Method and device for determining bottom water breakthrough time in vertical wells of triple-medium bottom water gas reservoirs

Abstract

The present disclosure provides a method and device for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, and belongs to the field of oil and gas production. The method includes establishing a pressure distribution model of the formation; establishing a water cone height model based on the pressure distribution model; determining the bottom water seepage velocity in the vertical direction based on the water cone height model; and determining the bottom water breakthrough time based on the seepage velocity. The pressure distribution of the formation will affect the height of the bottom water cone surface. A water cone height model is established based on the pressure distribution model of the formation. The water cone height model reflects the height of the bottom water boundary at different positions of the bottom of the vertical well, thereby reflecting the shape of the bottom water cone surface. The bottom water seepage velocity in the vertical direction is determined based on the water cone height model. The bottom water seepage velocity affects the bottom water breakthrough time. The faster the seepage velocity, the shorter the bottom water breakthrough time, and vice versa. Therefore, a relatively accurate bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir can be determined.

Description

Technical Field

[0001] The present invention relates to the field of oil and gas exploitation, and in particular to a method and a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir. Background Art

[0002] A vertical well is a well whose surface wellhead position is consistent with the geographic coordinates of the well bottom position where the target layer is drilled, and the wellbore is drilled vertically from the wellhead to the designed depth. In actual drilling construction, it is impossible to drill a completely vertical well due to the influence of many factors such as formation and process. The vertical well usually refers to a well that is close to vertical.

[0003] Since the reservoir is affected by the sedimentary environment, diagenesis, weathering and tectonic action during its formation, the spatial distribution and internal properties of pores, fractures and caves in the triple-medium bottom-water gas reservoir are relatively random. The size, shape, distribution characteristics and matching relationship of pores, fractures and caves are ever-changing, which makes it difficult to accurately describe the non-uniform water channeling characteristics of triple-medium bottom-water gas reservoirs and to determine the bottom water breakthrough time when developing gas reservoirs with vertical wells. Summary of the invention

[0004] The disclosed embodiment provides a method and device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, which can facilitate determination of the bottom water breakthrough time when a vertical well is used for development in a triple-medium bottom water gas reservoir. The technical solution is as follows:

[0005] In a first aspect, an embodiment of the present disclosure provides a method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, the method comprising:

[0006] Establish a pressure distribution model for the formation;

[0007] Establishing a water cone height model based on the pressure distribution model;

[0008] Determining the vertical seepage velocity of bottom water based on the water cone height model;

[0009] The bottom water breakthrough time is determined based on the seepage velocity.

[0010] Optionally, establishing a formation pressure distribution model includes:

[0011] Determine the inner zone radius and outer zone radius of gas well control;

[0012] The following pressure distribution model is established:

[0013]

[0014] Among them, p(r) r1 is the pressure in the inner zone of the perforation section, p(r)r2 is the pressure in the outer zone of the perforation section, r is the radial distance from the center of the wellbore, and p wf is the bottom hole flowing pressure, p e is the outer boundary pressure of the gas reservoir top, K1 is the inner zone permeability, K2 is the outer zone permeability, R e is the outer radius, R1 is the inner radius, R w is the wellbore radius.

[0015] Optionally, establishing a water cone height model based on the pressure distribution model includes:

[0016] The following water cone height model is established:

[0017]

[0018] Where z(r) is the height of the water cone, p gwc is the air-water interface pressure, p(r) rj is the pressure in the inner or outer zone of the perforation section, j∈{1,2}, ρ g is the density of natural gas in the formation, ρ w is the density of groundwater in the formation, g is the acceleration of gravity, h is the thickness of the gas reservoir, and h p is the perforation thickness.

