A method and system for analyzing fluid potential in fractured-vuggy reservoirs

Abstract

The present invention discloses a method for analyzing the fluid potential of a fractured-vuggy reservoir, comprising: carving a target fractured-vuggy unit to determine the geometric morphology model of the target fractured-vuggy unit, and based on this, combining the drilling and logging data of the fractured-vuggy unit to obtain the geological model of the target fractured-vuggy unit; based on the geological model, according to the current carving results and the historical production data of the target fractured-vuggy unit, using numerical simulation technology to fit the development and production history of the target fractured-vuggy unit, and establishing an initial distribution model of the target fractured-vuggy unit including the reservoir pressure field, oil saturation field and fluid velocity field; according to the initial distribution model, statistically calculating the fluid potential energy at each position in the model to obtain the fluid potential energy distribution model of the target fractured-vuggy unit. The present invention proposes a fluid potential analysis model and characterization for the development of fractured-vuggy reservoirs, providing a theoretical basis for the regulation technology of balanced exploitation of fractured-vuggy reservoirs.

Description

Technical Field

[0001] The present invention relates to the technical field of unconventional oil and gas reservoir energy development, and particularly relates to a method and system for calculating the fluid potential of a fracture-vuggy reservoir. Background Art

[0002] Compared with clastic reservoirs, the fracture-vuggy reservoir has diverse storage and permeability media, discrete spatial distribution of reservoirs, and significant spatio-temporal differences in flow patterns and development methods. Fluid potential is the total mechanical energy possessed by fluids within a reservoir, and it is a classical theoretical method for studying the migration laws of underground oil, gas, water, and other fluids from the perspective of energy conservation. The research on mass fluid potential in hydrocarbon accumulation mainly focuses on the field of petroleum geology of hydrocarbon migration and accumulation. With the continuous deepening of oilfield development theories and understandings, fluid potential has begun to be applied from the hydrocarbon exploration field to the development fields such as the identification of preferential flow channels in clastic reservoirs, remaining oil prediction, and tapping potential measures, and good application effects have been achieved. Due to the complexity of fracture-vuggy reservoirs, there is no publicly reported theoretical research and application of fluid potential in the exploration and development of fracture-vuggy reservoirs.

[0003] Although there are many research results on pore-type and fracture-pore type carbonate reservoirs at home and abroad, and their corresponding development theories are relatively mature. However, compared with pore-type and fracture-pore type carbonate reservoirs, fracture-vuggy reservoirs have complex reservoir types and greater development difficulties. Due to the existence of pores, fractures, and dissolution holes in fracture-vuggy reservoirs, the flow forms are diverse and the flow patterns are complex, and their development models and control strategies cannot simply copy the development experience of foreign carbonate reservoirs dominated by fractures. At present, although some control technical methods have been formed in China for the construction of injection-production well patterns for fracture-vuggy reservoir bodies, the dynamic and static processing calculations of fracture-vuggy reservoirs, the dynamic analysis of water injection in fracture-vuggy reservoirs, and the adjustment of flow channels, each technology has its adaptability. On the one hand, it comes from the assumed conditions of the method itself, and on the other hand, it comes from the quality and abundance of data acquisition.

[0004] Specifically, the development of existing carbonate fractured-vuggy reservoirs has the following problems: Since the fluid flow in the fracture-vug media of the main body of fractured-vuggy reservoirs does not conform to Darcy's seepage law, the development of such oilfields cannot draw on the mature development theories and technologies of clastic rocks. With the deepening of development, the following specific problems have gradually emerged in the development of the oilfield: ① Due to the strong heterogeneity of the Ordovician fractured-vuggy reservoir and the complexity of the oil-water relationship, the water breakthrough in oil wells is sudden and difficult to predict, and the production decline caused by violent water flooding accounts for a relatively large proportion; ② As the main body of storage and percolation in the Ordovician fractured-vuggy reservoir of Tahe, caves and fractures are mainly characterized by pipe flow, and the diverse oil-water flow patterns result in poor development laws of oil wells. The reservoir engineering theoretical methods of clastic rock oil reservoirs based on Darcy's law are not applicable to the development dynamic analysis and index prediction of fractured-vuggy carbonate reservoirs; ③ Field production shows that the production decline caused by insufficient formation energy is 5-7 percentage points, and the energy supplement methods and technical policies in the middle and late stages of the development of fractured-vuggy reservoirs need to be further improved; ④ Due to the complex geological characteristics and development methods of fractured-vuggy carbonate reservoirs, the understanding of the water flooding mechanism is unclear, the water injection response is single, water channeling is likely to occur, and the number of ineffective water injection wells is gradually increasing.

[0005] After more than 20 years of development, Tahe Oilfield has experienced elastic development mainly relying on natural energy, single-well water injection huff and puff in fixed-volume caves, and water injection displacement development methods for multi-well connected fracture-vug units. Currently, it has entered the stage of popularizing enhanced oil recovery by gas injection. Due to the limitations in the accuracy of static characteristic description of fracture-vug reservoirs and the accurate characterization of complex flow patterns in fracture-vug media, the comprehensive control technical policies and parameter optimization strategies for water control and oil stabilization and production decline delay adopted by Tahe Oilfield lack systematic theoretical support, and the actual effects in the field are often much lower than the expected effects of theoretical research.

[0006] Therefore, there is a lack of a method in the existing technology that can be used to analyze the fluid potential distribution characteristics of fractured-vuggy reservoirs. Summary of the Invention

[0007] To solve the above technical problems, the present invention provides a method for analyzing the fluid potential of fractured-vuggy reservoirs. The method includes: Step 1, engrave the target fracture-vug unit to determine the geometric shape model of the target fracture-vug unit. Based on this, combined with the drilling and logging data of the fracture-vug unit, obtain the geological model of the target fracture-vug unit; Step 2, based on the geological model, according to the current engraving results and the historical production data of the target fracture-vug unit, use numerical simulation technology to fit the development and production history of the target fracture-vug unit, and establish an initial distribution model of the target fracture-vug unit including an oil reservoir pressure field, an oil saturation field, and a fluid velocity field; Step 3, according to the initial distribution model, statistically analyze the fluid potential energy at each position in the model to obtain the fluid potential energy distribution model of the target fracture-vug unit.

