Coiled tubing eccentric annulus sand washing construction displacement decision-making method and system

Abstract

The invention provides a coiled tubing eccentric annulus sand washing construction displacement decision-making method and system.The method comprises the steps that an eccentric annulus solid-liquid two-phase flowing space geometric model is established according to sand washing operation equipment parameters, and a coiled tubing eccentric annulus solid-liquid two-phase flowing space grid system is formed through grid system numerical processing; the sand washing process of the coiled tubing under the condition that proppant particles with different masses are preset under different displacement settings is simulated through a fluid mechanics calculation platform, multi-aspect stress data of the proppant particles are analyzed, the critical condition of motion of the proppant particles is determined, and the moving proppant particles are determined; further representing the motion incidence rate of the proppant particles according to the mass distribution of the moving proppant particles, and analyzing the motion incidence rate distribution conditions of the proppant particles corresponding to different sand washing displacements so as to decide the target displacement. By the adoption of the scheme, the problems that influence factors are not considered comprehensively and the sand washing effect is poor in the prior art can be solved, and reliable guidance is provided for high-quality implementation of coiled tubing sand washing operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil and gas sand washing process optimization, and particularly relates to a continuous tubing eccentric annular sand washing construction discharge decision method and system, which can be used for continuous tubing sand washing engineering after large-scale hydraulic fracturing of horizontal wells in tight sandstone, shale and other unconventional oil and gas reservoirs and in the production process. BACKGROUND

[0002] After large-scale hydraulic fracturing of horizontal wells in tight sandstone, shale and other unconventional oil and gas reservoirs and in the production process, it is usually necessary to treat the proppant particles retained in the wellbore due to various reasons to maximize the recovery of oil and gas production channels and ensure the subsequent production, testing and secondary development of horizontal wells. The continuous tubing sand washing process is currently the main means to remove the proppant particles retained in the wellbore, and how to use the continuous tubing to efficiently remove the proppant particles retained in the wellbore and ensure the smoothness of the production operation channel of the horizontal well becomes an important link in the economic and efficient exploitation of tight sandstone, shale and other unconventional oil and gas reservoirs.

[0003] At present, the sand washing operation of the continuous tubing is usually determined according to the engineering experience, and the existing theoretical calculation method is influenced by the incomplete consideration of the stress analysis of the proppant particles and the accumulation characteristics, which often leads to low sand washing efficiency and poor sand washing effect in the actual construction process. Therefore, it is urgent to systematically analyze the solid-liquid two-phase flow in the eccentric annular space of the horizontal well continuous tubing.

[0004] The information disclosed in the background section of this application is only intended to deepen the understanding of the general background of the application and should not be considered as recognition or in any form as suggesting that this information constitutes prior art known to those skilled in the art. SUMMARY

[0005] To solve the above problems, the present application provides a continuous tubing eccentric annular sand washing construction discharge decision method, which can overcome the problem of incomplete consideration of influencing factors and poor sand washing effect in the prior art, and provide reliable guidance for high-quality implementation of continuous tubing sand washing operation. By establishing a solid-liquid two-phase flow space geometry model of the eccentric annular space and using a grid system for numerical processing to form a continuous tubing eccentric annular solid-liquid two-phase flow space grid system, a calculation platform simulates the continuous tubing sand washing process under different discharge settings with different mass proppant particles, analyzes the multi-aspect stress data of the proppant particles to determine the critical conditions of the proppant particle movement, and determines the moving proppant particles. Further, the mass distribution of the moving proppant particles is used to represent the occurrence rate of the proppant particle movement, and the target discharge is decided based on the analysis. Preferably, in one embodiment, the method comprises:

[0006] Step S10: A continuous tubing eccentric annulus solid-liquid two-phase flow space geometric model is established according to the equipment parameters of the sand washing operation, and a continuous tubing eccentric annulus solid-liquid two-phase flow space grid system is formed by using a grid processing system to numerically establish the model;

[0007] Step S20: Based on the continuous tubing eccentric annulus solid-liquid two-phase flow space grid system, the continuous tubing sand washing process under the condition of presetting different mass of proppant particles under different displacement settings is simulated through a fluid mechanics calculation platform;

[0008] Step S30: The critical condition of the proppant particles in the continuous tubing eccentric annulus to move is determined based on the comprehensive stress condition of the proppant particles, and the proppant particles that meet the critical condition are determined as moving proppant particles;

[0009] Step S40: The movement occurrence rate of the proppant particles is characterized according to the mass distribution of the moving proppant particles, which is used as an index of the sand washing effect of the continuous tubing sand washing operation; and the target displacement that meets the operation requirements is determined according to the distribution of the movement occurrence rate of the proppant particles corresponding to different sand washing displacements.

[0010] In an optional embodiment, in the step S10, a continuous tubing eccentric annulus solid-liquid two-phase flow space geometric model matched with the sand washing operation is established through a three-dimensional drawing system according to the casing inner diameter data and the continuous tubing outer diameter data.

[0011] Further, in an embodiment, in the step S10, the continuous tubing eccentric annulus solid-liquid two-phase flow space geometric model is divided into grids in the grid processing system to form a continuous tubing eccentric annulus solid-liquid two-phase flow space grid system for numerical simulation;

[0012] Preferably, in an embodiment, in the step S20, the following steps are included:

[0013] When simulating the continuous tubing sand washing process under the condition of presetting different mass of proppant particles, the continuous tubing eccentric annulus solid-liquid two-phase flow grid simulation operation system is imported into the fluid mechanics calculation platform, the discrete element method is used to model and solve the proppant particles, and the initial conditions and boundary conditions are set to simulate the continuous tubing sand washing process under the condition of presetting a certain mass of proppant particles in the continuous tubing eccentric annulus of the horizontal well.

