Calculation method of gas-water interface rise height in fracture-cavity carbonate condensate gas reservoirs

Abstract

The invention discloses a method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir, which relates to the technical field of experimental simulation calculation of oil and gas reservoir development, and comprises the following steps: obtaining the height of the gas-water interface of a production well in a study area based on PVT test, well logging interpretation and gas test data; determining the water avoidance height of the formation and the volume of a reservoir body corresponding to the water avoidance height in the production well based on the height of the gas-water interface in the production well; obtaining the water intrusion amount of the production well; establishing a geological model for the rising of the gas-water interface in the fracture-cavity carbonate condensate gas reservoir, and obtaining the volume of formation water required for each rise of 1 m in the gas-water interface height based on the water avoidance height and the volume of the reservoir body; calculating the rising height of the gas-water interface based on the water intrusion amount and the volume of formation water required for each rise of 1 m in the gas-water interface height; in this way, the original gas-water interface is reasonably determined by using the production dynamic data of the oil and gas reservoir and the pressure recovery well test data, and the calculation of the water intrusion amount is dynamically updated to improve the calculation accuracy.

Description

Technical Field

[0001] The invention relates to the technical field of experimental simulation calculation of oil and gas reservoir development, and in particular to a method for calculating the rising height of a gas-water interface in a fracture-cavity carbonate condensate gas reservoir. Background Art

[0002] Understanding the gas-water distribution characteristics of gas reservoirs, the water production rules of gas wells, and formulating effective exploitation strategies are the key to improving the reserve utilization efficiency of water-bearing gas reservoirs. However, most studies on water invasion characteristics are based on numerical simulation results of mechanism models, and the research objects are mostly homogeneous sandstone oil and gas reservoirs. They have limited guiding role in the production and development of fracture-cavity carbonate condensate gas reservoirs. At the same time, the required parameters are complex and the calculation process is cumbersome, which cannot meet the technical needs of the front-line of oilfield production.

[0003] For example, a patent with publication number CN115935776A involves a water cone early warning method for carbonate fracture-cavity bottom water reservoirs. The invention aims to provide a technical solution: by determining water cone early warning evaluation indicators for carbonate fracture-cavity bottom water reservoirs, including water cone risk geological indicators and water cone risk production dynamic indicators, these two indicators are refined into primary indicators and secondary indicators, and then the degree of influence of each secondary indicator on the water cone of the oil well is graded, preferably 5 evaluation levels, and each evaluation level is assigned an evaluation vector, which is determined in combination with the experience of technical personnel in this field and expert scoring. Then, the weights of the water cone risk geological index and the water cone risk production dynamic index and the weights of their indicators at all levels are determined respectively. Finally, the comprehensive evaluation vector is multiplied by their respective weights and summed to obtain the water cone risk comprehensive evaluation vector. The maximum value corresponds to the risk level of the target well. This method has the following problems: First, there are too many indicator classifications and the required parameters are complex, which makes it difficult to obtain some data. In addition, the risk comprehensive evaluation vector is affected by the scoring standards of technicians and experts, and the human influence factor is relatively large. Second, this method mainly relies on reservoir development characteristics such as fracture-cavity reservoir type, oil-water distribution pattern, bottom water communication mode and reservoir production dynamic characteristics such as monthly pressure decline, monthly production decline and monthly water content increase to carry out water cone risk warning, and there is no calculation method for the relevant gas-water interface height. Summary of the invention

[0004] The main purpose of the present invention is to propose a method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir, aiming to solve the above-mentioned problem.

[0005] To achieve the above object, the present invention proposes a method for calculating the rise height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir. The method for calculating the rise height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir comprises the following steps:

[0006] Step S1, obtaining the gas-water interface height of the production wells in the study area based on PVT testing, well logging interpretation and gas testing data;

[0007] Step S2, based on the gas-water interface height of the production well, determining the water avoidance height of the formation and the volume of the reservoir corresponding to the water avoidance height in the production well;

[0008] Step S3, obtaining the water intrusion of the production well;

[0009] Step S4, establishing a geological model of the gas-water interface rise of the fracture-cavity carbonate condensate gas reservoir, and obtaining the volume of formation water required for each 1 m rise in the gas-water interface height based on the water avoidance height and the volume of the reservoir;

[0010] Step S5, calculating the rising height of the gas-water interface based on the water intrusion of the production well and the volume of formation water required for each 1 m rise in the height of the gas-water interface.