[0008] Preferably, the fluid potential energy is the sum of various mechanical energies, where the mechanical energies include potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy.

[0009] Preferably, in the step of carving the target fracture-cavity unit, it includes: based on the three-dimensional seismic model of the target fracture-cavity unit, extracting the frequency division attribute, tensor attribute, and spatial splitting attribute of the fracture-cavity unit body, and carving the reservoir body in the target fracture-cavity unit according to the extracted attribute characteristics.

[0010] Preferably, the geological model includes the karst system of the fracture-cavity unit reservoir body and reservoir type information.

[0011] Preferably, in the second step, based on the geological model, according to the current carving result and the historical production data, establish the structural morphology model, rock physics model, and production dynamic model of the target fracture-cavity unit, and use reservoir numerical simulation technology for fitting operation. After the fitting rate of the single-well production volume in the target fracture-cavity unit reaches the preset fitting qualified threshold, generate the initial distribution model.

[0012] Preferably, the method further includes: according to the fluid potential distribution characteristics in space in the target fracture-cavity unit, determining the well group connectivity between oil wells and water wells, and the distribution characteristics of various mechanical energies at the bottom of the well in the unit, and optimizing the injection-production well control technology.

[0013] Preferably, when the kinetic energy in the fluid potential energy at the bottom of the well to be analyzed exceeds the preset high kinetic energy threshold, the oil nozzle opening is reduced to convert the kinetic energy of the oil production well into fluid pressure energy; when the kinetic energy at the bottom of the well to be analyzed is less than the preset low kinetic energy threshold and the pressure energy in the fluid potential energy exceeds the preset high pressure energy threshold, the drainage speed is increased to balance the flow potential energy at the current bottom of the well.

[0014] On the other hand, the present invention also provides a system for analyzing the fluid potential of a fracture-cavity reservoir. The system includes: a geological model generation module configured to carve a target fracture-cavity unit, determine the geometric morphology model of the target fracture-cavity unit, and based on this, combine the drilling and logging data for the fracture-cavity unit to obtain the geological model of the target fracture-cavity unit; a production history fitting module configured to, based on the geological model, use numerical simulation technology to fit the development and production history of the target fracture-cavity unit according to the current carving result and the historical production data of the target fracture-cavity unit, and establish an initial distribution model of the target fracture-cavity unit including an oil reservoir pressure field, an oil saturation field, and a fluid velocity field; a fluid potential energy calculation module configured to, according to the initial distribution model, count the fluid potential energy at each position in the model to obtain the fluid potential energy distribution model of the target fracture-cavity unit.

[0015] Preferably, the fluid potential energy is the sum of various mechanical energies, where the mechanical energies include potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy.

[0016] Preferably, the system further includes: a regulation technology selection module configured to determine the well group connectivity between oil wells and water wells and the distribution characteristics of various mechanical energies at the bottom of the unit according to the fluid potential distribution characteristics in the target fracture-cavity unit in space, and preferably select injection-production well regulation technologies.

[0017] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0018] The present invention discloses a method and system for analyzing the fluid potential of a fracture-cavity reservoir. Based on the special geological characteristics and development methods of the fracture-cavity reservoir, the present invention deduces and establishes a general mathematical model for the fluid potential of the fracture-cavity reservoir development, provides a calculation method for the fluid potential of the fracture-cavity reservoir development based on numerical simulation results. At the same time, it enriches and expands the application scope of the numerical simulation results of conventional reservoirs, solves the technical blank of the fluid potential calculation model and characterization method in the prior art that only targets clastic sandstone reservoirs and does not target the fracture-cavity reservoir development, and provides a theoretical basis for the comprehensive regulation technology of the balanced exploitation of the fracture-cavity reservoir. In addition, the present invention also proposes corresponding oil well and water well regulation measures according to the analysis results of the fluid potential distribution characteristics of the fracture-cavity reservoir unit. Therefore, for the balanced exploitation of the fracture-cavity reservoir with diverse reservoir spaces and extremely strong reservoir heterogeneity, it has obvious field applicability and practicality, provides a new technical direction for the comprehensive tapping of potential and adjustment of the old fracture-cavity reservoir units, and is convenient for practice and easy to promote.

[0019] Other features and advantages of the present invention will be described in the following specification, and some of them will become obvious from the specification or be understood by implementing the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the specification, claims, and drawings. Description of the Drawings

[0020] The drawings are used to provide a further understanding of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0021] Figure 1 is a step diagram of the method for analyzing the fluid potential of a fracture-cavity reservoir according to an embodiment of the present application.

[0022] Figure 2 is a specific flowchart of the method for analyzing the fluid potential of a fracture-cavity reservoir according to an embodiment of the present application.

[0023] Figure 3It is a schematic diagram of the implementation principle of the method for analyzing the fluid potential of a fracture-vuggy reservoir in an embodiment of the present application.

[0024] Figure 4 It is a module block diagram of the system for analyzing the fluid potential of a fracture-vuggy reservoir in an embodiment of the present application. Detailed implementation manners

[0025] The following will combine the accompanying drawings and embodiments to elaborate in detail on the implementation manners of the present invention, so as to fully understand how the present invention applies technical means to solve technical problems and the implementation process of achieving technical effects and implement accordingly. It should be noted that as long as there is no conflict, each embodiment in the present invention and each feature in each embodiment can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

[0026] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. And although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than here.