[0014] In an embodiment, in the step S20, a liquid phase turbulent motion equation of the solid-liquid two-phase flow is established, and the Realizable k-ε equation is used to characterize the liquid phase turbulent motion of the solid-liquid two-phase flow as follows:

[0015]

[0016] In the formula, ρf The density of the flushing fluid is expressed in kg / m³. 3 ;u i The velocity is expressed in m / s; μ represents the dynamic viscosity of the sand-fluid, in Pa·s; μ t G represents the turbulent viscosity coefficient; b This represents the turbulent kinetic energy caused by buoyancy, expressed in kg / (m·s). 3 );G k This represents the turbulent kinetic energy caused by the average velocity gradient, in kg / (m·s). 3 );Y M σ represents the contribution of compressible turbulent pulsating expansion to the total dissipation rate; k represents the turbulent kinetic energy, J; ε represents the turbulent kinetic energy dissipation rate, J / s; σ k σ represents the Prandtl number corresponding to the turbulent kinetic energy k; ε The Prandtl number represents the turbulent kinetic energy dissipation rate ε; E represents the modulus of the mean strain rate tensor; S ij C1, C2, and C3 represent intermediate parameters; C1, C2, and C3 all represent operational coefficients, which are constants.

[0017] Furthermore, in one embodiment, in step S20, corresponding initial conditions and boundary conditions are set, and the gravity, buoyancy, drag force and lifting force acting on the proppant particles are calculated separately based on them, so as to perform dynamic analysis of the sand flushing process of coiled tubing.

[0018] Wherein, the gravity F acting on the proppant particles is expressed by the following formula. G Perform the calculation:

[0019]

[0020] The buoyancy F acting on the proppant particles is expressed by the following formula. B Perform the calculation:

[0021]

[0022] The drag force F acting on the proppant particles is given by the following formula. D Perform the calculation:

[0023]

[0024] The lifting force F acting on the proppant particles is given by the following formula. L Perform the calculation:

[0025]

[0026] In the formula, d p The diameter of the proppant particles is expressed in meters (m); ρ p This indicates the density of the proppant particles, in kg / m³. 3g represents gravitational acceleration; C D Re represents the drag coefficient; p Represents the particle Reynolds number; u f The velocity of the flushing fluid is expressed in m / s; C L This represents the lift factor.

[0027] In a preferred embodiment, in step S20, the cohesive force F acting on the supporting particles is further calculated using the following formula. A Perform the calculation:

[0028]

[0029] In the formula, δ represents the thickness of the liquid film on the particle surface, in meters (m); d p The diameter of the proppant particles is expressed in meters (m).

[0030] Furthermore, in one embodiment, step S20 also considers the additional mass force F caused by the influence of the proppant particles on concealment according to the following formula. M Perform the calculation:

[0031]

[0032] In the formula: α M ξ represents the area coefficient related to the additional mass force caused by concealment; ξ represents concealment, which is dimensionless. ρ represents the average diameter of the retained proppant particles, in meters; Δ represents the vertical distance between the lowest point of the proppant particle and the contact point with the downstream proppant particle, in meters; p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; d p The diameter of the proppant particles is expressed in meters (m); ρ f The density of the flushing fluid is expressed in kg / m³. 3 .

[0033] Optionally, in one embodiment, in step S30, the critical condition for the proppant particles in the eccentric annulus of the coiled tubing to reach motion is determined as follows:

[0034] 0.5d p (F B cosθ+F L cosθ+F D sinθ)≥0.5d p (F M sinθ+F G cosθ+2F A sinθcosθ)

[0035] In the formula, F G F represents the gravity acting on the proppant particles.B F represents the buoyancy force acting on the proppant particles; D F represents the drag force acting on the proppant particles. L F represents the lifting force acting on the proppant particles; A F represents the cohesive force acting on the supporting particles; M θ represents the additional mass force caused by the concealment effect; θ represents the angle of packing of the proppant particles, in °.

[0036] Furthermore, in one embodiment, in step S40, after calculating the proppant particle movement rate in the eccentric annulus of the coiled tubing under different sand flushing operation displacements, a curve showing the change in proppant particle movement rate with the sand flushing operation displacement is plotted; and then the target displacement is determined based on the curve distribution.

[0037] Based on other aspects of the methods described in any one or more of the foregoing embodiments, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more of the foregoing embodiments.

[0038] Based on the application aspects of the methods described in any one or more of the above embodiments, the present invention also provides a continuous tubing eccentric annulus sand flushing construction displacement decision system, which executes the methods described in any one or more of the above embodiments.

[0039] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0041] Figure 1 This is a flowchart illustrating the displacement decision method for eccentric annular sand flushing construction of coiled tubing provided in an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the geometric model of the solid-liquid two-phase flow space in the eccentric annulus of a horizontal well coiled tubing according to an embodiment of the present invention.

[0043] Figure 3 This invention relates to a spatial grid system for numerical simulation of solid-liquid two-phase flow in a horizontal well coiled tubing eccentric annulus.

