A method and device for optimizing the pressure-bearing and plugging effect of well wall reinforcement materials

Abstract

This invention discloses a method and apparatus for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials. The method includes: establishing a formation leakage state prediction model before wellbore reinforcement construction; calculating fracture characteristics and fluid leakage characteristics at different times before construction based on the formation leakage state prediction model; establishing an analysis model for the pressure-bearing sealing effect of the wellbore reinforcement material; calculating the changes in fracture characteristics and leakage properties over time after wellbore reinforcement at different sealing locations, using the obtained leakage and fracture characteristics before construction as initial values; adjusting relevant parameters based on these changes, and calculating the optimized values ​​for the amount of wellbore reinforcement material to be added and the particle size distribution based on the required fluid leakage for sealing. This invention combines dynamic fracture deformation with dynamic material filling, thereby more realistically simulating the pressure-bearing sealing situation under actual formation conditions.

Description

Technical Field

[0001] This invention relates to the field of drilling engineering technology, specifically to a method and apparatus for optimizing the pressure-bearing and plugging effect of wellbore reinforcement materials. Background Technology

[0002] Wellbore reinforcement technology is a major means of preventing well leakage. However, the existing evaluation methods and optimization design criteria for wellbore reinforcement materials cannot meet the needs of field use, resulting in a relatively low success rate for the implementation of this technology. Therefore, it is urgent to carry out research on the evaluation and optimization design methods of the pressure-bearing sealing effect of wellbore reinforcement materials.

[0003] Existing evaluation methods for wellbore reinforcement materials primarily rely on experimental research, employing simulated plugging test devices to evaluate the sealing and pressure-bearing capacity of wellbore reinforcement materials under different fracture characteristics and simulated formation temperatures. However, because these simulated test devices are all made of steel plates, they cannot simulate the actual high temperatures and high pressures of real formations, resulting in limited experimental conditions. This makes it impossible to simulate the impact of dynamic fracture aperture changes on the pressure-bearing and plugging effect of wellbore reinforcement materials. Furthermore, during the filling process of wellbore reinforcement materials, the filtration effect of the fracture wall surface can enhance the compression effect of the fracture on the plugging layer; however, due to limitations in experimental conditions, the indoor experimental process is difficult to simulate.

[0004] Existing numerical simulation methods for the sealing effect of wellbore reinforcement materials mainly rely on particle flow models based on the discrete element method (DEM) or fracture propagation models based on the finite element method (FEM). Particle flow simulations using the DEM cannot account for fracture propagation morphology influenced by rock mechanics, while fracture propagation simulations using the FEM cannot incorporate the effects of the sealing properties of wellbore reinforcement materials. Therefore, the fracture propagation and sealing process of wellbore reinforcement materials cannot be combined, failing to realistically simulate pressure-bearing sealing under actual formation conditions. Summary of the Invention

[0005] To address the above problems, this invention provides a method and apparatus for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials, along with a computer device and a computer-readable storage medium. The optimization design method and apparatus provided by this invention fully consider the dynamic characteristics and leakage state of fractures before wellbore reinforcement construction, establish a prediction model of formation leakage state before wellbore reinforcement construction, and based on the calculation results of this model, establish an analysis model of the pressure-bearing sealing effect after wellbore reinforcement material filling, analyzing the pressure-bearing sealing effect of wellbore reinforcement materials under two processes (the front and rear ends of fracture sealing). This overcomes the deficiency of traditional wellbore reinforcement sealing effect prediction models that cannot consider the influence of material filling characteristics on fracture morphology, combining dynamic fracture deformation with dynamic material filling to more realistically simulate the pressure-bearing sealing situation under actual formation conditions.

[0006] The first objective of this invention is to provide a method for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials, comprising:

[0007] S1: Establish a prediction model for formation leakage state before wellbore reinforcement construction;

[0008] Based on the formation leakage state prediction model before wellbore reinforcement construction, the fracture characteristics and fluid leakage characteristics at different times before construction were calculated.

[0009] S2: Establish an analysis model for the pressure-bearing and plugging effect of wellbore reinforcement materials;

[0010] S3: Based on the well wall reinforcement material pressure sealing effect analysis model, and using the leakage characteristics and crack characteristics obtained in S1 before construction as the initial values, calculate the changes in crack characteristics and leakage characteristics of well wall reinforcement at different sealing locations over time.

[0011] S4: Based on the changes described in S3, adjust the relevant parameters and, in conjunction with the fluid loss required for plugging, back-calculate the amount of wellbore reinforcement material to be added and the optimized particle size distribution;

[0012] The crack characteristics include the pressure, length, and aperture within the crack, and the fluid leakage characteristics include the leakage amount at any location within the crack and the total leakage amount.

[0013] In an optional embodiment, the method for establishing the formation leakage state prediction model before wellbore reinforcement construction is as follows:

[0014] S101: Obtain basic parameters including fracture and wellbore reinforcement materials;

[0015] S102: Based on the basic parameters and the fluid leakage state prediction model of the wellbore reinforcement material under different rheological modes, establish a formation leakage state prediction model before wellbore reinforcement construction.

