CN116223213B - Stratum stress sensitivity evaluation method based on acoustic response - Google Patents
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Abstract
The invention provides a stratum stress sensitivity evaluation method based on acoustic response. The method comprises the following steps of 1, calculating and determining effective confining pressure of a stratum and experimental testing confining pressure points; step 2, representative core test sample preparation and acoustic wave test frequency selection; step 3, testing the sonic wave velocity of the core sample under different confining pressures; and 4, calculating stress sensitivity coefficients of the core sample under different confining pressures by using the sonic wave velocity. The method is not only suitable for high Kong Gaoshen stratum and mesoporous medium permeability stratum, but also can conveniently evaluate the stress sensitivity of low pore low permeability, ultra-low Kong Tedi permeability and other stratum, and overcomes the problems that the permeability of the low pore low permeability and ultra-low Kong Te low permeability stratum is long in time consumption, large in difficulty, large in error and even incapable of being accurately measured under the condition of high confining pressure, so that the sensitivity cannot be accurately and reasonably evaluated. The invention has important significance for safe drilling of deep oil gas, especially shale oil gas and other ultra-low permeability and unconventional oil gas resources and long-term high-efficiency development.
Description
Technical Field
The invention belongs to the fields of petroleum geology, oil and gas well engineering, oil and gas field development engineering, petroleum and natural gas exploitation and the like, and particularly relates to a stratum stress sensitivity evaluation method based on acoustic response.
Background
The stress sensitivity evaluation of the reservoir is an important basis for determining reasonable production pressure difference of the oil and gas well and specifying the oil and gas exploitation implementation scheme, and has important significance for guaranteeing long-term safe and efficient exploitation of the oil and gas reservoir and improving the recovery ratio of the oil and gas reservoir. At present, permeability of a rock core under different confining pressures or different flow pressures is directly tested by a steady-state method or a pulse attenuation method, and the change of the permeability along with the confining pressures or the flow pressures is analyzed to realize evaluation of reservoir stress sensitivity; however, for low permeability and ultra-low permeability reservoirs, due to poor core permeability of the reservoirs, the problems of long time consumption, large error, large influence of a tested fluid medium on results, incapability of even measuring permeability under the confining pressure condition and the like are faced, so that scientific and effective evaluation of stratum stress sensitivity cannot be realized.
Disclosure of Invention
Aiming at the defects of the prior art for evaluating the stress sensitivity of a reservoir, the invention provides a method for evaluating the stress sensitivity of the stratum based on acoustic response based on the basic principle that acoustic waves have obvious influence on the confining pressure and the pore structure of the stratum. According to the method, the effective confining pressure of the stratum is calculated, the sound wave frequency is selected, sound wave tests under different confining pressures are carried out, the stress sensitivity coefficient of the rock core is calculated by utilizing the sound wave speed, the stress sensitivity coefficient of the stratum is determined, and the stress sensitivity is scientifically and effectively evaluated by utilizing the response of sound waves to the confining pressure.
The invention adopts the following technical scheme:
a stratum stress sensitivity evaluation method based on acoustic response comprises the following steps:
step 1, calculating and determining effective confining pressure and experimental testing confining pressure points of stratum
(1) Determining effective confining pressure
Calculating effective formation confining pressure P ec according to the initial pressure coefficient of the reservoir and the average density of overlying strata rock,
Wherein: DEPTH is the mid-DEPTH of the formation being evaluated; den is the average density of the overburden, P p is the formation pressure coefficient of the formation being evaluated; d dep is the formation depth.
(2) Determining minimum test confining pressure and maximum test confining pressure
Wherein the minimum test confining pressure P min is not more than 3.0MPa; the maximum test confining pressure P max is calculated by the formula (2);
Pmax＝Pec·A (2)
Wherein A is the calculated coefficient of the maximum test confining pressure. The value of the coefficient A is determined according to the maximum effective confining pressure required by the oil and gas exploitation operation; when the oil and gas exploitation engineering can not be determined, the value can be taken:
(3) A test confining pressure point P T is determined.