[0044] Figure 4This is a schematic diagram of proppant particles pre-placed at the bottom of a horizontal well casing in an embodiment of the present invention;

[0045] Figure 5 This is a schematic diagram of the force analysis of proppant particles in a certain shape of accumulation in an embodiment of the present invention;

[0046] Figure 6 This is the simulation result of sand flushing in the eccentric annulus of a horizontal well with a displacement of 500 L / min in this embodiment of the invention;

[0047] Figure 7 This is a curve showing the change in proppant particle movement rate with sand flushing discharge rate in an embodiment of the present invention;

[0048] Figure 8 This is a schematic diagram of the displacement decision system for eccentric annular sand flushing construction of coiled tubing provided in an embodiment of the present invention. Detailed Implementation

[0049] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0050] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0051] Computer equipment includes user equipment and network equipment. User equipment or clients include, but are not limited to, computers, smartphones, and PDAs (Personal Digital Assistants); network equipment includes, but is not limited to, a single network server, a server group consisting of multiple network servers, or a cloud based on cloud computing consisting of a large number of computers or network servers. Computer equipment can operate independently to implement this invention, or it can connect to a network and implement this invention through interaction with other computer devices within the network. The network in which the computer equipment resides includes, but is not limited to, the Internet, wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), and VPN networks.

[0052] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0053] After large-scale hydraulic fracturing of horizontal wells in unconventional oil and gas reservoirs such as tight sandstone and shale, and during the production process, it is usually necessary to treat the proppant particles that remain in the wellbore for various reasons in order to restore the oil and gas production channel to the greatest extent possible and ensure subsequent production, testing and secondary development operations of the horizontal well.

[0054] Coiled tubing sand flushing is currently the main method for removing proppant particles retained in wellbores. How to efficiently remove proppant particles retained in wellbores using coiled tubing and ensure unobstructed production channels in horizontal wells has become a crucial aspect of the economical and efficient exploitation of unconventional oil and gas reservoirs such as tight sandstone and shale.

[0055] Currently, sand flushing operations in coiled tubing typically determine the flushing displacement based on engineering experience. Furthermore, existing theoretical calculation methods often fail to fully consider the stress conditions of proppant particles and the impact of their accumulation and concealment characteristics. This often results in low flushing efficiency and poor flushing effects during actual operations. Therefore, a systematic analysis of the solid-liquid two-phase flow within the eccentric annulus of coiled tubing in horizontal wells is urgently needed.

[0056] After large-scale hydraulic fracturing and during production, some proppant particles may remain inside the wellbore due to various reasons. This invention addresses this issue by considering that these retained proppant particles, under gravity, accumulate in a certain shape at the bottom of the horizontal wellbore. During coiled tubing sand flushing operations, the coiled tubing also lies flat at the bottom of the horizontal wellbore under gravity, resulting in a solid-liquid two-phase flow within the eccentric annulus of the coiled tubing. This invention clarifies the initiation conditions of proppant particles within the eccentric annulus of the coiled tubing in horizontal wells, determining a reasonable and effective displacement for coiled tubing eccentric annulus sand flushing operations. This provides accurate and reliable field engineering reference guidance for determining the displacement for coiled tubing sand flushing operations in unconventional oil and gas reservoirs such as tight sandstone and shale.

[0057] The following describes the detailed flow of the method according to an embodiment of the present invention with reference to the accompanying drawings, the steps of which can be executed in a computer system containing, for example, a set of computer-executable instructions. Although the logical order of the steps is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than that shown here.

[0058] Example 1

[0059] Figure 1 This diagram illustrates the flow chart of the method for determining the displacement during eccentric annular sand flushing construction in coiled tubing according to Embodiment 1 of the present invention. (Refer to...) Figure 1 As can be seen, the method includes the following steps.

[0060] Step S10: Establish a corresponding geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus based on the equipment parameters of the sand flushing operation, and use the model established by the grid processing system to form a grid system of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus.

[0061] Step S20: Based on the eccentric annular solid-liquid two-phase flow spatial grid system of the coiled tubing, the sand flushing process of the coiled tubing under different displacement settings and with different mass proppant particles is simulated by a fluid dynamics calculation platform.

[0062] Step S30: Based on the comprehensive stress situation of the proppant particles, determine the critical conditions for the proppant particles in the eccentric annulus of the coiled tubing to move, and identify the proppant particles that meet the critical conditions as moving proppant particles.

[0063] Step S40: Characterize the proppant particle motion rate based on the mass distribution of the moving proppant particles, and use it as an indicator of the sand flushing effect in coiled tubing sand flushing operations; determine the target discharge rate to meet the operation requirements based on the proppant particle motion rate distribution corresponding to different sand flushing discharge rates.

[0064] The above embodiments of the present invention can reliably achieve the construction displacement rate for sand flushing in the eccentric annulus of horizontal well coiled tubing. This method calculates the solid-liquid two-phase flow of proppant and flushing fluid within the eccentric annulus of the horizontal well coiled tubing, comprehensively considering various forces acting on the proppant particles and the influence of the concealment of the accumulated proppant particles. It performs a force analysis on the proppant particles in a certain morphological accumulation within the eccentric annulus of the horizontal well coiled tubing, clarifying the initiation conditions of the proppant particles within the eccentric annulus of the horizontal well coiled tubing. Based on this, it calculates the proppant particle movement rate under different sand flushing construction displacement rates, determining the sand flushing construction displacement rate for the eccentric annulus of the horizontal well coiled tubing. This method is simple in principle, reliable in conclusion, and easy to operate. It has significant guiding and practical significance for sand flushing operations using coiled tubing after large-scale hydraulic fracturing of horizontal wells in unconventional oil and gas reservoirs such as tight sandstone and shale, and during production processes.

[0065] Preferably, in one embodiment, in step S10, a three-dimensional mapping system is used to establish a geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus that matches the sand flushing operation, based on the casing inner diameter data and the coiled tubing outer diameter data.

