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CN-121980660-A - Fault development gas storage operation upper limit pressure determining method considering overpressure operation condition

CN121980660ACN 121980660 ACN121980660 ACN 121980660ACN-121980660-A

Abstract

The application relates to a fault development gas storage operation upper limit pressure determining method considering overpressure operation conditions, which comprises the following steps of 1, establishing a three-dimensional geomechanical model of the gas storage covering a storage layer, a cover layer and peripheral faults, 2, performing geomechanical simulation, 3, determining the shearing damage resistance limit bearing capacity and the tensile stress damage resistance limit bearing capacity of the cover layer, 4, designing gas-measuring permeability test experiments of the cover layer rock under different static confining pressures, 5, determining the gas breakthrough pressure of the cover layer rock under different lifting coefficients, 6, determining the capillary sealing limit bearing capacity of the cover layer, 7, determining the anti-slip activation limit bearing capacity and the anti-expansion rupture limit bearing capacity of the fault, and 8, determining the operation upper limit pressure of the gas storage. According to the method, a four-dimensional geomechanical model is established, a stress path of the reservoir gas injection process is obtained through numerical simulation, and the dynamic horizontal main stress of the reservoir gas injection process is calculated and determined by taking the determined horizontal main stress of the reservoir top as a reference.

Inventors

  • SUN JUNCHANG
  • GAO GUANGLIANG
  • SHANG LIN
  • HE HAIYAN
  • LI CONG
  • HU CAIYUN
  • ZHANG ZIYU
  • HUANG XIN
  • ZHU SINAN
  • GAO TAO
  • ZHU SHASHA
  • HAN DONGLIANG
  • WANG QIJING
  • FU XIAOFEI
  • LIU WEI

Assignees

  • 东北石油大学

Dates

Publication Date
20260505
Application Date
20260209

Claims (11)