[0027] Compared with clastic rock reservoirs, the fracture-vuggy reservoir has diverse storage and seepage media, discrete spatial distribution of storage bodies, and significant spatio-temporal differences in flow patterns and development methods. Fluid potential is the total mechanical energy possessed by fluids inside a reservoir, and it is a classical theoretical method for studying the migration laws of underground oil, gas, water, etc. from the perspective of energy conservation. The research on the mass fluid potential in hydrocarbon accumulation mainly focuses on the field of petroleum geology of hydrocarbon migration and accumulation. With the continuous deepening of the theory and understanding of oilfield development, fluid potential has begun to be applied from the field of hydrocarbon exploration to the development fields such as the identification of preferential seepage channels in clastic rock reservoirs, remaining oil prediction, and tapping potential measures, and good application effects have been achieved. Due to the complexity of fracture-vuggy reservoirs, there is no publicly reported theoretical research and application of fluid potential in the exploration and development of fracture-vuggy reservoirs.

[0028] Although there are many research results on pore-type and fracture-pore-type carbonate reservoirs at home and abroad, and their corresponding development theories are relatively mature. However, compared with pore-type and fracture-pore-type carbonate reservoirs, the fracture-vuggy reservoir has a complex reservoir type and greater development difficulty. Due to the existence of pores, fractures, and solution cavities in the fracture-vuggy reservoir, the flow forms are diverse and the flow patterns are complex, and its development mode and regulation strategy cannot simply copy the development experience of foreign carbonate reservoirs mainly with fractures. At present, although some regulation technical methods for constructing injection-production well patterns for fracture-vuggy reservoir storage bodies, dynamic and static processing calculations for fracture-vuggy reservoirs, injection dynamic analysis for fracture-vuggy reservoirs, and flow path adjustment have been formed in China, each technology has its adaptability, on the one hand, from the assumed conditions of the method itself, and on the other hand, from the quality and abundance of data acquisition.

[0029] Therefore, to solve the above technical problems, the present invention proposes a method and system for analyzing the fluid potential of a fracture-vuggy reservoir. The method and system first construct a geological geometric model for the target fracture-vuggy unit and establish a geological model by combining the drilling and logging data of historical wells. Then, according to the historical oil well production data in the target fracture-vuggy unit, using numerical simulation technology, numerically fit the development and production history of the geological model of the target fracture-vuggy unit to convert the three-dimensional geological model into a numerical grid model, and obtain an initial distribution model of the target fracture-vuggy unit including the reservoir pressure field, oil saturation field, and fluid velocity field. Finally, according to the distribution characteristics of the pressure field, oil saturation, and fluid velocity data in the above initial distribution model, statistically calculate the fluid potential energy at each grid position in the model, so as to obtain the fluid potential energy distribution characteristics of the target fracture-vuggy unit. In this way, the present invention calculates the fluid potential energy distribution characteristics at different positions in the fracture-vuggy unit from the perspective of reservoir fluid potential energy according to the geological development characteristics of the fracture-vuggy reservoir. The present invention enriches and expands the application scope of the conventional reservoir numerical simulation results and solves the problem in the prior art that only the fluid potential energy of clastic sandstone reservoirs is studied.

[0030] In addition, the present invention uses the fluid potential energy distribution characteristic data of the target fracture-vuggy unit to propose corresponding oil well and water well control measures for balanced production from the perspective of energy conversion. Thus, the present invention provides a new technology for balanced production and adjustment of fracture-vuggy reservoirs with diverse reservoir spaces and extremely strong reservoir heterogeneity, which is convenient for practice and easy to promote.

[0031] Figure 1 It is a step diagram of the method for analyzing the fluid potential of a fracture-vuggy reservoir according to an embodiment of the present application. In step S110, the target fracture-vuggy unit is carved to determine the geometric model of the target fracture-vuggy unit, and then according to the constructed geometric model, combined with the drilling and logging data of the target fracture-vuggy unit, the geological model of the target fracture-vuggy unit is obtained. In step S110, first, the structure of the reservoir body in the target fracture-vuggy unit is carved to obtain a three-dimensional geometric model of the target fracture-vuggy unit. It should be noted that in the embodiment of the present invention, the target fracture-vuggy unit is the fracture-vuggy unit for which the fluid potential energy evaluation needs to be carried out currently. Then, step S110 will obtain the drilling data and logging data of these historical wells from the historical wells that have completed drilling in the current target fracture-vuggy unit, and convert the above geometric model into a geological model including the distribution characteristics of the karst system type and reservoir type of the target fracture-vuggy unit based on these data.

[0032] Step S120 is based on the geological model obtained in step S110. According to the current carving results and the historical production data of the target fracture-cavity unit, using numerical simulation technology, the development and production history of the target fracture-cavity unit is fitted, and an initial distribution model of the target fracture-cavity unit including a reservoir pressure field, an oil saturation field, and a fluid velocity field is established. In step S120, according to the geological carving results of the target fracture-cavity unit obtained in step S110 and the historical oil production and water production data of the target fracture-cavity unit (the oil well production data here is the historical production data of all production wells in the target fracture-cavity unit), using numerical simulation technology, the development and production history of the target fracture-cavity unit is numerically fitted based on the geological model of the target fracture-cavity unit (that is, it is necessary to fit the oil production and water production conditions at different times and different reservoir positions of the target fracture-cavity unit based on the geological model), and an initial distribution model of the target fracture-cavity unit including a reservoir pressure field, an oil saturation field, and a fluid velocity field is established, so as to enter step S130. Among them, the initial distribution model is a grid-based three-dimensional numerical model, which respectively shows the distribution characteristics of reservoir pressure data, oil saturation data, and fluid velocity data at each grid position in the target fracture-cavity unit, etc.

