A method and device for confirming the inter-well connectivity of an oil reservoir

Abstract

The present invention discloses a method for confirming the connectivity between wells in a reservoir, and the method includes: obtaining geological structure data of a fault-karst reservoir, and constructing a target inter-well connectivity model based on the geological structure data, with the target inter-well connectivity model including a plurality of characteristic parameters, and the characteristic parameters including conductivity; aiming at the actual seepage characteristics of the fault-karst reservoir, adding a non-Darcy permeability coefficient to the target inter-well connectivity model, taking the non-Darcy permeability coefficient as an adjustment object, and taking conductivity as a correction object to correct the conductivity, so that the simulated seepage process based on the target inter-well connectivity model matches the real seepage process of the fault-karst reservoir; and confirming the connectivity between wells in the reservoir based on the corrected conductivity.

Description

Technical Field

[0001] The present invention relates to the field of fault-karst reservoirs, and more specifically, to a method and device for confirming the inter-well connectivity of reservoirs. Background Art

[0002] In conventional oil and gas reservoirs, the seepage velocity of oil and gas phases in the reservoir is relatively slow, and the seepage process satisfies the classical Darcy's law. In fault-karst reservoirs, the reservoir types are mostly fracture-cave type reservoirs. This type of reservoir is composed of karst caves, fractures of different scales, and matrix with extremely low permeability and porosity. Among them, karst caves of different scales are the main oil and gas accumulation areas, and fractures are the main preferential channels in the seepage process. At present, for fault-karst reservoirs, due to the existence of a large number of pore-fracture structures, and for production systems with relatively high or extremely high production rates, when the applicability of Darcy's law is significantly reduced, it is impossible to accurately simulate the oil-water dynamics of fault-karst reservoirs, making it more in line with the actual production situation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method and device for confirming the inter-well connectivity of reservoirs for the technical problem that it is impossible to accurately simulate the oil-water dynamics of fault-karst reservoirs to make it more in line with the actual production situation.

[0004] The technical solution adopted by the present invention to solve its technical problem is: construct a method for confirming the inter-well connectivity of reservoirs, the method comprising:

[0005] S1. Obtain the geological structure data of the fault-karst reservoir, and construct a target inter-well connectivity model based on the geological structure data with multiple inter-well connectivity units; the target inter-well connectivity model includes multiple characteristic parameters, and the characteristic parameters include conductivity;

[0006] S2. For the actual seepage characteristics of the fault-karst reservoir, add a non-Darcy permeability coefficient to the target inter-well connectivity model, and use the non-Darcy permeability coefficient as the adjustment object and the conductivity as the correction object to correct the conductivity, so that the simulated seepage process based on the target inter-well connectivity model matches the real seepage process of the fault-karst reservoir;

[0007] S3. Confirm the inter-well connectivity of the reservoir based on the corrected conductivity.

[0008] In one embodiment, the characteristic parameters further include control volume, and the method further comprises:

[0009] S4. Perform implicit difference processing on the target inter-well connectivity model to obtain the oil-water flow rate and the fluid flow direction in each inter-well connectivity unit;

[0010] S5. Based on multiple inter-well flow points corresponding to the seepage process, randomly select a target flow point from the multiple inter-well flow points, and determine the upstream flow point corresponding to the target flow point according to the flow direction of the fluid;

[0011] S6. Determine the first water saturation reached at the target flow point, the second water saturation at the upstream flow point, and the cumulative dimensionless cumulative flow rate according to the oil-water flow rate, and calculate the water cut reached between the two wells at the corresponding time according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate;

[0012] S7. Calculate the actual production indexes required for each single well and the block according to the calculated water cut;

[0013] S8. Fit the actual production indexes, obtain the fitted characteristic parameters through the way of inversion optimization, and perform a secondary confirmation of the inter-well connectivity of the oil reservoir based on the fitted characteristic parameters.

[0014] In one embodiment, the obtaining the geological structure data of the fault-karst reservoir and constructing a target inter-well connectivity model based on the geological structure data, including:

[0015] Obtain the geological structure data of the fault-karst reservoir and construct an initial inter-well connectivity model based on the geological structure data;

[0016] Perform integral conversion on the initial inter-well connectivity model based on the control volume and time step to convert the initial inter-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation;

[0017] Perform equation simplification on the initial first expression to obtain a target first expression, and perform equation simplification on the initial second expression to obtain a target second expression;

[0018] Construct a target inter-well connectivity model by combining the target first and second expressions.

