CN-122021478-A - Perforation explosion pressure field calculation method considering perforation charge structure

CN122021478ACN 122021478 ACN122021478 ACN 122021478ACN-122021478-A

Abstract

The invention discloses a perforating explosion pressure field calculation method considering a perforating charge structure, which relates to the technical field of perforation completion and comprises the steps of collecting perforating charge parameters, shaft parameters, perforating string parameters and environmental parameters; dividing the well bore annulus into a plurality of well bore annulus nodes, dividing a plurality of charging nodes in a perforating charge charging area, calculating an initial detonation pressure field of perforating charge explosion, and calculating explosion pressure at each well bore annulus node to obtain a perforating explosion pressure field. The method is used for solving the problems of lack of accurate quantitative relation between the parameters of the charging structure and the distribution rule of the explosion pressure field, insufficient precision and poor engineering applicability of the existing calculation method in the prior art, and achieving the purposes of accurately calculating the perforation explosion pressure field distribution under different charging structure conditions and improving the safety of perforation completion operation and predictability of perforation effect.

Inventors

XU JIANFAN
WANG GUORONG
HU GANG
DENG JIE
DENG SHENGYI
ZHOU LI

Assignees

西南石油大学

Dates

Publication Date: 20260512
Application Date: 20260415

Claims (10)