[0066] Furthermore, in one embodiment, in step S10, the geometric model of the eccentric annulus solid-liquid two-phase flow space of the coiled tubing is meshed in the mesh processing system to form a mesh system for numerical simulation of the eccentric annulus solid-liquid two-phase flow space of the coiled tubing.

[0067] In practical applications, the three-dimensional mapping system can adopt a mature three-dimensional mapping software platform. Based on geometric parameters such as the casing inner diameter and the coiled tubing outer diameter, a geometric model of the solid-liquid two-phase flow space of the eccentric annulus in the horizontal well coiled tubing is established in the three-dimensional mapping software platform. Furthermore, the mesh processing system can adopt a mature mesh processing software platform. Preferably, in one embodiment, the established geometric model of the solid-liquid two-phase flow space of the eccentric annulus in the horizontal well coiled tubing is reasonably meshed in the ICEM software platform to establish a mesh system for the solid-liquid two-phase flow space of the eccentric annulus in the horizontal well coiled tubing for numerical simulation.

[0068] Further, step S20 is executed, based on the eccentric annular solid-liquid two-phase flow spatial grid system of the coiled tubing, the sand flushing process of the coiled tubing under different displacement settings and with different mass proppant particles is simulated through a fluid dynamics calculation platform.

[0069] In an optional embodiment, in step S20, when simulating the sand flushing process of coiled tubing with different mass proppant particles, the coiled tubing eccentric annulus solid-liquid two-phase flow grid simulation system is imported into the fluid dynamics calculation platform. The discrete element method is used to model and solve the proppant particles, and corresponding initial conditions and boundary conditions are set to simulate the coiled tubing sand flushing process with a certain mass of proppant particles pre-placed in the eccentric annulus of the horizontal well coiled tubing.

[0070] The fluid dynamics calculation platform can adopt a mature computational fluid dynamics software platform; for example, in actual operation, the established spatial grid system for numerical simulation of solid-liquid two-phase flow in eccentric annulus of horizontal well coiled tubing can be imported into Fluent software or Open foam platform as the basis for simulation calculation of solid-liquid two-phase flow in eccentric annulus of horizontal well coiled tubing.

[0071] Furthermore, in one embodiment, in step S20, the liquid phase turbulent motion equation for the solid-liquid two-phase flow is established, and the following Realizable k-ε equation is used to characterize the liquid phase turbulent motion of the solid-liquid two-phase flow:

[0072]

[0073] In the formula, ρ f The density of the flushing fluid is expressed in kg / m³. 3 ;u i The velocity is expressed in m / s; μ represents the dynamic viscosity of the sand-fluid, in Pa·s; μ t G represents the turbulent viscosity coefficient; b This represents the turbulent kinetic energy caused by buoyancy, expressed in kg / (m·s). 3 );G k This represents the turbulent kinetic energy caused by the average velocity gradient, in kg / (m·s). 3 );Y M σ represents the contribution of compressible turbulent pulsating expansion to the total dissipation rate; k represents the turbulent kinetic energy, J; ε represents the turbulent kinetic energy dissipation rate, J / s; σ k σ represents the Prandtl number corresponding to the turbulent kinetic energy k; ε The Prandtl number represents the turbulent kinetic energy dissipation rate ε; E represents the modulus of the mean strain rate tensor; S ij The intermediate parameters are represented by C1, C2, and C3, which are operation coefficients or constants. In practical applications, they can be taken as 1.44, 1.9, and 0.09, respectively.

[0074] In practical applications, proppant particles are pre-placed at the bottom of the horizontal well casing and are subjected to a resultant force. For example, the resultant force acting on the proppant particles can be calculated based on Newton's second law according to research requirements using the following formula:

[0075]

[0076] Where: m i The mass of a single proppant particle is expressed in kg; F i The force, expressed in N, acts on the proppant particles.

[0077] The resultant force acting on the proppant particles includes the force acting from multiple factors; further, in step S20, corresponding initial conditions and boundary conditions are set to perform dynamic analysis and calculation of the sand flushing process of coiled tubing, specifically calculating the gravity, buoyancy, drag force, and lifting force acting on the proppant particles respectively;

[0078] Wherein, the gravity F acting on the proppant particles is expressed by the following formula. G Perform the calculation:

[0079]

[0080] The buoyancy F acting on the proppant particles is expressed by the following formula. B Perform the calculation:

[0081]

[0082] The drag force F acting on the proppant particles is given by the following formula. D Perform the calculation:

[0083]

[0084] The lifting force F acting on the proppant particles is given by the following formula. L Perform the calculation:

[0085]

[0086] In the formula, d p The diameter of the proppant particles is expressed in meters (m); ρ p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; C D Re represents the drag coefficient; p Represents the particle Reynolds number; u f The velocity of the flushing fluid is expressed in m / s; C L This represents the lift factor.

[0087] In an optional embodiment, in step S20, the cohesive force F acting on the supporting particles is further calculated using the following formula. A Perform the calculation:

[0088]

[0089] In the formula, δ represents the thickness of the liquid film on the particle surface; m, the contact area between two spherical particles is covered by a liquid film, which causes cohesion between the particles; this parameter is used to characterize the thickness of this liquid film; d p The diameter of the proppant particles is expressed in meters (m).

