Fracturing temporary plugging ball-throwing process method based on perforation hole abrasion calculation

Abstract

This invention relates to a fracturing temporary plugging ball deployment process based on perforation erosion calculation, comprising the following steps: S1, calculating the perforation inlet erosion amount of the perforation cluster under the erosion of pre-fracturing fluid and sand-containing fracturing fluid using a fluid-structure interaction numerical method, and updating the inlet diameter after perforation erosion; S2, calculating the required temporary plugging ball diameter range and number of temporary plugging balls based on the updated perforation cluster diameter; S3, analyzing whether the ball deployment diameter and number design are appropriate using a fluid-structure interaction algorithm, and if not, returning to step B to adjust the design; S4, deploying temporary plugging balls of different diameters in batches through a ball deployer into the wellbore; S5, pumping the temporary plugging balls to the target formation perforation cluster. This invention, by calculating and predicting perforation erosion of the perforation cluster, designs the temporary plugging ball diameter distribution and deployment batches, achieving controllable temporary plugging and efficient fracturing of closely spaced multi-cluster perforations, and realizing fracturing stimulation of shale gas reservoirs.

Description

Technical Field

[0001] This invention relates to the field of fracturing and production enhancement technology for unconventional shale gas reservoirs, and more specifically, to a fracturing temporary plugging ball-dropping process method based on perforation erosion calculation. Background Technology

[0002] With the urgent need for shale gas exploration, development, and production enhancement, a close-cut multi-cluster fracturing temporary plugging technology has attracted much attention. This technology is one of the existing diversion fracturing technologies. Compared to chemical diversion and fiber diversion, ball-dropping temporary plugging fracturing technology can reliably achieve temporary plugging, is easier to unplug, and causes less damage and impact on reservoir fractures. In its implementation, a plugging ball is dropped into the wellbore to temporarily plug some perforations with relatively simple fracture propagation, diverting more fracturing fluid so that other perforations that are not prone to fracturing can generate sufficient fractures. This achieves fracturing control of multi-cluster perforations and significantly increases shale gas production per well. However, due to the complex flow of the plugging ball in the downhole wellbore, the diameter of the perforation orifice changes under the abrasion of fracturing fluid particles, resulting in the plugging ball's setting effect and efficiency often not reaching satisfactory levels. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a fracturing temporary plugging ball-dropping process method based on perforation erosion calculation, so as to achieve controllable temporary plugging and efficient fracturing of multiple clusters of perforations in close-cut fracturing.

[0004] The technical solution adopted by this invention to solve its technical problem is: to construct a fracturing temporary plugging ball-dropping process method based on perforation hole erosion calculation, including the following steps:

[0005] S1. Calculate the inlet abrasion of the perforation cluster under the erosion of pre-fracturing fluid and sand-containing fracturing fluid using the fluid-structure interaction numerical method, and update the inlet diameter after the abrasion.

[0006] S2. Based on the updated diameter of the perforation cluster, calculate the range of temporary plugging ball diameters and the number of temporary plugging balls required for temporary plugging;

[0007] S3. Use fluid-structure interaction algorithm to analyze whether the design of the ball diameter and number is appropriate. If it is not appropriate, return to step S2 to adjust the design.

[0008] S4. Insert temporary plugging balls of different diameters into the wellbore in batches through the ball launcher;

[0009] S5. Pump the temporary plugging ball to the perforation cluster at the target layer.

[0010] According to the above scheme, the fluid-structure interaction numerical simulation calculation in step S1 incorporates on-site parameters such as sand particle diameter, pumping rate, formation pressure, and wellbore dimensions. In step S1, the fracturing fluid and sand particle solid-liquid two-phase flow are simulated using a DPM model, employing an incompressible fluid, steady-state solid-liquid two-phase flow model. Perforation wear is considered in terms of particle impact velocity, impact angle, and the geometric parameters of the particles and wall materials; the erosion rate is calculated using a formula.