[0019] Optionally, determining the vertical seepage velocity of bottom water based on the water cone height model includes:

[0020] Determine the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area:

[0021]

[0022]

[0023] Among them, Ω w is the seepage resistance of the bottom water cone, Ω g is the seepage resistance of the pure gas zone, μ w is the viscosity of groundwater in the formation, μ g is the viscosity of natural gas in the formation, K j is the inner zone permeability or the outer zone permeability, A(r) is the seepage cross-sectional area;

[0024] Determine the vertical seepage velocity of bottom water:

[0025]

[0026] Where v(r) is the vertical seepage velocity of bottom water.

[0027] Optionally, determining the bottom water breakthrough time based on the seepage velocity comprises:

[0028] The bottom water breakthrough time is determined based on the seepage resistance of the bottom water cone entry area and the vertical seepage velocity of the bottom water:

[0029]

[0030] Where t is the bottom water breakthrough time, φ is the formation porosity, S wi is the bound water saturation, S gr is the residual gas saturation.

[0031] In a second aspect, the disclosed embodiment further provides a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, the device comprising:

[0032] A model building module, used to build a pressure distribution model of the formation, and to build a water cone height model based on the pressure distribution model;

[0033] A first determination module is used to determine the vertical seepage velocity of bottom water based on the water cone height model;

[0034] The second determination module is used to determine the bottom water breakthrough time based on the seepage velocity.

[0035] Optionally, the model building module is used to build a pressure distribution model of the formation in the following manner:

[0036] Determine the inner zone radius and outer zone radius of gas well control;

[0037] The following pressure distribution model is established:

[0038]

[0039] Among them, p(r) r1 is the pressure in the inner zone of the perforation section, p(r) r2 is the pressure in the outer zone of the perforation section, r is the radial distance from the center of the wellbore, and p wf is the bottom hole flowing pressure, p e is the outer boundary pressure of the gas reservoir top, K1 is the inner zone permeability, K2 is the outer zone permeability, R e is the outer radius, R1 is the inner radius, R w is the wellbore radius.

[0040] Optionally, the model building module is used to build the following water cone height model:

[0041]

[0042] Where z(r) is the height of the water cone, p gwc is the air-water interface pressure, p(r) rjis the pressure in the inner or outer zone of the perforation section, j∈{1,2}, ρ g is the density of natural gas in the formation, ρ w is the density of groundwater in the formation, g is the acceleration of gravity, h is the thickness of the gas reservoir, and h p is the perforation thickness.

[0043] Optionally, the first determination module is used to determine the vertical seepage velocity of bottom water in the following manner:

[0044] Determine the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area:

[0045]

[0046]

[0047] Among them, Ω w is the seepage resistance of the bottom water cone, Ω g is the seepage resistance of the pure gas zone, μ w is the viscosity of groundwater in the formation, μ g is the viscosity of natural gas in the formation, K j is the inner zone permeability or the outer zone permeability, A(r) is the seepage cross-sectional area;

[0048] Determine the vertical seepage velocity of bottom water:

[0049]

[0050] Where v(r) is the vertical seepage velocity of bottom water.

[0051] Optionally, the second determination module is used to determine the bottom water breakthrough time in the following manner:

[0052] The bottom water breakthrough time is determined based on the seepage resistance of the bottom water cone entry area and the vertical seepage velocity of the bottom water:

[0053]

[0054] Where t is the bottom water breakthrough time, φ is the formation porosity, S wi is the bound water saturation, S gr is the residual gas saturation.

[0055] In a third aspect, the disclosed embodiment further provides a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, comprising:

[0056] processor;

[0057] a memory for storing instructions executable by a processor;

[0058] Wherein, the processor is configured to execute the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir as described in the first aspect above.

[0059] In a fourth aspect, an embodiment of the present disclosure further provides a computer-readable storage medium, wherein the storage medium stores at least one instruction, and the instruction is loaded and executed by a processor to implement the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir as described in the first aspect above.