[0033] Step S130 calculates the fluid potential energy at each grid position in the preliminary distribution model according to the initial distribution model obtained in step S120 and various information displayed therein, and obtains a fluid potential energy distribution model of the target fracture-cavity unit. In step S130, according to the reservoir pressure data, oil saturation data, fluid velocity data, position data of the current grid in the space of the target fracture-cavity unit, fluid density data, reservoir type (reservoir body type) to which the current grid position belongs and other information in the initial distribution model, the total mechanical energy (i.e., fluid potential energy) at each grid position is calculated, so as to obtain a model (i.e., fluid potential energy distribution model) that characterizes the distribution characteristics of the fluid potential energy of the target fracture-cavity unit at different unit positions.

[0034] Furthermore, in order to comprehensively and accurately analyze the fluid potential energy at each grid position in the model, in the embodiment of the present invention, the fluid potential energy includes: potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy. Specifically, the potential energy is the energy generated by the change in position caused by the fluid density and the vertical depth position of the unit volume of fluid. The pressure energy refers to the energy possessed by the fluid per unit volume in the reservoir (grid) due to the formation pressure. The kinetic energy is the energy generated by the fluid flow. The interfacial energy is the additional energy generated by the interfacial tension at the immiscible interface between the oil and water phases. The viscous force energy is the energy possessed by the viscous force generated by the internal frictional force between the fluid layers in contact with each other inside the fluid.

[0035] Thus, through the above steps S110 to S130, the present invention deeply analyzes the distribution of various mechanical energies of the target fracture-vug unit, expands the application scope of the numerical simulation results, and proposes a fluid potential analysis scheme applicable to carbonate fracture-vug reservoirs with complex reservoir structures, providing a theoretical basis for the comprehensive control technology of balanced exploitation of fracture-vug reservoirs.

[0036] Figure 2 It is a specific flowchart of the method for analyzing the fluid potential of a fracture-vug reservoir in an embodiment of the present application. Figure 3 It is a schematic diagram of the implementation principle of the method for analyzing the fluid potential of a fracture-vug reservoir in an embodiment of the present application. The following refers to Figure 2 and Figure 3 to describe the method for analyzing the fluid potential of a fracture-vug reservoir (hereinafter referred to as "fluid potential analysis method") described in the embodiments of the present invention.

[0037] As Figure 2 shown, in step S201, geological carving is performed on the target fracture-vug unit to determine the three-dimensional geometric model of the target fracture-vug unit. In step S201, it is necessary to first obtain a high-precision all-round three-dimensional seismic model of the target fracture-vug unit, and use the Geophyics module in Petrel software to extract attribute information such as frequency division attributes, tensor attributes, and spatial splitting attributes of the target fracture-vug unit body. Then, based on these attribute information, fracture-vug structure carving is performed on the reservoir body in the target fracture-vug unit to determine the reservoir geometric shape of the fracture-vug unit, and then enter step S202.

[0038] Based on the three-dimensional geometric model generated in step S201, in step S202, a three-dimensional geological model of the target fracture-vug unit is constructed according to the drilling data and logging data of each historical well in the target fracture-vug unit. In step S202, it is necessary to combine all the drilling data and logging data of the target fracture-vug unit to analyze the distribution of the karst background system and the internal fracture-vug structure in the unit three-dimensional space of the target fracture-vug unit to determine the three-dimensional geological model of the target fracture-vug unit. In addition, the three-dimensional geological model in the embodiments of the present invention, in addition to referring to the drilling data and logging data, can also, on this basis, refer to the core test results, well test data, etc. of each historical well in the target fracture-vug unit. The present invention does not make specific limitations in this regard, and those skilled in the art can adjust according to the actual accuracy of the geological model, the data types required to be displayed, etc.

[0039] In the embodiments of the present invention, the three-dimensional geological model of the target fracture-vug unit includes: the karst system of the fracture-vug unit reservoir body and the reservoir type information. The information of the karst system of the fracture-vug unit reservoir body refers to the system type of the geological karst background where the reservoir body is located in the target fracture-vug unit. The karst system information is selected from one or a combination of several of fault-controlled karst, weathering crust karst, and composite karst. The reservoir type information includes: the spatial distribution positions of different reservoir bodies in the target fracture-vug unit, and the reservoir type to which each reservoir body belongs. The reservoir type to which each reservoir body belongs is selected from one of semi-filled fracture-vug reservoir bodies, acid-fractured cracks, and unfilled cracks.

[0040] After obtaining the three-dimensional geological model of the target fracture-vug unit, it enters step S203. Based on the three-dimensional geological model constructed in step S202, according to the reservoir carving results obtained in step S201 and the historical production data of all production wells in the target fracture-vug unit, a structural morphology model, a petrophysical model, and a production performance model of the target fracture-vug unit are established, and a fitting operation is performed using reservoir numerical simulation technology. In step S203, first, based on the three-dimensional geological model obtained in step S202, according to the reservoir carving results obtained in step S201, laboratory chemical analysis data such as crude oil and formation water, and production data of oil and water production over the years, a structural morphology model, a petrophysical model, and a production performance model for the target fracture-vug unit are established; then, based on these newly established models, taking the historical oil production and water production data of all production wells in the target fracture-vug unit as the fitting target, using reservoir numerical simulation technology, by continuously adjusting reservoir properties such as reservoir permeability, the block production history of the reservoir block of the target fracture-vug unit at different times and the (single-well) production history of individual wells at different positions within the block at different times are numerically fitted and simulated with the real historical data, thereby establishing an initial distribution (numerical) model for the target fracture-vug unit. Among them, the initial distribution numerical model is a model that grids the three-dimensional target fracture-vug unit, and characteristic information such as reservoir pressure data, fluid flow velocity data, fluid oil saturation data, the reservoir type of the reservoir body to which the current grid belongs, the position of the current grid in the three-dimensional target fracture-vug unit, and fluid density can be obtained in each three-dimensional grid. In this way, the various characteristic information contained in the positions of each grid in the initial distribution numerical model can be used as the data basis for calculating the fluid potential energy of the corresponding grid position, and then it enters step S204.

