum complete vibration level Mc, calculating fault activation potential coefficients FAP in the grid cells based on a corrected mole-coulomb fault activation criterion, calculating a geological structure evaluation index TRI of the grid cells, fusing seismic b values in the seismic monitoring data, constructing ETAS models, calculating the external triggering rate of engineering activities, calculating a seismic activity disturbance index SDI of the grid cells, and calculating the geological stability index by utilizing the geological structure evaluation index TRI and the seismic activity disturbance index SDI The geological stability of the shale gas development area was evaluated. The method can realize dynamic tracking evaluation of the geological stability of the shale gas in the whole development period.

Inventors

OUYANG LIMING
CHEN DISHU
YANG QISHAN
WANG WEI
GUO XIAOZHONG
ZHANG YE
HUANG YANLING
WU XIAOCHUAN
WANG JINXI
ZHANG ZHIPING
XU DIAO

Assignees

重庆华地资环科技有限公司
重庆地质矿产研究院

Dates

Publication Date: 20260508
Application Date: 20260408

Claims (5)

1. The shale gas development geological stability evaluation method is characterized by comprising the following steps of: Step S1, collecting geological structure data and earthquake monitoring data of a shale gas development area, dividing a space demarcation diagram of the shale gas development area into a plurality of grid units, and determining a minimum complete earthquake level Mc according to the earthquake monitoring data; S2, calculating fault activation potential coefficients FAP in the grid cells based on the corrected mole-coulomb fault activation criteria by using geological structure data in the grid cells, objectively weighting the geological structure data in the grid cells through principal component analysis PCA, and calculating a geological structure evaluation index TRI of the grid cells; S3, fusing the seismic b values in the seismic monitoring data to obtain standardized coefficients of the seismic b values, constructing ETAS models to calculate external trigger rates of engineering activities, calculating the standardized coefficients of the external trigger rates, and calculating seismic activity disturbance indexes SDI of the grid units based on the standardized coefficients of the seismic b values and the standardized coefficients of the external trigger rates; step S4, calculating a geological stability index by using the geological structure evaluation index TRI and the seismic activity disturbance index SDI The geological stability of the shale gas development area was evaluated.
2. The method for evaluating the geological stability of shale gas development according to claim 1, wherein the step S2 comprises: S21, calculating fault activation potential coefficients FAP in the grid cells based on the corrected mole-coulomb fault activation criterion by using geological structure data in the grid cells; ; Wherein, the For the shear stress on the fault plane, Is the static internal friction coefficient of the fault plane, As normal stress on the fault plane, For pore fluid pressure on the fracture surface, For the cohesive force of the fracture surface, Is a valued function of the fault inclination angle influence coefficient, Is a valued function of the fault extension length influence coefficient, Is a valued function of fault interval influence coefficient, Is the fault dip angle; Step S22, inclination angle of fault Standardized processing is carried out on the extension length L and the vertical fault distance H to obtain a fault inclination angle coefficient Coefficient of extension length And a vertical break-distance coefficient ; , , ; Wherein, the Respectively the maximum value and the minimum value of the fault dip angle of the shale gas development area, The maximum value and the minimum value of the fault extension length of the shale gas development area are respectively, Respectively the maximum value and the minimum value of the fault vertical fracture distance of the shale gas development area; step S23, according to the fault inclination angle coefficient of each grid unit Coefficient of extension length And a vertical break-distance coefficient Construction of fault parameter standardization matrix ; ; Where m is the number of grid cells, Fault inclination coefficients of the mth grid cell respectively Coefficient of extension length And a vertical break-distance coefficient ; Step S24, normalizing the matrix according to fault parameters Calculating a correlation coefficient matrix ; ; Step S25, solving the characteristic equation Obtaining the characteristic values of fault dip angle, extension length and vertical fault distance , Is a unit vector; step S26, according to the characteristic value Objective weighting of computed fault inclination, extension length and vertical fault distance ; ; Step S27, utilizing objective weights And fault dip coefficient Coefficient of extension length And a vertical break-distance coefficient Calculating a geological structure evaluation index TRI of the grid unit; 。
3. the shale gas development geological stability evaluation method of claim 2, wherein the fault inclination angle influence coefficient is a valued function The method comprises the following steps: ; The value function of the fault extension length influence coefficient The method comprises the following steps: ; The value function of the fault interval influence coefficient The method comprises the following steps: Wherein H is the vertical fault distance of the fault.
4. The method for evaluating the geological stability of shale gas development according to claim 2, wherein the step S3 comprises: s31, calculating a seismic b value according to the minimum complete magnitude Mc; ; Wherein e is a natural constant, The earthquake time average earthquake magnitude is the earthquake time average magnitude with the earthquake magnitude being greater than or equal to the minimum complete earthquake magnitude Mc; step S32, carrying out standardization processing on the seismic b value to obtain a standardization coefficient of the seismic b value in the grid unit ; ; Step S33, constructing ETAS model to calculate earthquake occurrence rate ; ; Wherein t is the time of the time, K is the residual earthquake excitation capacity coefficient and is the background earthquake incidence rate, The time of the occurrence of the ith seismic event, c is the aftershock attenuation time constant, p is the aftershock attenuation index, As the influence coefficient of the magnitude on the occurrence rate of the aftershocks, The magnitude of the ith seismic event; Step S34, according to the occurrence rate of earthquake Calculating external trigger rate of engineering activities within grid cells ; ; Step S35 external trigger Rate to grid cell Performing normalization processing to obtain normalized coefficient of external trigger rate of grid cell ; ; Wherein, the The minimum value and the maximum value of the internal and external triggering rates of the shale gas development area are respectively; step S36, according to the normalized coefficient of the seismic b value And normalized coefficients of external trigger rate Calculating an earthquake activity disturbance index SDI of the grid unit; ; Wherein, the The weight coefficients of engineering activity and earthquake activity are respectively adopted.
5. The method for evaluating the geological stability of shale gas development according to claim 4, wherein said step S4 comprises: step S41 setting a threshold value of the geological structure evaluation index TRI of the grid cell And a threshold value of the seismic activity disturbance index SDI Calculating a geological stability index ; ; Step S42, setting a geological stability index Threshold of (2) If (1) And judging that the shale gas development area corresponding to the grid unit is poor in geological stability, otherwise, judging that the shale gas development area corresponding to the grid unit is good in geological stability.