  1. 1. A method for determining an upper limit pressure of a fault development gas storage considering overpressure operation conditions, the method comprising the steps of: The method comprises the following steps of (1) establishing a three-dimensional geomechanical dynamic model of a gas storage, which covers a storage layer, a cover layer and peripheral faults, and correcting the model according to actual measurement or regional ground stress evaluation results; Utilizing the corrected model to carry out geomechanical simulation, determining a three-dimensional main stress path of the reservoir in the process of establishing a reservoir and injecting gas, and calculating dynamic three-dimensional main stress in the process of establishing the reservoir and injecting gas; Based on the dynamic three-way main stress in the process of building a warehouse and injecting gas, adopting shearing and stretching safety indexes to respectively determine the shearing resistance and the tensile failure limit bearing capacity of the cover layer; the gas-measuring permeability experiment after 50 times of alternating load action of the cover layer rock under different effective stress is designed and developed based on the injection-production ground stress disturbance characteristics of the gas storage reservoir determined by geomechanical simulation; step (5), determining the rock gas breakthrough pressure of the cover layer under different lifting coefficients by adopting the conversion relation between the rock gas permeability and the gas breakthrough pressure; drawing a relation chart of the normalized dynamic breakthrough pressure of the cap layer rock and the pressure increasing coefficient of the gas storage, establishing a functional relation, and analyzing and determining the sealing limit bearing capacity of the cap layer capillary; Based on dynamic three-way main stress in the process of establishing a warehouse and injecting gas, adopting a slip trend index and an expansion trend index to respectively determine anti-slip activation and anti-expansion fracture limit bearing capacity of a fault; and (8) taking the pressure increasing coefficient as an abscissa, taking the evaluation indexes such as the capillary sealing limit bearing capacity of the cover layer, the mechanical damage resistance limit bearing capacity of the cover layer and the fault as an ordinate, drawing a cross-plot, and determining the operation upper limit pressure of the gas storage.
  2. 2. The method for determining the upper limit pressure of fault development gas storage taking overpressure operation conditions into consideration as set forth in claim 1, wherein the three-dimensional dynamic geomechanical simulation in the step (1) is a dynamic mechanical model established by combining fluid-solid coupling numerical simulation on the basis of a three-dimensional geomechanical model, and is used for determining formation pressure and ground stress change characteristics in the gas storage construction, injection and production operation process.
  3. 3. The method for determining the upper limit pressure of fault development gas storage in consideration of overpressure operation conditions as set forth in claim 1, wherein the reservoir horizontal stress path during formation pressure elevation in step (2) is formulated as follows Calculating; Wherein, the Pore pressure changes in the gas storage process; Three-dimensional principal stress change in the process of gas injection of gas storage, including maximum horizontal principal stress change Minimum horizontal principal stress variation ,MPa; Horizontal principal stress path in gas injection process of gas storage, including maximum horizontal principal stress path And a minimum horizontal principal stress path 。
  4. 4. The method for determining the upper limit pressure of fault development gas storage taking into account overpressure operation conditions as set forth in claim 1, wherein in step (2), dynamic three-dimensional principal stress in the process of gas injection in the process of building the gas storage is determined by using a formula Calculating; Wherein, the Dynamic three-dimensional principal stress for gas storage gas injection process, including maximum horizontal principal stress Minimum horizontal principal stress ,MPa; Three-dimensional principal stress before reservoir establishment for oil and gas reservoirs, including maximum horizontal principal stress before reservoir establishment Minimum horizontal principal stress before warehouse construction ,MPa; Formation pressure at different moments in the reservoir gas injection process for the reservoir; Formation pressure before reservoir construction.
  5. 5. The method for determining the upper limit pressure of fault development gas storage taking into account overpressure operation conditions as set forth in claim 1, wherein said cap layer tensile failure limit pressure in step (3) is expressed by the following formula Performing a calculation from the cap layer tension safety index formula Performing iterative analysis and determination; Wherein, the The tensile stress of the cover layer is the breaking limit pressure, MPa; dynamic minimum horizontal principal stress in the reservoir building and gas injection process is MPa; Is a tensile safety index, and is dimensionless; formation pressure and MPa at different moments in the reservoir gas injection process; The cover layer generates dynamic minimum horizontal main stress in the reservoir building and gas injection process of the oil and gas reservoir Using the formula Calculating; Wherein, the Minimum principal stress, MPa, before library construction for the cap layer; maximum principal stress before library construction for the cap layer, MPa; Is the minimum horizontal main stress path; Formation pressure before reservoir construction.