1. A perforation explosion pressure field calculation method considering a perforation charge structure is characterized by comprising the following steps: S1, acquiring perforating charge parameters based on a perforating charge charging structure, wherein the perforating charge parameters comprise charging node density, and acquiring shaft parameters, perforating string parameters and environmental parameters; S2, setting annular node density, dividing a shaft annular space into a plurality of nodes, and defining the nodes as shaft annular space nodes; S3, dividing a plurality of nodes in the perforating charge charging area according to the charging node density, and defining charging nodes so that the charging nodes are uniformly distributed in the perforating charge charging area; s4, calculating an initial detonation pressure field of charge explosion of the perforating charges based on the divided charge nodes; S5, based on the divided shaft annular nodes and the initial detonation pressure fields, calculating the detonation pressure at each shaft annular node to obtain a perforation detonation pressure field.
2. A method of calculating a perforating explosion pressure field taking into account the charge configuration of a perforating charge as recited in claim 1, the method is characterized in that in the step S1: The perforating charge parameters also comprise any one or more of TNT equivalent of explosive, initial specific volume of explosive, explosive explosion speed, explosive density, charging node density, unit area explosive quality, unit area explosive initial radius, perforating charge geometric shape, perforating charge size, perforating charge charging area, the parameters of the model of the explosive JWL, the coordinates of the detonation point of each perforating charge and the detonation time of each perforating charge; the wellbore parameters include any one or more of wellbore radius, pocket length, casing inner radius, casing material density, casing material sonic velocity; the perforating string parameters comprise any one or more of the following parameters of the outer radius of the perforating gun, the inner radius of the perforating gun, the density of the perforating gun material, the sound velocity of the perforating gun material and the outer diameter of the string; the environmental parameters comprise any one or more of air medium density, air medium sound velocity, air medium pressure wave attenuation coefficient, perforating fluid medium density, perforating fluid medium sound velocity, perforating fluid medium pressure wave attenuation coefficient and environmental pressure.
3. The method for calculating the perforation explosion pressure field by considering the perforation charge structure according to claim 1, wherein in the step S2, in the process of dividing the well bore annulus into a plurality of nodes, the well mouth is taken as a starting point, the well section where the perforation gun is positioned is taken as a center, and in the process of dividing the plurality of nodes in the perforation charge area, in the step S3, the detonation point of perforation charge is taken as the center, and the charge area formed by the inner side of the perforation charge shell and the outer side of the liner is taken as a boundary.
4. The method of claim 1, wherein the method of calculating the initial detonation pressure field for detonation of the charge comprises: S401, determining a near-field boundary distance of charge explosion of the perforating charges to obtain a detonation area range caused by the charge explosion of the perforating charges; s402, calculating primary impact pressure of each charging node on a shaft annular node in the detonation region range; S403, determining impact time corresponding to each primary impact pressure; S404, combining the initial impact pressure and the corresponding impact time to obtain an initial detonation pressure field for explosive charge explosion of the perforating charges.
5. A method of calculating a perforating explosion pressure field in consideration of the charge configuration of perforating charges as recited in claim 4 wherein the primary percussion pressure is calculated by the formula: ; Wherein P nbji0 represents the primary impact pressure caused by the jth explosive loading node of the nth perforating charge to a shaft annular node i in the detonation region range, A, B, R 1 、R 2 , omega and E 0 are all parameters of a model of the explosive JWL, V nji is the explosive expansion volume of the unit region, R 0 is the initial radius of the explosive of the unit region, and exp represents a natural exponential function; wherein, the explosive expansion volume V nji of the unit area is calculated by the following formula: ; Wherein L nji is the distance from a shaft annular node i to a j-th loading node of an n-th perforating charge, and the following formula is satisfied: ; ; ; Wherein (X i ,y i ) is the coordinate of a well bore annular node i, (X n ,y n ) is the coordinate of an nth perforating charge detonating point, (X j ,y j ) is the coordinate of a jth explosive loading node, X nj is the distance between the jth explosive loading node and the nth perforating charge detonating point along the X axis, and Y nj is the distance between the jth explosive loading node and the nth perforating charge detonating point along the Y axis.
6. The method of claim 5, wherein the moment of impact corresponding to the initial impact pressure is calculated by the following formula: ; wherein t nji0 represents the impact time corresponding to P nbji0 , D exp is the expansion speed of the explosive in the detonation stage, and t j is the delayed excitation time of the explosive at the j-th explosive loading node, and the requirements are as follows: , ; wherein L nj is the distance between the j-th loading node of the nth perforating charge and the detonation point of the nth perforating charge.
7. A method of calculating a perforating explosion pressure field taking into account the charge configuration of a perforating charge as recited in claim 5, the method is characterized in that the step S5 specifically comprises the following steps: s501, calculating the evolution process of the initial detonation pressure at annulus nodes of all the wellbores; s502, calculating the evolution process of bubble pulsation pressure at annulus nodes of all the wellbores; s503, determining pressure wave propagation paths in well bore annulus nodes based on well bore parameters and perforating string parameters, and calculating evolution processes of reflected pressure in the well bore annulus nodes; s504, superposing the evolution process of the initial detonation pressure at the annular nodes of the wellbores, the evolution process of the bubble pulsation pressure at the annular nodes of the wellbores and the evolution process of the reflection pressure at the annular nodes of the wellbores, and calculating the explosion pressure at the annular nodes of the wellbores to obtain a perforation explosion pressure field.
8. The method of claim 7, wherein the evolution of the initial detonation pressure at each well bore annulus node is calculated by the following equation: ; Wherein P nbji (t) represents the explosion pressure of the j-th charge node of the nth perforating charge and the impact pressure caused to the well bore annular node i at the moment t, P nbji represents the initial impact pressure caused to the well bore annular node i by the j-th charge node of the nth perforating charge, t a is positive pressure duration time, and b a is an attenuation coefficient; For a wellbore annulus node within the detonation zone: ; For wellbore annulus nodes outside the detonation zone range: ; Wherein L c is the near field boundary distance of charge explosion of the perforating charges, L nji is the distance from a shaft annular node i outside the detonation region to a j-th charge node of the nth perforating charge; The evolution process of the bubble pulsation pressure in the well bore ring space is calculated by the following formula: ; Wherein P bni (t) represents the bubble pulsation pressure of bubbles at the annular node i of the shaft at the axial position of the nth perforating bullet at the moment t, ρ q is the density of perforating liquid medium, and R b is the bubble radius; Is the movement speed of the bubble wall, P 0 is the ambient pressure, sigma is the surface tension of the bubble, l ni is the distance from the center of the bubble to the annular node i of the shaft at the axial position of the nth perforating bullet, and P b is the detonation initial pressure of the perforating bullet at the outer wall of the perforating gun in the perforating direction, which meets the following conditions: ; ; Wherein m is the total number of charge nodes, A, B, R 1 、R 2 , omega and E 0 are parameters of a model of the explosive JWL, exp represents a natural exponential function, R 0 is the initial radius of the explosive in a unit area, (x b ,y b ) is the coordinate of the perforating bullet at the outer wall of the perforating gun in the perforating direction, and x j ,y j ) is the coordinate of the j-th charge node; is the outer radius of the perforating gun; the evolution process of the reflection pressure at the annular nodes of each well barrel is calculated by the following formula: ; Wherein P nbjim (t) represents the explosion pressure of the j-th loading node of the nth perforating bullet and the reflection pressure caused to the annular node i of the shaft at the moment t; a transmission coefficient for pressure waves propagating from the air medium to the inner surface of the perforating gun; a transmission coefficient for pressure waves to propagate from the perforating gun to the perforating fluid medium; a reflection coefficient for a pressure wave propagating from the air medium to the inner surface of the perforating gun; a reflection coefficient for pressure waves propagating from the perforating fluid medium to the inner surface of the casing; The number of internal reflections of the perforating gun; The number of reflections in the annulus fluid; The distance between the j loading node which is the nth perforating bullet and the annular node i of the shaft; represents the pressure wave propagation paths of the different propagation phases, where s=2, 3,..m g + m q +1, and α is the peak pressure decay index.
9. A method of calculating a perforating explosion pressure field in view of the charge configuration of perforating charges as recited in claim 8 wherein the reflectance of pressure waves propagating from the air medium to the interior surface of the perforating gun is calculated by: ; the reflection coefficient of a pressure wave propagating from the perforating fluid medium to the inner surface of the casing is calculated by: ; the transmission coefficient of a pressure wave propagating from the air medium to the inner surface of the perforating gun is calculated by: ; the transmission coefficient of a pressure wave propagating from the perforating gun to the perforating fluid medium is calculated by: ; Wherein: Is the propagation impedance of the explosion pressure in the air medium, ; Resistance to propagation of detonation pressure in the perforating gun material: ; propagation resistance for detonation pressure in perforating fluid medium: ; resistance to propagation of explosion pressure in the casing material: ; wherein: Is the density of the air medium; is the speed of sound of the air medium; a density of material for the perforating gun; Sound velocity for perforating gun material; Is the density of the perforating fluid medium; Sound velocity for perforating fluid medium; Is the density of the sleeve material; Sound velocity for the casing material.
10. The method of claim 8, wherein in step S504, the method of calculating the detonation pressure at each wellbore annulus node comprises: It is judged whether or not the value of P nbji (t)、P bn (t)、P nbjim (t) is 0 at the same timing: If two or more non-0 values exist at the same time, pi (t) = ; If there is only one non-0 value, pi (t) = ; If it is Pi (t) =0; Where Pi (t) is the total pressure of the well bore annulus node i at time t and k is the interference coefficient.