[0011] Furthermore, the step S1 specifically includes:

[0012] Step S11, based on PVT test, well logging interpretation and gas test data, at least static pressure data, pressure gradient data, original formation pressure data, formation condensate gas density data and formation water density data measured by the production well are obtained;

[0013] Step S12: Calculate the gas-water interface height of the production well according to the gas-water interface height calculation formula, the gas-water interface height calculation formula is: Where D gw is the height of the gas-water interface of the production well, D is the height of the middle part of the condensate gas reservoir, P i is the original formation pressure measured in the production well, P w is the hydrostatic pressure at the same depth measured in the production well, ρ g is the density of formation condensate gas, ρ w is the density of formation water.

[0014] Furthermore, the step S2 specifically includes:

[0015] Step S21, importing the geological model of the study area into the petrel modeling software, and determining the position of the gas-water interface of the production well based on the height of the gas-water interface;

[0016] Step S22, obtaining the water avoidance height based on the position of the gas-water interface of the production well and the position of the bottom of the production well;

[0017] Step S23, obtaining the volume of the reservoir corresponding to the water avoidance height.

[0018] Furthermore, the step S3 specifically includes:

[0019] Step S31, obtaining a water influx calculation formula based on a material balance equation for a water-driven condensate gas reservoir;

[0020] Step S32, obtaining actual development data of the production well according to the gas reservoir engineering method, and drawing a curve of relationship between pseudo-pressure and cumulative production to obtain a water storage coefficient;

[0021] Step S33, combining the water storage coefficient and using the water influx calculation formula to calculate the water influx of the production well.

[0022] Furthermore, the water intrusion calculation formula is W e =W p B w +GB gi ω, where W e is the current water influx of the production well, W p is the cumulative water production of the production well, B w is the formation water volume coefficient, G is the original geological reserves of the condensate gas reservoir, B gi is the original natural gas volume coefficient.

[0023] Furthermore, the water storage coefficient is Where ω is the water storage coefficient, ΔP p is the difference between the original gas reservoir pressure and the current gas reservoir pressure, Z is the natural gas deviation factor under the current formation pressure, dimensionless, P is the current formation pressure of the gas reservoir, and γ is the condensate volume coefficient.

[0024] Furthermore, the gas-water interface rising geological model is a triangular cone model, and the water volume corresponding to the gas-water interface rising height is the triangular cone volume;

[0025] Based on the water avoidance height and the volume of the reservoir, the volume of formation water required for each 1m rise in the gas-water interface height is Wherein, V2 is the volume of the reservoir corresponding to the water avoidance height, and H1 is the water avoidance height.

[0026] Furthermore, the volume of formation water required for each 1m rise in the gas-water interface height is Where NTG is the ratio of the effective volume of the reservoir to the total volume of the reservoir.

[0027] Furthermore, based on the water intrusion of the production well and the volume of formation water required for each 1m rise in the gas-water interface height, the rising height of the gas-water interface h=W e / V1, where W e is the water intrusion of the production well, and V1 is the volume of formation water required for each 1m rise in the gas-water interface height.