The m+1 test confining pressure points P T are determined by equation (3):
PT＝{P0,P1,…,Pi,…PM} (3)
Wherein, P 0＝Pmin,PM＝Pmax is used for preparing the high-performance high-voltage power cable, M≥3
Step 2. Representative core test sample preparation and Acoustic test frequency selection
(1) Representative test specimens were drilled
Drilling N standard plunger core samples S 1、S2、...Si...SN with the same lithology but obvious difference in porosity from a downhole full-diameter core of an evaluated reservoir as representative core samples for evaluating formation stress sensitivity, wherein the number N of the drilled plunger samples is more than or equal to 5, and the end faces of the plunger core samples are polished smoothly and the two ends are parallel;
(2) Acoustic frequency selection for formation stress sensitivity evaluation
And respectively applying confining pressure P 0 to N standard plunger core samples S 1、S2、…、Si、…、SN, and selecting sound wave frequencies by performing preliminary sound wave test on the samples, wherein the selection of the incident sound wave frequencies is as follows: the test frequency is greater than 50KHz, and the selected frequency sound wave is utilized to test each sample, so that complete and clear waveforms can be obtained.
(3) Sonic wave velocity of sample under test confining pressure P 0
Applying confining pressure P 0 to N standard plunger core samples S 1、S2、...Si...SN respectively, and performing sonic wave velocity test to obtain sonic wave velocities SV 10、SV20、…、SVi0、…、SVN0 of N samples under confining pressure P 0;
Step 3. Sonic wave velocity test of core sample under different surrounding pressures
The formation stress sensitivity evaluation needs to respectively carry out acoustic wave tests on the core sample under the loading path condition and the unloading path condition, and specifically comprises the following steps:
(1) The sonic velocity of the sample under loading conditions was tested.
Confining pressure P 1,…,Pi,…,PM is applied to a standard plunger core sample in sequence. After confining pressure is applied to stabilize, the holding time is not less than 5min, and then the sonic wave velocity of the sample under each confining pressure condition is testedAnd respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain sonic wave velocities SV + of the N samples under the loading condition and the test surrounding pressure of M+1.
Wherein,The acoustic wave velocity of the sample i under the confining pressure P j is the loading condition.
(2) Testing sonic velocity of sample under unloading conditions
After confining pressure is applied to P M, the confining pressure is sequentially removed to P M-1,…,Pi,…P1,P0. After the confining pressure is stable, the holding time is not less than 5min, and then the sonic wave velocity of the sample under each confining pressure condition is testedAnd respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain N standard plunger core samples, and respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain sonic wave velocities SV - of the N samples under the loading condition and the test surrounding pressure of M+1.
Wherein,The sonic velocity of sample i at ambient pressure P j is the unloading condition.
Step 4, calculating stress sensitivity coefficients of the core sample under different surrounding pressures by using the sonic wave velocity
The stratum stress sensitivity evaluation is used for respectively calculating the stress sensitivity coefficient of the core sample under different confining pressures of the loading path and the stress sensitivity coefficient under different confining pressures of the unloading path, and specifically comprises the following steps:
(1) Under loading condition, calculating stress sensitivity coefficient of sample under each surrounding pressure
And (3) calculating stress sensitivity coefficients of the loading process by the formula (6), and respectively calculating stress sensitivity coefficients of the N standard plunger core samples at M confining pressure points to obtain stress sensitivity coefficient matrixes Ss + of the N samples under loading conditions and M different confining pressures, wherein the stress sensitivity coefficient matrixes are shown in the formula (7).
The stress sensitivity coefficient of the sample i under the confining pressure P j is the loading condition; the larger the value, the stronger the stress sensitivity of the stratum represented by the sample i under the loading confining pressure P j is shown.
(2) Under the unloading condition, calculating the stress sensitivity coefficient of the sample under each surrounding pressure.
The stress sensitivity coefficient for the unloading process is calculated by equation (8). Respectively calculating stress sensitivity coefficients of N standard plunger core samples at M confining pressure points to obtain stress sensitivity coefficients Ss - of the N samples under unloading conditions and M different confining pressures, wherein the stress sensitivity coefficients are shown in a formula (9):
Stress sensitivity coefficient of the sample i under the confining pressure P j for unloading conditions; the larger the value, the stronger the stress sensitivity of the stratum represented by the sample i under the unloading confining pressure P j is shown.