[0016] The method for establishing the wellbore reinforcement material pressure-bearing sealing effect analysis model is as follows:

[0017] S201: Considering the fracture characteristics, fluid leakage characteristics, fluid flow characteristics of wellbore reinforcement materials, and filling and sealing factors obtained in S102, establish a calculation model for the pressure inside the fracture after filling with wellbore reinforcement materials, so as to know the change of pressure inside the fracture over time after filling.

[0018] S202: Based on the relationship between fracture pressure and fracture aperture obtained in S201, and the continuity equation of radial flow of fluid in fracture, a calculation model for fracture morphology changes after filling with wellbore reinforcement material is established to obtain the changes in fracture length and aperture over time after filling.

[0019] S203: Based on the relationship between the concentration of the wellbore reinforcement material and the fracture aperture obtained in S202, and the fact that the injected wellbore reinforcement material conforms to the mass conservation equation, a calculation model for the particle distribution in the fracture after the wellbore reinforcement material is filled is established to obtain the concentration distribution of the wellbore reinforcement material in the fracture after filling, the sealing location, the leakage at any location, and the total leakage.

[0020] In an optional embodiment, the basic parameters include the length and aperture of natural formation fractures, the plastic viscosity, dynamic shear force and rheological characteristics of the workover fluid, the wellbore pressure and rock fracture strength parameters, and the initial concentration, maximum accumulation concentration, particle size, permeability of the plugging layer, and filtration properties of the plugging layer.

[0021] In an optional embodiment, the rheological modes of the wellbore reinforcement material include the Bingham mode and the HB mode, which respectively form the Bingham mode fluid leakage state prediction model and the HB mode fluid leakage state prediction model.

[0022] In an optional embodiment, based on the Bingham model fluid leakage state prediction model or the HB model fluid leakage state prediction model, the influence of well workover fluid leakage and fracture dynamic propagation is coupled to establish a formation leakage state prediction model before wellbore reinforcement construction.

[0023] In an optional embodiment, the filling and encapsulation factors of the wellbore reinforcement material include the concentration distribution of the wellbore reinforcement material and the sealing location;

[0024] For the flow of the leaking fluid before the wellbore reinforcement and sealing location, the rheological mode of the leaking fluid is set as a power-law flow pattern with yield value, and the flow mode conforms to the Poiseuille flow model. The pressure drop in the fracture from the fracture inlet to the sealing layer location is calculated.

[0025] For the crack sealing area, the flow pattern of the leaking fluid is set to conform to Darcy's law, and the pressure drop from the crack sealing location to the crack tip is calculated.

[0026] In an optional embodiment, the process of calculating the formation leakage state using the wellbore reinforcement construction prediction model in step S1 is as follows:

[0027] Step 1: Set the time step and total duration for the calculation;

[0028] Step 2: Set the pressure distribution within the fracture at the current moment, and calculate the fracture opening and fracture length at the current moment based on the formation leakage state prediction model before wellbore reinforcement construction;

[0029] Step 3: Based on the functional relationship between crack length and time, recalculate the pressure distribution within the crack and compare it with the set value in Step 2 to determine the pressure distribution error;

[0030] If the error meets the requirements, calculate the next time step until the crack characteristic parameters and fluid leakage characteristic parameters of the last moment of the last time step before construction are calculated.

[0031] If the error does not meet the requirements, pressure distribution correction is performed until the results of two adjacent iterations meet the error requirements.

[0032] In an optional embodiment, the method for calculating the pressure-bearing sealing effect of wellbore reinforcement materials in step S3 is as follows:

[0033] Step 1: Set the time step and total duration for the calculation;

[0034] Step 2: Use the crack and leakage characteristic parameters obtained at the last moment before construction as the initial values ​​for the well wall reinforcement material pressure sealing effect analysis model, set the sealing position, and calculate the crack and leakage characteristic parameters after filling.

[0035] Step 3: Calculate the concentration distribution and sealing location of the wellbore reinforcement material after filling based on the characteristic parameters of the cracks and leakage after filling, and compare it with the sealing location set in Step 2 to obtain the location error;

[0036] If the error is within the range, calculate the fluid leakage after reinforcement, calculate the situation of the next time step, until the leakage, total leakage and crack characteristics at any position of the crack at the last moment of the last time step after filling are obtained.

[0037] If the error is outside the acceptable range, the blocking position is corrected until the results of two adjacent iterations meet the error requirements.

[0038] In an optional embodiment, in step S4, based on the required leakage amount, the particle size, injection concentration, and plugging layer filtration coefficient are back-calculated to obtain the wellbore reinforcement material addition amount and particle size distribution optimization value.

[0039] In an optional embodiment, the particle size of the wellbore reinforcement material adopts any one of the following criteria: normal distribution, log-normal distribution, Alfred criterion, RR criterion, GS criterion, and Weiber distribution.

[0040] The second objective of this invention is to provide a device for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials, comprising:

[0041] The first model establishment and pre-construction characteristic parameter calculation module is used to establish a formation leakage state prediction model before wellbore reinforcement construction, and calculate the fracture characteristics and fluid leakage characteristics at different times before construction based on the formation leakage state prediction model before wellbore reinforcement construction.

[0042] The second model building module is used to build an analysis model of the pressure-bearing and plugging effect of well wall strengthening materials;

[0043] The enhanced characteristic parameter calculation module is used to calculate the changes in crack characteristics and leakage characteristics of the wellbore after enhancement over time, based on the wellbore reinforcement material pressure-bearing sealing effect analysis model and using the obtained leakage and crack characteristics before construction as initial values. A third objective of this invention is to provide a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements the wellbore reinforcement material pressure-bearing sealing effect optimization design method described in any of the above embodiments.