[0060] The beneficial effects brought by the technical solution provided by the embodiments of the present disclosure include at least:

[0061] By establishing a formation pressure distribution model, the formation pressure distribution will affect the height of the bottom water cone. Based on the formation pressure distribution model, a water cone height model is established. The water cone height model reflects the height of the bottom water boundary at different positions at the bottom of the vertical well, thereby reflecting the shape of the bottom water cone. The vertical seepage velocity of the bottom water is determined based on the water cone height model. The seepage velocity of the bottom water affects the bottom water breakthrough time. The faster the seepage velocity, the shorter the bottom water breakthrough time, and vice versa. Therefore, a more accurate bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir can be determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0063] Figure 1 It is a flow chart of a method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure;

[0064] Figure 2 It is a flow chart of a method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure;

[0065] Figure 3 is a schematic diagram of the control range of a gas well provided by an embodiment of the present disclosure;

[0066] Figure 4 is a schematic cross-sectional diagram of bottom water intrusion provided by an embodiment of the present disclosure;

[0067] Figure 5 It is a structural block diagram of a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure;

[0068] Figure 6It is a structural block diagram of a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0069] In order to make the objectives, technical solutions and advantages of the present disclosure more clear, the embodiments of the present disclosure will be further described in detail below with reference to the accompanying drawings.

[0070] Figure 1 1 is a flow chart of a method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure. The method is used to determine the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir. Figure 1 As shown, the method includes:

[0071] S11: Establish a formation pressure distribution model.

[0072] S12: Establish a water cone height model based on the pressure distribution model.

[0073] S13: Determine the vertical seepage velocity of bottom water based on the water cone height model.

[0074] S14: Determine the bottom water breakthrough time based on the seepage velocity.

[0075] By establishing a formation pressure distribution model, the formation pressure distribution will affect the height of the bottom water cone. Based on the formation pressure distribution model, a water cone height model is established. The water cone height model reflects the height of the bottom water boundary at different positions at the bottom of the vertical well, thereby reflecting the shape of the bottom water cone. The vertical seepage velocity of the bottom water is determined based on the water cone height model. The seepage velocity of the bottom water affects the bottom water breakthrough time. The faster the seepage velocity, the shorter the bottom water breakthrough time, and vice versa. Therefore, a more accurate bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir can be determined.

[0076] Figure 2 This is a flow chart of a method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an embodiment of the present disclosure. The method is used to determine the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir. The method includes:

[0077] S21: Determine the inner zone radius and outer zone radius of the gas well control.

[0078] Figure 3 It is a schematic diagram of the control range of the gas well provided in the embodiment of the present disclosure. Figure 3 The lower figure is a top view, and the upper figure is a cross-sectional view, showing the water invasion cross-section of a triple-medium bottom water gas reservoir. The upper figure only shows the lowermost part of the wellbore. In the upper figure, the upper filling area is the wellbore, and the lower filling area is the bottom water. The thickness of the gas reservoir is h, and the perforation thickness is h p. The gas well is a straight well, and the gas well control range is a circular area with the center of the wellbore as the center. Due to the heterogeneity of the permeability distribution of the triple-medium bottom water gas reservoir, the reservoir is simplified into a composite formation according to the distribution of permeability. According to the difference in permeability, the gas well control range is divided into inner zone 1 and outer zone 2, where inner zone 1 is a circular area with the center of the wellbore as the center, and outer zone 2 is an annular area with the center of the wellbore as the center, and outer zone 2 surrounds inner zone 1. The heterogeneity of the permeability distribution of inner zone 1 and outer zone 2 will lead to different pressure distribution characteristics of inner zone 1 and outer zone 2 in the radial direction of the perforation section, which will cause the water cone surface to deform at the junction of inner zone 1 and outer zone 2.

[0079] S22: Establish a pressure distribution model.

[0080] According to the steady seepage theory, the following pressure distribution model is established:

[0081]

[0082] Among them, p(r) r1 is the pressure in the inner area of ​​the perforation section, in MPa; p(r) r2 is the pressure in the outer zone of the perforation section, in MPa; r is the radial distance from the center of the wellbore, in m; p wf is the bottom hole flowing pressure, in MPa; p e is the outer boundary pressure of the gas reservoir top, in MPa; K1 is the inner zone permeability, in mD; K2 is the outer zone permeability, in mD; R e is the radius of the outer zone, in m; R1 is the radius of the inner zone, in m; R w is the wellbore radius, in m.