Step 5, comprehensive evaluation of stratum stress sensitivity under different confining pressures
(1) Under the loading condition, when the confining pressure P j is applied, the average stress sensitivity coefficient of the stratum is calculated according to the formula (10)Calculating the minimum stress sensitivity coefficient/> of the stratum from formula (11)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (12)
(2) Under the unloading condition, the average stress sensitivity coefficient of the stratum is calculated according to the formula (13) when the confining pressure P j is adoptedCalculating the minimum stress sensitivity coefficient/> of the stratum from formula (14)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (15)
The invention has the beneficial effects that:
The method is based on the basic principle that sound waves have obvious response to the formation confining pressure and pore structures, the effective confining pressure of the formation is calculated, the sound wave frequency is selected, the sound wave velocity of a sample under different confining pressures is tested, the change of the sound wave velocity along with the confining pressure is analyzed, and the formation stress sensitivity coefficient is built and calculated based on the wave velocity, so that the scientific and effective evaluation of the formation stress sensitivity is realized.
The method is not only suitable for high Kong Gaoshen stratum and mesoporous medium-permeability stratum, but also can conveniently evaluate the stress sensitivity of low-pore low-permeability and extremely low Kong Tedi-permeability stratum, and solves the problems that the permeability of the low-pore low-permeability and extremely low Kong Te-permeability stratum is long in time consumption, large in difficulty and large in error and even cannot be accurately measured under the condition of high confining pressure, so that the sensitivity cannot be accurately and reasonably evaluated.
The invention has important significance for safe drilling of deep oil gas, especially shale oil gas and other ultra-low permeability and unconventional oil gas resources and long-term high-efficiency development.
Drawings
FIG. 1 shows the sonic velocity of a sample 1 under loading and unloading of each confining pressure;
FIG. 2 shows the sonic velocity of the sample 3 under loading and unloading of each confining pressure;
FIG. 3 shows the sonic velocity of the sample 5 under loading and unloading of each confining pressure;
FIG. 4 is a graph showing stress sensitivity coefficients of each core sample under loading at each confining pressure;
FIG. 5 is a graph showing stress susceptibility coefficients of each core sample under each confining pressure under unloading conditions;
FIG. 6 is a graph of stress sensitivity coefficients of a formation under loading;
FIG. 7 is a plot of stress sensitivity coefficients of a formation in an unloaded condition;
FIG. 8 is a flow chart of the steps of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 8, the method for evaluating the formation stress sensitivity based on acoustic response of the present invention comprises the following steps:
step 1, calculating and determining effective confining pressure and experimental testing confining pressure points of stratum
(1) Determining effective confining pressure
Calculating effective formation confining pressure P ec according to the initial pressure coefficient of the reservoir and the average density of overlying strata rock,
Wherein: DEPTH is the mid-DEPTH of the formation being evaluated; den is the average density of the overburden, P p is the formation pressure coefficient of the formation being evaluated; d dep is the formation depth.
(2) Determining minimum test confining pressure and maximum test confining pressure
Wherein the minimum test confining pressure P min is not more than 3.0MPa; the maximum test confining pressure P max is calculated by the formula (2);
Pmax＝Pec·A (2)
Wherein A is the calculated coefficient of the maximum test confining pressure. The coefficient value is determined according to the maximum effective confining pressure required by the oil and gas exploitation operation; when the oil and gas exploitation engineering can not be determined, the value can be taken:
(3) A test confining pressure point P T is determined.
