Method for improving cementing replacement efficiency of glass steel pipe or aluminum alloy pipe in coalbed methane horizontal well

Abstract

The invention relates to a method for improving well cementation displacement efficiency of a glass reinforced plastic pipe or an aluminum alloy pipe of coalbed methane horizontal well. The method specifically comprises the following steps: calculating a cement slurry density needed by the body suspension of the glass reinforced plastic pipe or the aluminum alloy pipe in the horizontal section ofthe coalbed methane horizontal well; according to the average wellbore diameter of the horizontal section of the coalbed methane horizontal well and the diameter of the glass reinforced plastic pipe or the aluminum alloy pipe, building a finite element physical model of which the length is 10 m in FLUENT software and executing the grid partition, and executing the horizontal well two-phase fluid displacement numerical simulation under the different lower eccentricity centralizing degree conditions; through the morphological analysis of the displacement interface, to obtain the corresponding optimal lower eccentricity centralizing degree while the displacement interface is the shortest; and alternately installing glass fiber reinforced plastic and aluminum alloy centralizers on the glass reinforced plastic pipe or the aluminum alloy pipe, wherein the glass reinforced plastic pipe or the aluminum alloy pipe achieves the optimal lower eccentricity centralizing degree according to the sizeof the centralizers. The method is used for solving the problem that the displacement efficiency of the glass reinforced plastic pipe or the aluminum alloy pipe is low because of the pipe upper eccentricity in the well cementation displacement caused by the lower density.

Description

technical field [0001] The invention relates to coal bed gas cementing technology, in particular to a method for improving the cementing replacement efficiency of glass steel pipes or aluminum alloy pipes in coal bed gas horizontal wells. Background technique [0002] Coalbed methane, commonly known as gas, is an unconventional natural gas associated with coal and stored in the coal seam in an adsorbed state. It needs to be decomposed by drainage and pressure reduction. The effective development of coalbed methane can obtain clean energy on the one hand, and on the other hand, the exploitation of coalbed methane can reduce the gas explosion rate in the coal mining process by 70% to 85%, effectively reducing the risk of coal mining. Gas-bearing coal seams in my country are mostly low-porosity, low-permeability, and low-pressure reservoirs. Horizontal wells with open holes are prone to borehole collapse and severe sand production, resulting in frequent workover and wellbore sc...

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Problems solved by technology

[0008] The purpose of the present invention is to provide a method for improving the replacement efficiency of glass steel pipe or aluminum alloy pipe cementing in coalbed methane horizontal wells, which is used to solve the problem of glass steel pipe / aluminum The problem of low displacement efficiency caused by the eccentricity of the pipe string due to the low density of the alloy pipe during cementing displacement

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