[0083] When R w ≤r≤R1, the pressure in the inner zone of the perforation section is determined according to the relationship (1); when R1<r≤R e When , the pressure in the outer zone of the perforation section is determined according to equation (2).

[0084] The pressure distribution model reflects the pressure distribution in the radial direction of the perforation section. When using vertical wells to develop bottom water gas reservoirs, the perforation section is located at the top of the gas-bearing layer, and there is a certain water avoidance height at the bottom of the vertical well, that is, the vertical distance between the bottom of the vertical well and the bottom water. After the vertical well is put into production, a pressure drop funnel will be formed in the radial direction of the perforation section, and the pressure balance between the gas layer and the bottom water layer will be broken, causing the bottom water to move upward under the pressure difference between the gas layer and the bottom water layer. The pressure distribution in the radial direction of the perforation section affects the speed and height of the upward movement of the bottom water. By establishing a pressure distribution model, it is convenient to accurately determine the bottom water breakthrough time in the subsequent period.

[0085] S23: Establish a water cone height model.

[0086] When capillary pressure is ignored, the shape and stability of the gas-water interface depend on the vertical pressure difference between the gas layer and the bottom water layer and the gravity generated by the gas-water two phases. The conditions for the stability of the gas-water interface are:

[0087] p gwc -p(r) rj ≤ρ w gz-ρ g g[(hh p )-z] (3)

[0088] Among them, p gwc is the air-water interface pressure, in MPa; p(r) rj is the pressure in the inner or outer zone of the perforation section, in MPa; j∈{1,2}; ρ g is the density of natural gas in the formation, in kg / m 3 ρ w is the density of groundwater in the stratum, in kg / m 3 ; g is the acceleration of gravity; h is the thickness of the gas reservoir, in meters; h p is the perforation thickness, in m; z is the height of bottom water rise, in m.

[0089] If the relationship (5) holds true, the bottom water will remain stable after rising to a corresponding height z relative to the initial bottom water boundary and will not continue to rise. If the relationship (5) does not hold true, the bottom water will continue to rise after rising to a certain height z until it remains stable or until it enters the gas well, causing water to appear in the gas well. The height of the bottom water when water appears in the gas well is hh p .

[0090] Assuming that the air-water interface remains stable, the following water cone height model is established:

[0091]

[0092] Among them, z(r) is the height of the water cone surface, which is also the bottom water rise height, and the unit is m.

[0093] The water cone height z(r) is a piecewise function of r. When j=1, it corresponds to the water cone height in the inner zone, and when j=2, it corresponds to the water cone height in the outer zone. The water cone height is usually different at different distances from the center of the wellbore.

[0094] When water appears in the gas well, the height of the water cone is hh p , the bottom hole flowing pressure at this time is the critical pressure of gas well production, and the critical pressure satisfies the following relationship:

[0095] p wf(crit) =pgwc -ρ w g(hh p ) (5)

[0096] Among them, p wf(crit) It is the bottom hole flow pressure when water appears in the gas well, the unit is MPa.

[0097] From this, we can further obtain the critical production of the gas well:

[0098]

[0099] Among them, Q crit is the critical production of the gas well, in m 3 / s; μ g It is the viscosity of natural gas in the formation, in mPa·s.

[0100] S24: Determine the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area.

[0101] Before water appears in the gas well, the area from the gas-water interface to the bottom of the well is divided into the bottom water cone area and the pure gas area. According to the equivalent seepage resistance method, the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area are determined:

[0102]

[0103]

[0104] Among them, Ω w is the seepage resistance of the bottom water cone entry area, in MPa / (m / s); Ω g is the seepage resistance of the pure gas zone, in MPa / (m / s); μ w is the viscosity of groundwater in the formation, in mPa·s; μ g is the viscosity of natural gas in the formation, in mPa·s; K j is the inner zone permeability or outer zone permeability, in mD; A(r) is the seepage cross-sectional area at a distance r from the wellbore center, in m 2 .