[0090] Furthermore, in a preferred embodiment, step S20 also involves the additional mass force F caused by the influence of the proppant particles on concealment according to the following formula. M Perform the calculation:

[0091]

[0092] In the formula: α M ξ represents the area coefficient related to the additional mass force caused by concealment; ξ represents concealment, which is dimensionless. ρ represents the average diameter of the retained proppant particles, in meters; Δ represents the vertical distance between the lowest point of the proppant particle and the contact point with the downstream proppant particle, in meters; p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; d p The diameter of the proppant particles is expressed in meters (m); ρ f The density of the flushing fluid is expressed in kg / m³. 3 .

[0093] Next, step S30 determines the critical condition for the proppant particles in the eccentric annulus of the coiled tubing to roll based on the comprehensive stress condition of the proppant particles, and identifies the proppant particles that meet the critical condition as moving proppant particles.

[0094] When the proppant particles in the eccentric annulus of the coiled tubing in a horizontal well reach the critical condition for rolling, they begin to move. Therefore, the motion state of the proppant particles can be determined by the comprehensive force analysis of the proppant particles in step S30.

[0095] Optionally, in one embodiment, in step S30, the critical condition for the proppant particles in the eccentric annulus of the coiled tubing to reach the point of rolling is determined as follows:

[0096] 0.5d p (F B cosθ+F L cosθ+F D sinθ)≥0.5d p (F M sinθ+F G cosθ+2F A sinθcosθ)

[0097] In the formula, F GF represents the gravity acting on the proppant particles. B F represents the buoyancy force acting on the proppant particles; D F represents the drag force acting on the proppant particles. L F represents the lifting force acting on the proppant particles; A F represents the cohesive force acting on the supporting particles; M θ represents the additional mass force caused by the concealment effect; θ represents the angle of repose of the proppant particles, °; proppant particles that meet the above critical conditions can be identified as motion proppant particles.

[0098] Further, in step S40, the motion rate of the proppant particles is characterized by the mass distribution of the moving proppant particles, which serves as an indicator of the sand flushing effect in coiled tubing sand flushing operations; and the target discharge rate that meets the operational requirements is determined based on the distribution of the motion rate of the proppant particles corresponding to different sand flushing discharge rates.

[0099] In a preferred embodiment, the proppant particle movement rate is defined as the ratio of the mass of the moving proppant particles in the model to the total mass of the pre-set proppant particles in the model. This ratio serves as an evaluation standard for the effectiveness of proppant particle movement under a specific coiled tubing sand flushing operation, i.e., an indicator of the sand flushing effect of the coiled tubing sand flushing operation. In practical applications, the proppant particle movement rate can be calculated using the following formula:

[0100]

[0101] In the formula: η represents the proppant particle movement rate; m move The mass of the proppant particles involved in the motion is expressed in kg; m. all This represents the total mass of the pre-set proppant particles in the model, in kg.

[0102] In an optional embodiment, after calculating the proppant particle movement rate in the eccentric annulus of the coiled tubing under different sand flushing operation displacements in step S40, a curve showing the change in proppant particle movement rate with sand flushing operation displacement is plotted; and then the target displacement is determined based on the curve distribution.

[0103] In practical applications, by calculating the proppant particle movement rate in the eccentric annulus of a horizontal well coiled tubing, where proppant particles are stacked in a certain shape, under different sand flushing operation displacements, and plotting the curve of the proppant particle movement rate in the eccentric annulus of a horizontal well coiled tubing as a function of the sand flushing operation displacement, the sand flushing displacement of the eccentric annulus of a horizontal well coiled tubing can be determined in conjunction with the actual field conditions.

[0104] The present invention will be further described below with reference to specific embodiments. The scope of the present invention is not limited to the embodiments, but is defined in the claims.

[0105] The displacement decision method for eccentric annular sand flushing construction of coiled tubing provided in this embodiment of the invention includes the following steps.

[0106] Step S10: Establish a corresponding geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus based on the equipment parameters of the sand flushing operation, and use the model established by the grid processing system to form a grid system of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus.

[0107] Step S20: Based on the eccentric annular solid-liquid two-phase flow spatial grid system of the coiled tubing, the sand flushing process of the coiled tubing under different displacement settings and with different mass proppant particles is simulated by a fluid dynamics calculation platform.

[0108] Step S30: Based on the comprehensive stress situation of the proppant particles, determine the critical condition for the proppant particles in the eccentric annulus of the coiled tubing to roll, and identify the proppant particles that meet the critical condition as moving proppant particles.

[0109] Step S40: Characterize the proppant particle motion rate based on the mass distribution of the moving proppant particles, and use it as an indicator of the sand flushing effect in coiled tubing sand flushing operations; determine the target discharge rate to meet the operation requirements based on the proppant particle motion rate distribution corresponding to different sand flushing discharge rates.

[0110] Taking a coiled tubing sand flushing scenario as an example, the displacement decision method for coiled tubing eccentric annulus sand flushing construction of the present invention is implemented according to the following operations:

[0111] 1. Based on geometric parameters such as the casing inner diameter (114.3 mm in the implementation case) and the coiled tubing outer diameter (50.8 mm in the implementation case), a spatial geometric model of the solid-liquid two-phase flow in the eccentric annulus of the coiled tubing in a horizontal well is established in a 3D mapping software platform, such as... Figure 2 As shown;

[0112] 2. In a mature grid processing software platform, the established geometric model of the eccentric annulus solid-liquid two-phase flow space in horizontal well coiled tubing is rationally meshed to establish a grid system for numerical simulation of the eccentric annulus solid-liquid two-phase flow space in horizontal well coiled tubing. For example... Figure 3 As shown;

[0113] 3. The established spatial grid system for the eccentric annulus solid-liquid two-phase flow of horizontal well coiled tubing used for numerical simulation is imported into a mature computational fluid dynamics software platform as the basis for the simulation calculation of eccentric annulus solid-liquid two-phase flow of horizontal well coiled tubing.