[0044] The fourth objective of this invention is to provide a computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the above-described method for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials.

[0045] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0046] The optimized design method and apparatus provided by this invention fully consider the dynamic characteristics and leakage state of fractures before wellbore reinforcement construction, establish a formation leakage state prediction model before wellbore reinforcement construction, and based on the calculation results of this model, establish an analysis model of the pressure-bearing sealing effect after wellbore reinforcement material filling, and analyze the pressure-bearing sealing effect of wellbore reinforcement material under the action of the two processes; make up for the defect of traditional wellbore reinforcement sealing effect prediction model methods that cannot consider the influence of material filling characteristics on fracture morphology, and combine the dynamic deformation of fractures with the dynamic filling of materials, so as to more realistically simulate the pressure-bearing sealing situation under the actual formation conditions. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0048] Figure 1 A flowchart illustrating the optimized design method for pressure-bearing and plugging effects of wellbore reinforcement materials, provided in an embodiment of the present invention;

[0049] Figure 2 Flowchart for calculating the leakage state prediction model before well wall reinforcement construction;

[0050] Figure 3 A model of crack propagation during wellbore reinforcement construction;

[0051] Figure 4 A model for filling wellbore reinforcement material.

[0052] Figure 5 Flowchart for the calculation of the pressure-bearing and plugging effect analysis model of well wall reinforcement materials;

[0053] Figure 6 The graph shows the changes in fracture characteristics and leakage properties over time before wellbore reinforcement.

[0054] Figure 7 A graph showing the change in total leakage at the fracture surface after wellbore reinforcement material is used for sealing.

[0055] Figure 8 A graph showing the change in crack length after wellbore reinforcement material was used for plugging.

[0056] Figure 9 A graph showing the change in leakage at the fracture surface after wellbore reinforcement material is used for sealing.

[0057] Figure 10 A graph showing the pressure distribution within the fracture after the wellbore was sealed with reinforcing material.

[0058] Figure 11 This is a graph showing the concentration distribution of the wellbore reinforcement material.

[0059] Figure 12 This invention provides a diagram of a device for optimizing the pressure-bearing and plugging effect of well wall reinforcement materials.

[0060] The attached diagram shows the markings and corresponding component names:

[0061] 101 - First model establishment and pre-construction characteristic parameter calculation module; 102 - Second model establishment module; 103 - Enhanced characteristic parameter calculation module. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are only for explaining this invention and are not intended to limit this invention.

[0063] To address the current limitations in accurately evaluating and optimizing the pressure-bearing plugging effect of wellbore reinforcement materials in real-world formation environments, this invention provides a method for optimizing the pressure-bearing plugging effect of wellbore reinforcement materials. This method comprehensively considers the influence of factors such as fluid loss within fractures, fracture propagation, fluid flow, and solid particle filling, establishing an analytical model for the pressure-bearing plugging effect of wellbore reinforcement materials. Based on optimization theory, optimization models for parameters such as particle size, injection concentration, and filtration coefficient are established. Furthermore, these models are used to evaluate the changes in cumulative leakage, fracture aperture, and fracture concentration at different plugging locations during the wellbore reinforcement material filling process. Based on leakage requirements, the method guides the optimized design of the wellbore reinforcement formulation.

[0064] Specific optimization design methods, such as Figure 1 The process shown is as follows:

[0065] S1: Establish a prediction model for formation leakage state before wellbore reinforcement construction.

[0066] The following method is used to establish it:

[0067] S101: Obtain basic parameters including fracture and wellbore reinforcement materials.

[0068] Specifically, this involves obtaining basic parameters of fracture and wellbore reinforcement materials through field data or laboratory experiments to provide initial values ​​for simulation and evaluation methods. For example, well logging data can be used to obtain the length and aperture of natural formation fractures; well workover fluid rheological tests can be used to obtain the plastic viscosity, dynamic shear force, and rheological characteristics of the workover fluid; wellbore pressure and rock fracture strength parameters can be obtained based on well history data and reservoir core rock mechanics parameter tests; and initial construction parameters such as initial material concentration, maximum accumulation concentration, material particle size, permeability of the plugging layer, and filtration loss of the plugging layer can be set through wellbore reinforcement construction.

[0069] S102: Based on the basic parameters obtained in S101 and the fluid leakage state prediction model of wellbore reinforcement material under different rheological modes, establish a formation leakage state prediction model before wellbore reinforcement construction.

[0070] The rheological modes of wellbore reinforcement materials include the Bingham mode and the HB mode, which respectively form the Bingham mode fluid leakage state prediction model and the HB mode fluid leakage state prediction model.

[0071] When the rheological mode is Bingham mode, based on the Bingham mode fluid leakage state prediction model, coupled with the influence of well workover fluid leakage and fracture dynamic propagation, a formation leakage state prediction model before wellbore reinforcement construction is established. The current fracture characteristics and fluid leakage characteristics before construction are calculated, including the propagation morphology (fracture length, fracture aperture), fracture pressure and leakage status (leakage status refers to the leakage amount at any location in the fracture and the total leakage amount).

