Quantitative calculation method of fracture discharge volume based on fracture-pressure coupling

Abstract

The present invention provides a quantitative calculation method for fracture leakage volume based on the effects of fault-pressure coupling. This method includes the following steps: Step 1: Determine the study area and select the target oil source fault and target reservoir; Step 2: Determine the burial depth and pressure of the source rock and target reservoir connected by the fault; Step 3: Calculate various state parameters of the vertical migration process of oil and gas along the fault; Step 4: Calculate the leakage area of the fault zone; Step 5: Determine the height range of the fracture leakage zone and calculate the leakage volume of the fault zone. This quantitative calculation method for fracture leakage volume based on the effects of fault-pressure coupling enriches the theory of fault reservoir control and fault-pressure coupling, and is of great significance to oil and gas exploration and well site deployment. In particular, when deploying wells in fault oil and gas reservoirs, it can clearly define the effective well placement range around the fault, thereby improving the success rate of drilling around the fault.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield exploration, and in particular to a quantitative calculation method of fracture leakage volume based on fracture-pressure coupling. Background Art

[0002] Pressure and fractures are crucial factors in the formation of oil and gas reservoirs. When pressure is contained within an intact containment chamber, the pressure system is relatively stable. However, when a fracture breaks through the pressure containment chamber, the original pressure balance system is disrupted, forming a fracture pressure relief zone, which in turn affects the direction and range of fluid flow. Oil and gas exploration results have shown that fractures significantly control oil and gas migration and accumulation. Therefore, oil and gas are mostly concentrated along fracture zones, making them favorable exploration areas. However, in actual exploration well deployment, drilling is avoided along fractures because encountering fractures can easily cause the drill bit to slip, resulting in project failure. Therefore, for structural oil and gas reservoirs with overpressure, determining the fracture relief radius and range is extremely important, given the large trap area. This can prevent drilling accidents and improve drilling success rates.

[0003] Previous researchers in the study of fault pressure relief only proposed the theory of "fault-pressure dual control" and used the pressure drop model to calculate the pressure distribution during fault pressure relief. However, on the one hand, this pressure relief model does not conform to the pumping principle of the fault and does not dissect the fault discharge process in detail; on the other hand, the radius and range of the fault discharge are not quantitatively calculated, and the three-dimensional geological structure of the fault zone is not considered.

[0004] To this end, we invented a new quantitative calculation method for fracture discharge volume based on fracture-pressure coupling, which solved the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a quantitative calculation method of the fracture discharge volume under the effect of fault-pressure coupling, which is based on the identification of the longitudinal pressure relief zone and determines the fracture discharge volume, so as to provide theoretical guidance and technical support for the exploration and deployment of structural oil and gas reservoirs.

[0006] The objectives of the present invention can be achieved through the following technical measures: a quantitative calculation method for the fracture leakage volume under the action of fault-pressure coupling, the quantitative calculation method for the fracture leakage volume under the action of fault-pressure coupling comprising: step 1, determining the study area, selecting the target oil source fracture and the target reservoir; step 2, determining the burial depth and pressure of the source rock and the target reservoir connected by the fault; step 3, calculating various state parameters of the vertical migration process of oil and gas along the fault; step 4, calculating the leakage area of the fault zone; step 5, determining the height range of the fracture leakage zone, and calculating the leakage volume of the fracture zone.

[0007] The purpose of the present invention can also be achieved by the following technical measures:

[0008] In step 1, the fracture penetration position is determined based on the seismic interpretation data, and the main oil source fracture is selected accordingly; the target reservoir is determined based on the exploration results and objectives of the study area, which is the main oil and gas bearing stratum in the study area.

[0009] In step 2, based on the seismic interpretation data and the work area overview, the burial depth H1 of the bottom source rock layer of the fault communication and the burial depth H2 of the target reservoir are determined; the Eaton method or the equivalent depth method is selected to predict the pressure of the study area, thereby determining the pressure P0 of the bottom source rock layer of the fault communication and the pressure P2 of the target reservoir.

