Quantitative characterization method and device for water seal gas degree of deep water gas reservoir

Abstract

The invention discloses a quantitative characterization method and device for the water seal gas degree of a deep water gas reservoir. The method comprises the steps that according to corresponding permeability, saturation and relative permeability index parameters in seepage control parameters of the deep water gas reservoir, the water-phase and gas-phase relative permeability of a matrix and a crack is determined, and the seepage control parameters are obtained based on a seepage mechanism of the water gas reservoir and comprise matrix and crack fluid channeling coefficients; determining displacement capillary pressure and imbibition capillary pressure according to water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters; according to the given numerical value of the seepage control parameters and the determined parameters, water seal gas seepage simulation is conducted, and the natural gas recovery degree and the water seal gas degree are determined. According to the method, seepage control parameters are provided based on a water gas reservoir seepage mechanism, the natural gas recovery degree and the water seal gas degree are determined through seepage simulation, and specific quantification of the water seal gas degree is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of deep water gas reservoir development, and in particular to a method and device for quantitatively characterizing the water-sealed gas degree of deep water gas reservoirs. Background Art

[0002] In the discovered condensate gas reservoirs, edge and bottom water is often developed. Water invasion is the key factor that leads to poor gas reservoir development effect and reduced recovery rate. The reserves of deep gas reservoirs (below 3500m) discovered in my country are gradually increasing. The reservoir characteristics and seepage laws of such gas reservoirs are extremely complex, and the fracture system is relatively developed. The flow law of gas and water in complex media is difficult to accurately describe, and the characteristics of water-sealed gas are difficult to quantify. Figure 1 As shown in the figure, it is a schematic diagram of four different water invasion modes of deep water-containing gas reservoirs. The water production problem of gas wells in strong heterogeneous deep high-pressure gas reservoirs is serious, and water-locked gas is easily formed after water production, resulting in a large amount of natural gas that cannot be produced and a significant reduction in the recovery rate. There are certain differences in the production characteristics, water-locked gas modes, and influencing factors of reservoirs with different heterogeneous characteristics. Therefore, establishing a representative water-locked gas characterization method and analyzing the formation of water-locked gas, fluid distribution characteristics, and influencing factors are of great guiding significance for formulating reasonable development technology strategies, mitigating and controlling water-locked gas, and are helpful to promote the exploration of effective ways to prevent and control water-locked gas. Summary of the invention

[0003] In order to at least partially solve the technical problems existing in the prior art, the inventors have made the present invention, and through a specific implementation method, provide a method and device for quantitatively characterizing the degree of water-locked gas in deep water-containing gas reservoirs. The method and device can propose seepage control parameters based on the seepage mechanism of water-containing gas reservoirs, and realize the specific quantification of the degree of water-locked gas through seepage simulation.

[0004] In a first aspect, an embodiment of the present invention provides a method for quantitatively characterizing the degree of water-locked gas in a deep water-containing gas reservoir, comprising:

[0005] Determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability respectively according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir, wherein the seepage control parameters are obtained based on the seepage mechanism of the water gas reservoir, including the matrix and fracture crossflow coefficient;

[0006] Determine the displacement capillary pressure and the imbibition capillary pressure according to the water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters;

[0007] According to the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, water-sealed gas seepage simulation is performed, the degree of natural gas recovery is determined according to the simulation results, and the degree of water-sealed gas is determined according to the degree of natural gas recovery.

[0008] In a second aspect, an embodiment of the present invention provides a device for quantitatively characterizing the degree of water-sealed gas in a deep water-containing gas reservoir, comprising:

[0009] A relative permeability determination module is used to determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir, wherein the seepage control parameters are obtained based on the seepage mechanism of the water gas reservoir, including the matrix and fracture crossflow coefficients;

[0010] A capillary pressure determination module, for determining displacement capillary pressure and imbibition capillary pressure according to water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters;

[0011] The water-sealed gas degree determination module is used to perform water-sealed gas seepage simulation based on the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, determine the natural gas production degree based on the simulation results, and determine the water-sealed gas degree based on the natural gas production degree.