  6. 6. The method for determining the upper limit pressure of fault development gas storage taking into account overpressure operation conditions as set forth in claim 1, wherein said cap layer shear failure limit pressure in step (3) is formulated as follows Performing a calculation from the cap shear safety index formula Performing iterative analysis and determination; Wherein, the The shear failure resistance limit pressure of the cover layer is MPa; Is cohesive force, MPa; Is an internal friction angle; Dynamic minimum principal stress in the reservoir building and gas injection process is MPa; dynamic maximum principal stress in the reservoir building and gas injection process, MPa, To shear safety index, dimensionless Is cohesive force, MPa; Is an internal friction angle; Dynamic maximum effective principal stress in the reservoir building and gas injection process is MPa; dynamic minimum effective principal stress in the reservoir building and gas injection process is MPa; and the dynamic maximum principal stress in the reservoir building and gas injection process of the oil and gas reservoir And minimum principal stress The values are different in different ground stress states, wherein ① is the value when the ground stress state is the normal fault stress state at a certain moment in the gas injection process of the reservoir building of the oil and gas ), , ② When the ground stress state is reverse fault stress state at a certain moment in the gas injection process of the reservoir construction ), , ③ When the ground stress state is the slip fault stress state at a certain moment in the gas injection process of the reservoir construction ), , ; Wherein, the Dynamic maximum horizontal principal stress in the reservoir building and gas injection process is MPa; dynamic minimum horizontal principal stress in reservoir construction and gas injection process for oil and gas reservoirs, and MPa Dynamic vertical principal stress in reservoir building and gas injection process for oil and gas reservoirs Maximum horizontal main stress at a certain moment in the process of establishing a reservoir and injecting gas for a hydrocarbon reservoir, and MPa Minimum horizontal main stress at a certain moment in the process of establishing a reservoir and injecting gas for a hydrocarbon reservoir, and MPa Vertical main stress at a certain moment in the process of establishing a reservoir and injecting gas for the oil and gas reservoir; dynamic maximum horizontal principal stress in the reservoir building and gas injection process of the oil and gas reservoir And a minimum horizontal principal stress Using the formula And Calculating; Wherein, the The maximum horizontal main stress is MPa before warehouse establishment; Is the minimum horizontal main stress before warehouse establishment and MPa; is the maximum horizontal main stress path; A minimum horizontal principal stress path; formation pressure and MPa at different moments in the reservoir gas injection process; formation pressure before reservoir establishment of a hydrocarbon reservoir, and MPa.
  7. 7. The method for determining the upper limit pressure of fault development gas storage taking into account overpressure operation conditions as set forth in claim 1, wherein in step (5) the determination of the cap layer rock gas breakthrough pressure at different minimum levels of effective principal stress of the reservoir is performed by using a functional relationship between rock gas permeability and cap layer static breakthrough pressure Calculating; Wherein, the Rock gas breakthrough pressure, MPa, for different upper pressures; And a and b are parameters of a mathematical fitting function relation.
  8. 8. The method for determining the upper limit pressure of fault development gas storage taking overpressure operation conditions into consideration as set forth in claim 1, wherein in the step (6), the drawing of the relationship diagram of the normalized dynamic breakthrough pressure of the overburden rock and the gas storage pressure increasing coefficient means that the gas storage pressure increasing coefficient is taken as an abscissa, the normalized dynamic breakthrough pressure is taken as an ordinate, a relationship curve is drawn, and a binomial, logarithmic or exponential functional relationship is established, and when the binomial functional relationship is adopted, the expression is as follows: ; Wherein, the The dynamic breakthrough pressure is normalized; rock gas breakthrough pressure, MPa, for different upper pressures; Break through pressure in hydrostatic pressure, MPa; The method is characterized in that the method is used for increasing the pressure coefficient of the gas storage, the pressure coefficient is the ratio of the upper limit pressure to the hydrostatic pressure, and a, b and c are parameters of a mathematical fitting function relation.
  9. 9. The method for determining the upper limit pressure of fault development gas storage taking into account overpressure operation conditions as set forth in claim 1, wherein in step (6) said dynamic capillary seal limit pressure-bearing capacity of the cap layer means that the pressure difference of the cap layer is continuously increased during gas injection in the gas reservoir building process, and when the cap layer dynamically breaks through the pressure Is smaller than the dynamic sealing limit of the capillary tube of the cover layer when the pressure difference of the cover layer is smaller than the pressure difference of the cover layer in the process of gas injection in the reservoir building of the oil and gas reservoir, and the pressure bearing capacity of the dynamic capillary tube of the cover layer at the moment adopts a formula Calculating; Wherein, the The sealing limit bearing capacity of the capillary tube of the cover layer under the alternating load working condition is MPa; the pressure is the break-through pressure of the original cover layer, namely the cover layer before the pressure raising operation, and is MPa; Is hydrostatic pressure.