[0010] In step 3, the parameters (P, H, V) are used to represent the state of oil and gas at each stage, where P is pressure, H is burial depth, and V is volume. The pressure P1 of the oil and gas fluid that has reached the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir is calculated. When the source rock expels hydrocarbons, high-pressure oil and gas enter the fault zone. At this time, the state parameters of the oil and gas are (P0, H1, V1). Under the pumping action of the fault, the high-pressure oil and gas migrate vertically to the target reservoir. In this process, it is approximately assumed that the residual pressure remains unchanged, so formula (1) is obtained, and then the pressure P1 that has reached the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir is calculated, as shown in formula (2):

[0011] P0-ρ w gH1=P1-ρ w gH2 (1)

[0012] P1=P0-ρ w g(H1-H2) (2)

[0013] Wherein, P0 is the pressure of the source rock connected by the fault, MPa; P1 is the pressure of the oil and gas fluid that has reached the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir, MPa; P2 is the pressure of the target reservoir, MPa; ρ w is the density of formation water, g / cm 3 , take 1.0g / cm 3 ; g is the acceleration due to gravity, which is 9.8m / s 2 ; H1 is the depth of the source rock connected by the fault, km; H2 is the depth of the target reservoir, km.

[0014] In step 3, when the fluid enters the reservoir at depth H2 along the fault zone, it mixes with the original formation fluid inside the reservoir. The pressure P after mixing is calculated. 混 Considering fluid compression and pore compression, the law of conservation of mass is used to obtain formula (3), in which the original fluid in the target layer and the fluid migrating along the fault are at the mixed pressure P 混Under these conditions, the density and porosity change, as shown in formula (4)-formula (7). Substituting formula (4)-formula (7) into formula (3), the pressure P after mixing can be calculated by the simultaneous equations: 混 , due to the parameters β0 and β c The order of magnitude is very small, β0β c =10 -17 kPa -1 , orders of magnitude smaller, so with β0β c The binomial can be ignored, and the final calculation formula for Pmix is shown in formula (8); where V1 is the volume of fluid that migrates along the fault to the target reservoir, that is, the volume of hydrocarbons expelled by the source rock, that is, the ratio of the hydrocarbon expulsion volume of the source rock to the density of crude oil, as shown in formula (9), and V2 is the volume of the original fluid in the formation, that is, the pore system in the sandstone within the trap, as shown in formula (10):

[0015]

[0016] ρ1=ρ 混 [1+β0(P1-P 混 )] (4)

[0017] ρ2=ρ 混 [1+β0(P2-P 混 )] (5)

[0018]

[0019]

[0020]

[0021]

[0022]

[0023] Where ρ1 is the density of high-pressure fluid migrating along the fault, g / cm 3 ; ρ2 is the density of the original fluid in the target reservoir, g / cm 3 ρ 混 is the density of the fluid after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, g / cm 3 ; β0 is the fluid compressibility coefficient, a constant, with a value of 10 -10 kPa -1 β c is the rock compression coefficient, a constant, with a value of 10 -7 kPa -1 ; is the porosity of the rock where the high-pressure fluid migrates along the fault, %; is the porosity of the rock where the original fluid of the target reservoir is located, %; is the rock porosity after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, %; V1 is the volume of the high-pressure fluid migrating along the fault, m 3 ; V2 is the volume of the original fluid in the formation, m 3 ;m oil For oil and gas generated from source rocks, 10 11 kg; H source is the thickness of source rock, m; S source is the area of source rock, km 2 ρ source is the density of source rock, g / cm 3 ; C0 is the original organic carbon, %; B oil is the oil production rate, mg / g; ρ oil is the density of crude oil, g / cm 3 , generally take 0.8g / cm 3 ; 10 -7 is the unit conversion constant; S t is the enclosed area, m 2 ;h t is the trap height, m; V sh is the sand-to-land ratio, %; is the formation porosity, %; P1 is the oil and gas fluid pressure that reaches the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir, MPa; P2 is the pressure of the target reservoir, MPa.