[0019] In one embodiment, the performing equation simplification on the initial first expression to obtain a target first expression includes:

[0020] Simplify the initial first expression according to the high-speed divergence theorem to obtain the corresponding target first expression.

[0021] In one embodiment, obtaining the target second expression by performing equality simplification processing on the initial second expression includes:

[0022] Performing time integration on the initial second expression, and without considering the action of the gravity term, using the rectangular method estimation theorem to obtain a target second expression adapted to the initial second expression.

[0023] In one embodiment, calculating the water cut reached between two wells at a corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate includes:

[0024] According to the first water saturation S w , the second water saturation S wu , and the cumulatively obtained dimensionless cumulative flow rate Q V , constructing a first calculation formula for calculating the derivative of the comprehensive water cut corresponding between the target flow point and the upstream flow point; wherein, the first calculation formula is specifically:

[0025]

[0026] wherein, f w '(*) refers to solving the derivative of the comprehensive water cut for "*";

[0027] Obtaining the third water saturation corresponding to the flow of oil and water from well i to well j at time t and the dimensionless cumulative flow rate cumulatively reached by the flow of oil and water from well i to well j and constructing a second calculation formula based on the first calculation formula for calculating the water cut reached between well i and well j at time t; wherein, the second calculation formula is specifically:

[0028]

[0029] wherein, represents the derivative form of the dimensionless cumulative flow rate corresponding to the flow of oil and water from well i to well j at time t ; min{a, b} refers to taking the minimum value of a and b;

[0030] Performing integral calculation on the second calculation formula to obtain the water cut reached between the two wells at the corresponding moment.

[0031] A device for confirming the inter-well connectivity of an oil reservoir disclosed in the present application, the device includes:

[0032] A building module, configured to obtain geological structure data of a fault-karst reservoir and construct a target inter-well connectivity model based on the geological structure data, where the target inter-well connectivity model includes a plurality of characteristic parameters, and the characteristic parameters include conductivity and control volume;

[0033] A correction module, configured to add a non-Darcy permeability coefficient to the target inter-well connectivity model according to the actual seepage characteristics of the fault-karst reservoir, take the non-Darcy permeability coefficient as an adjustment object, and take the conductivity as a correction object to correct the conductivity, so that the simulated seepage process based on the target inter-well connectivity model matches the real seepage process of the fault-karst reservoir;

[0034] A primary confirmation module, configured to confirm the inter-well connectivity of the reservoir based on the corrected conductivity.

[0035] In one embodiment, the device further includes:

[0036] A first calculation module, configured to perform implicit difference processing on the target inter-well connectivity model to obtain the oil-water flow rate and the fluid flow direction in each inter-well connectivity unit;

[0037] A selection module, configured to select a target flow point from the plurality of inter-well flow points corresponding to the seepage process, and determine the upstream flow point corresponding to the target flow point according to the fluid flow direction;

[0038] A second calculation module, configured to determine the first water saturation at the target flow point, the second water saturation at the upstream flow point, and the dimensionless cumulative flow rate obtained cumulatively according to the oil-water flow rate, and calculate the water cut reached between the two wells at the corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate;

[0039] A third calculation module, configured to calculate the actual production indexes required for each single well and the block according to the calculated water cut;

[0040] A fitting module, configured to fit the actual production indexes, invert the fitted connectivity parameters, and further clarify the inter-well connectivity.

[0041] In one embodiment, the building module is further configured to obtain geological structure data of the fault dissolution reservoir, and construct an initial inter-well connectivity model based on the geological structure data with multiple inter-well connectivity units as the basis; perform integral conversion on the initial inter-well connectivity model based on the control volume and time step to convert the initial inter-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation; perform equation simplification on the initial first expression to obtain a target first expression, and perform equation simplification on the initial second expression to obtain a target second expression; construct a target inter-well connectivity model by combining the target first and second expressions.