[0041] During the numerical fitting process, the Eclipse reservoir numerical simulation software is used to simulate and calculate the production history data of the target fracture-cavity unit. By continuously adjusting reservoir permeability and other properties, the simulated production indicators are fitted to the real historical data. When the fitting rate of the single-well production in the target fracture-cavity unit reaches the preset fitting qualified threshold, it indicates that the current fitting operation meets the accuracy requirements. At this time, an initial distribution model of the reservoir pressure field, oil saturation field, water saturation field, and fluid velocity field reflecting the underground situation of the reservoir can be obtained. Among them, in the embodiments of the present invention, the above-mentioned fitting qualified threshold is preferably 85%.

[0042] Step S204 calculates the fluid potential energy (total mechanical energy) of each grid position in the initial distribution numerical model according to various characteristic information included in each grid position, so as to obtain an initial distribution numerical model characterizing the spatial distribution characteristics of the fluid potential energy of the target fracture-cavity unit. In the embodiments of the present invention, since the calculation method of the fluid potential energy of each grid position is the same, the calculation process of the fluid potential energy for one grid position is described below.

[0043] Specifically, in step S204, it is necessary to calculate the fluid potential energy, fluid pressure energy, fluid kinetic energy, interfacial energy, and fluid viscous force energy of the current grid respectively. Then, after summing up the calculation results of various mechanical energies of the current grid, the total mechanical energy of the current grid is obtained.

[0044] Furthermore, in the embodiments of the present invention, it is necessary to calculate the fluid potential energy (the first type of mechanical energy) of the current grid according to the fluid density per unit volume corresponding to the current grid and the grid position. Among them, the fluid potential energy of the current grid is calculated according to the following expression:

[0045] E Z = ρgz (1)

[0046] Among them, Ez represents the fluid potential energy, with the unit of J; ρ represents the fluid density, with the unit of kg / m 3 ; g represents the acceleration due to gravity, 9.8m / s 2 ; z represents the depth of the current grid relative to the reference plane, with the unit of m.

[0047] Furthermore, in the embodiments of the present invention, it is necessary to calculate the fluid pressure energy (the second type of mechanical energy) of the current grid according to the formation pressure exerted on the fluid corresponding to the current grid and the fluid density per unit volume. Among them, the fluid pressure energy of the current grid is calculated according to the following expression:

[0048]

[0049] Among them, Ep represents the fluid pressure energy, with the unit of J; p represents the formation pressure, with the unit of MPa.

[0050] Furthermore, since the kinetic energy value of the fluid in the reservoir grid is positively correlated with the density of the fluid per unit volume and the square of the velocity in the reservoir, in the embodiments of the present invention, it is necessary to calculate the fluid kinetic energy (the third type of mechanical energy) of the current grid according to the fluid density and the fluid flow velocity per unit volume corresponding to the current grid. Among them, the fluid kinetic energy of the current grid is calculated according to the following expression:

[0051]

[0052] Among them, Ev represents the fluid kinetic energy, with the unit of J; v represents the fluid flow velocity in the reservoir grid, with the unit of m / s. For the carbonate fracture-vug type fracture-vug unit, the fluid flow velocity in each grid is determined by the reservoir type of the reservoir body where the grid is located. Since the flow types corresponding to different reservoir body types are different, when calculating the grid fluid flow velocity of different reservoir types, different fluid flow velocity calculation methods need to be selected.

[0053] Specifically, if the reservoir type of the reservoir body where the current grid is located is a semi-filled fracture-vug reservoir body, the fluid flow velocity in the grid is calculated according to the following expression:

[0054]

[0055] Among them, K represents the formation permeability corresponding to the current grid, with the unit of mD; μ represents the fluid viscosity, with the unit of Pa·s; represents the fluid potential difference between two adjacent grids, with the unit of J.

[0056] If the reservoir type of the reservoir body where the current grid is located is a large acid-fractured or unfilled fracture, the fluid flow velocity in the grid is calculated according to the following expression:

[0057]

[0058] Among them, β represents the Forchheimer coefficient.

[0059] Furthermore, in the embodiments of the present invention, it is necessary to calculate the interfacial energy (the fourth type of mechanical energy) of the current grid according to the oil-water interfacial tension and the static wetting angle of the interface corresponding to the current grid. Among them, the interfacial energy of the current grid is calculated according to the following expression:

[0060]

[0061] Among them, Eσ represents the interfacial energy, with the unit of J; σ represents the oil-water interfacial tension, with the unit of mN / m; θ represents the static wetting angle of the oil-water interface, with the unit of °; r represents the average pore throat radius of all pores in the current grid, with the unit of m.

[0062] Further, in the embodiments of the present invention, it is necessary to calculate the viscous force energy (the fifth type of mechanical energy) of the current grid according to the fluid density per unit volume, fluid viscosity, and fluid flow velocity corresponding to the current grid. The viscous force energy of the current grid is calculated according to the following expression:

[0063]

[0064] where E η represents the viscous force energy, with the unit of J; η represents the fluid viscosity, with the unit of mPa·s; y represents the vertical distance of the fluid between two adjacent layers of grids, with the unit of m.

[0065] Thus, after calculating the five types of mechanical energies of the current grid respectively, the calculation results of these five types of mechanical energies are summed up to obtain the fluid potential energy (expression) corresponding to the current grid.

[0066] That is to say, in the embodiments of the present invention, according to various types of characteristic information included in each grid position in the initial distribution model, the fluid potential energy of each grid is calculated by using a preset fluid potential energy calculation model. The fluid potential energy calculation model is expressed by the following expression:

[0067]

[0068] where Φ represents the fluid potential energy. Finally, after substituting the above expressions (1) to (7) into the expression, the corresponding fluid potential energy expressions are listed for each grid, and further, by solving the fluid potential energy gradient method, the fluid potential energy of each grid is obtained.