[0012] In a third aspect, an embodiment of the present invention provides a computer storage medium, wherein the computer storage medium stores computer executable instructions, and when the computer executable instructions are executed by a processor, the above-mentioned method for quantitatively characterizing the degree of water-sealed gas in deep water-containing gas reservoirs is implemented.

[0013] In a fourth aspect, an embodiment of the present disclosure provides a server, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for quantitatively characterizing the degree of water-sealed gas in deep water-containing gas reservoirs is implemented.

[0014] The beneficial effects of the above technical solution provided by the embodiment of the present invention include at least:

[0015] The method for quantitatively characterizing the degree of water-locked gas in deep water-containing gas reservoirs provided in an embodiment of the present invention proposes seepage control parameters based on the seepage mechanism of water-containing gas reservoirs, and determines the degree of natural gas recovery and the degree of water-locked gas through seepage simulation of the process of water-locked gas caused by complex flow of gas and water during the development of deep water-containing gas reservoirs, thereby achieving specific quantification of the degree of water-locked gas. The method is widely applicable to dynamic characteristic analysis, recovery rate evaluation and numerical simulation research of deep condensate gas reservoir development.

[0016] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0017] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0019] Figure 1 This is a schematic diagram of water invasion mode in deep water gas reservoirs;

[0020] Figure 2 It is a schematic diagram of the microscopic water-sealed gas mechanism;

[0021] Figure 3 This is a flow chart of a method for quantitatively characterizing the degree of water-locked gas in a deep water-containing gas reservoir in Example 1 of the present invention;

[0022] Figure 4 This is an example diagram of water production dynamics when water seal gas is considered and when water seal gas is not considered in the second embodiment of the present invention;

[0023] Figure 5 A comparison diagram of reservoir water saturation changes when water seal gas is considered and when water seal gas control parameters are not considered in Example 2 of the present invention;

[0024] Figure 6 Schematic diagram of the structure of a device for quantitatively characterizing the degree of water-locked gas in a deep water-containing gas reservoir in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0026] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0027] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which the invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0028] New understanding of gas-water flow mechanism in deep, high-pressure, complex water-containing gas reservoirs:

[0029] The water-sealed gas in the bottom water-gas reservoir with fractures or high-permeability strips is formed under the comprehensive effect of macro water invasion, water channeling and micro water lock and water seal, with seepage channel isolation and pressure isolation as macro manifestations and wettability and capillary force as micro manifestations.

[0030] From a macroscopic perspective, edge and bottom water invades high permeability strips or cracks and flows along the high permeability strips or cracks toward the production wells with stronger flow capacity. The water replenishment leads to higher pressure in the cracks or high permeability strips, making it difficult to produce the gas phase in the matrix. Water enters the cracks or high permeability strips and water invasion occurs. As production progresses, water will flow to the bottom of the well, causing a large amount of water production in the gas well. However, from a mechanistic analysis, it is mainly because the high permeability strips first see water, the water saturation of the main flow channel increases, the flow capacity of the gas in the main flow channel decreases, and the seepage channel is blocked; in addition, the high permeability strips first see water, the pressure in the main flow channel is replenished, and the pressure difference with the matrix is ​​reduced, making it difficult for the gas phase to enter the main flow channel, forming a pressure blockage, which makes it difficult for the gas in the matrix to be produced through the cracks.

[0031] Because the water in the fractures or high permeability zones will enter the matrix pores under the action of capillary force and displacement pressure difference, forming water seals and water locks, which will increase the bound water saturation in the pores and reduce the relative permeability of the gas phase. At the same time, the capillary force is an additional resistance to the gas-water-displacing process, which is a microscopic water-sealed gas. From the perspective of mechanism, first, the water in the fractures and high permeability zones enters the matrix under the action of capillary force and displacement pressure difference, the water saturation in the matrix pores increases, the relative permeability of the gas phase decreases, and the gas flow is difficult; second, the water in the fractures or high permeability zones spontaneously infiltrates into the matrix under the action of capillary force, forming an infiltration zone isolation. The capillary force is a resistance to gas-water-displacing in the matrix, such as Figure 2 shown.