[0042] In one embodiment, the second calculation module is further configured to construct a first calculation formula according to the first water saturation S w , the second water saturation S wu and the cumulatively obtained dimensionless cumulative flow rate Q V , where the first calculation formula is used to calculate the derivative of the comprehensive water cut corresponding to the target flow point and the upstream flow point; specifically, the first calculation formula is:

[0043]

[0044] where f w '(*) means to solve the derivative of the comprehensive water cut for "*";

[0045] Obtain the third water saturation corresponding to the flow of oil and water from well i to well j at time t and the dimensionless cumulative flow rate accumulated by the flow of oil and water from well i to well j and construct a second calculation formula based on the first calculation formula, where the second calculation formula is used to calculate the water cut reached between well i and well j at time t; specifically, the second calculation formula is:

[0046]

[0047] where represents the derivative form of the dimensionless cumulative flow rate corresponding to the flow of oil and water from well i to well j at time t ; min{a, b} means to take the minimum value of a and b;

[0048] Perform integral calculation on the second calculation formula to obtain the water cut reached between the two wells at the corresponding time.

[0049] To implement a method and device for confirming the inter-well connectivity of an oil reservoir according to the present invention, first, considering the geological structure data of a fault-karst reservoir, the complex fault-karst structure is simplified into a target inter-well connectivity model based on multiple inter-well connectivity units, effectively reducing the computational complexity. Secondly, in view of the actual seepage characteristics of the fault-karst reservoir, a high-speed non-Darcy seepage term is considered to be added to the target inter-well connectivity model, further forming a material balance equation for the connectivity unit based on the fault-karst reservoir, and the oil-water dynamics of the fault-karst reservoir is simulated in a more accurate manner. Finally, with the non-Darcy permeability coefficient as the adjustment object and the conductivity as the correction object, the conductivity is corrected, effectively performing a dynamic sensitivity analysis of the connectivity, and making it more in line with the actual production situation while accurately simulating the oil-water dynamics of the fault-karst reservoir. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0051] Figure 1 is a flowchart of a method for confirming the inter-well connectivity of an oil reservoir in an embodiment of the present invention;

[0052] Figure 2 is a flowchart of a method for confirming the inter-well connectivity of an oil reservoir in another embodiment of the present invention;

[0053] Figure 3 is a system structure diagram of a device for confirming the inter-well connectivity of an oil reservoir in an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0054] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the drawings.

[0055] In one embodiment, as Figure 1 shown, a method for confirming the inter-well connectivity of an oil reservoir is provided. Taking the application of this method to a computer device (the computer device may specifically be a terminal or a server. The terminal may specifically be, but is not limited to, various personal computers, laptop computers, smart phones, tablet computers, and portable wearable devices. The server may be an independent server or a server cluster composed of multiple servers) as an example, the method includes the following steps:

[0056] Step S102, obtaining the geological structure data of the fault-karst reservoir, and constructing a target inter-well connectivity model based on the geological structure data, where the target inter-well connectivity model includes multiple characteristic parameters, and the characteristic parameters include conductivity.

[0057] Among them, the fault-karst reservoir can be composed of karst caves, fractures of different scales, and matrix with extremely low permeability and porosity. Among them, karst caves of different scales are the main oil and gas accumulation areas; fractures are the main preferential channels during the seepage process. Therefore, for the fault-karst reservoir, due to the existence of a large number of pore-fracture structures, and for production systems with relatively high or extremely high production rates, the applicability of Darcy's law will be significantly reduced.

[0058] Specifically, obtaining the geological structure data of the fault-karst reservoir and constructing a target well-to-well connectivity model based on the geological structure data, including: obtaining the geological structure data of the fault-karst reservoir and constructing an initial well-to-well connectivity model based on the geological structure data; performing integral conversion on the initial well-to-well connectivity model based on the control volume and time step to convert the initial well-to-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation; performing equation simplification on the initial first expression to obtain a target first expression, and performing equation simplification on the initial second expression to obtain a target second expression; constructing a target well-to-well connectivity model by combining the target first and second expressions.

[0059] In one embodiment, the mathematical expression of the initial well-to-well connectivity model is:

[0060]

[0061] Among them, is the gradient operator; is the fluid density, with the unit of kg / m 3 ; v v is the seepage velocity of the karst cave unit, with the unit of m / s; q v is the source-sink phase, with the unit of kg / m 3 ; τ is the cross-flow rate of the fluid from the fracture unit to the karst cave unit per unit volume, with the unit of m 3 / s; φ is the average porosity, with the unit of f; is the partial derivative with respect to time t.

[0062] In one embodiment, the mathematical expression of the integral equation is:

[0063]

[0064] Among them, V t is the well-to-well control volume between two well points of well i and well j, with the unit of m 3 ; V is the control volume, with the unit of m 3 .