[0011]

[0012] In the formula: It is the mass flux of the p-th particle; It is a particle size function; It is the impact angle between the particle path and the wall surface; It is the impact angle function; It is the particle impact velocity; It is a particle impact velocity function; It is the wall area; This refers to the number of particles; C, f, and b, as boundary conditions of the wall, need to be determined manually, and specific actual values ​​should be selected based on the different particles and materials. It is expressed as erosion rate, defined as the mass of wall material eroded by a unit mass of particles impacting it.

[0013] According to the above scheme, in step S1, the equivalent inlet diameter of the abraded orifice is calculated by extracting the area of ​​the abraded orifice, and the equivalent inlet diameter is the updated perforation orifice diameter.

[0014] According to the above scheme, in step S2, the inlet diameter of all perforations in the perforation cluster after abrasion is calculated based on fluid-structure interaction numerical analysis, and the diameter and required number of temporary plugging balls are selected based on the distribution of the abrasion diameter.

[0015] According to the above scheme, in step S3, the fluid-structure interaction algorithm is used to analyze whether the design of the ball diameter and number is appropriate. If it is not appropriate, the process returns to step S2 to adjust the design.

[0016] According to the above scheme, in step S3, the fluid-structure interaction algorithm analysis mainly uses the finite volume-discrete element coupling method to perform numerical simulation calculations of the temporary blocking ball, and then introduces the influence of the buoyancy of the temporary blocking ball to define the turning index of the temporary blocking ball:

[0017]

[0018] in F I It is the inertial force of the temporarily blocked ball; F u It is the drag force of the perforating fluid on the temporary plugging ball; It is the angle between the longitudinal direction of the horizontal well and the direction of the drag force; , These are the buoyancy and gravity of the temporarily blocked ball, respectively. When temporarily blocked, the ball will change direction from horizontal to move along the firing hole. This evaluation index can be used to calculate and analyze temporarily blocked ball throws. The larger the value, the stronger the ball's turning ability and the easier it is to temporarily block the perforation hole.

[0019] According to the above scheme, in step S4, the design of the temporary plugging ball needs to calculate the force and moment required for the temporary plugging ball to effectively seal the perforation. The calculation formula is as follows:

[0020] The force requirement for the temporary blocking ball to effectively seal the perforation is:

[0021]

[0022] In the formula, It is the force exerted by the pipe wall on the temporary plugging ball at point A of the perforation. It is the angle between the longitudinal direction of the horizontal well and the central axis of the perforation; It is the ratio of the distance from the center of the temporary plug ball to the pipe wall to the radius of the temporary plug ball;

[0023] Based on the force analysis of the temporary jacking ball setting the perforation, the following requirements are proposed to ensure the effective setting of the perforation by the temporary jacking ball: The formulas for calculating mechanical conditions M1 and M2 are as follows:

[0024]

[0025]

[0026] In the formula: M1 and M2 are the moments generated at point A by the temporary plug ball sealing the perforation in the horizontal direction and the perforation direction, respectively; It is the diameter of the contact profile between the temporary plug ball and the perforation hole when the ball is set. It is the diameter of the temporary blocking ball.

[0027] According to the above scheme, in step S4, according to the calculated and updated perforation inlet diameter distribution, temporary plugging balls of different diameters are thrown in proportion, with the diameter of the temporary plugging ball being 1.05 to 1.5 times the diameter of the perforation orifice.

[0028] According to the above scheme, in step S5, after the ball is thrown, the pumping volume is reduced by 10% to 30%, and the temporarily blocked ball is pumped to the target layer.