[0072] The formula for calculating the pressure inside the crack is:

[0073]

[0074] In the formula, p(r) is the pressure inside the fracture, Δp is the formation pressure difference, and r is the radial distance from a certain location inside the fracture to the center of the wellbore. w r is the radius of the wellbore. f n is the radial distance from the fracture tip to the center of the wellbore. q The formula for calculating the crack aperture, a characteristic index for calculating pressure within a crack, is as follows:

[0075]

[0076] In the formula, w0 is the initial crack aperture, w0 = 0 for induced cracks, and w0 > 0 for natural cracks. K f This is the crack fracture strength factor.

[0077] The formula for calculating the leakage at any location within the crack is:

[0078]

[0079] In the formula, q represents the leakage at any point, Q represents the total leakage, and t represents the leakage time. C is an inverse function of crack length and leakage time. L r is the fluid loss coefficient of the workover fluid. * This is the integral value.

[0080] The formula for calculating the total leakage is:

[0081]

[0082] In the formula, w0 is the initial crack aperture, and r f K is the radial distance from the fracture tip to the center of the wellbore (i.e., the fracture length). f n is the crack fracture strength factor. q The characteristic index is calculated for the pressure within the crack.

[0083] The formula for calculating crack length is:

[0084]

[0085]

[0086]

[0087]

[0088] In the formula, τ y For the dynamic shear force of the workover fluid, μp C represents the plastic viscosity of the workover fluid. L F1, F2, and F3 are the integral parameters of the fracture dynamic length calculation formula, respectively, where t is the workover fluid filtration coefficient. a (r*) is the inverse function of the leakage time t and the integral value r*.

[0089] When the rheological mode is HB mode, based on the HB mode fluid leakage state prediction model, coupled with the influence of well workover fluid leakage and fracture dynamic propagation, a formation leakage state prediction model before wellbore reinforcement construction is established. The current fracture characteristics and fluid leakage characteristics before construction are calculated, including the propagation morphology (fracture length, fracture aperture), fracture pressure and leakage situation (leakage at any location in the fracture, total leakage).

[0090] The formula for calculating the pressure inside the crack in this model is:

[0091]

[0092] In the formula, Δp is the formation pressure difference, m and k are the characteristic coefficients of the workover fluid rheological parameters, Q is the total leakage, and r f τ is the crack length, w is the crack aperture, and τ is the crack length. y Let denoted as the well workover fluid shear force, u as the leakage velocity at a certain location within the fracture at a certain moment, and r* as the integral value.

[0093] The formula for calculating crack aperture is:

[0094]

[0095] In the formula, w0 is the initial crack aperture, p(r) is the expression for the pressure distribution within the crack, and K... f This is the crack fracture strength factor.

[0096] The formula for calculating crack length is:

[0097]

[0098] The leakage amount is calculated based on the crack length, opening and pressure inside the crack. Substituting these values ​​into formulas (3) and (4) will yield the values ​​of total leakage and transient leakage.

[0099] Then, based on the formation leakage state prediction model established in S1 before wellbore reinforcement construction, the fracture characteristics (including fracture length, fracture aperture, and fracture pressure) and fluid leakage characteristics (transient leakage at any location within the fracture and total leakage) at different times before construction are calculated.

[0100] Specifically, the process involves using numerical methods to determine the leakage model before wellbore reinforcement construction. The calculation process for the leakage state prediction model before wellbore reinforcement construction is as follows: Figure 2As shown.

[0101] Depend on Figure 2 It is known that before the calculation, the time step and total duration of the calculation are set. Based on the basic data collected in step S101 and the model established in step S102, the pressure distribution within the crack at the current moment is assumed, the crack aperture at the current moment is calculated, and then the crack length at the current moment is calculated. Based on the functional relationship between crack length and time, the pressure distribution within the crack is recalculated, and the new pressure distribution is compared with the assumed value to obtain the pressure distribution error. If the error meets the requirements, the next time step is calculated until the leakage characteristics and crack characteristics at the last moment of the last time step before construction are calculated, including crack aperture, crack length, and total leakage. If the error does not meet the requirements, the pressure distribution is corrected, and the crack characteristic parameters are recalculated iteratively using the latest calculated pressure distribution within the crack until the results of two adjacent iterations meet the error requirements. After the pressure calculation within the crack meets the error, the crack aperture, length, and total leakage at that moment can be calculated.

[0102] S2: Establish an analysis model for the pressure-bearing and plugging effect of wellbore reinforcement materials.

[0103] The following methods are specifically adopted:

[0104] S201: Considering the fracture characteristics, fluid leakage characteristics, fluid flow characteristics of wellbore reinforcement materials, and filling and sealing factors obtained in S102, establish a calculation model for the pressure inside the fracture after filling with wellbore reinforcement materials, so as to know the change of pressure inside the fracture over time after filling.

[0105] Specifically, a pressure calculation model for the fracture after wellbore reinforcement material filling is established, taking into account factors such as fluid loss within the fracture, fracture propagation, fluid flow, and wellbore reinforcement material filling and sealing. The filling and sealing factors of the wellbore reinforcement material include the concentration distribution of the material and the sealing location.

[0106] Assuming that during wellbore reinforcement, the cracks expand outward in a ring-like pattern, the expansion model is as follows: Figure 3 As shown.