[0065] In one embodiment, according to the high-speed divergence theorem, the initial first expression is simplified to obtain the corresponding target first expression. The mathematical expression of the target first expression is as follows:

[0066]

[0067] where j is the center point of the second control volume adjacent to the first control volume i; where is the conductivity between well i and well j, with the unit of m 3 ·d -1 ·MPa -1 ; A ij is the interface area between control volume i and control volume j, with the unit of m 2 ; k v is the permeability of the cavern unit, with the unit of mD; μ is the fluid viscosity, with the unit of mPa·s; L ij is the spacing distance between well point i and well point j, with the unit of m; is the pressure gradient; t is the time, with the unit of d (days); β is the high-speed non-Darcy seepage coefficient, with the unit of m -1 .

[0068] In one embodiment, the time integration of the initial second expression is performed, and without considering the action of the gravity term, the rectangular method estimation theorem is used to obtain the target second expression adapted to the initial second expression. The mathematical expression of the target second expression is as follows:

[0069]

[0070] where is the source-sink term of node i; V i is the control volume of node i, with the unit of m 3 , is the cross-flow rate from the fracture unit to the cavern unit; C t,i is the comprehensive compressibility of the reservoir, with the unit of MPa -1 ; p i is the average pressure of well i in the oil drainage area, with the unit of MPa.

[0071] In one embodiment, the mathematical expression of the target well connection model constructed by combining formula (3) and formula (4) is as follows:

[0072]

[0073] where p j is the average pressure of well i in the oil drainage area, with the unit of MPa.

[0074] Step S104. According to the actual seepage characteristics of the fracture-vug reservoir, a non-Darcy permeability coefficient is added to the target well-to-well connectivity model, and the non-Darcy permeability coefficient is used as the adjustment object, and the conductivity is corrected with the conductivity as the correction object, so that the simulated seepage process based on the target well-to-well connectivity model matches the actual seepage process of the fracture-vug reservoir.

[0075] Specifically, referring to formula (5), a non-Darcy seepage coefficient β is added to the basis of formula (5), and combined with formula (3), it can be known that there is a correction and adjustment correlation between the conductivity T ij and the non-Darcy seepage coefficient β. Therefore, in this embodiment, the conductivity T can be indirectly corrected by changing the non-Darcy seepage coefficient β ij to make the flow simulation more in line with the actual flow of the fracture-vug reservoir, so as to make the connectivity more accurate.

[0076] Step S106. Confirm the well-to-well connectivity of the reservoir based on the corrected conductivity.

[0077] A method for confirming the well-to-well connectivity of an oil reservoir disclosed in this application. First, considering the geological structure data of the fracture-vug reservoir, the complex fracture-vug structure is simplified into a target well-to-well connectivity model based on multiple well-to-well connectivity units, effectively reducing the computational complexity. Second, according to the actual seepage characteristics of the fracture-vug reservoir, a high-speed non-Darcy seepage term is considered to be added to the target well-to-well connectivity model, and further a material balance equation of the connectivity unit based on the fracture-vug reservoir is formed, and the oil-water dynamics of the fracture-vug reservoir is simulated in a more accurate way. Finally, with the non-Darcy permeability coefficient as the adjustment object and the conductivity as the correction object, the conductivity is corrected, and the dynamic sensitivity analysis of the connectivity is effectively carried out. Under the condition of accurately simulating the oil-water dynamics of the fracture-vug reservoir, it makes it more in line with the actual production situation.

[0078] In one embodiment, as Figure 2 shown, a method for confirming the well-to-well connectivity of an oil reservoir provided by this application further includes the following steps:

[0079] Step S202. Perform implicit difference processing on the target well-to-well connectivity model to obtain the oil-water flow rate and the fluid flow direction in each well-to-well connectivity unit.

[0080] Among them, the implicit difference method represents the differential equation as a difference equation defined on discrete grid points (that is, the numerical relationship between grid points reflected by the differential equation), and calculates the numerical values on the unknown boundary through the difference relationship between adjacent grid points by the given boundary conditions.

[0081] Step S204: From the multiple inter-well flow points corresponding to the seepage process, randomly select a target flow point, and determine the upstream flow point corresponding to the target flow point according to the flow direction of the fluid.

[0082] Step S206: Determine the first water saturation reached at the target flow point, the second water saturation at the upstream flow point, and the cumulative dimensionless cumulative flow rate obtained, and calculate the water cut reached between the two wells at the corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate.

