Well repairing method capable of washing whole barrel pump without releasing casing pressure

Abstract

The invention relates to the coal bed gas development, exhaust and mining and utilization technology, in particular to a method for washing a coal bed gas well whole barrel pump without releasing casing pressure. The method has the main thought that during conventional coal bed gas well pump inspection, the wellhead casing pressure needs to be released, and then an oil pumping rod, an oil pipe, apump barrel and a pump barrel plunger are all lifted out of a shaft, inspected and washed on the ground and then put in the shaft. The oil pumping rod and the pump barrel plunger are lifted out underthe condition that the pressure is not released, the hollow oil pumping rod is put in the oil pipe to the position of a fixing valve of the pump barrel, the fixing valve, the pump barrel and the oil pipe are washed through water circulation, and the pump barrel plunger is washed on the ground. The method has the significance that 1, the casing pressure is not released, harm to a coal reservoir iseffectively avoided, and the later gas yield is guaranteed; and 2, an oil lifting pipe is not needed in pump inspection, and the workload is reduced.

Description

technical field [0001] The invention belongs to the technical field of coal bed gas drainage, and in particular relates to a workover method capable of cleaning a whole cylinder pump without unloading casing pressure. Background technique [0002] According to the development theory of coalbed methane wells summarized by predecessors, the core is drainage and pressure reduction. The drainage process should be continuous and stable, so as to reduce the damage to coal reservoirs, effectively communicate coal seam fractures, and maximize the productivity of coalbed methane wells. There are many kinds of coalbed methane well drainage equipment, including pumping unit combined with integral barrel pump, screw pump, gas lift and other methods. The commonly used drainage method is the combination of oil pumping unit and integral barrel pump. In the initial stage, with the prolongation of the drainage time and the emergence of coal seam pulverization and other phenomena, the pump ef...

AI Technical Summary

Problems solved by technology

There are many kinds of coalbed methane well drainage equipment, including pumping unit combined with integral barrel pump, screw pump, gas lift and other methods. The commonly used drainage method is the combination of oil pumping unit and integral barrel pump. In the initial stage, with the prolongation of the drainage time and the emergence of coal seam pulverization and other phenomena, the pump efficiency of the drainage pump will decrease, resulting in the inability to meet the drainage requirements. The casing pressure is released and blown out. If the gas continues to be produced, the well needs to be killed, and then all the downhole strings are pulled out to clean and maintain the pump.

This kind of operation is contrary to the continuous and stable theory of drainage. It takes a long time to restore the gas production after the workover is resumed. In soft and low-permeability areas, the gas production of many wells cannot be restored, which greatly affects the coalbed methane wells. production capacity

[0003] The above situation is a contradictory problem. The pump efficiency of the drainage pump is reduced and cannot meet the needs of drainage, so it is necessary to carry out workover, but the well workover must remove the casing pressure, which will damage the coal reservoir and affect the productivity of the coalbed methane well.

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