  10. 10. The method for determining the upper limit pressure of the fault development gas storage taking into account the overpressure operation condition as set forth in claim 1, wherein the fault anti-slip activation limit bearing capacity in the step (7) is expressed by the following formula Calculating; Wherein, the The anti-slip active limit bearing capacity of the fault is MPa; is the friction coefficient of fault; positive section stress and MPa when the fault is activated in a sliding way; shear stress of a section when the fault is in slip activation is MPa; While the fault is subjected to positive fracture stress when anti-slip activation Shear stress of cross section Using the formula Performing iterative analysis and calculation; Wherein, the Is a fault slip trend index; establishing a reservoir for the oil and gas reservoir, and injecting gas in the process of dynamic section normal stress and MPa; dynamic section shear stress in the reservoir building and gas injection process is applied to the oil and gas reservoir, and the pressure is MPa; formation pressure at different moments in the process of establishing a reservoir for a hydrocarbon reservoir and injecting gas, and the dynamic section normal stress Using the formula Calculating and shearing stress of section Using the formula Calculating; Wherein, the 、 Dynamic maximum and minimum horizontal principal stress in the reservoir building and gas injection process; Dynamic vertical principal stress in the reservoir building and gas injection process; Is a fault azimuth; is the fault dip angle; And the dynamic maximum horizontal main stress in the reservoir construction and gas injection process of the steps And a minimum horizontal principal stress Using the formula And Calculating; Wherein, the The maximum horizontal main stress is MPa before warehouse establishment; Is the minimum horizontal main stress before warehouse establishment and MPa; is the maximum horizontal main stress path; A minimum horizontal principal stress path; formation pressure and MPa at different moments in the reservoir gas injection process; formation pressure and MPa before reservoir establishment of a hydrocarbon reservoir.
  11. 11. The method for determining the upper limit pressure of a fault-developed gas storage in consideration of overpressure operation conditions as set forth in claim 1, wherein said fault expansion and rupture limit bearing capacity in step (7) is as follows When adopting the formula Calculate when When adopting the formula Calculating; Wherein, the The fracture resistance, expansion and fracture limit bearing capacity and MPa; the maximum main stress is MPa when the fault is expanded and broken; the minimum main stress is MPa when the fault is expanded and broken; The fracture surface main stress is MPa when the fracture layer is expanded and broken; the tensile strength of the rock is MPa; While the fault has maximum principal stress when anti-slip activation Minimum principal stress Using the formula Performing iterative analysis and calculation; Wherein, the Is an expansion trend index; establishing a reservoir for the oil and gas reservoir, and injecting the dynamic maximum principal stress in MPa; Dynamic minimum principal stress in the reservoir building and gas injection process is MPa; establishing a reservoir for the oil and gas reservoir, and injecting gas in the process of dynamic section normal stress and MPa; and the dynamic maximum principal stress in the reservoir building and gas injection process of the oil and gas reservoir And maximum principal stress The values are different in different ground stress states, wherein ① is that the ground stress state is normal fault stress state at a certain moment in the gas injection process of the reservoir building of the oil and gas ) In the time-course of which the first and second contact surfaces, , ② When the ground stress state of a certain moment in the gas injection process of the reservoir construction of the oil and gas is the reverse fault stress state ) In the time-course of which the first and second contact surfaces, , ③ When the ground stress state of the oil and gas reservoir is the slip fault stress state at a certain moment in the reservoir building and gas injection process ) In the time-course of which the first and second contact surfaces, , ; Wherein, the Dynamic maximum horizontal principal stress in the reservoir building and gas injection process is MPa; dynamic minimum horizontal principal stress in reservoir construction and gas injection process for oil and gas reservoirs, and MPa Dynamic vertical principal stress in reservoir building and gas injection process for oil and gas reservoirs Maximum horizontal main stress at a certain moment in the process of establishing a reservoir and injecting gas for a hydrocarbon reservoir, and MPa Minimum horizontal main stress at a certain moment in the process of establishing a reservoir and injecting gas for a hydrocarbon reservoir, and MPa Vertical main stress at a certain moment in the process of establishing a reservoir and injecting gas for the oil and gas reservoir; And the dynamic maximum horizontal main stress in the reservoir construction and gas injection process of the steps And a minimum horizontal principal stress Using the formula And Calculating; Wherein, the The maximum horizontal main stress is MPa before warehouse establishment; Is the minimum horizontal main stress before warehouse establishment and MPa; is the maximum horizontal main stress path; is the minimum horizontal principal stress path; formation pressure and MPa at different moments in the reservoir gas injection process; formation pressure and MPa before reservoir establishment of a hydrocarbon reservoir.