[0083] Specifically, calculating the water cut reached between the two wells at the corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate includes:

[0084] According to the first water saturation S w , the second water saturation S wu , and the cumulative dimensionless cumulative flow rate Q V , construct a first calculation formula for calculating the derivative of the comprehensive water cut corresponding between the target flow point and the upstream flow point; where the first calculation formula is specifically:

[0085]

[0086] where f’ w (*) means solving the derivative of the comprehensive water cut for "*";

[0087] Obtain the third water saturation corresponding to the oil and water flowing from well i to well j at time t and the dimensionless cumulative flow rate cumulatively reached by the oil and water flowing from well i to well j and construct a second calculation formula based on the first calculation formula for calculating the water cut reached between well i and well j at time t; where the second calculation formula is specifically:

[0088]

[0089] where, represents the derivative form of the dimensionless cumulative flow rate corresponding to the oil and water flowing from well i to well j at time t ; min{a, b} means taking the minimum value of a and b;

[0090] Perform integral calculation on the second calculation formula to obtain the water cut reached between the two wells at the corresponding moment.

[0091] Step S208: Calculate the actual production targets required for each individual well and the block based on the calculated water cut.

[0092] Among them, the actual production target represents the liquid actually produced by the oil well from the formation every day, and the produced liquid includes oil and water. For an individual well, the oil production = liquid production × (1 - water cut), and the water production = liquid production × water cut; for a block, the block liquid production is the sum of the liquid productions of all oil wells, the block oil production is the sum of the oil productions of all oil wells, and the block water production is the sum of the water productions of all oil wells.

[0093] Step S210: Fit the actual production targets, obtain the fitted characteristic parameters through the method of inversion optimization, and based on the fitted characteristic parameters, perform a secondary confirmation of the inter-well connectivity of the reservoir.

[0094] Specifically, since the generation of the actual production targets depends on the characteristic parameters (conductivity and control volume) of the target inter-well connectivity model. Therefore, in the current embodiment, the computer device will, based on the historical fitting method, simulate the historical fitting problem of the fault dissolution reservoir and construct the corresponding fitting objective function. Perform inversion optimization based on this fitting objective function to obtain the fitted characteristic parameters.

[0095] In one embodiment, the mathematical expression of the fitting objective function is:

[0096]

[0097] Among them, O(*) is the fitting objective function; e is a vector composed of characteristic parameters; s(e) is the vector of dynamic indicators predicted based on the target inter-well connectivity model; d obs is the actual production target of the oil and water wells, C d is the dynamic covariance matrix; is the conductivity, is the connected volume.

[0098] In one embodiment, the projection gradient method is used to iteratively solve formula (8), where the mathematical expression form of the characteristic parameters output after each iteration is:

[0099]

[0100] Among them, m n+1 is the characteristic parameter output by fitting after the (n + 1)-th iteration step; m n is the characteristic parameter output by fitting after the n-th iteration step; γ is the iteration step; I is the identity matrix; N e is the constraint condition coefficient matrix; is the stochastic perturbation approximate gradient. Among them, the SPSA algorithm is used for the independent variable Perform synchronous perturbation to obtain a random perturbation approximate gradient Specifically:

[0101]

[0102] Wherein, is the optimal control variable obtained at the l-th iteration step, ε n is the perturbation step size, Δ n is N u is an N u -dimensional random perturbation vector, and the elements included therein (i = 1, 2,..., N

[0103] In one embodiment, as Figure 3 shown, a confirmation device 300 for the inter-well connectivity of an oil reservoir is provided. The device 300 includes:

[0104] A construction module 301, configured to obtain geological structure data of a fault-karst reservoir and construct a target inter-well connectivity model based on the geological structure data. The target inter-well connectivity model includes a plurality of characteristic parameters, and the characteristic parameters include conductivity and control volume.

[0105] A correction module 302, configured to add a non-Darcy permeability coefficient to the target inter-well connectivity model according to the actual seepage characteristics of the fault-karst reservoir, and take the non-Darcy permeability coefficient as an adjustment object and the conductivity as a correction object to correct the conductivity, so that the simulated seepage process based on the target inter-well connectivity model matches the actual seepage process of the fault-karst reservoir.

[0106] A primary confirmation module 303, configured to confirm the inter-well connectivity of the oil reservoir based on the corrected conductivity.