[0105] When R w ≤r≤R1, j=1, and equations (7) and (8) correspond to the inner region; when R1<r≤R e When j=2, equations (7) and (8) correspond to the outer region.

[0106] S25: Determine the vertical seepage velocity of the bottom water based on the seepage resistance of the bottom water cone entry zone and the seepage resistance of the pure gas zone.

[0107] According to the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area, the seepage velocity of the bottom water at any position in the inner and outer areas can be determined. The seepage velocity satisfies the following relationship:

[0108]

[0109] Wherein, v(r) is the vertical seepage velocity of bottom water at a distance r from the center of the wellbore, in m / s.

[0110] The seepage velocity v(r) is also a piecewise function of r. In the inner region, R w ≤r≤R1, j=1; in the outer region, R1<r≤R e , j=2.

[0111] S26: Determine the bottom water breakthrough time based on the seepage resistance of the bottom water cone entry zone and the vertical seepage velocity of the bottom water.

[0112] Based on the seepage velocity, the relationship between the distance and time of bottom water moving vertically at any position can be determined. The distance and time of bottom water moving vertically satisfy the following relationship:

[0113]

[0114] Where dz is the distance the bottom water moves vertically in time dt, in meters; φ is the formation porosity, dimensionless.

[0115] Based on the consideration of the original bound water saturation and residual gas saturation, equation (12) is transformed into:

[0116]

[0117] Among them, S wi is bound water saturation, dimensionless; S gr is the residual gas saturation, dimensionless.

[0118] When the gas well is produced using a working system with a pressure difference greater than the critical production pressure, the bottom water will rise to the perforation section, causing water to appear in the gas well. The speed of the bottom water rise is affected by the vertical pressure difference and vertical permeability of the formation. Combining equations (9) and (11), the following equation is obtained:

[0119]

[0120] Wherein, t is the bottom water breakthrough time, in seconds.

[0121] Since the permeabilities are different in the inner and outer zones, that is, K1 and K2 are different, the bottom water breakthrough time will also be different.

[0122] Figure 4 Schematic diagram of bottom water intrusion cross section provided by the embodiment of the present disclosure. Figure 4 As shown in the figure, when the inner zone permeability K1 is greater than the outer zone permeability K2, the bottom water preferentially reaches the perforation section along the center of the wellbore. When the inner zone permeability K1 is much smaller than the outer zone permeability K2, the bottom water may preferentially rise to the perforation section at the junction of the inner zone and the outer zone.

[0123] When the bottom water preferentially reaches the perforation section along the center of the wellbore,

[0124]

[0125] Among them, t1 is the bottom water breakthrough time when the bottom water preferentially reaches the perforation section along the center direction of the wellbore, and the unit is s.

[0126] When the bottom water rises preferentially to the perforation section at the junction of the inner and outer zones,

[0127]

[0128] Among them, t2 is the bottom water breakthrough time when the bottom water preferentially rises from the boundary between the inner zone and the outer zone to the perforation section, and the unit is s.

[0129] As an example, a gas well in a triple-medium bottom-water gas reservoir opens part of the gas layer at the top of the gas layer. The thickness of the gas reservoir is h, which is 60 m, and the wellbore radius is R. w is 0.106m, the inner radius R1 is 100m, and the outer radius R e is 600m, gas density ρ under formation conditions g 240Kg / m 3 , the viscosity of natural gas in the formation μ g is 0.015 mPa·s, and the formation water density ρ w 1000Kg / m 3 , the original formation pressure p at the top of the gas layer e It is 55.0MPa.