Description

Fault development gas storage operation upper limit pressure determining method considering overpressure operation condition Technical Field The invention relates to the technical field of underground storage of natural gas, in particular to a fault development gas storage operation upper limit pressure determining method considering overpressure operation conditions. Background The upper limit operating pressure refers to the highest reservoir pressure allowed to be reached in the process of gas storage (UGS) injection and production operation, the upper limit operating pressure is a key parameter related to the safety and economy of the gas storage, and the safety of a geological structure is the most important and fundamental factor for the upper limit pressure design. The nature of the gas storage is to store high pressure natural gas by using geological structures such as underground depleted oil and gas reservoirs, salt caverns or aquifers, and each geological structure has inherent rock mechanical pressure bearing limit. If the operating pressure exceeds the upper limit, the cover layer is possibly cracked or activated by faults, the tightness of the gas storage is destroyed, and the natural gas is leaked to the shallow layer or the ground surface, so that not only is the resource lost, but also the safety accident is possibly caused. In the past, when designing the upper limit pressure of the gas storage, the traditional concept generally considers that the original formation pressure is the maximum pressure which the rock has born, so the upper limit pressure of the gas storage should not exceed the original formation pressure. However, this concept is not entirely accurate, and the key reason is that the maximum pressure that a subterranean formation can withstand is not determined by the original formation pressure, i.e., the earth's stress. The set reference for the upper operating limit pressure is the current ground stress field and rock mechanics characteristics, not the original pressure in history. It is therefore possible for the upper operating pressure of the reservoir to exceed the original formation pressure. Moreover, gas reservoirs are a relatively invested infrastructure, and the operation pursues a long-term economic value on a safety basis. The upper operating limit determines the amount of gas reservoir work. The higher the upper limit of the operation of the gas storage is set, the larger the theoretical working gas amount is, but the overpressure operation is absolutely not blind to improve the pressure, and the feasibility is established on the premise of more accurately and comprehensively evaluating the dynamic sealing limit bearing capacity of the geologic body. However, because of the special operation condition of the gas storage, high-pressure, high-speed injection and production and alternating load conditions are needed to be fastened for determining the dynamic sealing limit bearing capacity of the gas storage geological body. In the high-speed strong injection and production process, the formation pressure is steeply increased and suddenly reduced, periodic disturbance of a regional ground stress field is caused, and according to the simulation of CO 2 overpressure sealing numerical values, after the gas injection formation pressure exceeds hydrostatic pressure, the horizontal main stress of a reservoir and a cover layer is increased, but the increase of the former is far greater than the latter, the horizontal effective main stress of the reservoir and the cover layer is reduced, and abrupt change phenomenon exists on both sides of an interface between the reservoir and the cover layer. Disclosure of Invention The invention aims to provide a fault development gas storage operation upper limit pressure determining method considering overpressure operation conditions, which comprises the steps of establishing a fitting corrected three-dimensional dynamic elastoplastic geomechanical model, determining a gas storage reconstruction by three-dimensional geomechanical simulation, and determining a horizontal main stress path in the process of increasing the stratum pressure of the gas storage by adopting three-dimensional ground stress fields at different moments in the circulating injection and production process under the overpressure condition, and accurately evaluating the mechanical damage limit bearing capacity of the cover layer of the gas storage by adopting the cover layer stretching and shearing damage criterion under the influence of the ground stress hysteresis effect of the elastoplastic deformation of the stratum. Meanwhile, the stress disturbance characteristics revealed by the three-dimensional geomechanical simulation are based on to guide the subsequent experimental design. Firstly, designing a gas permeability test of the overburden rock by taking the minimum level effective principal stress value of different reservoirs obtained through simulation as co