[0024] In step 3, when the fluid enters the reservoir, it meets the Darcy flow condition. The deformation of the Darcy formula is used to calculate the distance of oil and gas migration, that is, the fracture leakage radius, as shown in formula (11):

[0025]

[0026] ΔP=P 混 -P2 (12)

[0027] Where r is the discharge radius, cm; K is the rock permeability, μm 2 ; μ is the fluid viscosity, mPa˙s; ΔP is the pressure change of the mixed fluid, MPa; v is the fluid flow rate, cm / s, P 混 is the pressure after mixing, MPa; P2 is the pressure of the target reservoir, MPa.

[0028] In step 4, from a plane perspective, the range of the fault zone is approximately a rectangle. The discharge area of the fault zone is a rounded rectangle with the fault discharge radius r as the radius, the fault extension length l as the length, and the fault zone width c as the width. Therefore, the calculation formula for the fault zone discharge area is shown in formula (13):

[0029] S=lc+2r(l+c)+πr 2 (13)

[0030] Where S is the fracture discharge area, km 3 ; l is the length of the fault, km; c is the width of the fault zone, km.

[0031] In step 5, the depth range of the longitudinal pressure relief zone is determined based on the variation of organic matter pyrolysis parameters S1 / (S1+S2), Tmax, illite content, and Ro value with depth. When the organic matter pyrolysis parameters S1 / (S1+S2) and Tmax deviate from the normal trend line, and the illite content and Ro value suddenly increase, it can be indicated that the fluid has migrated through the layers, which can be used as a method for identifying the longitudinal pressure relief zone. Based on the determination of the height range of the fault longitudinal discharge zone, the discharge volume of the fault can be calculated using formula (14):

[0032] V=(lc+2r(l+c)+πr 2 )h (14)

[0033] Where V is the fracture discharge volume, km 3 ; h is the discharge height, km; l is the fault extension length, km; c is the fault zone width, km; r is the fault discharge radius, km.

[0034] The quantitative calculation method of the fracture leakage volume under the action of fault-pressure coupling in the present invention is based on the detailed dissection of the fracture leakage process, establishes a calculation method for the fracture leakage radius, takes the three-dimensional geological structure of the fracture into consideration, calculates the fracture leakage area, and finally determines the fracture leakage volume on the basis of identifying the longitudinal pressure relief zone, in order to provide theoretical guidance and technical support for the exploration and deployment of structural oil and gas reservoirs. The present invention is based on the in-depth dissection of the fracture leakage process, and calculates the different states of the fluid (including pressure, burial depth and volume) in four stages: the stage in which the source rock enters the fracture zone after hydrocarbon expulsion and has not yet undergone vertical migration, the stage in which the fluid migrates vertically along the fracture to the target reservoir and has not yet entered the reservoir, the stage in which the fluid enters the reservoir and mixes with the original fluid in the reservoir, and the stage in which the mixed fluid migrates laterally along the reservoir under the action of residual pressure until the migration stops, and uses the Darcy seepage principle to determine the fracture leakage radius. Finally, the fracture zone width, fracture extension length and longitudinal leakage height are taken into consideration to determine the fracture zone leakage area and leakage volume. This method can be used to determine the fracture pressure relief radius and volume, clarifying the migration patterns of fluids (such as oil and gas) under the dual control of fault and pressure. This method enriches the theory of fault reservoir control and fault-pressure coupling, and is of great significance to oil and gas exploration and well deployment. In particular, when deploying wells in fault oil and gas reservoirs, it can clearly define the effective well layout range around the fault, thereby improving the success rate of drilling around the fault. This invention can be widely applied in various fields such as geological exploration of oil and gas resources and optimization of favorable areas, and is of great significance to oil and gas exploration and deployment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a flow chart of a specific embodiment of the method for quantitatively calculating the fracture discharge volume based on the fracture-pressure coupling effect of the present invention;