[0130] From equation (8), we can conclude that the critical production of the gas well is:

[0131]

[0132] Take the inner zone permeability K1 = 5mD and compare different perforation thicknesses h p , the critical production of gas wells under different inner and outer zone permeability ratios (i.e. the ratio of K1 to K2). The critical production of gas wells increases with the increase of the inner and outer zone permeability ratio K1 / K2, which means that the higher the permeability of the outer zone, the stronger the natural gas supply capacity to the inner zone, and the higher the gas well production under a certain production pressure difference.

[0133] The critical production of a gas well increases first and then decreases with the increase of perforation thickness. This is because the contact area between the wellbore and the gas layer and the production pressure difference jointly affect the critical production of the gas well. Although a smaller perforation thickness of a gas well is conducive to increasing the critical production pressure difference of the gas well, it will cause the seepage area in contact with the gas layer to be too small, resulting in a low critical gas production of the gas well. Although a larger perforation thickness of a gas well is conducive to increasing the seepage area in contact with the gas layer, it will reduce the critical production pressure difference of the gas well, which may also cause a low critical gas production of the gas well. When the perforation thickness is half the thickness of the gas layer, the critical production of the gas well reaches the maximum.

[0134] Take the perforation thickness h p =30m, according to equations (13) and (14), we can conclude that:

[0135]

[0136] In the perforation thickness h p =30m, by comparing the relationship between the water breakthrough time of the inner and outer zones of the gas layer in the radial direction of the perforation section under different bottom hole pressures and different inner and outer zone permeability ratios, it can be concluded that: when the bottom hole pressure is constant, the water breakthrough time ratio t1 / t2 of the inner and outer zones decreases with the increase of the permeability ratio K1 / K2. When K1 / K2 increases to a certain extent, the phenomenon of t1 / t2>1 will appear, that is, when the permeability of the outer zone is much greater than that of the inner zone, the bottom water will first break through in the outer zone far away from the bottom of the well; when the permeability ratio K1 / K2 of the inner and outer zones is constant, the water breakthrough time ratio t1 / t2 of the inner and outer zones decreases with the increase of the bottom hole pressure. This is because with the increase of the production pressure difference, the proportion of the pressure loss in the radial direction of the perforation section to the production pressure difference will be greatly reduced, resulting in p gwc -p wf With p gwc -p(r=R1) ratio becomes smaller and smaller, making the influence of permeability on the bottom water rising speed more and more obvious, so that the bottom water rising speed in the outer zone is getting closer and closer to that in the inner zone. If the permeability of the outer zone is much greater than that of the inner zone (such as large cracks or high permeability fracture-hole strips in the stratum far away from the bottom of the well), under the condition of lower bottom hole pressure production, the bottom water rising speed in the outer zone may exceed that of the inner zone.

[0137] Figure 5 The present invention provides a block diagram of a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir. The device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir is used to execute Figure 1 or Figure 2 The method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir is shown in FIG. Figure 5 As shown, the determination device includes a model building module 10 , a first determination module 20 and a second determination module 30 .

[0138] The model building module 10 is used to build a pressure distribution model of the formation, and to build a water cone height model based on the pressure distribution model. The model building module 10 can be used to execute the aforementioned steps S11, S12, and S21 to S23.

[0139] The first determination module 20 is used to determine the vertical seepage velocity of bottom water based on the water cone height model. The first determination module 20 can be used to execute the aforementioned steps S13, S24 and S25.

[0140] The second determination module 30 is used to determine the bottom water breakthrough time based on the seepage velocity. The second determination module 30 can be used to execute the aforementioned steps S14 and S26.

[0141] By establishing a formation pressure distribution model, the formation pressure distribution will affect the height of the bottom water cone. Based on the formation pressure distribution model, a water cone height model is established. The water cone height model reflects the height of the bottom water boundary at different positions at the bottom of the vertical well, thereby reflecting the shape of the bottom water cone. The vertical seepage velocity of the bottom water is determined based on the water cone height model. The seepage velocity of the bottom water affects the bottom water breakthrough time. The faster the seepage velocity, the shorter the bottom water breakthrough time, and vice versa. Therefore, a more accurate bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir can be determined.