[0069] In this way, through the above expressions (1) to (8), the three-dimensional initial distribution numerical model obtained in step S203 can be directly converted into a three-dimensional fluid potential energy distribution model, and the distribution characteristics of the fluid potential energy at different positions (different three-dimensional grids) in the target fracture-cavity unit can be displayed.

[0070] In addition, in order to expand the application scope of the fluid potential energy distribution characteristic model, after the present invention obtains the fluid potential energy distribution characteristic representation model (fluid potential energy distribution model) applicable to the fracture-cavity reservoir based on the numerical simulation results, according to the fluid potential energy distribution characteristics of the target fracture-cavity unit characterized by this model, injection-production control measures for balanced production are selected for the target fracture-cavity unit to improve the recovery rate of the target fracture-cavity unit.

[0071] Further, the fluid potential analysis method described in the embodiments of the present invention further includes (step S140): analyzing the well group connection situation between oil wells and water wells, and the distribution characteristics of various types of mechanical energies at the bottom of the well in the target fracture-cavity unit according to the fluid potential energy distribution characteristics in space in the target fracture-cavity unit, and preferably selecting the injection-production well control technology that suits them.

[0072] In the injection-production well control technology preferably adapted to the current target fracture-vug unit, it is necessary to first obtain the three-dimensional display diagram, longitudinal sectional view and horizontal sectional view of the three-dimensional fluid potential energy distribution model obtained in step S130, clarify the connection relationship between the oil wells and water wells in the target fracture-vug unit, and analyze the fluid potential energy distribution in each unit (including: analyzing the kinetic energy distribution, analyzing the potential energy distribution, analyzing the pressure energy distribution, analyzing the interfacial energy distribution, analyzing the viscous force energy distribution, and analyzing the total mechanical energy distribution), so as to respectively determine the high-value areas and low-value areas of the fluid potential energy and various types of mechanical energy.

[0073] Among them, when analyzing the high-value areas and low-value areas of various types of energy, according to the characteristic data of the corresponding type of energy distribution in the target fracture-vug unit, the area where all grids belonging to the preset first threshold range corresponding to the current mechanical energy category in the corresponding type of energy data are located is marked as the high-value area, and the area where all grids belonging to the preset second threshold range corresponding to the current mechanical energy category in the corresponding type of energy data are located is marked as the low-value area. In the embodiment of the present invention, each type of mechanical energy corresponds to a corresponding first threshold range and a second threshold range, so as to analyze the high-value areas and low-value areas of each type of mechanical energy characteristics.

[0074] After completing the characteristic analysis of the target fracture-vug unit, it is necessary to select control measures adapted to this characteristic for each production well in the target area according to the fluid potential energy distribution characteristics of the target fracture-vug unit, so as to achieve the balanced exploitation of the entire target fracture-vug unit. In the embodiment of the present invention, the control measures include: oil-water well control measures such as liquid control, liquid lifting, and drainage. Liquid control (oil-water mixture) regulation is the distribution characteristic of the fluid potential energy at different positions in the target fracture-vug unit shown in the three-dimensional fluid potential energy distribution model, reducing the daily water production of the production wells located in the high water potential area, reducing the kinetic energy of the water phase, ensuring the balanced rise of the bottom water, converting the pressure energy and kinetic energy of the water body into the pressure energy of the oil reservoir, and reasonably utilizing the oil-water fluid potential energy of the oil reservoir. Liquid lifting regulation is to select a water source well or a high-water-cut well located on the water invasion path as the production well, and by increasing the daily water production of the current production well, slow down the water invasion speed flowing into the affected production well in the oil reservoir, reduce the water cut increase rate of the affected oil well, and then improve the development effect of the oil well. Drainage regulation is aimed at a well group with one injection well corresponding to more than two affected production wells. On the one hand, reduce the liquid production intensity of the affected production wells located in the main water breakthrough channel, and at the same time artificially increase the liquid production of the production wells located in the secondary channels, change the inherent water line, and convert the injection kinetic energy into the kinetic energy of the oil phase to achieve the purpose of starting the unused remaining oil.

[0075] Further, in the embodiments of the present invention, when the kinetic energy in the fluid potential energy at the bottom of the well to be analyzed exceeds a preset high kinetic energy threshold, the opening of the choke is reduced to convert the kinetic energy of the bottom-hole fluid of the oil production well into fluid pressure energy. Specifically, for wells with high kinetic energy in the fluid potential energy at the bottom, they usually belong to well groups with insufficient energy connection of bottom water. It is necessary to adjust the working system such as choke reduction to complete the liquid control and regulation strategy, so as to reduce the bottom-hole kinetic energy of the oil production well while suppressing the water cone inside the reservoir, and reduce the water cut of the oil well and convert it into the pressure energy of the fracture-vug unit, thereby extending the water-free oil production period of the target fracture-vug unit. For example: If the kinetic energy at the bottom of well TK653 in a certain fracture-vug unit is significantly high and the water cut of this well is high, then through liquid control and regulation (for example: adjusting the bottom water from 40m 3 / d to 20m 3 / d), the fluid kinetic energy is converted into fluid pressure energy.