[0114] 4. The liquid phase turbulence motion equation for the solid-liquid two-phase flow is described using the Realizable k-ε equation; the discrete element method is used to model and solve the proppant particles, which are pre-placed at the bottom of the horizontal well casing. Figure 4 As shown, the resultant force acting on the proppant particles can be calculated based on Newton's second law according to requirements.

[0115] 5. Set the appropriate initial and boundary conditions to calculate the eccentric annulus sand flushing model of coiled tubing. The relevant parameter values ​​are shown in Table 1. Calculate and analyze the gravity, buoyancy, drag force, lift force, and cohesion acting on the proppant particles, as well as the additional mass force caused by the concealment effect. The force analysis diagram of the proppant particles is shown in the figure. Figure 5 As shown, the motion state of the proppant particles is determined based on the comprehensive stress analysis of the proppant particles. The simulation results of sand flushing in the eccentric annulus of a horizontal well with a displacement of 500 L / min are as follows: Figure 6 As shown.

[0116] Table 1. Parameter values ​​for calculating displacement during eccentric annular sand flushing construction in coiled tubing.

[0117] No. Parameter Value No. Parameter Value 1 Proppant particle size 0.00015m 5 Proppant particle packing angle 30° 2 Sand washing fluid density 1050 kg / m 3 ]] 6 Pre-set proppant particle mass 2 kg 3 Proppant particle density 2650 kg / m 3 ]] 7 Sand washing operation discharge 150-500 L / min 4 Sand washing fluid viscosity 15 mPa·s — —

[0118] 6. Calculate the proppant particle movement rate in the eccentric annulus of a horizontal well coiled tubing, where proppant particles are arranged in a specific shape, under different flushing rates. In the implementation case, the flushing rates were 150, 200, 250, 300, 350, 400, 450, and 500 L / min. Plot the curves showing the variation of proppant particle movement rate in the eccentric annulus of a horizontal well coiled tubing with the flushing rate, as shown below. Figure 7 As shown in the implementation case, when the sand flushing rate is greater than 400L / min, the proppant particle movement rate is greater than 80%. Based on the actual on-site construction conditions, it can be basically recommended that the sand flushing rate of the eccentric annulus of the coiled tubing in the horizontal well be determined to be 400L / min.

[0119] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0120] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0121] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new method for determining the displacement of coiled tubing eccentric annulus sand flushing construction, so as to achieve reliable decision-making and optimization of coiled tubing sand flushing construction parameters.

[0122] Example 2:

[0123] Based on the methods in any one or more of the above embodiments of the present invention, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more of the above embodiments. When the program code is executed by the operating system, it can implement the displacement decision method for continuous tubing eccentric annular sand flushing construction as described above.

[0124] Example 3:

[0125] The methods described in detail in the above-disclosed embodiments of the present invention can be implemented using various forms of devices or systems. Therefore, based on other aspects of the methods described in any one or more of the above embodiments, the present invention also provides a continuous tubing eccentric annulus sand flushing construction displacement decision system. This system is used to execute the continuous tubing eccentric annulus sand flushing construction displacement decision method described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0126] Specifically, Figure 8 The diagram shows a schematic representation of the displacement decision system for eccentric annular sand flushing construction in coiled tubing provided in an embodiment of the present invention. Figure 8 As shown, the system includes:

[0127] The grid flow space construction module is configured as follows: based on the equipment parameters of the sand flushing operation, a corresponding geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus is established, and the model is numerically established using the grid processing system to form a grid system of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus.

[0128] The continuous sand flushing analysis module is configured to simulate the continuous tubing sand flushing process under different displacement settings and with different mass proppant particles pre-loaded, based on the eccentric annular solid-liquid two-phase flow spatial grid system of the continuous tubing, through a fluid dynamics calculation platform.

[0129] The motion proppant identification module is configured to determine the critical conditions for the motion of proppant particles in the eccentric annulus of coiled tubing based on the comprehensive stress conditions of the proppant particles, and identify proppant particles that meet the critical conditions as motion proppant particles.

[0130] The sand flushing displacement decision module is configured to characterize the motion occurrence rate of proppant particles based on the mass distribution of moving proppant particles, serving as an indicator of the sand flushing effect in coiled tubing sand flushing operations; and to determine the target displacement that meets the operational requirements based on the distribution of proppant particle motion occurrence rate corresponding to different sand flushing displacements.

[0131] In an optional embodiment, the grid flow space construction module is configured to: establish a geometric model of the eccentric annular solid-liquid two-phase flow space of the coiled tubing that matches the sand flushing operation using a three-dimensional mapping system based on the casing inner diameter data and the coiled tubing outer diameter data.

[0132] Furthermore, in one embodiment, the grid flow space construction module performs grid division on the geometric model of the eccentric annulus solid-liquid two-phase flow space of the coiled tubing in the grid processing system to form a grid system for the eccentric annulus solid-liquid two-phase flow space of the coiled tubing for numerical simulation.

[0133] Preferably, in one embodiment, the continuous sand flushing analysis module is configured as follows:

[0134] When simulating the sand flushing process of coiled tubing under different pre-placed proppant particles, the solid-liquid two-phase flow grid simulation system of the coiled tubing eccentric annulus is imported into the fluid dynamics calculation platform. The discrete element method is used to model and solve the proppant particles, and the corresponding initial conditions and boundary conditions are set to simulate the sand flushing process of coiled tubing under the condition of a certain mass of proppant particles pre-placed in the eccentric annulus of horizontal well coiled tubing.