[0142] Optionally, the model building module 10 is used to build a pressure distribution model as shown in equations (1) and (2), and to build a water cone surface height model as shown in equation (4).

[0143] The process of the model building module 10 building the pressure distribution model refers to the aforementioned steps S21 to S22, and the process of building the water cone height model refers to the aforementioned step S23, which will not be described in detail here.

[0144] Optionally, the process of the first determining module 20 determining the vertical seepage velocity of the bottom water refers to the aforementioned steps S24 and S25, which will not be described in detail here.

[0145] Optionally, the process of determining the bottom water breakthrough time by the second determination module 30 refers to the aforementioned step S26, which will not be described in detail here.

[0146] Figure 6 FIG. 1 is a block diagram showing a device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided by an exemplary embodiment of the present disclosure. Figure 6As shown, the determining device 300 includes a central processing unit (CPU) 301, a system memory 304 including a random access memory (RAM) 302 and a read-only memory (ROM) 303, and a system bus 305 connecting the system memory 304 and the central processing unit 301. The determining device 300 also includes a basic input / output system (I / O system) 306 that helps to transmit information between various components in the computer, and a large-capacity storage device 307 for storing an operating system 313, application programs 314 and other program modules 315.

[0147] The basic input / output system 306 includes a display 308 for displaying information and an input device 309 such as a mouse and a keyboard for user inputting information. The display 308 and the input device 309 are connected to the central processing unit 301 through an input / output controller 310 connected to the system bus 305. The basic input / output system 306 may also include an input / output controller 310 for receiving and processing inputs from a plurality of other devices such as a keyboard, a mouse, or an electronic stylus. Similarly, the input / output controller 310 also provides output to a display screen, a printer, or other types of output devices.

[0148] The mass storage device 307 is connected to the central processing unit 301 through a mass storage controller (not shown) connected to the system bus 305. The mass storage device 307 and its associated computer readable medium provide non-volatile storage for the determination device 300. That is, the mass storage device 307 may include a computer readable medium (not shown) such as a hard disk or a CD-ROM drive.

[0149] Without loss of generality, computer readable media may include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information such as computer readable instructions, data structures, program modules or other data. Computer storage media include RAM, ROM, EPROM, EEPROM, flash memory or other solid-state storage technologies, CD-ROM, DVD or other optical storage, cassettes, magnetic tapes, disk storage or other magnetic storage devices. Of course, those skilled in the art will appreciate that computer storage media are not limited to the above. The above-mentioned system memory 304 and mass storage device 307 can be collectively referred to as memory.

[0150] According to various embodiments of the present disclosure, the determining device 300 can also be connected to a remote computer on the network through a network such as the Internet. That is, the determining device 300 can be connected to the network 312 through the network interface unit 311 connected to the system bus 305, or the network interface unit 311 can also be used to connect to other types of networks or remote computer systems (not shown).

[0151] The memory also includes one or more programs, which are stored in the memory and configured to be executed by the CPU. The one or more programs include instructions for performing the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir as described above in the embodiment of the present disclosure.

[0152] The present disclosure also provides a non-transitory computer-readable storage medium, wherein the storage medium stores at least one instruction, which is loaded and executed by a processor to implement Figures 1-2 A method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided in any one of the items.

[0153] A computer program product containing instructions that, when executed on a computer, causes the computer to perform Figure 1-2 A method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir provided in any one of the items.

[0154] It should be noted that: the device for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom-water gas reservoir provided in the above embodiment only uses the division of the above-mentioned functional modules as an example when determining the bottom water breakthrough time of a vertical well in a triple-medium bottom-water gas reservoir. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the device for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom-water gas reservoir provided in the above embodiment and the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom-water gas reservoir belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0155] A person skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware or by instructing related hardware through a program, and the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a disk or an optical disk, etc.