[0032] Based on the above understanding of the seepage mechanism of water-bearing gas reservoirs, the true simulation of the gas-water flow mechanism in complex reservoirs needs to achieve the following two points: First, the mechanical description of the original state of gas and water. The control parameters include static models such as initial permeability and porosity, as well as irreducible water saturation and gas-water capillary pressure; Second, the accurate description of the gas-water flow state. The control parameters include gas-water relative permeability, imbibition capillary pressure, matrix and fracture crossflow coefficient. Therefore, the seepage control parameters of deep water-bearing gas reservoirs are obtained. Some seepage control parameters and their corresponding relationship with the degree of water-sealing gas are shown in Table 1:

[0033] Table 1 Seepage control parameters of deep water gas reservoirs

[0034]

[0035] S wi is the bound water saturation, C wd is the threshold pressure, A wd is the pore distribution coefficient;

[0036] WPV is water volume multiple;

[0037] S wif is the fracture bound water saturation, S grf is the residual gas saturation of the fracture, k rgf (S wif ) is the gas phase relative permeability at the maximum gas saturation of the fracture, k rwf (S grf ) is the relative permeability of water phase at the maximum water saturation of the fracture, N gf is the fracture gas phase relative permeability index, N wf is the relative permeability index of fracture water phase;

[0038] S wim is the matrix bound water saturation, S grm is the matrix residual gas saturation, k rgm (S wim ) is the relative permeability of the gas phase at the maximum gas saturation of the matrix, k rwm (Sgrm ) is the relative permeability of water phase at the maximum water saturation of the matrix, N wm is the matrix water phase relative permeability index, N gm is the matrix gas phase relative permeability index;

[0039] α is the displacement contact angle, β is the imbibition contact angle;

[0040] γ is the matrix and crack cross-flow coefficient.

[0041] Embodiment 1

[0042] The first embodiment of the present invention provides a method for quantitatively characterizing the degree of water-locked gas in deep water-bearing gas reservoirs. Figure 3 As shown, the following steps are included:

[0043] Step S31: Determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir.

[0044] The seepage control parameters are obtained based on the seepage mechanism of water-containing gas reservoirs, including matrix and fracture crossflow coefficients, as described above.

[0045] Determine matrix water and gas phase relative permeabilities, including:

[0046] The relative permeabilities of the matrix water phase and gas phase are determined using the following equations (1) and (2), respectively:

[0047]

[0048]

[0049] In formula (1) and formula (2), k rwm (S wm ) is the relative permeability of matrix water phase, k rwm (S grm ) is the relative permeability of the water phase at the maximum water saturation of the matrix, k rgm (S gm ) is the matrix gas phase relative permeability, k rgm (S wim ) is the gas phase relative permeability at the maximum gas saturation of the matrix, S gm is the matrix gas saturation, S wm is the matrix water saturation, S wim is the matrix bound water saturation, S grm is the matrix residual gas saturation, N wm is the matrix water phase relative permeability index, N gm is the matrix gas permeability index.

[0050] Determine the relative permeability of water and gas phases in fractures, including:

[0051] The relative permeabilities of the water phase and gas phase in the fracture are determined using the following equations (3) and (4), respectively:

[0052]

[0053]

[0054] In formula (3) and formula (4), k rwf (S wf ) is the relative permeability of fracture water phase, k rwf (S grf ) is the relative permeability of water phase at the maximum water saturation of the fracture, k rgf (S gf ) is the relative permeability of fracture gas phase, k rgf (S wif ) is the gas phase relative permeability at the maximum gas saturation of the fracture, S gf is the fracture gas saturation, S wf is the fracture water saturation, S wif is the fracture bound water saturation, S grf is the residual gas saturation of the fracture, N wf is the relative permeability index of fracture water phase, N gf is the fracture gas permeability index.