[0036] Figure 2 This is a schematic diagram of the process of fracture leakage in a specific embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of calculating the fracture leakage area in a specific embodiment of the present invention;

[0038] Figure 4 A diagram showing the relationship between the displacement of compressional-torsional fractures and the width of the fracture zone in the Junggar region in a specific embodiment of the present invention;

[0039] Figure 5 In a specific embodiment of the present invention, a fracture drainage height map of the F1 fracture and the S1 well is determined using multiple parameters. DETAILED DESCRIPTION

[0040] In order to make the above and other objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings.

[0041] like Figure 1 As shown, Figure 1 The flowchart of the quantitative calculation method of the fracture discharge volume based on the fracture-pressure coupling effect of the present invention.

[0042] (1) Determine the research object. Determine the study area and select the target oil-source fault and target reservoir. Based on the seismic interpretation data, determine the fracture penetration level and select the main oil-source fault accordingly. The target reservoir is determined based on the exploration results and objectives of the study area and is the main oil and gas bearing strata in the study area.

[0043] (2) Determine the burial depth and pressure of the source rock and target reservoir connected by the fault. First, determine the burial depth H1 of the bottom source rock layer of the fault connection and the burial depth H2 of the target reservoir based on the seismic interpretation data and the work area overview. Use any of the various pressure prediction methods, such as the Eaton method or the equivalent depth method, to predict the pressure in the study area and determine the pressure P0 of the bottom source rock layer of the fault connection and the pressure P2 of the target reservoir.

[0044] (3) Calculate the various state parameters (including pressure, burial depth and volume) of the vertical migration process of oil and gas along the fault. Below, the parameters (P, H, V) are used to represent the state of oil and gas at each stage, where P is pressure, H is burial depth, and V is volume. The entire fault pressure relief process can be explained in three steps (see Appendix). Figure 2 ):

[0045] 1. Calculate the pressure P1 of the oil and gas fluid along the fault zone that has reached the target reservoir depth H2 but has not yet entered the reservoir. When the source rock expels hydrocarbons, high-pressure oil and gas enter the fault zone. At this time, the state parameters of the oil and gas are (P0, H1, V1). Under the pumping action of the fault, the high-pressure oil and gas migrate vertically to the target reservoir. Previous literature indicates that in this process, the residual pressure is approximately assumed to be unchanged, so formula (1) can be obtained. This can then be used to infer the pressure P1 along the fault zone that has reached the target reservoir depth H2 but has not yet entered the reservoir, as shown in formula (2).

[0046] P0-ρ w gH1=P1-ρ w gH2 (1)

[0047] P1=P0-ρ w g(H1-H2) (2)

[0048] Wherein, P0 is the pressure of the source rock connected by the fault, MPa; P1 is the pressure of the oil and gas fluid that has reached the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir, MPa; P2 is the pressure of the target reservoir, MPa; ρ w is the density of formation water, g / cm 3 , take 1.0g / cm 3 ; g is the acceleration due to gravity, which is 9.8m / s2 ; H1 is the depth of the source rock connected by the fault, km; H2 is the depth of the target reservoir, km.

