Method for resuming production and unsealing of sealed gas wells

A technology for unblocking and gas wells, which is applied in earthwork drilling, flushing wellbore, wellbore/well components, etc. It can solve problems such as low pressure coefficient of low-pressure gas wells, poor plugging removal effect, and inability to remove viscous materials, etc., to achieve improvement Reservoir seepage conditions, improving production capacity, and preventing gas wells from blowing out

Active Publication Date: 2022-05-06
CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD +1
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AI Technical Summary

Problems solved by technology

Conventional acid can only remove pollutants formed by inorganic substances, but cannot remove viscous substances formed by high molecular polymers. At the same time, the pressure coefficient of low-pressure gas wells is low, and the formed residual acid cannot be effectively carried out. The effect is poor, and the productivity of the gas well cannot be effectively exerted

Method used

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  • Method for resuming production and unsealing of sealed gas wells
  • Method for resuming production and unsealing of sealed gas wells
  • Method for resuming production and unsealing of sealed gas wells

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Embodiment Construction

[0035] The invention discloses a method for resuming production and unsealing a sealed gas well, which comprises the following steps:

[0036] Step 1. Coiled tubing hollowing out for liquid and gas lift

[0037] Lower the coiled tubing to the bottom boundary of the perforated well section, pump cleaning fluid into the coiled tubing to clean the coiled tubing and replace the killing fluid out of the wellhead. The cleaning fluid is preferably diesel oil; then inject nitrogen to clean the cleaning fluid in the wellbore. Empty, the depth of hollowing out until the pressure generated by the remaining liquid column in the wellbore is 10% higher than the formation pressure.

[0038] In this step, the calculation method of hollowing depth is:

[0039]

[0040] In the formula: h - hollowing out depth, refers to the height between the wellhead and the liquid level in the wellbore, in m;

[0041] H—well depth in the middle of the reservoir, unit m;

[0042] p—formation pressure, un...

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Abstract

The invention discloses a method for resuming production and unsealing of a sealed gas well. The first step is to replace liquid with a coiled tubing and hollow out by gas lift. The second step is polymer deblocking, the purpose of which is to reduce the viscosity of the viscous material formed by the polymer through injection of the plugging agent through the coiled tubing pump. The third step is the unsealing of inorganic substances, the purpose of which is to pump and divert acid through coiled tubing to remove the pollution formed by inorganic substances. The fourth step is coiled tubing gas lift, which aims to use coiled tubing to lift viscous, residual acid and cleaning fluid out of the wellbore to restore the self-flowing ability of the gas well. The present invention can carry out targeted plugging removal for polymers and inorganic substances respectively, effectively removes bottom-hole pollutants such as inorganic substances and high-molecular polymers, improves the seepage conditions of reservoirs near the bottom of the well, and improves long-term storage and low-pressure resumption of production. gas well production capacity.

Description

technical field [0001] The invention belongs to the technical field of natural gas exploitation, and in particular relates to a method for reproducing and unsealing a sealed gas well, in particular to a method for unsealing a long-term sealed low-pressure gas well for reproducing. Background technique [0002] In the process of gas field development, some complex gas wells or engineering abandoned wells will be sealed up due to immature mining technology or repair technology, and the storage time can reach several years or even ten years; Factors such as production impact gradually reduced to form low-pressure gas wells. When the gas well is sealed, the wellbore is filled with killing fluid, and the bottom of the well may also be mixed with drilling fluid. These liquids contain various polymers. When they are exposed to high temperature and high pressure for a long time, the properties of the fluid will change, and some substances will precipitate. Cemented into sticky matt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B37/06E21B43/16E21B21/14
CPCE21B37/06E21B43/166E21B21/14
Inventor 张文彪刘荣和郑可孟中华范竞仁张李蔡坤赤江林蔚
Owner CHINA NAT PETROLEUM CORP CHUANQING DRILLING ENG CO LTD
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