Description

Perforation explosion pressure field calculation method considering perforation charge structure Technical Field The invention relates to the technical field of perforation completion, in particular to a perforation explosion pressure field calculation method considering a perforation charge structure. Background The perforation completion technology is a key technology for realizing the scale benefit development of oil and gas resources by forming metal jet flow through explosion of perforating charges and forming perforation channels between a shaft and a reservoir. Perforation effect directly affects productivity and economic benefits of oil and gas wells, and pressure field distribution generated by perforation charge explosion is a core factor for determining perforation effect. In the traditional perforation operation design, perforation effect is usually improved by changing perforation charge type, charge quantity, geometric shape and other modes, however, the modes improve perforation effect and simultaneously influence the peak value and spatial distribution characteristics of an explosion pressure field in a shaft, so that accidents such as pipe column buckling, screen pipe fracture, packer failure and the like are caused, and great threat is brought to perforation pipe string safety and shaft integrity. The perforation charge structure parameters comprise key factors such as charge type, charge amount, charge geometry, detonation position and the like, and the different combinations of the parameters directly determine the peak intensity, the spatial distribution characteristics and the attenuation rule of the pressure field in the explosion process. The traditional perforation design is mostly based on an empirical formula and a simplified assumption, lacks deep analysis of the distribution relation of the loading structure parameters and the pressure field, and is difficult to accurately predict the perforation effect and potential risk under the complex well condition. In the prior art, the method (1) adopts an empirical formula method and carries out quick estimation through a simplified mathematical model, but the method usually simplifies the shape of the charge into a sphere or a cylinder, ignores the complex influence of the charge structure difference on the pressure field, and has limited calculation precision and narrow application range. (2) The numerical simulation method adopts methods such as finite element, finite difference or molecular dynamics to establish a refined model, the theoretical precision is higher, but the calculation cost is huge, the existing research is focused on single parameter influence analysis, and systematic consideration of the parameters of a charging structure is lacked. (3) The experimental test method can obtain the real pressure field data, but has long experimental period and high cost, and is difficult to cover the parameter space of all the charge structure combinations. Therefore, the main problems in the prior art include (1) insufficient matching with the charge structure of the perforating charges, difficulty in fully reflecting the influence of charge structure parameters such as charge type, charge quantity, geometric shape and the like on an explosion pressure field in the existing calculation method, (2) contradiction exists between calculation accuracy and engineering practicability, the calculation complexity of the high-accuracy method is too high, the accuracy requirement cannot be met by a simplified method, the calculation accuracy and efficiency are difficult to balance, and the applicability and universality of the calculation method are difficult to improve and the engineering application requirements of different types of perforating charges are difficult to meet. These technical bottlenecks limit the further development of perforation completion technology, and affect the development efficiency and operation safety of oil and gas wells. Therefore, it is needed to develop a precise calculation method of the perforation explosion pressure field, which can fully consider the charge structure characteristics of the perforation charges, and provide reliable theoretical basis and technical support for perforation completion design optimization and safety guarantee. Disclosure of Invention The invention provides a perforation explosion pressure field calculation method considering a perforation charge structure, which aims to solve the problems of lack of accurate quantitative relation between charge structure parameters and explosion pressure field distribution rules, insufficient accuracy and poor engineering applicability of the existing calculation method in the prior art, and realize the purposes of accurately calculating perforation explosion pressure field distribution under different charge structure conditions and improving the safety of perforation completion operation and predictability of perforation effect. The invention i