[0055] Step S32: Determine the displacement capillary pressure and the imbibition capillary pressure according to the water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters.

[0056] Specifically, the displacement capillary pressure is determined according to the water saturation, irreducible water saturation, threshold pressure and pore distribution coefficient in the control parameters:

[0057]

[0058] In formula (5), P cdra is the displacement capillary pressure, C wd is the threshold pressure, A wd is the pore distribution coefficient, S wi is the bound water saturation, S w is the water saturation.

[0059] According to the displacement capillary pressure, displacement contact angle and imbibition contact angle in the control parameters, the imbibition capillary pressure is determined:

[0060]

[0061] In formula (6), P cimbis the imbibition capillary pressure, α is the displacement contact angle, and β is the imbibition contact angle.

[0062] Step S33: Perform water-sealed gas seepage simulation according to the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, determine the degree of natural gas recovery according to the simulation results, and determine the degree of water-sealed gas according to the degree of natural gas recovery.

[0063] According to the simulation results of water-seal gas seepage, the following understandings are obtained:

[0064] (1) When the key control parameters of the water-sealed gas effect are considered, water breakthrough in the main fractures is faster and more severe, which is more consistent with the actual development dynamics of deep high-pressure gas wells.

[0065] (2) In fractured bottom water gas reservoirs, the lower the matrix permeability, the more obvious the water-sealing gas effect, the gradually increasing cumulative water production, the lower the recovery factor, and the greater the impact of water-sealing gas on the recovery factor.

[0066] (3) In fractured gas reservoirs, the worse the physical properties and the greater the capillary pressure, the capillary force hysteresis is the key factor affecting the recovery rate, while the stronger the influence of the phase permeability hysteresis effect, the lower the natural gas recovery rate.

[0067] (4) In gas reservoirs with high permeability zones, the more severe the relative permeability hysteresis is, the lower the recovery rate is. Moreover, the relative permeability hysteresis is the key factor affecting the recovery rate, and the influence of the relative permeability hysteresis exceeds the influence of the capillary force hysteresis effect.

[0068] (5) In gas reservoirs with high permeability zones, the smaller the matrix permeability, the lower the cumulative gas production and the greater the degree of water-locked gas. When water-locked gas is not considered, if the matrix permeability increases by 2 times, almost no water will be produced, which is inconsistent with the production dynamics.

[0069] (6) The configuration relationship between deep high-pressure gas wells and high-permeability strips or fractures has a significant impact on the degree of water-sealed gas and the natural gas recovery rate.

[0070] The quantitative standard of water-sealed air degree is shown in Table 2:

[0071] Table 2 Classification of water-sealed air degree

[0072]

[0073] If the natural gas recovery degree is greater than 70%, the water-locked gas degree is determined to be extremely weak;

[0074] If the natural gas recovery degree is greater than 50% and not greater than 70%, the water-locked gas degree is determined to be medium;

[0075] If the natural gas recovery rate is not less than 30% and not more than 50%, the water-locked gas level is determined to be severe;

[0076] If the natural gas recovery rate is less than 30%, it is determined that the water-locked gas level is extremely serious.

[0077] The method for quantitatively characterizing the degree of water-locked gas in deep water-containing gas reservoirs provided in Example 1 of the present invention proposes seepage control parameters based on the seepage mechanism of water-containing gas reservoirs, and determines the degree of natural gas recovery and the degree of water-locked gas through seepage simulation of the process of water-locked gas caused by complex flow of gas and water during the development of deep water-containing gas reservoirs, thereby achieving specific quantification of the degree of water-locked gas. The method is widely applicable to dynamic characteristic analysis, recovery rate evaluation and numerical simulation research of deep condensate gas reservoir development.