[0028] In the technical scheme of the present invention, in view of the strong heterogeneity and the absence of a unified gas-water interface of fracture-cavity carbonate condensate gas reservoirs, a method for calculating the rising height of the gas-water interface of fracture-cavity carbonate condensate gas reservoirs is provided. The gas-water interface height of each production well in the study area is obtained by using the oil and gas reservoir production dynamic data and pressure recovery test data obtained based on PVT testing, well logging interpretation and gas testing data, that is, the original gas-water interface of each production well is reasonably determined; and the calculation of water invasion is dynamically updated according to the measured flow static pressure data and production data to realize the dynamic monitoring of the calculation results of the rising height of the gas-water interface; in addition, a relatively accurate water invasion is obtained by a gas reservoir engineering method, and the reservoir volume corresponding to the water avoidance height is obtained by using the petrel modeling software combined with the actual formation conditions, and further, according to the different development conditions and distribution patterns of the three types of reservoirs of the target layer of the production well, namely, caves, fractures and pores, the reservoir ratio is used to describe the dominant channel of water seepage, and the calculation is no longer constrained by the reservoir type, thereby obtaining the lifting height of the gas-water interface, thereby improving the accuracy of the calculation results. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0030] Figure 1 A flow chart of an embodiment of a method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir provided by the present invention;

[0031] Figure 2 for Figure 1 Flow chart of step S1 in FIG.

[0032] Figure 3 for Figure 1 Flow chart of step S2;

[0033] Figure 4 for Figure 1 Flow chart of step S3;

[0034] Figure 5 Carve a map from the gas-water interface to the bottom of the production well;

[0035] Figure 6 It is the relationship curve between the simulated pressure and cumulative production of the production well;

[0036] Figure 7 The gas-water interface uplift height model for production wells.

[0037] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0040] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0041] Understanding the gas-water distribution characteristics of gas reservoirs, the water production rules of gas wells, and formulating effective exploitation strategies are the key to improving the reserve utilization efficiency of water-bearing gas reservoirs. However, most studies on water invasion characteristics are based on numerical simulation results of mechanism models, and the research objects are mostly homogeneous sandstone oil and gas reservoirs. They have limited guiding role in the production and development of fracture-cavity carbonate condensate gas reservoirs. At the same time, the required parameters are complex and the calculation process is cumbersome, which cannot meet the technical needs of the front-line of oilfield production.

[0042] For example, a patent with publication number CN115935776A involves a water cone early warning method for carbonate fracture-cavity bottom water reservoirs. The invention aims to provide a technical solution: by determining water cone early warning evaluation indicators for carbonate fracture-cavity bottom water reservoirs, including water cone risk geological indicators and water cone risk production dynamic indicators, these two indicators are refined into primary indicators and secondary indicators, and then the degree of influence of each secondary indicator on the water cone of the oil well is graded, preferably 5 evaluation levels, and each evaluation level is assigned an evaluation vector, which is determined in combination with the experience of technical personnel in this field and expert scoring. Then, the weights of the water cone risk geological index and the water cone risk production dynamic index and the weights of their indicators at all levels are determined respectively. Finally, the comprehensive evaluation vector is multiplied by their respective weights and summed to obtain the water cone risk comprehensive evaluation vector. The maximum value corresponds to the risk level of the target well. This method has the following problems: First, there are too many indicator classifications and the required parameters are complex, which makes it difficult to obtain some data. In addition, the risk comprehensive evaluation vector is affected by the scoring standards of technicians and experts, and the human influence factor is relatively large. Second, this method mainly relies on reservoir development characteristics such as fracture-cavity reservoir type, oil-water distribution pattern, bottom water communication mode and reservoir production dynamic characteristics such as monthly pressure decline, monthly production decline and monthly water content increase to carry out water cone risk warning, and there is no calculation method for the relevant gas-water interface height.

[0043] In view of this, the present invention provides a method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir. Figures 1 to 4 The present invention provides a flow chart of a method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir.

[0044] See also Figure 1 The method for calculating the rising height of the gas-water interface in the fracture-cavity carbonate condensate gas reservoir comprises the following steps:

[0045] Step S1, obtaining the gas-water interface height of production wells in the study area based on PVT testing, well logging interpretation and gas testing data.