[0107] In one of the embodiments, the device further includes:

[0108] A first calculation module, configured to perform implicit difference processing on the target inter-well connectivity model to obtain the oil-water flow rate and the fluid flow direction in each inter-well connectivity unit.

[0109] A selection module, configured to select an arbitrary target flow point from the plurality of inter-well flow points corresponding to the seepage process, and determine the upstream flow point corresponding to the target flow point according to the fluid flow direction.

[0110] A second calculation module, configured to determine, according to the oil-water flow rate, a first water cut saturation reached at the target flow point, a second water cut saturation at the upstream flow point, and a dimensionless cumulative flow rate obtained cumulatively, and calculate a water cut reached between two wells at a corresponding moment according to the first water cut saturation, the second water cut saturation, and the dimensionless cumulative flow rate.

[0111] A third calculation module, configured to calculate actual production indexes required for each individual well and the block according to the calculated water cut.

[0112] A fitting module, configured to fit the actual production indexes, inversely obtain the fitted connectivity parameters, and further clarify the inter-well connectivity.

[0113] In one embodiment, the construction module 301 is further configured to obtain geological structure data of the fault-karst reservoir, and construct an initial inter-well connectivity model based on a plurality of inter-well connectivity units based on the geological structure data; perform integral conversion on the initial inter-well connectivity model based on a control volume and a time step to convert the initial inter-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation; perform equation simplification processing on the initial first expression to obtain a target first expression, and perform equation simplification processing on the initial second expression to obtain a target second expression; construct a target inter-well connectivity model by combining the target first and second expressions.

[0114] In one embodiment, the second calculation module is further configured to construct a first calculation formula according to the first water cut saturation S w , the second water cut saturation S wu , and the dimensionless cumulative flow rate Q V obtained cumulatively, where the first calculation formula is used to calculate a comprehensive water cut derivative corresponding between a target flow point and an upstream flow point; specifically, the first calculation formula is:

[0115]

[0116] where f’ w (*) means to solve the comprehensive water cut derivative of "*";

[0117] Obtain a third water cut saturation corresponding to the flow of oil and water from well i to well j at time t and a dimensionless cumulative flow rate cumulatively reached by the flow of oil and water from well i to well j and construct a second calculation formula based on the first calculation formula, where the second calculation formula is used to calculate a water cut reached between well i and well j at time t; specifically, the second calculation formula is:

[0118]

[0119] Among them, characterizes the dimensionless cumulative flow corresponding to the flow of oil and water from well i to well j at time t in derivative form; min{a, b} refers to taking the minimum value of a and b;

[0120] Integrate the second calculation formula to obtain the water cut reached between the two wells at the corresponding time.

[0121] In one embodiment, the construction module 301 is further configured to simplify the initial first expression according to the high-speed divergence theorem to obtain a corresponding target first expression.

[0122] In one embodiment, the construction module 301 is further configured to perform a time integration on the initial second expression, and without considering the action of the gravity term, use the rectangular method estimation theorem to obtain a target second expression adapted to the initial second expression.

[0123] A confirmation device for inter-well connectivity in an oil reservoir disclosed in the present application. First, considering the geological structure data of a fault-karst reservoir, the complex fault-karst structure is simplified into a target inter-well connectivity model based on multiple inter-well connectivity units, effectively reducing the computational complexity. Second, aiming at the actual seepage characteristics of the fault-karst reservoir, considering adding a high-speed non-Darcy seepage term to the target inter-well connectivity model, a connectivity unit material balance equation based on the fault-karst reservoir is further formed, and the dynamic simulation of the oil and water in the fault-karst reservoir is realized in a more accurate manner. Finally, taking the non-Darcy permeability coefficient as the adjustment object and the conductivity as the correction object, the conductivity is corrected, effectively performing a dynamic sensitivity analysis of the connectivity. While accurately realizing the dynamic simulation of the oil and water in the fault-karst reservoir, it makes it more in line with the actual production situation.

[0124] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. These all belong to the protection scope of the present invention.