[0076] Further, in the embodiments of the present invention, when the kinetic energy at the bottom of the well to be analyzed is less than a preset low kinetic energy threshold and the pressure energy at the bottom exceeds a preset high pressure energy threshold, the total flow potential energy at the current bottom hole is balanced by increasing the liquid drainage rate. Specifically, for wells where the kinetic energy at the bottom is less than the above low kinetic energy threshold and the pressure energy at the bottom exceeds the above high pressure energy threshold, they usually belong to well groups with relatively sufficient energy connection of bottom water. It is necessary to increase the liquid drainage rate of high water cut wells to convert the high-pressure energy into water kinetic energy and potential energy, reduce the mechanical energy of the water phase in the entire fracture-vug unit, increase the mechanical energy of the oil phase, and restore or improve the oil well productivity. For example: If the kinetic energy at the bottom of well TK628 in a certain fracture-vug unit is low and the pressure energy is high, through the liquid lifting (from 30m 3 / d to 50m 3 / d) control measures, the total fluid potential of the reservoir is balanced, thereby achieving balanced exploitation.

[0077] Further, in the embodiments of the present invention, for well groups in which the target fracture-vug unit has a phenomenon of one injection and multiple productions due to different diversion capabilities of the main channel and secondary channels, the injection water pressure energy is converted into crude oil potential energy and kinetic energy by diverting the injection water to the production well with a lower bottom-hole pressure in the current well group. Specifically, for well groups in which the target fracture-vug unit has a phenomenon of one injection and multiple productions due to different diversion capabilities of the main channel and secondary channels, by increasing the liquid production rate of the oil wells communicated by the secondary channels, the injection water is diverted to the poorly affected oil wells, and the injection water pressure energy is converted into oil potential energy and oil kinetic energy, thereby achieving balanced exploitation of the target fracture-vug unit.

[0078] On the other hand, based on the above method for analyzing the fluid potential of a fracture-vug type reservoir, the present invention also proposes a system for analyzing the fluid potential of a fracture-vug type reservoir. Figure 4 It is a module block diagram of the system for analyzing the fluid potential of a fracture-vug type reservoir in the embodiments of this application. AsFigure 4 As shown in Figure 4 , the system for analyzing fluid potential in a fracture-vug reservoir (hereinafter referred to as "fluid potential analysis system") according to the present invention includes: a geological model generation module 41, a production history matching module 42, and a fluid potential energy calculation module 43.

[0079] Furthermore, the geological model generation module 41 is implemented according to the method described in step S110 above, and is configured to engrave the target fracture-vug unit to determine the geometric shape model of the target fracture-vug unit. Based on this, combined with the drilling and logging data of the fracture-vug unit, the geological model of the target fracture-vug unit is obtained. The production history matching module 42 is implemented according to the method described in step S120 above, and is configured to, based on the geological model output by the geological model generation module 41, use numerical simulation technology to match the development and production history of the current target fracture-vug unit according to the current engraving results and the historical production data of the current target fracture-vug unit, and establish an initial distribution model of the target fracture-vug unit including the reservoir pressure field, oil saturation field, and fluid velocity field. The fluid potential energy calculation module 43 is implemented according to the method described in step S130 above, and is configured to, according to the initial distribution model output by the production history matching module 42, calculate the fluid potential energy at each position in the model to obtain the fluid potential energy distribution model of the target fracture-vug unit.

[0080] Furthermore, in the embodiment of the present invention, the fluid potential energy is the sum of various mechanical energies, where the mechanical energy includes potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy.

[0081] In addition, the above fluid potential analysis system further includes: a regulation technology selection module 44. Among them, the regulation technology selection module 44 is implemented according to the method described in step S140 above, and is configured to determine the well group connection situation between oil wells and water wells, as well as the distribution characteristics of various mechanical energies at the bottom of the unit according to the fluid potential distribution characteristics in the target fracture-vug unit in space, and optimize the injection-production well regulation technology.

[0082] The present invention discloses a method and system for analyzing the fluid potential of a fracture-vug reservoir. The method and system include: by deeply analyzing the karst background and internal fracture-vug structure of a target fracture-vug unit, constructing a three-dimensional geological model of a typical unit, and applying reservoir numerical simulation technology to fit the production history of the block and single wells to be evaluated, establishing a three-dimensional model of the reservoir formation pressure, fluid saturation, and grid velocity of the target fracture-vug unit at the current development stage; according to the karst background, reservoir type of the target fracture-vug unit, and the fluid production data of oil wells, selecting corresponding energy calculation formulas, calculating the potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy of the fracture-vug unit, applying the calculation model of the development fluid potential of the fracture-vug reservoir, and calculating the total mechanical energy at each grid position. In this way, based on the special geological characteristics and development mode of the fracture-vug reservoir, the present invention deduces and establishes a general mathematical model of the development fluid potential of the fracture-vug reservoir, provides a calculation method for the development fluid potential of the fracture-vug reservoir based on the numerical simulation results. At the same time, it enriches and expands the application scope of the conventional reservoir numerical simulation results, solves the technical blank of the fluid potential calculation model and characterization method in the prior art that only targets clastic sandstone reservoirs and does not target the development of fracture-vug reservoirs, and provides a theoretical basis for the comprehensive control technology of balanced exploitation of fracture-vug reservoirs.

[0083] In addition, the present invention will also propose corresponding oil well and water well control measures such as liquid control, liquid lifting, drainage, and flow disturbance according to the distribution characteristics and high and low distribution characteristics of the fluid potential at different times and different positions. Thus, according to the control method provided by the present invention, it has obvious field applicability and practicability for the balanced exploitation of fracture-vug reservoirs with diverse reservoir spaces and extremely strong reservoir heterogeneity, provides a new technical direction for the comprehensive tapping of potential and adjustment of old units in fracture-vug reservoirs, and is convenient for practice and easy to promote.

[0084] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

[0085] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps, or materials disclosed herein, but should extend to equivalent alternatives of these features understood by those of ordinary skill in the relevant art. It should also be understood that the terms used herein are only for the purpose of describing specific embodiments and do not mean to limit.

[0086] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures, or characteristics described in connection with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" that appear throughout the specification do not necessarily all refer to the same embodiment.

