Well killing process using fuzzy ball well killing fluid for natural gas well without reduction of pressure

Abstract

The invention relates to a well killing process using a fuzzy ball well killing fluid for a natural gas well without reduction of pressure. According to the process, under the condition that the pressure of a wellhead of the natural gas well is maintained not to reduce, the fuzzy ball well killing fluid for repairing the natural gas well is prepared, wherein the density is 0.80-0.90 g/cm<3>, the apparent viscosity is 40-70 mPa s, and the dynamic plastic ratio is 0.90-1.50 Pa/mPa s. The fuzzy ball well killing fluid for repairing the natural gas well is prepared by adding 2.4-4.8 parts by weight of ball fuzz agent, 7.2-14.4 parts by weight of ball body agent and 2.4-4.8 parts by weight of ball liner agent into 1000 parts by weight of clean water. A fluid pump is utilized to directly pump the fuzzy ball well killing fluid into a well shaft at the pumping speed of 5-20 m<3>/h to achieve well killing operation under the condition that the pressure of the wellhead is not reduced, wherein the fuzzy ball well killing fluid is 0.1-2.0 times size of the well shaft. This process effectively solves the problems that in conventional natural gas well repair work, the construction period is prolonged and the subsequent formation gas production capacity recovers slowly since the pressure of the wellhead is reduced.

Description

technical field [0001] The invention relates to the technical field of natural gas well workover, in particular to a well killing process in the natural gas well workover process. Background technique [0002] After a long-term production of natural gas wells, measures such as replacement of pipe strings and salvage of fallen objects are required through workover operations. At this time, natural gas formations often have the characteristics of low pressure coefficient, early fracturing, and formation artificial fractures kept open after acidification. Conventional clean water well killing fluid has serious leakage after entering the wellbore, and the workover procedures such as replacing pipe strings and salvaging debris cannot be carried out smoothly when the wellbore is in a state of gas and high pressure. Therefore, during the workover operation of natural gas wells, it is necessary to stabilize temporary plugging or isolation formations and implement safe well killing....

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide a method that effectively avoids the problems of prolonged construction period and slow recovery of subsequent formation gas production capacity caused by depressurization at the wellhead during workove...

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