[0046] In the fracture-cavity carbonate condensate gas reservoir formation, reservoirs and fracture surfaces are developed vertically, and seepage channels of formation fluids are formed, which causes gravity differentiation of gas and water in the formation, thereby forming a gas-water interface, that is, all gas is above the interface, and all water is below the interface. In this step, in view of the strong heterogeneity and lack of a unified gas-water interface of fracture-cavity carbonate condensate gas reservoirs, the production dynamic data of oil and gas reservoirs and pressure recovery test data obtained based on PVT testing, well logging interpretation and gas test data are used to obtain the gas-water interface height of each production well in the study area, that is, the original gas-water interface of each production well is reasonably determined.

[0047] For further information, see Figure 2 , the step S1 specifically comprises:

[0048] Step S11, based on PVT testing, well logging interpretation and gas testing data, at least static pressure data, pressure gradient data, original formation pressure data, formation condensate gas density data and formation water density data measured by the production well are obtained.

[0049] Step S12: Calculate the gas-water interface height of the production well according to the gas-water interface height calculation formula, the gas-water interface height calculation formula is: Where D gw is the height of the gas-water interface of the production well, in m, D is the height of the middle part of the condensate gas reservoir, in m, P i is the original formation pressure measured in the production well, in MPa, P w is the hydrostatic pressure at the same depth measured in the production well, in MPa, ρ g is the density of formation condensate gas, in g / cm 3 , ρ w is the density of formation water, in g / cm 3 .

[0050] More specifically, the air-water interface height calculation formula is derived based on Newton's second law.

[0051] Based on Newton's second law, F = ADρg, ​​F is gravity, unit N, A is area, unit m 2 , D is the depth of the middle part of the condensate gas reservoir, unit is m, ρ is the formation fluid density, unit is kg / m 3 , g is the acceleration due to gravity, unit is m / s 2 ; After dividing both sides of the equation by A, we can get the expression of pressure, which is P = 0.01ρD in SI practical units. Then the pressure gradient can be expressed as G p =dp / dD=0.01ρD. From this formula, we can know that the formation pressure gradient is proportional to the formation fluid density. If there is a gas-water interface in a condensate gas reservoir, the pressure gradient of the gas layer can be expressed as G g =dp / dD, and then we can get dp=G g dD.

[0052] Furthermore, the pressure at the gas-water interface and the original formation pressure are taken as the upper and lower limits of the integral on the left side of the equal sign, and the depth of the gas-water interface and the middle depth of the condensate gas reservoir are taken as the upper and lower limits of the integral on the right side of the equal sign. The integral form can be expressed as Integrate both sides of the equal sign to get P gw -P i =G g (D gw -D), and then the calculation formula for the air-water interface height can be obtained.

[0053] Step S2: based on the gas-water interface height of the production well, determine the water avoidance height of the formation and the volume of the reservoir in the production well corresponding to the water avoidance height.

[0054] For further information, see Figure 3 , the step S2 specifically includes:

[0055] Step S21, importing the geological model of the study area into the petrel modeling software, and determining the position of the gas-water interface of the production well based on the height of the gas-water interface.

[0056] Step S22: obtaining the water avoidance height based on the position of the gas-water interface of the production well and the position of the bottom of the production well.

[0057] In this step, the water avoidance height is the distance from the gas-water interface to the bottom of the production well. Figure 5 shown.

[0058] Step S23, obtaining the volume of the reservoir corresponding to the water avoidance height (eg Figure 7 (as shown in ① in the figure).

[0059] Step S3, obtaining the water intrusion amount of the production well.

[0060] For further information, see Figure 4 , the step S3 specifically includes:

[0061] Step S31, obtaining a water influx calculation formula based on a material balance equation for a water-driven condensate gas reservoir.