[0049] ② When the fluid enters the reservoir at a depth of H2 along the fault zone, it mixes with the original formation fluid inside the reservoir. Calculate the pressure P after mixing. 混 Considering fluid compression and pore compression, the law of conservation of mass can be used to obtain formula (3), in which the original fluid in the target layer and the fluid migrating along the fault are at the mixed pressure P 混 Under these conditions, the density and porosity change, as shown in formula (4)-formula (7). Substituting formula (4)-formula (7) into formula (3), the pressure P after mixing can be calculated by the simultaneous equations: 混 , due to the parameters β0 and β c The order of magnitude is very small, β0β c =10 -17 kPa -1 , orders of magnitude smaller, so with β0β c The binomial can be ignored, and the final calculation formula for Pmix is shown in formula (8). Among them, V1 is the volume of fluid that migrated to the target reservoir along the fault, that is, the volume of hydrocarbons expelled by the source rock, that is, the ratio of the hydrocarbon expulsion volume of the source rock to the density of crude oil, as shown in formula (9), and V2 is the volume of the original fluid in the formation, that is, the pore system in the sandstone within the trap, as shown in formula (10).

[0050]

[0051] ρ1=ρ 混 [1+β0(P1-P 混 )] (4)

[0052] ρ2=ρ 混 [1+β0(P2-P 混 )] (5)

[0053]

[0054]

[0055]

[0056]

[0057]

[0058] Where ρ1 is the density of high-pressure fluid migrating along the fault, g / cm 3 ; ρ2 is the density of the original fluid in the target reservoir, g / cm 3 ρ 混is the density of the fluid after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, g / cm 3 ; β0 is the fluid compressibility coefficient, a constant, generally taken as 10 -10 kPa -1 β c is the rock compression coefficient, a constant, generally taken as 10 -7 kPa -1 ; is the porosity of the rock where the high-pressure fluid migrates along the fault, %; is the porosity of the rock where the original fluid of the target reservoir is located, %; is the rock porosity after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, %; V1 is the volume of the high-pressure fluid migrating along the fault, m 3 ; V2 is the volume of the original fluid in the formation, m 3 ;m oil For oil and gas generated from source rocks, 10 11 kg; H source is the thickness of source rock, m; S source is the area of source rock, km 2 ρ source is the density of source rock, g / cm 3 ; C0 is the original organic carbon, %; B oil is the oil production rate, mg / g; ρ oil is the density of crude oil, g / cm 3 , generally take 0.8g / cm 3 ; 10 -7 is the unit conversion constant; S t is the enclosed area, m 2 ;h t is the trap height, m; V s is the sand-to-land ratio, %; is the formation porosity, %.

[0059] ③ Calculate the fracture leakage radius r. When the fluid enters the reservoir, it meets the Darcy flow conditions. The deformation of the Darcy formula can be used to calculate the distance of oil and gas migration, that is, the fracture leakage radius, as shown in formula (11).

[0060]

[0061] ΔP=P 混 -P2 (12)

[0062] Where r is the discharge radius, cm; K is the rock permeability, μm 2 ; μ is the fluid viscosity, mPa˙s; ΔP is the pressure change of the mixed fluid, MPa; v is the fluid flow rate, cm / s.

[0063] (4) Calculate the discharge area of the fault zone. The fault zone is a three-dimensional structure with a fault zone width. Therefore, from a plane perspective, the range of the fault zone can be approximated as a rectangle. The discharge area of the fault zone is a rounded rectangle with the fault discharge radius r as the radius, the fracture extension length l as the length, and the fault zone width c as the width. Figure 3 As shown. Therefore, the calculation formula for the discharge area of the fault zone is shown in formula (13). There are many methods for determining the width of the fault zone. Previous researchers have determined the relationship between the width of the fault zone and the fault distance based on the results of field geological surveys at home and abroad. The width of the fault zone can also be determined based on the division of the fault zone structure using well logging data. In the specific embodiment, any method can be selected.

[0064] S=lc+2r(l+c)+πr 2 (13)

[0065] Where S is the fracture discharge area, km 3 ; l is the length of the fault, km; c is the width of the fault zone, km.