Claims

1. A method for confirming the inter-well connectivity of a reservoir, characterized in that, the method comprises: S1. Obtain the geological structure data of the fault-karst reservoir, and construct a target inter-well connectivity model based on the geological structure data with multiple inter-well connectivity units; the target inter-well connectivity model includes multiple characteristic parameters, and the characteristic parameters include conductivity and control volume; The mathematical expression of the target inter-well connectivity model is: Among them, A ij is the interface area between control volume i and control volume j, with the unit of m 2 , k v is the permeability of the karst unit, with the unit of mD, μ is the fluid viscosity, with the unit of mPa·s, L ij is the interval distance between well point i and well point j, p i is the average pressure of well i in the oil drainage area, with the unit of MPa, p j is the average pressure of well i in the oil drainage area, with the unit of MPa, C t,i is the comprehensive compressibility of the reservoir, with the unit of MPa -1 ;, Q i is the source-sink term of node i, Q ci is the cross-flow rate from the fracture unit to the karst unit, V t is the inter-well control volume between well point i and well point j of well i and well j, with the unit of m 3 , β is the high-speed non-Darcy seepage coefficient, with the unit of m -1 , is the fluid density, with the unit of kg / m 3 , v v is the seepage velocity of the karst unit, with the unit of m / s; S2. For the actual seepage characteristics of the fault-karst reservoir, add the non-Darcy permeability coefficient to the target inter-well connectivity model, and use the non-Darcy permeability coefficient as the adjustment object and the conductivity as the correction object to correct the conductivity, so that the simulated seepage process based on the target inter-well connectivity model matches the real seepage process of the fault-karst reservoir; S3. Confirm the inter-well connectivity of the reservoir based on the corrected conductivity.

2. The method according to claim 1, characterized in that, the characteristic parameters further include control volume, and the method further comprises: S4. Perform implicit difference processing on the target inter-well connectivity model to obtain the oil-water flow rate and the fluid flow direction in each inter-well connectivity unit; S5. According to multiple inter-well flow points corresponding to the seepage process, randomly select a target flow point from the multiple inter-well flow points, and determine the upstream flow point corresponding to the target flow point according to the fluid flow direction; S6. Determine the first water saturation reached at the target flow point, the second water saturation at the upstream flow point, and the cumulative dimensionless cumulative flow rate according to the oil-water flow rate, and calculate the water cut reached between the two wells at the corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate; S7. Calculate the actual production indexes required for each single well and the block according to the calculated water cut; S8. Fit the actual production indexes, and obtain the fitted characteristic parameters through the way of inversion optimization, and perform secondary confirmation of the inter-well connectivity of the reservoir based on the fitted characteristic parameters.

3. The method according to claim 1, characterized in that, the obtaining the geological structure data of the fault-karst reservoir and constructing a target inter-well connectivity model based on the geological structure data with multiple inter-well connectivity units includes: Obtain the geological structure data of the fault-karst reservoir, and construct an initial inter-well connectivity model based on the geological structure data with multiple inter-well connectivity units; Perform integral conversion on the initial inter-well connectivity model based on the control volume and time step to convert the initial inter-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation; Perform equation simplification processing on the initial first expression to obtain a target first expression, and perform equation simplification processing on the initial second expression to obtain a target second expression; Construct a target inter-well connectivity model by combining the target first and second expressions.

4. The method according to claim 3, characterized in that, Performing equality simplification processing on the initial first expression to obtain a target first expression includes: Simplifying the initial first expression according to the high-speed divergence theorem to obtain a corresponding target first expression.

5. The method according to claim 3, wherein, Performing equality simplification processing on the initial second expression to obtain a target second expression includes: Performing time integration on the initial second expression, and without considering the action of the gravity term, using the rectangular method estimation theorem to obtain a target second expression adapted to the initial second expression.

6. The method according to claim 2, wherein, Calculating the water cut reached between two wells at a corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate includes: According to the first water saturation S w , the second water saturation S wu , and the cumulative dimensionless cumulative flow rate Q V , a first calculation formula is constructed, and the first calculation formula is used to calculate the comprehensive water cut derivative corresponding between the target flow point and the upstream flow point; wherein, the first calculation formula is specifically: where f w '(*) denotes the solution of the derivative of the comprehensive moisture content with respect to "*". Obtain the third water saturation corresponding to the flow of oil and water from well i to well j at time t and the dimensionless cumulative flow rate accumulated by the flow of oil and water from well i to well j And construct a second calculation formula based on the first calculation formula, where the second calculation formula is used to calculate the water cut reached between well i and well j at time t; wherein, the second calculation formula is specifically: Among them, represents the dimensionless cumulative flow corresponding to the flow of oil and water from well i to well j at time t in derivative form; min{a, b} means taking the minimum value of a and b; Performing integral calculation on the second calculation formula to obtain the water cut reached between two wells at a corresponding moment.

