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Method of balancing pressure for well cementation

A technology of balancing pressure and cementing, which is applied in the field of oil and gas well cementing, and achieves the effect of wide applicable formation range, prevention of pressure leakage, and low risk of environmental pollution.

Inactive Publication Date: 2013-01-16
CHINA UNIV OF PETROLEUM (EAST CHINA)
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Problems solved by technology

Before cementing, first, a certain amount of air or nitrogen is injected into the hollow drill pipe or annular space at the wellhead, and the static liquid level height of the drilling fluid in the annular space is measured by the sonar depth sounder to calculate the predetermined pressure, and then through the wellhead The pressure relief valve adjusts the injection pressure to control the bottom hole pressure to be lower than the formation pressure; but this method is only applied to liner cementing

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  • Method of balancing pressure for well cementation
  • Method of balancing pressure for well cementation
  • Method of balancing pressure for well cementation

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Embodiment Construction

[0021] The present invention will be described in detail below in conjunction with specific embodiments.

[0022] The principle of the present invention is as figure 1 (the vertical dotted line in the figure is the shaft centerline, the same below). A gas injection pipe connected with a check valve 5 at the lower end is lowered into the annular space 7 between the casing 1 and the well wall 4, and the gas-liquid two-phase flow is formed in the annular space above the gas injection point through gas injection, thereby The annulus pressure of the wellbore above the gas injection point is reduced, and the annulus below the gas injection point still adopts the conventional pad fluid and conventional density cement slurry system. During the gas injection process, as the cement slurry returns upward in the annular space, the gas gradually returns upward in the annular space. Due to the gradual decrease in the density of the drilling fluid mixed with the gas, a negative pressure is ...

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Abstract

The invention discloses a method of balancing pressure for well cementation. The method comprises the following steps: a), adopting a cement slurry system of conventional density on a cementing isolation section; b), reducing pressure of a liquid pillar at the upper part of an annulus; and c), controlling wellhead back pressure of the annulus to ensure that the pressure in a weak layer is kept balanced. According to the well cementation process technology provided by the invention, a stratum can be effectively prevented from being pressed to leak, so as to soundly protect an oil-gas production layer; the strength of a cement sheath is guaranteed; the risk of environment pollution is low; the range of a stratum is wide; and the method is suitable for a reservoir stratum which is easy to leak and low in pressure.

Description

technical field [0001] The invention relates to a process method for balancing pressure well cementing in an oil field, and belongs to the field of well cementing of oil and gas wells. Using this method can achieve the purpose of protecting oil and gas reservoirs while ensuring the quality of cementing, and meet the requirements of balanced pressure cementing. Background technique [0002] With the development of low permeability reservoirs, the application of underbalanced drilling technology is more and more extensive. However, when performing cementing operations after underbalanced drilling, in order to meet the "pressure stability" requirements of cementing, the cement slurry density with the liquid column pressure greater than the formation pressure is often used. During the cement slurry injection process, the cementing fluid is very easy to When flowing into the wellbore, the solid phase particles in the cementing fluid can directly block the formation fluid channel...

Claims

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Application Information

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IPC IPC(8): E21B33/13
Inventor 步玉环李斐郭胜来
Owner CHINA UNIV OF PETROLEUM (EAST CHINA)
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