[0062] Specifically, the material balance equation of the water-driven condensate gas reservoir is:

[0063]

[0064] Where G is the original geological reserves of condensate gas reservoir, unit 10 8 m 3 ;

[0065] B gi is the original natural gas volume coefficient, dimensionless;

[0066] G p is the current cumulative production of condensate gas reservoirs, unit 10 8 m 3 ;

[0067] B g is the volume coefficient of natural gas at current pressure, dimensionless;

[0068] C w is the compression coefficient of the formation bound water, unit: MPa-1 ;

[0069] S wi is the irreducible water saturation of the gas reservoir;

[0070] C f is the compression coefficient of formation rock, unit: MPa -1 ;

[0071] C o is the condensate oil compressibility coefficient, unit: MPa -1 ;

[0072] S o is the oil saturation of the gas reservoir;

[0073] ΔP is the difference between the original gas reservoir pressure and the current gas reservoir pressure, in MPa;

[0074] W e is the current water influx of the production well, in units of 10 8 m 3 ;

[0075] W p is the cumulative water production of the production well, in units of 10 8 m 3 ;

[0076] B w is the formation water volume coefficient, dimensionless;

[0077] V cs is the volume of condensate oil precipitated, unit: 108m 3 .

[0078] Considering the comprehensive compression factor Gas Equation of State Condensate volume factor and water storage volume coefficient The material balance equation of water-driven condensate gas reservoir is converted into Among them, C t is the comprehensive compression coefficient of the gas reservoir, unit: MPa -1 , P is the current formation pressure of the gas reservoir, unit MPa, P i is the original formation pressure of the gas reservoir, unit MPa, Z is the natural gas deviation factor under the current formation pressure, dimensionless, Z i is the natural gas deviation factor at the original formation pressure, dimensionless, and γ is the condensate volume coefficient, dimensionless.

[0079] Furthermore, the pressure parameter is converted into the form of pseudo-pressure, that is, the original gas reservoir pseudo-pressure is The current gas reservoir pseudo pressure is Then the pseudo-pressure form of the gas reservoir material balance equation can be changed to

[0080]

[0081] Furthermore, the pseudo-pressure form of the gas reservoir material balance equation is simplified. Specifically, let the original pseudo-pressure P of the water-driven gas reservoir be ci =P pi , let the current pseudo pressure of water drive gas reservoir P c =P p (1-C t Δp-ω-γ), then the pseudo-pressure form of the material balance equation of the water-driven gas reservoir is:

[0082] Furthermore, in the early stage of condensate gas reservoir development, the formation pressure drop funnel has not propagated to the gas-water interface, so the water storage coefficient ω = 0, and there is no reverse condensation phenomenon in the early stage, so the condensate oil volume coefficient γ = 0, and the natural gas expansion energy is much greater than the expansion energy of the gas reservoir volume, so C t Δp is also close to 0, indicating that the early development characteristics of the water-driven condensate gas reservoir are consistent with the characteristics of the fixed-volume gas reservoir. The material balance of the fixed-volume gas reservoir is:

[0083] It can be obtained that the water intrusion calculation formula is W e =W p B w +GB gi ω.

[0084] Step S32: obtaining the actual development data of the production well according to the gas reservoir engineering method, and drawing a curve of the relationship between pseudo-pressure and cumulative production to obtain the water storage coefficient.

[0085] Specifically, the relationship curve between the pseudo-pressure and the cumulative production is as follows: Figure 6 As shown, from the figure we can get:

[0086]

[0087] In this way, the water storage coefficient can be expressed as

[0088] Step S33, combining the water storage coefficient and using the water influx calculation formula to calculate the water influx of the production well.

[0089] In this step, the water storage coefficient is substituted into the water intrusion calculation formula, then

[0090]

[0091] It should be noted that if the condensate gas reservoir has low condensate oil content or the condensate gas reservoir has not yet experienced retrograde condensation, γ = 0, then the water intrusion calculation formula is:

[0092] Step S4, establishing a geological model of the gas-water interface rise of the fracture-cavity carbonate condensate gas reservoir, and based on the water avoidance height and the volume of the reservoir, obtaining the formation water volume required for each 1 m rise in the gas-water interface height.

[0093] Furthermore, since carbonate rocks have strong heterogeneity, the gas-water interface rising geological model is simplified to a triangular pyramid model (such as Figure 1 As shown in ②, the water volume corresponding to the rising height of the air-water interface is the volume of a triangular cone. The volume of the water body raised by the air-water interface can be calculated from the triangular cone volume formula as follows: Where V2 is the volume of the reservoir corresponding to the water avoidance height, in units of 10 4 m 3 .

