Method of plugging leak of medium-depth well via cross-linked polymer gel plugging agent

Abstract

The invention relates to a method of plugging a leak of a medium-depth well via cross-linked polymer gel plugging agent. Raw materials include, by weight, 120 parts of refined cotton sodium salt solution, 75-85 parts of acrylamide, 13-17 parts of ammonium persulfate, 2-5 parts of ceric sulfate, 4 parts of beta-D-mannuronic acid (M), 1-1.5 parts of ammonium dihydrogen phosphate, 100 parts of composite Portland cement mortar, 150-200 parts of mixed microfiber. A water-cement ratio of the composite Portland cement mortar is 0.44. The plugging agent is obtained by adding the acrylamide, ammonium persulfate granules, ceric sulfate granules, the beta-D-mannuronic acid (M), the composite Portland cement mortar, the mixed microfiber and the ammonium dihydrogen phosphate in order into the refined cotton sodium salt solution and mixing them well; the plugging agent is delivered to a leak layer; a pressure test is run after mud replacement is performed in a drill pipe; if bottom hole pressure rises, borehole mud replacement is performed after standing and pressure holding; after standing and pressure holding for 12 hours, a leak plugging pressure-bearing test is run; if pump pressure is normal, drilling is continued. The method allows reliable leak plugging and resistance to high temperature and pressure.

Description

technical field [0001] The invention relates to a method for plugging medium and deep wells by using a cross-linked polymer gel plugging agent, which belongs to the technical field of petroleum drilling. Background technique [0002] Lost circulation is a technical problem often encountered in the drilling process, especially high-temperature lost circulation will cause a large loss of drilling fluid, leading to an increase in drilling costs, and at the same time, it will cause changes in bottomhole pressure, induce wellbore instability, well collapse, The occurrence of complex accidents such as well kick and blowout seriously restricts the improvement of drilling speed. [0003] At present, when oil drilling encounters a high-temperature formation loss section, due to the lack of high-temperature resistant plugging technology, conventional plugging agents are generally used for plugging. In China, bridging plugging is generally used to deal with high-temperature well leaka...

AI Technical Summary

Problems solved by technology

Although the conventional plugging method has played a role in the plugging project of oil drilling, there are disadvantages or deficiencies at the same time, such as low high temperature resistance, short validity period, poor plugging efficiency, large consumption of plugging materials, long plugging time, and High-temperature deep wells and geothermal wells have a poor plugging safety factor, and downhole complex situations are prone to occur. These shortcomings directly affect the drilling and development process of high-temperature wells and geothermal wells. Therefore, traditional high-temperature plugging materials are far from being able to meet the growing deep and complex wells. Therefore, it is very necessary to study a high-temperature anti-high-temperature plugging agent for high-temperature deep wells.