The m+1 test confining pressure points P T are determined by equation (3):
PT＝{P0,Pl,…,Pi,…PM} (3)
Wherein, P 0＝Pmin,PM＝Pmax is used for preparing the high-performance high-voltage power cable, M≥3
Step 2. Representative core test sample preparation and Acoustic test frequency selection
(1) Representative test specimens were drilled
Drilling N standard plunger core samples S 1、S2、...Si...SN with the same lithology but obvious difference in porosity from a downhole full-diameter core of an evaluated reservoir as representative core samples for evaluating formation stress sensitivity, wherein the number N of the drilled plunger samples is more than or equal to 5, and the end faces of the plunger core samples are polished smoothly and the two ends are parallel;
(2) Acoustic frequency selection
Applying confining pressure P 0 to N standard plunger core samples S 1、S2、…、Si、…、SN respectively, and selecting sound wave frequencies by performing preliminary sound wave test on the samples, wherein the selection basis of the incident sound wave frequencies is as follows: and the wave form is larger than 50KHz, and the complete and clear wave form can be obtained by testing each sample.
(3) Sonic wave velocity of sample under test confining pressure P 0
And respectively applying confining pressure P 0 to N standard plunger core samples S 1、S2、...Si...SN, and performing sonic wave velocity test to obtain sonic wave velocity SV 10、SV20、…、SVi0、SVN0 of each sample N under confining pressure P 0.
Step 3. Sonic wave velocity test of core sample under different surrounding pressures
(1) The sonic velocity of the sample under loading conditions was tested.
Confining pressure P 1,…,Pi,…,PM is applied to a standard plunger core sample in sequence. After confining pressure is applied to stabilize, the holding time is not less than 5min, and then the sonic wave velocity of the sample under each confining pressure condition is testedAnd respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain sonic wave velocities SV + of the N samples under the loading condition and the test surrounding pressure of M+1.
Wherein,The acoustic wave velocity of the sample i under the confining pressure P j is the loading condition.
(2) Testing sonic velocity of sample under unloading conditions
After confining pressure is applied to P M, the confining pressure is sequentially removed to P M-1,…,Pi,…P1,P0. After the confining pressure is stable, the holding time is not less than 5min, and then the sonic wave velocity of the sample under each confining pressure condition is testedAnd respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain N standard plunger core samples, and respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain sonic wave velocities SV - of the N samples under the loading condition and the test surrounding pressure of M+1.
Wherein,The sonic velocity of sample i at ambient pressure P j is the unloading condition.
Step 4, calculating stress sensitivity coefficients of the core sample under different surrounding pressures by using the sonic wave velocity
(1) Under loading condition, calculating stress sensitivity coefficient of sample under each surrounding pressure
For the stress sensitivity coefficient in the loading process, the stress sensitivity coefficient matrix Ss + of N samples under the loading condition and M different surrounding pressures is calculated by the formula (6), and is shown as the formula (7).
The stress sensitivity coefficient of the sample i under the confining pressure P j is the loading condition; the larger the value, the stronger the stress sensitivity of the stratum represented by the sample i under the loading confining pressure P j is shown.
(2) Under the unloading condition, calculating the stress sensitivity coefficient of the sample under each surrounding pressure.
The stress sensitivity coefficient for the unloading process is calculated by equation (8). Respectively calculating stress sensitivity coefficients of N standard plunger core samples at M confining pressure points to obtain stress sensitivity coefficients Ss - of the N samples under unloading conditions and M different confining pressures, wherein the stress sensitivity coefficients are shown in a formula (9):
Stress sensitivity coefficient of the sample i under the confining pressure P j for unloading conditions; the larger the value, the stronger the stress sensitivity of the stratum represented by the sample i under the unloading confining pressure P j is shown.