[0087] Although the embodiments disclosed in the present invention are as above, the content described is only an embodiment adopted for the convenience of understanding the present invention and is not intended to limit the present invention. Any person skilled in the art within the technical field to which the present invention pertains may make any modifications and changes in the form of implementation and details without departing from the spirit and scope disclosed by the present invention. However, the scope of patent protection of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A method for analyzing the fluid potential of a fracture-cavity reservoir, characterized in that The method includes: Step 1: Carve the target fracture-cavity unit to determine the geometric morphology model of the target fracture-cavity unit. Based on this, combined with the drilling and logging data of the fracture-cavity unit, obtain the geological model of the target fracture-cavity unit, including: extracting the frequency division attribute, tensor attribute, and spatial splitting attribute of the fracture-cavity unit body based on the three-dimensional seismic model of the target fracture-cavity unit, and carving the reservoir body in the target fracture-cavity unit according to the extracted attribute characteristics; Step 2: Based on the geological model, according to the current carving results and the historical production data of the target fracture-cavity unit, use numerical simulation technology to fit the development and production history of the target fracture-cavity unit, and establish an initial distribution model of the target fracture-cavity unit including the reservoir pressure field, oil saturation field, and fluid velocity field; Step 3: According to the initial distribution model, calculate the fluid potential energy at each position in the model to obtain the fluid potential energy distribution model of the target fracture-cavity unit; Step 4: According to the fluid potential distribution characteristics in space within the target fracture-cavity unit, determine the well group connection situation between oil wells and water wells, and the distribution characteristics of various mechanical energies at the bottom of the well in the unit, so as to determine the high-value areas and low-value areas of fluid potential energy and various mechanical energies respectively, and optimize the injection-production well control technology, including: When the kinetic energy in the fluid potential energy at the bottom of the well to be analyzed exceeds the preset high kinetic energy threshold, it is determined that the current well to be analyzed belongs to a well group with insufficient bottom water connection energy, and the nozzle opening is reduced to convert the kinetic energy of the oil production well into fluid pressure energy; When the kinetic energy at the bottom of the well to be analyzed is less than the preset low kinetic energy threshold and the pressure energy in the fluid potential energy exceeds the preset high pressure energy threshold, it is determined that the current well to be analyzed belongs to a well group with relatively sufficient bottom water connection energy, and the drainage rate is increased to balance the flow potential energy at the current bottom of the well; For the well group with the phenomenon of one injection and multiple production due to different diversion capabilities of the main channel and secondary channels in the target fracture-cavity unit, the injection water pressure energy is converted into crude oil potential energy and kinetic energy by diverting the injection water to the production well with a lower bottom hole pressure in the current well group; 2. The method according to claim 1, wherein The fluid potential energy is the sum of multiple mechanical energies, where the mechanical energies include potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy; 3. The method according to claim 1 or 2, characterized in that, In the step of carving the target fracture-cavity unit, it includes: Extracting the frequency division attribute, tensor attribute, and spatial splitting attribute of the fracture-cavity unit body based on the three-dimensional seismic model of the target fracture-cavity unit, and carving the reservoir body in the target fracture-cavity unit according to the extracted attribute characteristics; 4. The method according to claim 1 or 2, characterized in that, The geological model includes the karst system of the fracture-cavity unit reservoir body and reservoir type information; 5. The method according to claim 1 or 2, characterized in that, In the said Step 2, Based on the geological model, according to the current carving results and the historical production data, establish the structural morphology model, rock physics model, and production dynamic model of the target fracture-cavity unit, and use reservoir numerical simulation technology for fitting operations. After the fitting rate of the single-well production volume in the target fracture-cavity unit reaches the preset fitting qualified threshold, generate the initial distribution model; 6. A system for analyzing the fluid potential of a fracture-vuggy reservoir, characterized in that, The system includes: A geological model generation module configured to carve a target fracture-cavity unit to determine a geometric morphology model of the target fracture-cavity unit, and based on this, combine drilling and logging data for the fracture-cavity unit to obtain a geological model of the target fracture-cavity unit; A production history matching module configured to, based on the geological model, use numerical simulation technology to match the development and production history of the target fracture-cavity unit according to the current carving results and the historical production data of the target fracture-cavity unit, and establish an initial distribution model of the target fracture-cavity unit including an oil reservoir pressure field, an oil saturation field, and a fluid velocity field; A fluid potential energy calculation module configured to, according to the initial distribution model, calculate the fluid potential energy at each position in the model to obtain a fluid potential energy distribution model of the target fracture-cavity unit; A regulation technology optimization module configured to, according to the fluid potential distribution characteristics in the spatial domain of the target fracture-cavity unit, determine the well group connection situation between oil wells and water wells, as well as the distribution characteristics of various mechanical energies at the bottom of the well in the unit, so as to respectively determine the high-value areas and low-value areas of the fluid potential energy and various mechanical energies, and optimize the injection-production well regulation technology, including: When the kinetic energy in the fluid potential energy at the bottom of the well to be analyzed exceeds a preset high kinetic energy threshold, reduce the nozzle opening to convert the kinetic energy of the oil production well into fluid pressure energy; When the kinetic energy at the bottom of the well to be analyzed is less than a preset low kinetic energy threshold and the pressure energy in the fluid potential energy exceeds a preset high pressure energy threshold, balance the flow potential energy at the current well bottom by increasing the liquid drainage speed; For a well group with a one-injection-multiple-production phenomenon occurring in the target fracture-cavity unit due to different diversion capabilities of the main channel and the secondary channel, convert the injection water pressure energy into crude oil potential energy and kinetic energy by diverting the injected water to the production well with a lower bottom hole pressure in the current well group; 7. The system according to claim 6, characterized in that, The fluid potential energy is the sum of multiple mechanical energies, where the mechanical energies include potential energy, pressure energy, kinetic energy, interfacial energy, and viscous force energy.

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