[0078] The embodiment of the present invention establishes a water-sealing gas effect characterization method based on refined zoning processing and bound water saturation calibration, comprehensively considers the relative permeability difference of gas and water in the fracture matrix, water phase retention and relative permeability hysteresis effect in the water-locked zone, capillary force hysteresis and resistance effect, and forms a water-sealing gas numerical simulation characterization method.

[0079] Embodiment 2

[0080] Embodiment 2 of the present invention provides a specific application of a method for quantitatively characterizing the degree of water-sealing gas in deep water-bearing gas reservoirs. Based on the dynamic model fitted by the KX203 well, the high permeability bands and fracture development characteristics of the reservoir are considered to simulate and compare the impact on the production and development of water-bearing gas reservoirs. The gas well is set to produce at a fixed rate of 800,000 cubic meters per day, with a minimum bottom hole pressure of 30 MPa and a matrix permeability of 0.1 mD. The dynamic characteristics of development when the water-sealing gas effect is considered and when the water-sealing effect is not considered are compared.

[0081] Compare the dynamic features developed when considering the water-sealing gas effect and not considering the water-sealing effect, such as Figure 4 As shown in Table 3, water appeared earlier when water-sealed gas was considered, and the cumulative water production when water-sealed gas was considered was 4 times that when water-sealed gas was not considered, and water channeling was more serious; under the production conditions of fixed gas production, the recovery factor when water-sealed gas effect was considered was about 30% lower than that when water-sealed gas was not considered. This is because when water-sealed gas was considered, on the one hand, the channeling ability of water in the high permeability strip was stronger, so it would channel to the bottom of the well faster along the high permeability strip, and on the other hand, the water in the high permeability strip was absorbed into the two sides to form a water seal area, and the bound water saturation of the water seal area increased and the gas phase flow ability weakened, which made it more difficult for water to enter the matrix, so the effect of water driving gas was weakened, and more water flowed to the bottom of the well along the high permeability strip and fractures.

[0082] Table 3 Cumulative production and recovery factor with and without considering water-sealed gas

[0083] No consideration of water seal gas Consider water seal gas <![CDATA[Cumulative gas production, 10 6 m 3 > 1555.5 798.44 <![CDATA[Cumulative produced water, 10 4 m 3 > 84.61 332.83 Recovery rate, % 65.4 33.57

[0084] Figure 5This is the variation characteristics of water saturation in the reservoir when water-sealed gas is considered and not considered. Since high-permeability strips are generally developed in reservoirs, it is necessary to pay attention to both water-sealing and displacement effects. As can be seen from the figure, when water-sealed gas is considered, water is produced early and in large quantities from the high-permeability strips; when water-sealed gas is not considered, water can play a better role in displacement, and the degree of natural gas recovery is higher, which is inconsistent with the actual situation.

[0085] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a device for quantitatively characterizing the water-sealed gas degree of a deep water-containing gas reservoir. The structure of the device is as follows: Figure 6 As shown, including:

[0086] The relative permeability determination module 61 is used to determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir, wherein the seepage control parameters are obtained based on the seepage mechanism of the water gas reservoir, including the matrix and fracture crossflow coefficients;

[0087] A capillary pressure determination module 62 is used to determine displacement capillary pressure and imbibition capillary pressure according to water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters;

[0088] The water-sealed gas degree determination module 63 is used to perform water-sealed gas seepage simulation based on the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, determine the natural gas production degree based on the simulation results, and determine the water-sealed gas degree based on the natural gas production degree.

[0089] Regarding the device in the above embodiment, the specific manner in which each module performs operations has been described in detail in the embodiment of the method, and will not be elaborated here.

[0090] Based on the inventive concept of the present invention, an embodiment of the present invention further provides a computer storage medium, wherein the computer storage medium stores computer executable instructions, and when the computer executable instructions are executed by a processor, the above-mentioned method for quantitatively characterizing the degree of water-sealing gas in deep water-containing gas reservoirs is implemented.

[0091] Based on the inventive concept of the present invention, an embodiment of the present invention also provides a server, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for quantitatively characterizing the degree of water-sealed gas in deep water-containing gas reservoirs is implemented.