[0094] Furthermore, based on the water avoidance height and the volume of the reservoir, the volume of formation water required for each 1m rise in the gas-water interface height is Unit 10 4 m 3 , where H1 is the water avoidance height, in meters.

[0095] Furthermore, since the total volume in the fracture-cavity carbonate condensate gas reservoir cannot represent the effective volume in the formation, the effective volume after considering the reservoir ratio (NTG) is the dominant channel volume of the water body. In this way, the formation water volume required for each 1m increase in the gas-water interface height is:

[0096]

[0097] Where V1 is the volume of formation water required for the gas-water interface to rise by 1 m, in units of 10 4 m 3 ; NTG is the ratio of the effective volume of the reservoir to the total volume of the reservoir, dimensionless.

[0098] Step S5, calculating the rising height of the gas-water interface based on the water intrusion of the production well and the volume of formation water required for each 1 m rise in the height of the gas-water interface.

[0099] In this step, based on the water intrusion of the production well and the volume of formation water required for each 1m rise in the gas-water interface height, the rising height of the gas-water interface h=W e / V1, unit m, where W e is the water intrusion of the production well, unit 10 8 m 3 , V1 is the volume of formation water required for the gas-water interface to rise by 1 m, in units of 10 4 m 3.

[0100] Furthermore, based on the above-mentioned gas-water interface height, the required formation water volume for each 1m rise is The rising height of the air-water interface is

[0101]

[0102] In the technical scheme of the present invention, in view of the strong heterogeneity and the lack of a unified gas-water interface of fracture-cavity carbonate condensate gas reservoirs, a method for calculating the rising height of the gas-water interface of fracture-cavity carbonate condensate gas reservoirs is provided. The gas-water interface height of each production well in the study area is obtained by using the oil and gas reservoir production dynamic data and pressure recovery test data obtained based on PVT testing, well logging interpretation and gas testing data, that is, the original gas-water interface of each production well is reasonably determined; and the calculation of water invasion is dynamically updated according to the measured flow static pressure data and production data to realize the dynamic monitoring of the calculation results of the rising height of the gas-water interface; in addition, a relatively accurate water invasion is obtained by a gas reservoir engineering method, and the reservoir volume corresponding to the water avoidance height is obtained by using the petrel modeling software combined with the actual formation conditions, and further, according to the different development conditions and distribution patterns of the three types of reservoirs of the target layer of the production well, namely, caves, fractures and pores, the reservoir ratio is used to describe the dominant channel of water seepage, and the calculation is no longer constrained by the reservoir type, thereby obtaining the lifting height of the gas-water interface, thereby improving the accuracy of the calculation results.

[0103] Specifically, in a specific embodiment of the present invention, for a fractured-cavity carbonate rock area in a certain northwest region of China, based on PVT testing, logging interpretation and gas testing data, it is determined that the original gas-water interface of the fractured-cavity carbonate condensate gas reservoir in the area is 8058.84m underground, the completion depth is 7779.87m, the water avoidance height is 278.97m, and the reservoir volume corresponding to the water avoidance height is 8.72 million cubic meters, with a water content of 8.9%. After 8 months, the water content rises to 15.4%. In this way, the water invasion is calculated to be 238,500 cubic meters, the reservoir ratio of the well is 0.15, the volume of the dominant channel of the water body lifted by the gas-water interface is calculated to be 436,000 cubic meters, and the gas-water interface lifting height is 105.21m, then the new gas-water interface height is 7906.17m.

[0104] Furthermore, by using the static pressure data of the flow measured after the well was shut down, the gas-water interface height was recalculated to be 7883.12 m, which is only 23.05 m different from the 7906.17 m calculated by the method of the present invention, confirming that the method has a good field application effect.

[0105] The method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir provided by the present invention can be used to determine the current gas-water interface height and the estimated time of water breakthrough for gas wells in the gas reservoir, help condensate gas wells determine a reasonable production system, and take effective water control measures, thereby delaying the time of water breakthrough in the gas reservoir and reducing the damage of formation water invasion to gas reservoir development; the method is simple, fast, and accurate in calculation, can effectively guide gas reservoir development work, and provides effective support for determining a reasonable production system for gas wells and scientific water control measures.