Step 5, comprehensive evaluation of stratum stress sensitivity under different confining pressures
(1) Under the loading condition, when the confining pressure P j is applied, the average stress sensitivity coefficient of the stratum is calculated according to the formula (10)Calculating the minimum stress sensitivity coefficient/> of the stratum from formula (11)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (12)
(2) Under the unloading condition, the average stress sensitivity coefficient of the stratum is calculated according to the formula (13) when the confining pressure P j is adoptedCalculating the minimum stress sensitivity coefficient/> of the stratum from formula (14)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (15)
Examples
When the burial depth of the middle part of the stratum to be evaluated is 4000m, the average stratum density is 2.3g/cm 3, the stratum pressure coefficient is 1.3, and the effective stratum confining pressure is calculated to be 40MPa. The maximum confining pressure of the stratum is evaluated to be 60MPa. A total of 12 test confining pressure points for the formation evaluated were determined, where m=11, as follows:
PT＝{P0,P1,…,pi,…,PM}＝{5，10，15，20，25，30，35，40，45，50，55，60}；
The formation evaluated was determined to have 6 samples drilled altogether, i.e., n=6. The acoustic test frequency of the formation being evaluated was determined to be 250KHz using the method described above. The sound wave speeds of 6 samples of the stratum to be evaluated at the confining pressure P 0 =5 MPa measured by the method are respectively as follows: 3080.62m/s, 3298.12m/s, 3240.58m/s, 3118.70m/s, 2829.20m/s and 3085.26m/s. The above method is used to measure the sonic velocity of 6 samples under each confining pressure of the stratum to be evaluated, such as the sonic velocity of loading/unloading the sample 1 under each confining pressure, the sonic velocity of loading/unloading the sample 3 under each confining pressure, and the sonic velocity of loading/unloading the sample 5 under each confining pressure in fig. 1,2, and 3. The stress sensitivity coefficients of each core sample under the loading condition and under each confining pressure are calculated by the method, and are shown in figure 4; the stress sensitivity coefficients of each core sample under each confining pressure under the unloading condition are calculated and shown in fig. 5. The average stress sensitivity coefficient of the stratum under the loading condition is calculated by the method Minimum stress sensitivity coefficient/>Maximum stress sensitivity coefficient/>As shown in fig. 6. Calculating to obtain the average stress sensitivity coefficient/>, of the stratum under the unloading conditionMinimum stress sensitivity coefficientMaximum stress sensitivity coefficient/>As shown in fig. 7, it can be seen that the formation representative samples have significant differences in the stress sensitivity coefficients at different confining pressures, indicating the reliability of the method of the present invention for evaluating formation stress sensitivity.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (2)
1. The stratum stress sensitivity evaluation method based on the acoustic response is characterized by comprising the following steps of:
step 1, calculating and determining effective confining pressure and experimental testing confining pressure points of stratum
(1) Determining effective confining pressure
Calculating effective formation confining pressure P ec according to the initial pressure coefficient of the reservoir and the average density of overlying strata rock,
Wherein: DEPTH is the mid-DEPTH of the formation being evaluated; den is the average density of the overburden, P p is the formation pressure coefficient of the formation being evaluated; d dep is the formation depth;
(2) Determining minimum test confining pressure and maximum test confining pressure
Wherein the minimum test confining pressure P min is not more than 3.0MPa; the maximum test confining pressure P max is calculated by the formula (2);
Pmax＝Pec·A (2)
wherein: a is the calculation coefficient of the maximum test confining pressure;
(3) Determining a test confining pressure point P T
The m+1 test confining pressure points P T are determined by equation (3):
PT＝{P0,P1,…,Pi,…PM} (3)
Wherein, P 0＝Pmin,PM＝Pmax is used for preparing the high-performance high-voltage power cable, M≥3；
Step 2. Representative core test sample preparation and Acoustic test frequency selection
(1) Representative test specimens were drilled
Drilling N standard plunger core samples S 1、S2、...Si...SN with the same lithology but obvious difference in porosity from a downhole full-diameter core of an evaluated reservoir as representative core samples for evaluating formation stress sensitivity, wherein the number N of the drilled plunger samples is more than or equal to 5, and the end faces of the plunger core samples are polished smoothly and the two ends are parallel;
(2) Acoustic frequency selection for formation stress sensitivity evaluation
And respectively applying confining pressure P 0 to N standard plunger core samples S 1、S2、…、Si、…、SN, and selecting sound wave frequencies by performing preliminary sound wave test on the samples, wherein the selection of the incident sound wave frequencies is as follows: the wave is larger than 50KHz, and the selected frequency sound wave is utilized to test each sample, so that complete and clear waveforms can be obtained;