[0092] Unless otherwise specifically stated, terms such as processing, computing, calculating, determining, displaying, etc. may refer to the actions and / or processes of one or more processing or computing systems, or similar devices, which operate and convert data represented as physical (e.g., electronic) quantities within registers or memories of a processing system into other data similarly represented as physical quantities within memories, registers, or other such information storage, transmission, or display devices of the processing system. Information and signals may be represented using any of a variety of different techniques and methods. For example, data, instructions, commands, information, signals, bits, symbols, and chips mentioned throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, or any combination thereof.

[0093] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of protection of the present disclosure. The attached method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0094] In the above detailed description, various features are grouped together in a single embodiment to simplify the disclosure. This method of disclosure should not be interpreted as reflecting an intention that an embodiment of the claimed subject matter requires more features than those set forth in each claim. On the contrary, as reflected in the appended claims, the invention is in a state of having less than all the features of the disclosed individual embodiments. Therefore, the appended claims are hereby expressly incorporated into the detailed description, with each claim standing on its own as a separate preferred embodiment of the invention.

[0095] Those skilled in the art will also appreciate that the various illustrative logic blocks, modules, circuits, and algorithmic steps described in conjunction with the embodiments herein can all be implemented as electronic hardware, computer software, or a combination thereof. In order to clearly illustrate the interchangeability between hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above around their functions. Whether such functions are implemented as hardware or software depends on specific applications and the design constraints imposed on the entire system. A skilled person can implement the described functions in an alternative manner for each specific application, but such implementation decisions should not be interpreted as departing from the scope of protection of the present disclosure.

[0096] The steps of the method or algorithm described in conjunction with the embodiments herein may be directly embodied as hardware, a software module executed by a processor, or a combination thereof. The software module may be located in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a mobile disk, a CD-ROM, or any other form of storage medium well known in the art. An exemplary storage medium is connected to the processor so that the processor can read information from the storage medium and can write information to the storage medium. Of course, the storage medium may also be an integral part of the processor. The processor and the storage medium may be located in an ASIC. The ASIC may be located in a user terminal. Of course, the processor and the storage medium may also be present in a user terminal as discrete components.

[0097] For software implementation, the techniques described in this application can be implemented with modules (e.g., procedures, functions, etc.) that perform the functions described in this application. These software codes can be stored in a memory unit and executed by a processor. The memory unit can be implemented within the processor or outside the processor. In the latter case, it is coupled to the processor in a communication manner via various means, which are well known in the art.

[0098] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but it should be recognized by those skilled in the art that the various embodiments may be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of protection of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the word is covered in a manner similar to the term "including", just as "including," is explained as a transitional word in the claims. In addition, any term "or" used in the specification of the claims is intended to mean "non-exclusive or".

Claims

1. A method for quantitatively characterizing the degree of water-locked gas in deep water-containing gas reservoirs, characterized in that: include: Determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability respectively according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir, wherein the seepage control parameters are obtained based on the seepage mechanism of the water gas reservoir, including the matrix and fracture crossflow coefficient; Determine the displacement capillary pressure and the imbibition capillary pressure according to the water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters; According to the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, water-sealed gas seepage simulation is performed, the degree of natural gas recovery is determined according to the simulation results, and the degree of water-sealed gas is determined according to the degree of natural gas recovery.

2. The method according to claim 1, characterized in that: Determine matrix water and gas phase relative permeabilities, including: The relative permeabilities of the matrix water phase and gas phase are determined using the following equations (1) and (2), respectively: In formula (1) and formula (2), k rwm (S wm ) is the relative permeability of matrix water phase, k rwm (S grm ) is the relative permeability of the water phase at the maximum water saturation of the matrix, k rgm (S gm ) is the matrix gas phase relative permeability, k rgm (S wim ) is the gas phase relative permeability at the maximum gas saturation of the matrix, S gm is the matrix gas saturation, S wm is the matrix water saturation, S wim is the matrix bound water saturation, S grm is the matrix residual gas saturation, N wm is the matrix water phase relative permeability index, N gm is the matrix gas permeability index.

