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Cementing technology and completion structure for shale gas wells

A technology for shale gas wells and well structures, which can be used in wellbore/well components, earthwork drilling, sealing/packing, etc., and can solve problems such as casing deformation and damage

Active Publication Date: 2018-02-06
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a cementing process and well completion structure for shale gas wells, so as to prevent and avoid the problem of casing deformation and damage during the development of shale gas wells

Method used

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  • Cementing technology and completion structure for shale gas wells
  • Cementing technology and completion structure for shale gas wells
  • Cementing technology and completion structure for shale gas wells

Examples

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Embodiment 1

[0033] refer to figure 1 and figure 2 , the present invention provides a cementing process for shale gas wells, on the basis of predicting in advance the well section p that is prone to casing deformation damage (that is, failure of wellbore integrity), the depth of the well section p is specified , and then during the cementing process along the well depth direction, inject cement slurry at the front (the position close to the wellhead is the front) and the rear (the position far from the wellhead is the rear) of the well section p to carry out normal cementing In the cementing operation, no cementing is performed in the annulus of the well section p, but a section of fluid is injected to form fluid section 1, such as figure 1 As shown, a completion structure of hard (cement sheath) + soft (fluid) + hard (cement sheath) similar to a "sandwich" structure is formed. The injection of cement slurry and fluid mentioned above refers to injection into the annular space formed bet...

Embodiment 2

[0045] Such as figure 1 As shown, in this embodiment, a well completion structure 100 for a shale gas well is provided, and the well completion structure is formed by the above cementing process. The well completion structure includes a wellbore and casing 10, and an annular space is formed between the casing 10 and the wellbore; in the annulus, there is a cement sheath for cementing along the well depth direction and the The cement sheath isolates the fluid section 1 . The fluid section 1 is sandwiched in the middle of the cement sheath, and there may be only one fluid section 1 along the well depth direction, or there may be two or more fluid sections 1 . The cement sheath is located at the top and the bottom (tail) of the annulus in the direction of the well depth; the cement sheath at the top returns (extends upward) to the wellhead. The fluid section 1 is formed by injecting fluid, and is located in the annulus of the well section prone to casing deformation and damage....

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Abstract

The invention provides a cementing technique and a well completion structure for a shale gas well. The cementing technique comprises the steps that on the basis that a well section which is prone to sleeve deformation and damage is predicted in advance, cement slurry is injected into the front portion and the rear portion of the well section in the well depth direction, cementing is not conducted in an annular space of the well section, instead, fluid is injected so that a fluid section can be formed, and a well completion structure similar to a sandwich structure which is composed of a hard portion (a cement ring), a soft portion (the fluid) and another hard portion (another cement ring) is formed. That is, the well completion structure formed through the cementing technique is provided with the cement rings used for cementing and the fluid section used for isolating the cement rings in the annular space in the well depth direction. By the adoption of the cementing technique and the well completion structure, extreme non-uniform external pressing loads, caused by local high-pressure areas of a stratum in the staged fracturing process, on a sleeve can be converted into uniform external pressing loads, and accordingly the purposes of preventing deformation of the sleeve and improving the integrity of a well shaft are achieved.

Description

technical field [0001] The invention relates to the technical field of shale gas well cementing, in particular to an improved well cementing process and well completion structure for shale gas wells. Background technique [0002] Shale gas development is an important part of my country's energy development strategy, and it is of positive significance to alleviate the increasing energy demand. Breakthroughs have been made in shale gas areas such as Sinopec Fuling and PetroChina Weiyuan-Changning, showing good development prospects. Multi-stage and staged fracturing is an important technical means to improve the development effectiveness of shale gas wells, but during the stimulation process, there have been serious problems of wellbore integrity failure. The casing deformation ratio in some blocks even reached 40%, resulting in the failure of staged fracturing, which has seriously restricted the development process of shale gas in my country. [0003] The main mechanism of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B33/13
CPCE21B33/13
Inventor 李军席岩
Owner CHINA UNIV OF PETROLEUM (BEIJING)