[0106] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir, characterized in that: The method for calculating the rising height of the gas-water interface in the fracture-cavity carbonate condensate gas reservoir comprises the following steps: Step S1, obtaining the gas-water interface height of the production wells in the study area based on PVT testing, well logging interpretation and gas testing data; Step S2, based on the gas-water interface height of the production well, determining the water avoidance height of the formation and the volume of the reservoir corresponding to the water avoidance height in the production well; Step S3, obtaining the water intrusion of the production well; Step S4, establishing a geological model of the gas-water interface rise of the fracture-cavity carbonate condensate gas reservoir, and obtaining the volume of formation water required for each 1 m rise in the gas-water interface height based on the water avoidance height and the volume of the reservoir; Step S5, calculating the rising height of the gas-water interface based on the water intrusion of the production well and the volume of formation water required for each 1m rise in the height of the gas-water interface; The step S3 specifically includes: Step S31, obtaining a water influx calculation formula based on a material balance equation for a water-driven condensate gas reservoir; Step S32, obtaining actual development data of the production well according to the gas reservoir engineering method, and drawing a curve of relationship between pseudo-pressure and cumulative production to obtain a water storage coefficient; Step S33, combining the water storage coefficient and using the water intrusion calculation formula to calculate the water intrusion volume of the production well; The water intrusion calculation formula is: , where W e is the current water influx of the production well, W p is the cumulative water production of the production well, B w is the formation water volume coefficient, G is the original geological reserves of the condensate gas reservoir, B gi is the original natural gas volume coefficient; The water storage coefficient is , where ω is the water storage coefficient, ΔP p is the difference between the original gas reservoir pressure and the current gas reservoir pressure, Z is the natural gas deviation factor under the current formation pressure, P is the current formation pressure of the gas reservoir, is the condensate volume coefficient; The gas-water interface rising geological model is a triangular cone model, and the water volume corresponding to the gas-water interface rising height is the triangular cone volume; Based on the water avoidance height and the volume of the reservoir, the volume of formation water required for each 1m rise in the gas-water interface height is , where V2 is the volume of the reservoir corresponding to the water avoidance height, and H1 is the water avoidance height; The volume of formation water required for each 1m rise in the gas-water interface height , where NTG is the ratio of the effective volume of the reservoir to the total volume of the reservoir.

2. The method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir according to claim 1, characterized in that: The step S1 specifically includes: Step S11, based on PVT test, well logging interpretation and gas test data, at least static pressure data, pressure gradient data, original formation pressure data, formation condensate gas density data and formation water density data measured by the production well are obtained; Step S12: Calculate the gas-water interface height of the production well according to the gas-water interface height calculation formula, the gas-water interface height calculation formula is: , where D gw is the height of the gas-water interface of the production well, D is the height of the middle part of the condensate gas reservoir, P i is the original formation pressure measured in the production well, P w is the hydrostatic pressure at the same depth measured in the production well, ρ g is the density of formation condensate gas, ρ w is the density of formation water.

3. The method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir according to claim 2, characterized in that: The step S2 specifically includes: Step S21, importing the geological model of the study area into the petrel modeling software, and determining the position of the gas-water interface of the production well based on the height of the gas-water interface; Step S22, obtaining the water avoidance height based on the position of the gas-water interface of the production well and the position of the bottom of the production well; Step S23, obtaining the volume of the reservoir corresponding to the water avoidance height.

4. The method for calculating the rising height of the gas-water interface in a fracture-cavity carbonate condensate gas reservoir according to claim 1, characterized in that: Based on the water intrusion of the production well and the volume of formation water required for each 1m rise in the gas-water interface height, the rising height of the gas-water interface , where is the water intrusion of the production well, and V1 is the volume of formation water required for each 1m rise in the gas-water interface height.

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