7. A device for confirming the inter-well connectivity of an oil reservoir, wherein, The device includes: A construction module, configured to obtain geological structure data of a fault-karst reservoir and construct a target inter-well connectivity model based on the geological structure data, with multiple inter-well connectivity units as the basis; the target inter-well connectivity model includes multiple characteristic parameters, and the characteristic parameters include conductivity and control volume; The mathematical expression of the target inter-well connectivity model is: Among them, A ij is the interface area between control volume i and control volume j, with the unit of m 2 , k v is the permeability of the karst unit, with the unit of mD, μ is the fluid viscosity, with the unit of mPa·s, L ij is the interval distance between well point i and well point j, p i is the average pressure of well i in the oil drainage area, with the unit of MPa, p j is the average pressure of well i in the oil drainage area, with the unit of MPa, C t,i is the comprehensive compressibility of the reservoir, with the unit of MPa -1 ;, Q i is the source-sink term of node i, Q ci is the crossflow rate from the fracture unit to the karst unit, V t is the inter-well control volume between well point i and well point j of well i and well j, with the unit of m 3 , β is the high-speed non-Darcy seepage coefficient, with the unit of m -1 , is the fluid density, with the unit of kg / m 3 , v v is the seepage velocity of the karst unit, with the unit of m / s; A correction module, configured to, in view of the actual seepage characteristics of the fault-karst reservoir, add a non-Darcy permeability coefficient to the target inter-well connectivity model, and use the non-Darcy permeability coefficient as an adjustment object and the conductivity as a correction object to perform conductivity correction, so that the simulated seepage process based on the target inter-well connectivity model matches the true seepage process of the fault-karst reservoir; A primary confirmation module, configured to confirm the inter-well connectivity of the oil reservoir based on the corrected conductivity.

8. The device according to claim 7, wherein, The device further includes: A first calculation module, configured to perform implicit difference processing on the target inter-well connectivity model to obtain the oil-water flow rate and the fluid flow direction within each inter-well connectivity unit; A selection module, configured to select a target flow point from the multiple inter-well flow points corresponding to the seepage process, and determine the upstream flow point corresponding to the target flow point according to the fluid flow direction; A second calculation module, configured to determine the first water saturation reached at the target flow point, the second water saturation at the upstream flow point, and the cumulative dimensionless cumulative flow rate according to the oil-water flow rate, and calculate the water cut reached between two wells at a corresponding moment according to the first water saturation, the second water saturation, and the dimensionless cumulative flow rate; A third calculation module, configured to calculate the actual production indexes required for each single well and the block according to the calculated water cut; A fitting module, configured to fit the actual production indexes, invert to obtain the fitted connectivity parameters, and further clarify the inter-well connectivity.

9. The device according to claim 7, wherein, The building block is also used to obtain geological structure data of the fracture-cavity reservoir, and construct an initial inter-well connectivity model based on multiple inter-well connectivity units based on the geological structure data; perform integral conversion on the initial inter-well connectivity model based on the control volume and time step to convert the initial inter-well connectivity model into a corresponding integral equation; the integral equation includes an initial first expression on the left side of the equation and an initial second expression on the right side of the equation; Perform equation simplification on the initial first expression to obtain a target first expression, and perform equation simplification on the initial second expression to obtain a target second expression; Construct a target inter-well connectivity model by combining the target first and second expressions.

10. The device according to claim 8, wherein, The second calculation module is further configured to construct a first calculation formula according to the first water saturation S w , the second water saturation S wu , and the dimensionless cumulative flow rate Q V obtained by accumulation, where the first calculation formula is used to calculate the comprehensive water cut derivative corresponding to the target flow point and the upstream flow point; wherein, the first calculation formula is specifically: Among them, f w '(*) means to solve the derivative of the comprehensive moisture content with respect to "*". Obtain the third water saturation corresponding to the flow of oil and water from well i to well j at time t and the dimensionless cumulative flow rate accumulated by the flow of oil and water from well i to well j And construct a second calculation formula based on the first calculation formula, where the second calculation formula is used to calculate the water cut reached between well i and well j at time t; wherein, the second calculation formula is specifically: Among them, represents the dimensionless cumulative flow corresponding to the flow of oil and water from well i to well j at time t in derivative form; min{a, b} refers to taking the minimum value of a and b; Perform integral calculation on the second calculation formula to obtain the water cut reached between the two wells at the corresponding moment.

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