[0135] In one embodiment, the continuous sand flushing analysis module is configured to establish the liquid phase turbulent motion equation for solid-liquid two-phase flow, using the following Realizable k-ε equation to characterize the liquid phase turbulent motion of solid-liquid two-phase flow:

[0136]

[0137] In the formula, ρ f The density of the flushing fluid is expressed in kg / m³. 3 ;u i The velocity is expressed in m / s; μ represents the dynamic viscosity of the sand-fluid, in Pa·s; μ t G represents the turbulent viscosity coefficient; b This represents the turbulent kinetic energy caused by buoyancy, expressed in kg / (m·s). 3 );G kThis represents the turbulent kinetic energy caused by the average velocity gradient, in kg / (m·s). 3 );Y M σ represents the contribution of compressible turbulent pulsating expansion to the total dissipation rate; k represents the turbulent kinetic energy, J; ε represents the turbulent kinetic energy dissipation rate, J / s; σ k σ represents the Prandtl number corresponding to the turbulent kinetic energy k; ε The Prandtl number represents the turbulent kinetic energy dissipation rate ε; E represents the modulus of the mean strain rate tensor; S ij C1, C2, and C3 represent intermediate parameters; C1, C2, and C3 all represent operational coefficients, which are constants.

[0138] Furthermore, in one embodiment, the continuous sand flushing analysis module is configured to set corresponding initial conditions and boundary conditions, and calculate the gravity, buoyancy, drag force and lifting force acting on the proppant particles respectively, so as to perform dynamic analysis of the continuous tubing sand flushing process.

[0139] The continuous sand flushing analysis module uses the following formula to measure the gravity F acting on the proppant particles. G Perform the calculation:

[0140]

[0141] The buoyancy F acting on the proppant particles is expressed by the following formula. B Perform the calculation:

[0142]

[0143] The drag force F acting on the proppant particles is given by the following formula. D Perform the calculation:

[0144]

[0145] The lifting force F acting on the proppant particles is given by the following formula. L Perform the calculation:

[0146]

[0147] In the formula, d p The diameter of the proppant particles is expressed in meters (m); ρ p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; C D Re represents the drag coefficient; p Represents the particle Reynolds number; u f The velocity of the flushing fluid is expressed in m / s; C L This represents the lift factor.

[0148] In a preferred embodiment, the continuous sand flushing analysis module further describes the cohesion F acting on the supporting particles according to the following formula. A Perform the calculation:

[0149]

[0150] In the formula, δ represents the thickness of the liquid film on the particle surface, in meters (m); d p The diameter of the proppant particles is expressed in meters (m).

[0151] Furthermore, in one embodiment, the continuous sand-washing analysis module also considers the additional mass force F caused by the influence of proppant particles on concealment according to the following formula. M Perform the calculation:

[0152]

[0153] In the formula: α M ξ represents the area coefficient related to the additional mass force caused by concealment; ξ represents concealment, which is dimensionless. ρ represents the average diameter of the retained proppant particles, in meters; Δ represents the vertical distance between the lowest point of the proppant particle and the contact point with the downstream proppant particle, in meters; p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; d p The diameter of the proppant particles is expressed in meters (m); ρ f The density of the flushing fluid is expressed in kg / m³. 3 .

[0154] Optionally, in one embodiment, the proppant motion identification module determines the critical condition under which the proppant particles in the coiled tubing eccentric annulus reach motion as follows:

[0155] 0.5d p (F B cosθ+F L cosθ+F D sinθ)≥0.5d p (F M sinθ+F G cosθ+2F A sinθcosθ)

[0156] In the formula, F G F represents the gravity acting on the proppant particles. B F represents the buoyancy force acting on the proppant particles; D F represents the drag force acting on the proppant particles. L F represents the lifting force acting on the proppant particles; A F represents the cohesive force acting on the supporting particles;M θ represents the additional mass force caused by the concealment effect; θ represents the angle of packing of the proppant particles, in °.

[0157] Furthermore, in one embodiment, the sand flushing displacement decision module is configured to: after calculating the proppant particle movement rate in the eccentric annulus of the coiled tubing under different sand flushing operation displacements, plot the change curve of the proppant particle movement rate with the sand flushing operation displacement; and then decide the target displacement based on the curve distribution.

[0158] In the coiled tubing eccentric annular sand flushing construction displacement decision system provided in this embodiment of the invention, each module or unit structure can operate independently or in combination according to the actual spatial model construction requirements and mechanical performance calculation requirements to achieve the corresponding technical effects.

[0159] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0160] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0161] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. A method for determining displacement during eccentric annular sand flushing construction in coiled tubing, characterized in that, The method includes: Step S10: Establish a corresponding geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus based on the equipment parameters of the sand flushing operation, and use the model established by the grid processing system to form a grid system of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus. Step S20: Based on the eccentric annular solid-liquid two-phase flow spatial grid system of the coiled tubing, the sand flushing process of the coiled tubing under different displacement settings and with different mass proppant particles is simulated by a fluid dynamics calculation platform. Step S30: Based on the comprehensive stress situation of the proppant particles, determine the critical conditions for the proppant particles in the eccentric annulus of the coiled tubing to move, and identify the proppant particles that meet the critical conditions as moving proppant particles. Step S40: Characterize the proppant particle motion rate based on the mass distribution of the moving proppant particles, and use it as an indicator of the sand flushing effect in coiled tubing sand flushing operations; determine the target discharge rate to meet the operation requirements based on the proppant particle motion rate distribution corresponding to different sand flushing discharge rates.