[0066] (5) Determine the height range of the fault discharge zone and calculate the discharge volume of the fault zone. The depth range of the longitudinal pressure relief zone is determined based on the variation of organic matter pyrolysis parameters S1 / (S1+S2), Tmax, illite content, Ro value and other parameters with depth. When the organic matter pyrolysis parameters S1 / (S1+S2) and Tmax deviate from the normal trend line, and the illite content and Ro value suddenly increase, it can indicate that the fluid has migrated through the layers, which can be used as a method for identifying the longitudinal pressure relief zone. Based on the determination of the height range of the fault longitudinal discharge zone, the discharge volume of the fault can be calculated using formula (14).

[0067] V=(lc+2r(l+c)+πr 2 )h (14)

[0068] Where V is the fracture discharge volume, km 3 ; h is the discharge height, km.

[0069] In a specific embodiment of the present invention, the following steps are included:

[0070] 1. This patent uses the S1 well in the Shawodi area of the Junggar Basin as an example to determine the fracture leakage volume using this method, which includes the following steps:

[0071] (1) Determine the research object. The study area is the Shawodi area of the Junggar Basin, and the F1 fault near the S1 well is the target fault. The source rock in the study area is the Permian, and the target reservoir is the Jurassic Sangonghe Formation.

[0072] (2) Determine the depth and pressure of the bottom of the fault communication and the target layer. First, based on the seismic interpretation data and the work area overview, the depth of the source rock layer at the bottom of the fault communication, H1, is determined to be 6.5 km, and the depth of the reservoir (target layer), H2, is determined to be 3.654 km. The pressure of the study area is predicted by any of the various pressure prediction methods, such as the Eaton method or the equivalent depth method. The Eaton method was selected in this study, and the pressure prediction formula was determined to be Formula (15). This results in the determination of the source rock pressure P0 at the bottom of the fault communication to be 147.97 MPa, and the target reservoir pressure P2 to be 35.97 MPa.

[0073] P=ρ m gH-(ρ m gH-ρ w gH)(Δt norm / Δt) 1.3 (15)

[0074] Where P is the fluid pressure at a certain point, MPa; H is the burial depth at a certain point, m; ρ m is the density of the overlying rock, g / cm 3 , obtain this value based on the well logging curve DEN; ρ w is the density of formation water, g / cm 3 , generally use 1.0g / cm 3 ; Δt is the measured sound wave time difference at a certain point, μs / ft; Δt norm is the normal sound wave time difference at a certain point, μs / ft; g is the acceleration of gravity, which is 9.8m / s 2 .

[0075] (3) Calculate the various state parameters (including pressure, depth and volume) of the vertical migration process of oil and gas along the fault.

[0076] Using formula (2), it is determined that P1 is 120 MPa when the high-pressure fluid migrates along the fault to the buried depth H2 and has not yet entered the reservoir. The thickness of the source rock H is source 200m, S source 165.86km 2 , ρ source 2.6g / cm 3 , C0 is 2.5%, B oil is 600 mg / g, and the enclosed area S t 16.6km 2 , trap height h t is 179.3m, and the sand-to-ground ratio is V s is 73.5%; the formation porosity Using formula (9) and formula (10), we can calculate V1 to be 1.62 km. 3 , V2 is 0.34km3 , and then use formula (8) to determine the mixed pressure P of the original fluid in the target layer and the fluid migrating along the fault 混 is 105.4MPa, so ΔP is calculated to be 69.5MPa. According to the characteristics of the study area, it is determined that when v=10 -6 cm / s, the fluid stops lateral migration; the rock permeability K is 9.6×10 -3 μm 2 , the fluid viscosity μ=18.1mPa˙s, and the fracture discharge radius L can be calculated as 3.69km using formula (11).

[0077] (4) Calculate the discharge area of the fault zone. Considering that the width of the fault zone has a three-dimensional structure, first, it is necessary to determine the width c of the fault zone. This embodiment mainly uses the results of field geological surveys in the Junggar Basin to determine the relationship between the fault throw and the width of the fault zone in the study area (see Appendix). Figure 4 ), using seismic interpretation data, the fault throw of F1 was measured to be 30m, and the corresponding fault zone width was 7m. Using the fault interpretation results, the extension length of F1 was measured to be 12.4km. Using formula (13), the discharge area of F1 fault was determined to be 134.41km 2 .