[0029] The fracturing plugging ball-dropping process method based on perforation erosion calculation of the present invention has the following beneficial effects:

[0030] The method of this invention is simple and reliable in principle, and highly feasible for field construction. It can control the temporary plugging sequence of wellbore perforation clusters and improve the efficiency of perforation plugging. This invention calculates and predicts perforation erosion in perforation clusters, designs the diameter distribution of plugging balls and the batching of balls, and achieves controllable temporary plugging and efficient fracturing of densely cut fracturing multi-cluster perforations, thus realizing the fracturing stimulation of shale gas reservoirs. Attached Figure Description

[0031] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0032] Figure 1 This is a schematic diagram of the fracturing temporary plugging ball-dropping process based on perforation hole erosion calculation;

[0033] Figure 2 This is a schematic diagram illustrating an example of calculating perforation erosion in a perforation cluster using a fluid-structure interaction numerical method.

[0034] Figure 3 This is a flow chart of the fluid-structure interaction process of the temporary plugging ball deployment method for fracturing based on the calculation of perforation hole erosion;

[0035] Figure 4 This is a schematic diagram of the numerical analysis results of the temporary plugging ball method for fracturing based on the calculation of perforation hole erosion. Detailed Implementation

[0036] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0037] like Figure 1-4 As shown, this invention provides a fracturing temporary plugging ball deployment process based on perforation erosion calculation. First, it is necessary to determine the sand content, sand particle size, and casing material parameters in the fracturing fluid according to the fracturing construction design and field process parameters. Then, a numerical method is used to calculate the diameter of the perforation inlet after wear, and the diameters of each perforation in the perforation cluster are updated. Based on the updated perforation inlet diameter, temporary plugging balls of different diameters are selected, and the temporary plugging balls are pumped to the target formation perforation cluster using a small-displacement pump. This method includes the following steps in sequence:

[0038] (1) The amount of perforation inlet abrasion of the perforation cluster under the erosion of fracturing pre-fracturing fluid and sand-containing fracturing fluid was calculated using the fluid-structure interaction numerical method, and the inlet diameter after perforation was updated.

[0039] (2) Calculate the range of temporary plugging ball diameters and the number of temporary plugging balls required for temporary plugging based on the perforation cluster hole update diameter;

[0040] (3) Use fluid-structure interaction algorithm to analyze whether the design of the ball diameter and number is appropriate. If it is not appropriate, return to (2) to adjust the design.

[0041] (4) Temporary plugging balls of different diameters are put into the wellbore in batches through the ball launcher;

[0042] (5) Use a small displacement pump to deliver the temporary plugging ball to the perforation cluster at the target layer;

[0043] Based on the above steps, the effective setting of the temporary blocking ball under different displacements was calculated, and its impact on the temporary blocking operation of the ball was also calculated. Specific calculation examples under different displacements are summarized in Table 1:

[0044] Table 1. Analysis of the temporary clogging force when the ball is effectively seated at the perforation point.

[0045]

[0046] Furthermore, the above-mentioned fluid-structure interaction numerical simulation calculations need to take into account on-site sand particle diameter, pumping rate, formation pressure, and wellbore size parameters;

[0047] Furthermore, in the above fluid-structure interaction calculation, the fracturing fluid and sand particles solid-liquid two-phase flow are modeled using the DPM model, employing an incompressible fluid, steady-state solid-liquid two-phase flow model. Perforation hole wear is considered in terms of particle impact velocity, impact angle, and the geometric parameters of the particles and wall materials; the erosion rate is calculated using the following formula:

[0048]

[0049] In the formula: It is the mass flux of the p-th particle; It is a particle size function; It is the impact angle between the particle path and the wall surface; It is the impact angle function; It is the particle impact velocity; It is a particle impact velocity function; It is the wall area; This refers to the number of particles; C, f, and b, as boundary conditions of the wall, need to be determined manually, and specific actual values ​​should be selected based on the different particles and materials. It is expressed as erosion rate, defined as the mass of wall material eroded by a unit mass of particles impacting it.

[0050] Furthermore, the above fluid-structure interaction calculation can obtain the area of ​​perforation hole erosion, and calculate the equivalent inlet diameter of the eroded hole. The equivalent inlet diameter is the updated perforation hole diameter.

