System and method for flushing fly ash in coalbed methane wells using nitrogen foam flushing fluid

Abstract

The invention relates to a system for flushing fly ash in coalbed methane wells with nitrogen foam well flushing fluid, comprising: a liquid distribution tank, a pump truck, a foam generator, a nitrogen making train unit, a command vehicle, a well control blowout gate valve, and a blowout prevention device, fluid channel conversion device, cock valve, flowback pipe, flowback liquid storage tank, coalbed methane well shaft, and well washing operation string; the top of the coalbed methane well shaft is equipped with a well control blowout gate valve, and the pump truck passes the pipeline to the liquid distribution tank. It is connected with the foam generator, the nitrogen generating train unit is connected with the foam generator through the pipeline, the command vehicle is connected with the pump truck and the nitrogen generating train unit through the cable, the foam generator is connected with the well control discharge gate valve, and the top of the well control discharge gate valve is installed There is a blowout preventer, a fluid channel conversion device is installed on the top of the blowout preventer, a cock valve is installed on the top of the fluid channel conversion device, and a flowback pipe is installed on the top of the cock valve. The invention has high ash removal efficiency, less formation filtration loss of well-flushing fluid, small water consumption, strong ash-carrying ability of well-flushing fluid, less damage to reservoirs, and strong plugging removal ability.

Description

technical field [0001] The invention belongs to the field of oil and gas resources development, and in particular relates to a system and a method for flushing fly ash in coalbed gas wells with nitrogen foam flushing fluid. Background technique [0002] Coalbed methane reservoirs (coal rocks) have low strength and well-developed joints and fissures. During the drilling of coalbed methane wells, the coal rocks around the wellbore are damaged by drilling disturbances, forming a large number of coal rock particles. At the same time, drainage and drainage are required in the process of coalbed methane exploitation, which causes coal rock particles and fly ash in coal rocks formed during drilling to be carried into the wellbore. These coal rock particles and fly ash will block the seepage channels of water and coalbed methane after a large amount of accumulation in the wellbore, resulting in the decline of coalbed methane production or even stop production. Therefore, in the pro...

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Problems solved by technology

[0007] In view of the serious stratum leakage, large water consumption, poor economy, low efficiency (poor ash-carrying ability), long construction period, and Due to the shortcomings of serious reservoir pollution and incomplete ash removal, the present invention provides a method for flushing fly ash in coalbed methane wells with nitrogen foam flushing fluid, so as to overcome the above-mentioned problems in the methods of flushing with clean water, mechanical salvage, and the combined use of the two. Disadvantages, improve the efficiency of fly ash fishing and avoid secondary pollution of the reservoir by fishing ash

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