[0078] (5) Determine the height range of the fracture discharge zone and calculate the discharge volume of the fracture zone. In this embodiment, the depth range of the longitudinal pressure relief zone is determined to be 3623-4000m (see Appendix 1) by using the variation law of three parameters such as organic matter pyrolysis parameter S1 / (S1+S2), Tmax, and Ro value with depth. Figure 5 ), the height of the longitudinal pressure relief zone is 377m, and using formula (14), the fracture discharge volume is determined to be 50.67km 3 .

Claims

1. A quantitative calculation method for the fracture discharge volume under the coupling effect of fracture and pressure, characterized by: The quantitative calculation method of the fracture discharge volume under the effect of fracture-pressure coupling includes: Step 1: determine the study area and select the target oil source fault and target reservoir; Step 2: Determine the burial depth and pressure of the bottom source rock and target reservoir connected by the fault; Step 3, calculating various state parameters of the vertical migration process of oil and gas along the fault; Step 4, calculate the discharge area of the fault zone; Step 5: determine the height range of the fault discharge zone and calculate the discharge volume of the fault zone; Step 3 includes: calculating the pressure P1 of the oil and gas fluid that has reached the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir; when the fluid enters the reservoir at the burial depth H2 along the fault zone, it mixes with the original formation fluid inside the reservoir, and calculating the pressure P1 after mixing. 混 ; Calculate the fracture drainage radius r, and use the deformation of Darcy's formula to calculate the distance of oil and gas migration, that is, the fracture drainage radius, as shown in the formula: As shown: Where ΔP=P 混 -P2; r is the discharge radius, cm; K is the rock permeability, μm 2 ; μ is the fluid viscosity, mPa˙s; ΔP is the pressure change of the mixed fluid, MPa; P2 is the pressure of the target reservoir, MPa; υ is the fluid flow rate, cm / s.

2. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 1, the fracture penetration position is determined based on the seismic interpretation data, and the main oil source fracture is selected accordingly; the target reservoir is determined based on the exploration results and objectives of the study area, which is the main oil and gas bearing stratum in the study area.

3. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 2, based on the seismic interpretation data and the work area overview, the burial depth H1 of the bottom source rock layer of the fault communication and the burial depth H2 of the target reservoir are determined; the Eaton method or the equivalent depth method is selected to predict the pressure of the study area, thereby determining the pressure P0 of the bottom source rock layer of the fault communication and the pressure P2 of the target reservoir.

4. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 3, the parameters P, H, and V are used to represent the state of oil and gas at each stage, where P is pressure, H is burial depth, and V is volume. After the source rock expels hydrocarbons, high-pressure oil and gas enter the fault zone. At this time, the state parameters of oil and gas are P0, H1, and V1. Under the pumping action of the fault, the high-pressure oil and gas migrate vertically to the target reservoir. In this process, the residual pressure is approximately assumed to be unchanged, so formula (1) is obtained, and then the pressure P1 at the target reservoir burial depth H2 along the fault zone but not yet entering the reservoir is calculated, as shown in formula (2): P0-ρ w gH1=P1-ρ w gH2 (1) P1=P0-ρ w g(H1-H2) (2) Wherein, P0 is the pressure of the bottom source rock of the fault connection, MPa; P1 is the pressure of the oil and gas fluid that reaches the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir, MPa; ρ w is the density of formation water, g / cm 3 , take 1.0g / cm 3 ; g is the acceleration due to gravity, which is 9.8m / s 2 ; H1 is the burial depth of the bottom source rock layer of the fault connection, km; H2 is the burial depth of the target reservoir, km.

5. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 3, considering fluid compression and pore compression, the law of conservation of mass is used to obtain formula (3), where the original fluid in the target reservoir and the fluid migrating along the fault are at the mixed pressure P 混 Under these conditions, the density and porosity change, as shown in formula (4)-formula (7). Substituting formula (4)-formula (7) into formula (3), the pressure P after mixing can be calculated by the simultaneous equations: 混 , due to the parameters β0 and β c The order of magnitude is very small, β0β c =10 -17 kPa -1 , orders of magnitude smaller, so with β0β c The binomial can be ignored, and finally we get P 混 The calculation formula is shown in formula (8); where V1 is the volume of fluid that migrated to the target reservoir along the fault, that is, the volume of hydrocarbons expelled by the source rock, that is, the ratio of the hydrocarbon expulsion volume of the source rock to the density of crude oil, as shown in formula (9), and V2 is the volume of the original fluid in the target reservoir, that is, the pore system in the sandstone within the trap, as shown in formula (10): p1=p 混 [1+β0(P1-P 混 )] (4) p2=p 混 [1+β0(P2-P 混 )] (5) Where ρ1 is the density of high-pressure fluid migrating along the fault, g / cm 3 ; ρ2 is the density of the original fluid in the target reservoir, g / cm 3 ρ 混 is the density of the fluid after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, g / cm 3 ; β0 is the fluid compressibility coefficient, a constant, with a value of 10 -10 kPa -1 β c is the rock compression coefficient, a constant, with a value of 10 -7 kPa -1 ; φ1 is the porosity of the rock where the high-pressure fluid migrates along the fault, %; φ2 is the porosity of the rock where the original fluid of the target reservoir is located, %; φ 混 is the rock porosity after the high-pressure fluid migrating along the fault is mixed with the original fluid of the target reservoir, %; V1 is the volume of the high-pressure fluid migrating along the fault, m 3 ; V2 is the volume of the original fluid in the target reservoir, m 3 ;m oil For oil and gas generated from source rocks, 10 11 kg; H source is the thickness of source rock, m; S source is the area of source rock, km 2 ρ source is the density of source rock, g / cm 3 ; C0 is the original organic carbon, %; B oil is the oil production rate, mg / g; ρ oil is the density of crude oil, g / cm 3 , take 0.8g / cm 3 ; 10 -7 is the unit conversion constant; S t is the enclosed area, m 2 ;h t is the trap height, m; V sh is the sand-to-formation ratio, %; φ is the formation porosity, %, P1 is the oil and gas fluid pressure that reaches the target reservoir burial depth H2 along the fault zone but has not yet entered the reservoir, MPa; P2 is the pressure of the target reservoir, MPa.

6. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 4, from a plane perspective, the range of the fault zone is approximately a rectangle. The discharge area of the fault zone is a rounded rectangle with the fault discharge radius r as the radius, the fault extension length l as the length, and the fault zone width c as the width. Therefore, the calculation formula for the fault zone discharge area is shown in formula (13): S=lc+2r(l+c)+πr 2 (13) Where S is the fracture discharge area, km 2 ; l is the length of the fault, km; c is the width of the fault zone, km.

7. The quantitative calculation method of fracture leakage volume based on fracture-pressure coupling according to claim 1 is characterized in that: In step 5, the depth range of the longitudinal pressure relief zone is determined based on the variation of organic matter pyrolysis parameters S1 / (S1+S2), Tmax, illite content, and Ro value with depth. When the organic matter pyrolysis parameters S1 / (S1+S2) and Tmax deviate from the normal trend line, and the illite content and Ro value suddenly increase, it can be indicated that the fluid has migrated through the layers, which can be used as a method to identify the longitudinal pressure relief zone. Based on the determination of the height range of the fault longitudinal discharge zone, the discharge volume of the fault can be calculated using formula (14): V=(lc+2r(l+c)+πr 2 )h (14) Where V is the fracture discharge volume, km 3 ; h is the discharge height, km; l is the fault extension length, km; c is the fault zone width, km; r is the fault discharge radius, km.

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