3. The method according to claim 1, characterized in that Determine the relative permeability of water and gas phases in fractures, including: The relative permeabilities of the water phase and gas phase in the fracture are determined using the following equations (3) and (4), respectively: In formula (3) and formula (4), k rwf (S wf ) is the relative permeability of fracture water phase, k rwf (S grf ) is the relative permeability of water phase at the maximum water saturation of the fracture, k rgf (S gf ) is the relative permeability of fracture gas phase, k rgf (S wif ) is the gas phase relative permeability at the maximum gas saturation of the fracture, S gf is the fracture gas saturation, S wf is the fracture water saturation, S wif is the fracture bound water saturation, S grf is the residual gas saturation of the fracture, N wf is the relative permeability index of fracture water phase, N gf is the fracture gas permeability index.

4. The method according to claim 1, characterized in that: Determining the displacement capillary pressure and the imbibition capillary pressure according to the water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the control parameters includes: Determining the displacement capillary pressure according to the water saturation, irreducible water saturation, threshold pressure and pore distribution coefficient among the control parameters; The imbibition capillary pressure is determined according to the displacement capillary pressure, the displacement contact angle and the imbibition contact angle in the control parameters.

5. The method according to claim 4, characterized in that The method of determining the displacement capillary pressure comprises: The displacement capillary pressure is determined using the following formula (5): In formula (5), P cdra is the displacement capillary pressure, C wd is the threshold pressure, A wd is the pore distribution coefficient, S wi is the bound water saturation, S w is the water saturation.

6. The method according to claim 5, characterized in that Determining the imbibition capillary pressure comprises: The imbibition capillary pressure is determined using the following formula (6): In formula (6), P cimb is the imbibition capillary pressure, α is the displacement contact angle, and β is the imbibition contact angle.

7. The method according to claim 1, characterized in that Determining the water-sealed gas degree according to the natural gas production degree includes: If the natural gas recovery degree is greater than 70%, the water-locked gas degree is determined to be extremely weak; If the natural gas recovery degree is greater than 50% and not greater than 70%, the water-locked gas degree is determined to be medium; If the natural gas recovery rate is not less than 30% and not more than 50%, the water-locked gas level is determined to be severe; If the natural gas recovery rate is less than 30%, it is determined that the water-locked gas level is extremely serious.

8. A device for quantitatively characterizing the degree of water-locked gas in deep water-filled gas reservoirs, characterized in that: The device comprises: A relative permeability determination module is used to determine the matrix water phase and gas phase relative permeability and the fracture water phase and gas phase relative permeability according to the corresponding permeability, saturation and relative permeability index parameters in the seepage control parameters of the deep water gas reservoir, wherein the seepage control parameters are obtained based on the seepage mechanism of the water gas reservoir, including the matrix and fracture crossflow coefficients; A capillary pressure determination module, for determining displacement capillary pressure and imbibition capillary pressure according to water saturation, irreducible water saturation, threshold pressure, pore distribution coefficient, displacement contact angle and imbibition contact angle in the seepage control parameters; The water-sealed gas degree determination module is used to perform water-sealed gas seepage simulation based on the given values ​​of the seepage control parameters and the determined relative permeabilities of the matrix, fracture water phase and gas phase, displacement capillary pressure and imbibition capillary pressure, determine the natural gas production degree based on the simulation results, and determine the water-sealed gas degree based on the natural gas production degree.

9. A computer storage medium, characterized in that: The computer storage medium stores computer executable instructions, and when the computer executable instructions are executed by the processor, the method for quantitatively characterizing the degree of water-sealed gas in deep water-containing gas reservoirs according to any one of claims 1 to 7 is implemented.

10. A server, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method for quantitatively characterizing the degree of water-sealed gas in a deep water-containing gas reservoir as claimed in any one of claims 1 to 7 is implemented.

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