Description

Shale gas development geological stability evaluation method Technical Field The invention relates to the field of shale gas development geological safety research, in particular to a shale gas development geological stability evaluation method. Background The hydraulic fracturing operation in the shale gas development process can inject high-pressure fluid into the stratum, so that the problems of pore pressure rise, fault activation, earthquake induction and other geological stability are easily caused, and the shale gas development area generates more than ML3.0 level earthquake related to hydraulic fracturing, so that casualties and property loss are caused, and the safe and efficient development of shale gas is severely restricted. Therefore, the evaluation of the geological stability in the shale gas development process is particularly important, and the related technology of the geological stability evaluation of the shale gas development area at present has the following defects: 1. The evaluation system is single in dimension, the prior art focuses on static evaluation of single fault activation risk, does not systematically merge regional geological structure background, seismic activity dynamic evolution and engineering development disturbance intensity multidimensional coupling effect, and cannot comprehensively represent the geological stability change of the shale gas development full period; 2. The induced earthquake identification and quantification capability is insufficient, the natural structure earthquake and the engineering induced earthquake are difficult to accurately separate in the prior art, the disturbance degree of engineering development activities on the geological stability of the region cannot be quantified, and the evaluation result cannot effectively guide the on-site construction management and control. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a shale gas development geological stability evaluation method, and the quantitative, refined and dynamic evaluation of the geological stability of a shale gas development area is realized by constructing an evaluation system of geological structure-seismic activity coupling. In order to achieve the aim of the invention, the invention adopts the following technical scheme: the shale gas development geological stability evaluation method comprises the following steps: Step S1, collecting geological structure data and earthquake monitoring data of a shale gas development area, dividing a space demarcation diagram of the shale gas development area into a plurality of grid units, and determining a minimum complete earthquake level Mc according to the earthquake monitoring data; S2, calculating fault activation potential coefficients FAP in the grid cells based on the corrected mole-coulomb fault activation criteria by using geological structure data in the grid cells, objectively weighting the geological structure data in the grid cells through principal component analysis PCA, and calculating a geological structure evaluation index TRI of the grid cells; S3, fusing the seismic b values in the seismic monitoring data to obtain standardized coefficients of the seismic b values, constructing ETAS models to calculate external trigger rates of engineering activities, calculating the standardized coefficients of the external trigger rates, and calculating seismic activity disturbance indexes SDI of the grid units based on the standardized coefficients of the seismic b values and the standardized coefficients of the external trigger rates; step S4, calculating a geological stability index by using the geological structure evaluation index TRI and the seismic activity disturbance index SDI The geological stability of the shale gas development area was evaluated. Further, step S2 includes: S21, calculating fault activation potential coefficients FAP in the grid cells based on the corrected mole-coulomb fault activation criterion by using geological structure data in the grid cells; ; Wherein, the For the shear stress on the fault plane,Is the static internal friction coefficient of the fault plane,As normal stress on the fault plane,For pore fluid pressure on the fracture surface,For the cohesive force of the fracture surface,Is a valued function of the fault inclination angle influence coefficient,Is a valued function of the fault extension length influence coefficient,Is a valued function of fault interval influence coefficient,Is the fault dip angle; Step S22, inclination angle of fault Standardized processing is carried out on the extension length L and the vertical fault distance H to obtain a fault inclination angle coefficientCoefficient of extension lengthAnd a vertical break-distance coefficient; ,,; Wherein, the Respectively the maximum value and the minimum value of the fault dip angle of the shale gas development area,The maximum value and the minimum value of the fault extension length