2. The method according to claim 1, characterized in that, In step S10, a three-dimensional mapping system is used to establish a geometric model of the solid-liquid two-phase flow space of the coiled tubing eccentric annulus that matches the sand flushing operation, based on the casing inner diameter data and the coiled tubing outer diameter data.

3. The method according to claim 1, characterized in that, In step S10, the geometric model of the eccentric annulus solid-liquid two-phase flow space of the coiled tubing is divided into grids in the grid processing system to form a grid system for numerical simulation of the eccentric annulus solid-liquid two-phase flow space of the coiled tubing.

4. The method according to claim 1, characterized in that, Step S20 includes: When simulating the sand flushing process of coiled tubing under different pre-placed proppant particles, the solid-liquid two-phase flow grid simulation system of the coiled tubing eccentric annulus is imported into the fluid dynamics calculation platform. The discrete element method is used to model and solve the proppant particles, and the corresponding initial conditions and boundary conditions are set to simulate the sand flushing process of coiled tubing under the condition of a certain mass of proppant particles pre-placed in the eccentric annulus of horizontal well coiled tubing.

5. The method according to claim 1, characterized in that, In step S20, the liquid phase turbulent motion equation for solid-liquid two-phase flow is established, and the following Realizable k-ε equation is used to characterize the liquid phase turbulent motion of solid-liquid two-phase flow: In the formula, ρ f The density of the flushing fluid is expressed in kg / m³. 3 ;u i The velocity is expressed in m / s; μ represents the dynamic viscosity of the sand-fluid, in Pa·s; μ t G represents the turbulent viscosity coefficient; b This represents the turbulent kinetic energy caused by buoyancy, expressed in kg / (m·s). 3 );G k This represents the turbulent kinetic energy caused by the average velocity gradient, in kg / (m·s). 3 );Y M σ represents the contribution of compressible turbulent pulsating expansion to the total dissipation rate; k represents the turbulent kinetic energy, J; ε represents the turbulent kinetic energy dissipation rate, J / s; σ k σ represents the Prandtl number corresponding to the turbulent kinetic energy k; ε The Prandtl number represents the turbulent kinetic energy dissipation rate ε; E represents the modulus of the mean strain rate tensor; S ij C1, C2, and C3 represent intermediate parameters; C1, C2, and C3 all represent operational coefficients.

6. The method according to claim 1, characterized in that, In step S20, corresponding initial conditions and boundary conditions are set, and the gravity, buoyancy, drag force and lifting force acting on the proppant particles are calculated separately based on them to perform dynamic analysis of the sand flushing process of coiled tubing. Wherein, the gravity F acting on the proppant particles is expressed by the following formula. G Perform the calculation: The buoyancy F acting on the proppant particles is expressed by the following formula. B Perform the calculation: The drag force F acting on the proppant particles is given by the following formula. D Perform the calculation: The lifting force F acting on the proppant particles is given by the following formula. L Perform the calculation: In the formula, d p The diameter of the proppant particles is expressed in meters (m); ρ p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; C D Re represents the drag coefficient; p Represents the particle Reynolds number; u f The velocity of the flushing fluid is expressed in m / s; C L This represents the lift factor.

7. The method according to claim 1, characterized in that, In step S20, the cohesive force F acting on the supporting particles is further expressed by the following formula. A Perform the calculation: In the formula, δ represents the thickness of the liquid film on the particle surface, in meters (m); d p The diameter of the proppant particles is expressed in meters (m).

8. The method according to claim 1, characterized in that, In step S20, the additional mass force F caused by the influence of the proppant particles on the concealment is also considered. M Perform the calculation: In the formula: α M ξ represents the area coefficient related to the additional mass force caused by concealment; ξ represents concealment, which is dimensionless. ρ represents the average diameter of the retained proppant particles, in meters; Δ represents the vertical distance between the lowest point of the proppant particle and the contact point with the downstream proppant particle, in meters; p This indicates the density of the proppant particles, in kg / m³. 3 g represents gravitational acceleration; d p The diameter of the proppant particles is expressed in meters (m); ρ f The density of the flushing fluid is expressed in kg / m³. 3 .

9. The method according to claim 1, characterized in that, In step S30, the critical condition for the proppant particles in the eccentric annulus of the coiled tubing to reach motion is determined as follows: 0.5d p (F B cosθ+F L cosθ+F D sinθ)≥0.5d p (F M sinθ+F G cosθ+2F A sinθcosθ) In the formula, F G F represents the gravity acting on the proppant particles. B F represents the buoyancy force acting on the proppant particles; D F represents the drag force acting on the proppant particles. L F represents the lifting force acting on the proppant particles; A F represents the cohesive force acting on the supporting particles; M θ represents the additional mass force caused by the concealment effect; θ represents the angle of packing of the proppant particles.

10. The method according to claim 1, characterized in that, In step S40, after calculating the proppant particle movement rate in the eccentric annulus of the coiled tubing under different sand flushing operation displacements, a curve showing the change in proppant particle movement rate with sand flushing operation displacement is plotted; then, the target displacement is determined based on the curve distribution.

11. A storage medium, characterized in that, The storage medium stores program code that can implement the method as described in any one of claims 1 to 10.

12. A displacement decision system for eccentric annular sand flushing construction in coiled tubing, characterized in that, The system performs the method as described in any one of claims 1 to 10.

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