(3) Sonic wave velocity of sample under test confining pressure P 0
Applying confining pressure P 0 to N standard plunger core samples S 1、S2、...Si...SN respectively, and performing sonic wave velocity test to obtain sonic wave velocities SV 10、SV20、…、SVi0、…、SVN0 of N samples under confining pressure P 0;
Step 3. Sonic wave velocity test of core sample under different surrounding pressures
The formation stress sensitivity evaluation needs to respectively carry out acoustic wave tests on the core sample under the loading path condition and the unloading path condition, and specifically comprises the following steps:
(1) Testing the sonic velocity of a sample under load
Sequentially applying confining pressure P 1,…,Pi,…,PM to a standard plunger core sample, maintaining for at least 5min after confining pressure stabilization is applied, and then testing the sonic wave velocity of the sample under each confining pressure conditionRespectively carrying out sonic wave velocity test on N standard plunger core samples to obtain sonic wave velocities SV + of the N samples under the loading condition and the test surrounding pressure of M+1;
Wherein, The sound wave velocity of the sample i under the loading condition and under the confining pressure P j;
(2) Testing sonic velocity of sample under unloading conditions
After confining pressure is applied to P M, sequentially removing the confining pressure to P M-1,…,Pi,…P1,P0, maintaining for at least 5min after confining pressure is stable, and then testing the sonic wave velocity of the sample under each confining pressure conditionRespectively carrying out sonic wave velocity test on N standard plunger core samples to obtain N standard plunger core samples, respectively carrying out sonic wave velocity test on the N standard plunger core samples to obtain sonic wave velocities SV - of the N samples under loading conditions and M+1 test surrounding pressures:
Wherein, The sound wave velocity of the sample i under the unloading condition under the confining pressure P j;
step 4, calculating stress sensitivity coefficients of the core sample under different surrounding pressures by using the sonic wave velocity
The stratum stress sensitivity evaluation is used for respectively calculating the stress sensitivity coefficient of the core sample under different confining pressures of the loading path and the stress sensitivity coefficient under different confining pressures of the unloading path, and specifically comprises the following steps:
(1) Under loading condition, calculating stress sensitivity coefficient of sample under each surrounding pressure
For the stress sensitivity coefficient in the loading process, the stress sensitivity coefficients of the N standard plunger core samples at M confining pressure points are calculated by a formula (6), so as to obtain a stress sensitivity coefficient matrix Ss + of the N samples under loading conditions and M different confining pressures, as shown in a formula (7):
is the stress sensitivity coefficient of the sample i under the loading condition and under the confining pressure P j; the larger the value, the stronger the stress sensitivity of the stratum represented by the sample i under the loading confining pressure P j is shown:
(2) Under the unloading condition, calculating stress sensitivity coefficient of the sample under each surrounding pressure
For the stress sensitivity coefficient in the unloading process, the stress sensitivity coefficients of the N standard plunger core samples at M confining pressure points are calculated by a formula (8), so as to obtain stress sensitivity coefficients Ss - of the N samples under the unloading condition and M different confining pressures, as shown in a formula (9):
is the stress sensitivity coefficient of the sample i under the unloading condition under the confining pressure P j; the larger the value is, the stronger the stress sensitivity of the stratum represented by the sample i under the unloading confining pressure P j is shown;
Step 5, comprehensive evaluation of stratum stress sensitivity under different confining pressures
(1) Under the loading condition, when the confining pressure P j is applied, the average stress sensitivity coefficient of the stratum is calculated according to the formula (10)Calculating the minimum stress sensitivity coefficient/> of the stratum from formula (12)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (11)
(2) Under the unloading condition, the average stress sensitivity coefficient of the stratum is calculated according to the formula (13) when the confining pressure P j is adoptedCalculating the minimum stress sensitivity coefficient/> of the stratum from formula (15)Calculating the maximum stress sensitivity coefficient/> of the stratum from formula (14)
2. The acoustic response-based stratum stress sensitivity evaluation method according to claim 1, wherein the maximum test confining pressure calculation coefficient value in step 1, step 2 is determined according to the maximum effective confining pressure required by the oil and gas exploitation operation; when the oil and gas exploitation engineering cannot be determined, the value is taken:
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