[0107] Depend on Figure 3 It can be seen that the fracture has an initial aperture w0, and the established model is a transient model. As the injection time increases, the fracture aperture and length continuously expand. The schematic diagram after the fracture is filled with wellbore reinforcement material is shown in the figure. Figure 4 As shown.

[0108] For the flow before the wellbore reinforcement sealing location, assuming the rheological mode of the leaking fluid is a power-law flow pattern with a yield value, and the flow mode conforms to the Poiseuille flow model, then the formula for calculating the pressure drop within the fracture from the fracture inlet to the sealing layer location is:

[0109]

[0110] In the formula, k and m are the characteristic coefficients of the workover fluid rheological parameters under the power-law mode with yield value, and τ y The dynamic shear force of the workover fluid under the power-law mode with yield value, w is the fracture aperture, r is the radial distance from a certain position in the fracture to the center of the wellbore, q is the leakage rate, and r p This is the radial distance from the sealing location to the center of the wellbore.

[0111] For the front end of the crack sealing region, assuming the flow pattern conforms to Darcy's law, the formula for calculating the pressure drop from the crack sealing location to the crack tip is:

[0112]

[0113]

[0114] In the formula, μ f k is the viscosity of the workover fluid filtrate within the fracture sealing layer. p q represents the permeability of the crack sealing layer. f Let w be the flow velocity of the fluid within the sealing layer, w be the fracture aperture, r be the radial distance from a certain location within the fracture to the center of the wellbore, and c be the flow velocity of the fluid within the sealing layer. max This represents the maximum accumulation concentration of the sealing material.

[0115] S202: Based on the relationship between fracture pressure and fracture aperture obtained in S201 (such as formulas 12, 13, and 14) and the continuity equation of radial flow of fluid in the fracture, a calculation model for fracture morphology changes after filling with well wall reinforcement material is established to obtain the changes in fracture length and aperture over time after filling.

[0116] The equation for calculating crack morphology changes is:

[0117]

[0118] In the formula, w0 is the initial crack aperture, p is the pressure inside the crack, and K f This is the crack fracture strength factor.

[0119] The continuity equation for radial flow is:

[0120]

[0121] In the formula, C L The filtration loss coefficient is... It is the inverse function of crack length and time.

[0122] S203: The changes in wellbore reinforcement material concentration and fracture aperture obtained in S202 (e.g., c in Formula 14) maxThe relationship between the wellbore reinforcement material and the injected wellbore reinforcement material conforms to the mass conservation equation. A calculation model for particle distribution in the fracture after filling with wellbore reinforcement material (i.e., a calculation model for plugging agent concentration) is established. Based on the particle distribution in the fracture, the concentration distribution of wellbore reinforcement material in the fracture after filling, the plugging location, the leakage at any location, and the total leakage are obtained.

[0123] The distribution equation of wellbore reinforcement material concentration along the radial distance within the fracture at the rear end of the fracture plugging layer is as follows:

[0124]

[0125] c(r) = c max ,r p ≤r<r f (18);

[0126] The mass conservation equation for wellbore reinforcement materials is:

[0127]

[0128] In the formula, c0 is the designed wellbore reinforcement material injection concentration, c max q represents the maximum concentration of the sealing layer formed after the wellbore reinforcement material is filled, and q represents the leakage at a certain time and location.

[0129] At the same time, based on the model assumptions, it is also necessary to determine the calculation boundary conditions such as the concentration of the sealing agent, the crack aperture, and the pressure distribution within the crack.

[0130] The model's concentration boundary conditions are as follows: the initial concentration is at the fracture inlet; the fracture aperture boundary conditions are as follows: the initial fracture aperture is at both the fracture inlet and fracture tip; the pressure at the fracture inlet is the wellbore pressure, and the pressure at the fracture tip is the formation pore pressure. The specific boundary conditions are expressed as follows:

[0131] r p (t)=r w

[0132] r f (t)=r w

[0133] p(r w ) = p w

[0134] p(r f ) = p p

[0135] c(r w )=c0 (20);

[0136] In the formula, P p P is the formation pore pressure. wr is the wellbore pressure. w Let c be the wellbore radius and c0 be the initial concentration.

[0137] S3: Based on the well wall reinforcement material pressure sealing effect analysis model established in S2, and using the leakage characteristics and crack characteristics obtained in S1 before construction as the initial values ​​for the pressure sealing effect analysis model, calculate the changes in crack characteristics and leakage characteristics of well wall reinforcement at different sealing locations over time.

[0138] Specifically, the numerical solution method is used to determine the calculation process of the analysis model for the pressure-bearing and sealing effect of well wall reinforcement materials.

[0139] Depend on Figure 5 As can be seen from the calculation process, before the calculation, the time step and total duration are first set. The leakage characteristic parameters and fracture characteristic parameters calculated in S1 are used as the initial values ​​(i.e., as initial parameters) for the pressure-bearing sealing effect analysis model. The filling position of the wellbore reinforcement material (i.e., the sealing position) is assumed. Based on the fracture pressure calculation model (such as formulas 12, 13, and 14) and fracture morphology change model (such as formulas 15 and 16) in the effect analysis model, the fracture pressure, leakage and total leakage (such as formulas 3 and 4), fracture aperture and fracture length are calculated. Then, based on the fracture characteristics and leakage parameters, the wellbore reinforcement material concentration distribution (i.e., sealing concentration) and sealing position are calculated based on the particle distribution calculation model in the fracture after filling (such as formulas 17 and 18). The calculated sealing position is compared with the assumed value. If the error is within the error range, the leakage is calculated, and all values ​​are used as initial values ​​to calculate the situation of the next time step until the leakage at any position of the crack, the total leakage, and the crack characteristics are obtained at the last moment of the last time step after filling. If the error does not meet the requirements, the calculated crack sealing position is used as the initial value to correct the sealing position, and the parameters at that moment are recalculated iteratively until the error meets the requirements.