[0051] Furthermore, due to the different inlet flow rates of each perforation in the perforation cluster, the inlet diameters after the perforations are eroded exhibit different distributions.

[0052] Furthermore, based on the distribution of perforation diameters after abrasion, the diameter and required number of temporary plugging balls are selected; a fluid-structure interaction algorithm is used to analyze whether the design of the plugging ball diameter and number is appropriate. If it is not appropriate, the process returns to step S2 to adjust the design.

[0053] Furthermore, the fluid-structure interaction algorithm analysis mainly utilizes the finite volume-discrete element method for numerical simulation of the temporary blocking ball, and then introduces the influence of the buoyancy of the temporary blocking ball to define its turning index:

[0054]

[0055] in F I It is the inertial force of the temporarily blocked ball; F u It is the drag force of the perforating fluid on the temporary plugging ball; It is the angle between the longitudinal direction of the horizontal well and the direction of the drag force; , These are the buoyancy and gravity of the temporarily blocked ball, respectively. When temporarily blocked, the ball will change direction from horizontal to move along the firing hole. This evaluation index can be used to calculate and analyze temporarily blocked ball throws. The larger the value, the stronger the ball's turning ability and the easier it is to temporarily block the perforation hole.

[0056] Furthermore, the design of the temporary clogging ball requires calculation of the forces and moments required for the temporary clogging ball to effectively seal the perforation. The calculation formula is as follows:

[0057] The force requirement for the temporary blocking ball to effectively seal the perforation is:

[0058]

[0059] In the formula, It is the force exerted by the pipe wall on the temporary plugging ball at point A of the perforation. It is the angle between the longitudinal direction of the horizontal well and the central axis of the perforation; It is the ratio of the distance from the center of the temporary plug ball to the pipe wall to the radius of the temporary plug ball;

[0060] Based on the force analysis of the temporary jacking ball setting the perforation, the following requirements are proposed to ensure the effective setting of the perforation by the temporary jacking ball: The formulas for calculating mechanical conditions M1 and M2 are as follows:

[0061]

[0062]

[0063] In the formula: M1 and M2 are the moments generated at point A by the temporary plug ball sealing the perforation in the horizontal direction and the perforation direction, respectively; It is the diameter of the contact profile between the temporary plug ball and the perforation hole when the ball is set. It is the diameter of the temporary blocking ball.

[0064] Furthermore, the diameter of the temporary plugging ball should be larger than the diameter of the perforation after abrasion, and the number should be 1.2 to 1.6 times the number of perforations.

[0065] Furthermore, the aforementioned temporary blocking balls of different diameters are thrown in proportion, with the diameter of the temporary blocking ball being 1.05 to 1.5 times the diameter of the perforation hole.

[0066] Furthermore, the pumping volume is reduced by 10% to 30%, and the temporary blocking ball is pumped to the target layer.