[0156] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, characterized in that: The method comprises: Determine the inner zone radius and outer zone radius of gas well control; The following pressure distribution model is established: Among them, p(r) r1 is the pressure in the inner zone of the perforation section, p(r) r2 is the pressure in the outer zone of the perforation section, r is the radial distance from the center of the wellbore, and p wf is the bottom hole flowing pressure, p e is the outer boundary pressure of the gas reservoir top, K1 is the inner zone permeability, K2 is the outer zone permeability, R e is the radius of the outer zone, R1 is the radius of the inner zone, and R w is the wellbore radius; The following water cone height model is established: Where z(r) is the height of the water cone, p gwc is the air-water interface pressure, p(r) rj is the pressure in the inner or outer zone of the perforation section, j∈{1,2}, ρ g is the density of natural gas in the formation, ρ w is the density of groundwater in the formation, g is the acceleration of gravity, h is the thickness of the gas reservoir, and h p is the perforation thickness; Determine the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area: Among them, Ω w is the seepage resistance of the bottom water cone entry area, Ω g is the seepage resistance of the pure gas zone, μ w is the viscosity of groundwater in the formation, μ g is the viscosity of natural gas in the formation, K j is the inner zone permeability or the outer zone permeability, A(r) is the seepage cross-sectional area; Determine the vertical seepage velocity of bottom water: Wherein, v(r) is the vertical seepage velocity of the bottom water; The bottom water breakthrough time is determined based on the seepage resistance of the bottom water cone entry zone and the vertical seepage velocity of the bottom water: Wherein, t is the bottom water breakthrough time, φ is the formation porosity, S wi is the bound water saturation, S gr is the residual gas saturation.

2. A device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, characterized in that: The determining device comprises: The model building module is used to build a pressure distribution model of the formation in the following way: Determine the inner and outer radius of the gas well control area; establish the following pressure distribution model: Among them, p(r) r1 is the pressure in the inner zone of the perforation section, p(r) r2 is the pressure in the outer zone of the perforation section, r is the radial distance from the center of the wellbore, and p wf is the bottom hole flowing pressure, p e is the outer boundary pressure of the gas reservoir top, K1 is the inner zone permeability, K2 is the outer zone permeability, R e is the radius of the outer zone, R1 is the radius of the inner zone, and R w is the wellbore radius; And establish the following water cone height model: Where z(r) is the height of the water cone, p gwc is the air-water interface pressure, p(r) rj is the pressure in the inner or outer zone of the perforation section, j∈{1,2}, ρ g is the density of natural gas in the formation, ρ w is the density of groundwater in the formation, g is the acceleration of gravity, h is the thickness of the gas reservoir, and h p is the perforation thickness; The first determination module is used to determine the vertical seepage velocity of bottom water in the following manner: Determine the seepage resistance of the bottom water cone area and the seepage resistance of the pure gas area: Among them, Ω w is the seepage resistance of the bottom water cone entry area, Ω g is the seepage resistance of the pure gas zone, μ w is the viscosity of groundwater in the formation, μ g is the viscosity of natural gas in the formation, K j is the inner zone permeability or the outer zone permeability, A(r) is the seepage cross-sectional area; Determine the vertical seepage velocity of bottom water: Wherein, v(r) is the vertical seepage velocity of the bottom water; The second determination module is used to determine the bottom water breakthrough time based on the seepage resistance of the bottom water cone entry area and the vertical seepage velocity of the bottom water: Wherein, t is the bottom water breakthrough time, φ is the formation porosity, S wi is the bound water saturation, S gr is the residual gas saturation.

3. A device for determining bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir, characterized in that: include: processor; a memory for storing instructions executable by a processor; Wherein, the processor is configured to execute the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir as described in claim 1.

4. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, which is loaded and executed by the processor to implement the method for determining the bottom water breakthrough time of a vertical well in a triple-medium bottom water gas reservoir as claimed in claim 1.

Images