[0140] S4: Based on the changes in crack characteristics and leakage characteristics of well wall reinforcement at different plugging locations as described in S3 over time, adjust the relevant parameters, and combine the fluid leakage required for plugging to back-calculate the addition amount and particle size distribution optimization value of well wall reinforcement material.

[0141] Specifically, based on the required leakage rate, the particle size, injection concentration, and filtration coefficient are calculated to obtain the amount of wellbore reinforcement material to be added and the particle size distribution.

[0142] First, the leakage rate and fracture aperture characteristics before wellbore reinforcement are calculated. Then, the effects of the amount of existing wellbore reinforcement material, particle size, and filtration coefficient of different particle size distributions on the leakage rate after wellbore reinforcement are calculated. Based on the actual leakage reduction requirements, the optimal solution satisfying the following equation is obtained:

[0143] ① After the well wall reinforcement construction, the leakage was minimized;

[0144] ② The concentration of the wellbore reinforcement material used is the lowest;

[0145] ③ The indoor experimental test showed that the filter loss coefficient of the well wall reinforcement material plugging layer was the lowest;

[0146] ④ The particle size of the wellbore reinforcement material is determined by the normal distribution criterion, log-normal distribution criterion, Alfred criterion, RR criterion, GS criterion, or Weiber distribution.

[0147] The calculation formulas for various particle size distribution models are as follows:

[0148] The formula for calculating the Weiber distribution model is as follows:

[0149]

[0150] In the formula, d is the particle size, and k w λ is the shape factor, λ is the scaling factor, and e is the natural constant.

[0151] The calculation formula for the Gaudin-Schuhmann (GS) model is as follows:

[0152]

[0153] In the formula, y is the cumulative mass fraction of particles smaller than particle size d, and d L This represents the maximum particle size.

[0154] The Alfred model is an improvement on the Gaudin-Schuhmann model, and its calculation formula is as follows:

[0155]

[0156] In the formula, d S Let n be the minimum particle size of the particulate system, and n be a dimensionless model parameter.

[0157] The calculation formula for the Rosin-Rammler (RR) model is as follows:

[0158]

[0159] In the formula, d is any particle size, R is the cumulative mass fraction of particles larger than d, and d e The characteristic particle size is the particle size corresponding to R = 0.368, and n is a model parameter, which is dimensionless.

[0160] The formula for calculating the cumulative normal distribution model is as follows:

[0161]

[0162] In the formula, F is the cumulative mass fraction of particles not greater than particle size x, μ is the mean particle size, σ is the standard deviation of particle size, and x is the arbitrary particle size to be solved.

[0163] The formula for calculating the log-cumulative normal distribution model is as follows:

[0164]

[0165] Based on the available particle size range of the sealing material on site, different particle size characteristic parameters, different dosages, and indoor experimental tests were conducted to measure the filtration coefficient of the sealing layer under various conditions. The initial values ​​for the well wall reinforcement material pressure sealing effect analysis model in step S2 were obtained. The leakage rate under each condition was analyzed to determine whether it met the requirements. Based on the optimal solution that satisfies the above equation, the dosage and particle size distribution of the well wall reinforcement material were obtained.

[0166] The following are specific examples.

[0167] Assuming that the basic parameters of the fracture and wellbore reinforcement materials are obtained through field data or laboratory experiments, providing initial values ​​for the simulation evaluation method, and the well workover fluid rheological mode is the HB mode, as shown in Table 1.

[0168] Table 1 Simulation parameters before wellbore reinforcement construction

[0169]

[0170]

[0171] Based on the parameters in Table 1, the crack characteristics and leakage characteristics before wellbore reinforcement construction can be calculated, such as... Figure 6 The figure shows the changes in fracture characteristics and leakage properties over time before wellbore reinforcement.

[0172] according to Figure 6 Using the calculated crack and leakage characteristics as initial values, the pressure-bearing sealing effect of the wellbore reinforcement material can be calculated. The basic parameters of the simulation are shown in Table 2.

[0173] Table 2 Simulation parameters of wellbore reinforcement materials

[0174] parameter numerical values Crack length 0.1m Fracture strength factor <![CDATA[2MPa·m 0.5 ]]> Initial crack aperture 500μm pressure difference 5MPa Dynamic shear force 5Pa rheological characteristic coefficient m 0.5 rheological characteristic coefficient k 0.6 Pa·s Filtration coefficient of sealing layer <![CDATA[1.5×10 -6 m·s -0.5 ]]> Initial wellbore reinforcement material concentration 0.1 Maximum filling concentration of wellbore reinforcement material 0.7 Permeability of sealing layer 10D

[0175] Based on the data in Table 2, the fracture characteristics and leakage situation after wellbore reinforcement can be calculated, such as... Figure 7 , 8 Figures 9, 10, and 11 show the changes in total leakage at the fracture surface, fracture length, leakage at the fracture surface, pressure distribution within the fracture, and concentration distribution of the wellbore reinforcement material after sealing with wellbore reinforcement material, respectively.

