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Method and device for maintaining seal integrity of cement sheath

A cement sheath and integrity technology, used in sealing/isolation, earthwork drilling, special data processing applications, etc., to improve the interface bonding strength, maintain integrity, and improve the stress state.

Active Publication Date: 2018-11-02
中石化石油工程技术服务有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although domestic scholars have also tried to solve the above problems through the finite element method, the existing research is still in a bottleneck state in how to prevent annular pressure by maintaining the integrity of the cement sheath seal.

Method used

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  • Method and device for maintaining seal integrity of cement sheath
  • Method and device for maintaining seal integrity of cement sheath
  • Method and device for maintaining seal integrity of cement sheath

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] see figure 1 A schematic flow chart of a method for maintaining the sealing integrity of the cement sheath provided by Embodiment 1 of the present invention, the method includes the following steps:

[0058] S11. Establish a finite element analysis model composed of casing, cement sheath and formation downhole of the gas well, wherein, in the gas well, the cement sheath is located between the casing and the formation;

[0059] Specifically, the main purpose of gas well cementing and cementing operations is to effectively isolate the outer annulus of the casing to prevent formation fluid channeling during gas well drilling, stimulation operations, and production; and to form a complete cement sheath to effectively support and protect casing. During the drilling and development of gas wells, the cement sheath is subject to such effects as casing internal pressure, formation rock confining pressure, temperature stress, etc. These loads often have an adverse effect on the ...

Embodiment 2

[0066] Referring to embodiment one of the present invention and figure 1 For the specific process of steps S11 to S13 described in , see figure 2 Corresponding to the second embodiment of the present invention figure 1 The schematic flow chart of the specific establishment of the finite element analysis model in the shown S11 step, figure 1 Step S11 specifically includes:

[0067] S111. Establish a three-dimensional geometric model composed of casing, cement sheath and formation according to the casing size actually used and the measured borehole expansion rate;

[0068] Specifically, it is preferable in the second embodiment, according to the size of the oil reservoir casing actually used on site and the measured diameter enlargement rate, while considering the elimination of the influence of the wellbore stress on the far-field stress and the end effect, through the ABAQUS finite element The software builds a three-dimensional geometric model of the casing-cement sheath-...

Embodiment 3

[0094] Corresponding to the methods for maintaining the sealing integrity of the cement sheath disclosed in Embodiments 1 and 2 of the present invention, Embodiment 3 of the present invention also provides a device for maintaining the sealing integrity of the cement sheath, see Figure 5 A schematic structural diagram of a device for maintaining the sealing integrity of the cement sheath provided in the third embodiment of the present invention, the device includes:

[0095] Model building module 1, used to build a finite element analysis model composed of casing, cement sheath and formation downhole in the gas well, wherein, in the gas well, the cement sheath is located between the casing and the formation ;

[0096] The calculation module 2 is used to analyze the parameters related to the stress characteristics of the cement sheath in the finite element analysis model, and calculate and obtain the back pressure range. Injected, the pressure range capable of maintaining the ...

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Abstract

The invention discloses a method and device for maintaining seal integrity of a cement sheath. The method comprises the steps of building a finite element analysis model which is under a gas well andis composed of a casing pipe, the cement sheath and a stratum; analyzing parameters related to stress features of the cement sheath in the finite element analysis model, and calculating to obtain a return pressure range; within the return pressure range, applying return pressure to the cement sheath which is subjected to well cementation construction for sealing. By means of the method and device,by maintaining the seal integrity of the cement sheath and reducing micro-annuli, the purpose of inhibiting the annulus belt pressure of a wellhead of the gas well is achieved.

Description

technical field [0001] The invention relates to the technical field of petroleum and natural gas exploration and development, in particular to a method and a device for maintaining the sealing integrity of a cement sheath during gas well fracturing. Background technique [0002] In the process of oil and gas exploration and development, the problem of pressure in the annular space between the oil casing and the technical casing has become increasingly prominent. There are many factors that cause annular pressure, such as poor cementing quality, pressure change or temperature change, etc., but the structural damage of cement sheath or the appearance of gaps are one of the key factors that cause annular pressure. When there is large-scale fracturing production in a gas well, the high pressure will cause irreversible radial plastic deformation of the cement sheath, that is, after the pressure is unloaded, an annulus will appear on the first cemented surface between the casing a...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B47/005E21B33/13E21B33/14G06F17/50
CPCE21B33/13E21B33/14G06F30/23E21B47/005
Inventor 马小龙兰凯杨玄郝小龙姚平均王鑫
Owner 中石化石油工程技术服务有限公司
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