[0067] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A fracturing temporary plugging ball-dropping process method based on perforation erosion calculation, characterized in that, Includes the following steps: S1. Calculate the inlet abrasion of the perforation cluster under the erosion of pre-fracturing fluid and sand-containing fracturing fluid using the fluid-structure interaction numerical method, and update the inlet diameter after the abrasion. S2. Based on the updated diameter of the perforation cluster, calculate the range of temporary plugging ball diameters and the number of temporary plugging balls required for temporary plugging; S3. Use fluid-structure interaction algorithm to analyze whether the design of the ball diameter and number is appropriate. If it is not appropriate, return to step S2 to adjust the design. S4. Insert temporary plugging balls of different diameters into the wellbore in batches through the ball launcher; S5. Pump the temporary plugging ball to the target layer perforation cluster; The fluid-structure interaction algorithm analysis method for the fracturing temporary plugging ball deployment process based on perforation hole erosion calculation utilizes the finite volume-discrete element method for numerical simulation calculation of the temporary plugging ball. Then, the influence of the buoyancy of the temporary plugging ball is introduced to define its turning index. in F I It is the inertial force of the temporarily blocked ball; F u It is the drag force of the perforating fluid on the temporary plugging ball; It is the angle between the longitudinal direction of the horizontal well and the direction of the drag force; , The buoyancy and gravity of the temporarily blocked ball are respectively When the ball is temporarily blocked, it will change direction from horizontal to move along the firing hole; when The larger the value, the stronger the ball's ability to change direction and the easier it is to temporarily block the perforation hole; In step S4, the design of the temporary plugging ball requires calculation of the forces and moments required for the temporary plugging ball to effectively seal the perforation. The calculation formula is as follows: The force requirement for the temporary blocking ball to effectively seal the perforation is: In the formula, It is the force exerted by the pipe wall on the temporary plugging ball at point A of the perforation. It is the power of sealing; It is the angle between the longitudinal direction of the horizontal well and the central axis of the perforation; It is the ratio of the distance from the center of the temporary plug ball to the pipe wall to the radius of the temporary plug ball; Based on the force analysis of the temporary jacking ball setting the perforation, the following requirements are proposed to ensure the effective setting of the perforation by the temporary jacking ball: The formulas for calculating mechanical conditions M1 and M2 are as follows: In the formula: M1 and M2 are the moments generated at point A by the temporary plug ball sealing the perforation in the horizontal direction and the perforation direction, respectively; It is the diameter of the contact profile between the temporary plug ball and the perforation hole when the ball is set. It is the diameter of the temporary blocking ball.

2. The fracturing temporary plugging ball-dropping process method based on perforation erosion calculation according to claim 1, characterized in that, The fluid-structure interaction numerical simulation in step S1 incorporates on-site parameters such as sand particle diameter, pumping rate, formation pressure, and wellbore dimensions. The fracturing fluid and sand particle solid-liquid two-phase flow in step S1 utilizes a DPM model, employing an incompressible fluid, steady-state solid-liquid two-phase flow model. Perforation wear is considered in terms of particle impact velocity, impact angle, and the geometric parameters of the particles and wall materials; the erosion rate is calculated using a formula. In the formula: It is the mass flux of the p-th particle; It is a particle size function; It is the impact angle between the particle path and the wall surface; It is the impact angle function; It is the particle impact velocity; It is a particle impact velocity function; It is the wall area; This refers to the number of particles; C, f, and b are the boundary conditions of the wall, which need to be determined manually, and the specific actual values ​​should be selected according to the different particles and materials. It is expressed as erosion rate, defined as the mass of wall material eroded by a unit mass of particles impacting it.

3. The fracturing temporary plugging ball-dropping process method based on perforation erosion calculation according to claim 2, characterized in that, In step S1, the equivalent inlet diameter of the perforated hole is calculated by extracting the area of ​​the perforation. The equivalent inlet diameter is the updated perforation hole diameter.

4. The fracturing temporary plugging ball-dropping process method based on perforation erosion calculation according to claim 1, characterized in that, In step S2, the inlet diameter of all perforations in the perforation cluster after abrasion is calculated based on fluid-structure interaction numerical analysis, and the diameter and required number of temporary plugging balls are selected based on the distribution of the abrasion diameter.

5. The fracturing temporary plugging ball-dropping process method based on perforation erosion calculation according to claim 1, characterized in that, In step S4, according to the calculated and updated perforation inlet diameter distribution, temporary plugging balls of different diameters are thrown in proportion, with the diameter of the temporary plugging ball being 1.05 to 1.5 times the diameter of the perforation orifice.

6. The fracturing temporary plugging ball-dropping process method based on perforation erosion calculation according to claim 1, characterized in that, In step S5, after the ball is thrown, the pumping volume is reduced by 10% to 30%, and the temporarily blocked ball is pumped to the target layer.

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