[0176] according to Figure 7 , 8 The results of 9, 10, and 11 can be used to adjust relevant parameters and calculate the influence of different wellbore reinforcement material characteristics on leakage characteristics, as shown in Table 3.

[0177] Table 3. Influence of Wellbore Reinforcing Material Properties on Leakage Characteristics

[0178]

[0179] According to the optimization design method, the leakage rate should be reduced to 0.2m after wellbore reinforcement. 3 Therefore, the optimal design method for wellbore reinforcement materials is the normal distribution criterion, with an addition amount of 15%, and the mean of the matching criterion is 400 μm and the variance is 200 μm.

[0180] The embodiments of this invention fully consider the dynamic characteristics and leakage state of the cracks before wellbore reinforcement construction, and based on the calculation results of the model, establish a calculation model for the leakage characteristics after wellbore reinforcement material filling, and analyze the pressure-bearing sealing effect of wellbore reinforcement material under the action of the two processes; make up for the defect of traditional wellbore reinforcement sealing effect prediction model methods that cannot consider the influence of material filling characteristics on crack morphology, and combine crack dynamic deformation with material dynamic filling.

[0181] Example 2:

[0182] This invention provides a device, which can be referred to in correspondence with the above-described method for optimizing the pressure-bearing and plugging effect of well wall reinforcement materials.

[0183] A device for optimizing the pressure-bearing and plugging effect of well wall reinforcement materials, such as Figure 12 As shown, it includes:

[0184] The first model establishment and pre-construction characteristic parameter calculation module 101 is used to establish a formation leakage state prediction model before wellbore reinforcement construction, and calculate the fracture characteristics and fluid leakage characteristics at different times before construction based on the formation leakage state prediction model before wellbore reinforcement construction.

[0185] The second model building module 102 is used to build an analysis model of the pressure-bearing and plugging effect of well wall strengthening materials;

[0186] The enhanced characteristic parameter calculation module 103 is used to calculate the changes in crack characteristics and leakage characteristics of the well wall after enhancement over time based on the well wall reinforcement material pressure sealing effect analysis model and the leakage and crack characteristics obtained before construction as the initial values.

[0187] Example 3:

[0188] This invention provides a computer device, which can be referred to in conjunction with the above-described method for optimizing the pressure-bearing and plugging effect of well wall reinforcement materials.

[0189] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it implements a method for optimizing the pressure-bearing and plugging effect of wellbore reinforcement materials as described in Embodiment 1.

[0190] Example 4:

[0191] This invention provides a computer-readable storage medium, which can be referred to in conjunction with the above-described method for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials.

[0192] A computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements a method for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials as described in Example 1.

[0193] All processes and methods not mentioned in this invention are known techniques or obtained through known techniques, and will not be described in detail here.

[0194] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD / ROM, optical storage, etc.) containing computer-usable program code.

[0195] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (devices), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0196] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0197] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0198] The above description is merely a specific embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any substitution of equivalent components or equivalent changes and modifications made within the scope of protection of this patent should still fall within the scope of this patent. Furthermore, the technical features, technical features and technical inventions, and technical inventions in this invention can be freely combined and used.

Claims

1. A method for optimizing the pressure-bearing sealing effect of wellbore reinforcing materials, characterized in that, include S1: Establish a prediction model for formation leakage state before wellbore reinforcement construction; Based on the formation leakage state prediction model before wellbore reinforcement construction, the fracture characteristics and fluid leakage characteristics at different times before construction were calculated. S2: Establish an analysis model for the pressure-bearing and plugging effect of wellbore reinforcement materials; S3: Based on the well wall reinforcement material pressure sealing effect analysis model, and using the fluid leakage characteristics and crack characteristics obtained in S1 before construction as the initial values ​​for calculation, calculate the changes in crack characteristics and fluid leakage characteristics of the well wall after reinforcement at different sealing locations over time. S4: Based on the changes described in S3, adjust the relevant parameters and, in conjunction with the fluid loss required for plugging, back-calculate the amount of wellbore reinforcement material to be added and the optimized particle size distribution; The crack characteristics include the pressure, length, and aperture within the crack, and the fluid leakage characteristics include the leakage amount at any location within the crack and the total leakage amount. The method for establishing the formation leakage state prediction model before wellbore reinforcement construction is as follows: S101: Obtain basic parameters including fracture and wellbore reinforcement materials; S102: Based on the basic parameters and the fluid leakage state prediction model of the wellbore reinforcement material under different rheological modes, establish the formation leakage state prediction model before wellbore reinforcement construction, and calculate the fracture characteristics and fluid leakage characteristics at different times before construction. The method for establishing the wellbore reinforcement material pressure-bearing sealing effect analysis model is as follows: S201: Considering the fracture characteristics, fluid leakage characteristics, fluid flow characteristics of wellbore reinforcement materials, and filling and sealing factors obtained in S102, establish a calculation model for the pressure inside the fracture after filling with wellbore reinforcement materials, so as to know the change of pressure inside the fracture over time after filling. S202: Based on the pressure change over time in the fracture after filling obtained in S201, and combined with the continuity equation of the radial flow of fluid in the fracture, a calculation model for the fracture morphology change after filling with well wall reinforcement material is established to obtain the changes in fracture length and aperture over time after filling. S203: Based on the changes in fracture length and aperture over time obtained in S202 and the fact that the injected wellbore reinforcement material conforms to the mass conservation equation, a calculation model for particle distribution in the fracture after filling with wellbore reinforcement material is established to obtain the concentration distribution of wellbore reinforcement material in the fracture after filling, the sealing location, the leakage at any location, and the total leakage. The process of calculating the formation leakage state using the wellbore reinforcement construction pre-construction prediction model in step S1 is as follows: Step 1: Set the time step and total duration for the calculation; Step 2: Set the pressure distribution within the fracture at the current moment, and calculate the fracture opening and fracture length at the current moment based on the formation leakage state prediction model before wellbore reinforcement construction; Step 3: Based on the functional relationship between crack length and time, recalculate the pressure distribution within the crack and compare it with the set value in Step 2 to determine the pressure distribution error; If the error meets the requirements, calculate the next time step until the crack characteristics and fluid leakage characteristics of the last moment of the last time step before construction are calculated. If the error does not meet the requirements, pressure distribution correction is performed until the calculation results of two adjacent iterations meet the error requirements. In step S3, the calculation method using the wellbore reinforcement material pressure-bearing sealing effect analysis model is as follows: Step 1: Set the time step and total duration for the calculation; Step 2: Use the crack characteristics and fluid leakage characteristics obtained at the last moment before construction as the initial values ​​for the well wall reinforcement material pressure sealing effect analysis model, set the sealing position, and calculate the crack characteristics and fluid leakage characteristics after filling. Step 3: Calculate the concentration distribution of the reinforcing material on the wellbore after filling and the sealing location based on the characteristics of the fractures and fluid leakage after filling. Compare this with the sealing location set in Step 2 to determine the location error. If the error is within the range, calculate the fluid leakage after filling, calculate the situation of the next time step, until the leakage, total leakage and crack characteristics at any position in the crack at the last moment of the last time step after filling are obtained. If the error is outside the acceptable range, the blocking position is corrected until the results of two adjacent iterations meet the error requirements.

2. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 1, characterized in that, The basic parameters include the length and aperture of natural formation fractures, the plastic viscosity, dynamic shear force and rheological characteristics of the workover fluid, the wellbore pressure and rock fracture strength parameters, and the initial concentration, maximum accumulation concentration, particle size, permeability of the wellbore reinforcement material, and filtration properties of the wellbore reinforcement material.

3. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 1, characterized in that, The rheological modes of wellbore reinforcement materials include the Bingham mode and the HB mode, which respectively form the Bingham mode fluid leakage state prediction model and the HB mode fluid leakage state prediction model.

4. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 3, characterized in that, Based on the Bingham model fluid leakage state prediction model or the HB model fluid leakage state prediction model, and coupled with the effects of workover fluid leakage and fracture dynamic propagation, a formation leakage state prediction model is established before wellbore reinforcement construction.

5. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 1, characterized in that, The factors influencing the filling and plugging of the wellbore reinforcement material include the concentration distribution of the wellbore reinforcement material and the plugging location; For the flow of the leaking fluid before the wellbore reinforcement and sealing location, the rheological mode of the leaking fluid is set as a power-law flow pattern with yield value, and the flow mode conforms to the Poiseuille flow model. The pressure drop in the fracture from the fracture inlet to the sealing location is calculated. For the crack sealing area, the flow pattern of the leaking fluid is set to conform to Darcy's law, and the pressure drop from the crack sealing location to the crack tip is calculated.

6. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 1, characterized in that, In step S4, based on the fluid loss required for plugging, the particle size, injection concentration, and plugging layer filtration coefficient are calculated to obtain the optimal values ​​for the amount of wellbore reinforcement material to be added and the particle size distribution.

7. The method for optimizing the pressure-bearing sealing effect of wellbore reinforcement materials according to claim 6, characterized in that, The particle size of the wellbore reinforcement material is determined by any one of the following criteria: normal distribution, log-normal distribution, Alfred criterion, RR criterion, GS criterion, or Weiber distribution.

8. An apparatus for implementing the optimized design method for pressure-bearing sealing effect of wellbore reinforcing materials as described in any one of claims 1 to 7, characterized in that, include: The first model establishment and pre-construction characteristic parameter calculation module is used to establish a formation leakage state prediction model before wellbore reinforcement construction, and calculate the fracture characteristics and fluid leakage characteristics at different times before construction based on the formation leakage state prediction model before wellbore reinforcement construction. The second model building module is used to build an analysis model of the pressure-bearing and plugging effect of well wall strengthening materials; The enhanced characteristic parameter calculation module is used to calculate the changes in the crack characteristics and fluid leakage characteristics of the well wall after enhancement over time based on the well wall reinforcement material pressure sealing effect analysis model and the fluid leakage characteristics and crack characteristics obtained before construction as the initial values.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for optimizing the pressure-bearing and plugging effect of wellbore reinforcing materials as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed by a processor, implements the method for optimizing the pressure-bearing and plugging effect of wellbore reinforcement materials as described in any one of claims 1 to 7.

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