Stepwise dissolution and plugging removal method for oil and water wells

Abstract

The invention discloses a stepwise dissolution and plugging removal method for oil and water wells: (1) injecting pretreatment liquid; injecting cleaning agent; (2) injecting into the main body dissolution system to dissolve different cuttings components in the deep part of the oil and water well; plugging removal radius Above 3.5m; the main corrosion system is selected from the following acid solution plugging removal systems: ①hydrochloric acid system with an acidity of 8% to 12%; ②earth acid system with an acidity of 11% to 16%; ③acidity of 12% to 14% slow acid system; ④ deep penetrating plugging removal acid system with an acidity of 8% to 10%; the injection method of the main corrosion system is gradual injection without flowback; the injection sequence is determined according to the cuttings content; ( 3) Inject protective fluid, no flowback, and the construction is over. The method of the present invention adopts different blocking-removing acid solutions for graded dissolution for different cuttings, which can effectively improve the pore-throat connectivity of the reservoir, improve the water absorption profile of the reservoir and expand the sweeping range of water flooding, and can realize low-porosity and low-permeability storage effective use of layers.

Description

technical field [0001] The invention relates to a method for removing plugging by staged dissolution of oil and water wells, which belongs to the plugging removal technology for oil and water wells with low porosity and low permeability. Background technique [0002] The matrix acidizing of conventional oil and water wells is generally considered to optimize the construction plan according to the type of reservoir rock, acidizing radius, acid dissolution rate, and dissolution time. It is generally believed in the industry that the treatment radius is within 1.5m. In recent years, a series of augmentation injection systems (retarded acid, polyhydric acid, active agent, etc.) The target still stays at the level of dissolved plugs and dissolved rock matrix. During the construction process, the pH value of the acid solution will increase significantly with the advancement of the dissolution radius and the high temperature of the reservoir, resulting in serious secondary precipit...

AI Technical Summary

Problems solved by technology

In recent years, a series of augmentation injection systems (retarded acid, polyhydric acid, active agent, etc.) The target still stays at the level of dissolved plugs and dissolved rock matrix. During the construction process, the pH value of the acid solution will increase significantly with the advancement of the dissolution radius and the high temperature of the reservoir, resulting in serious secondary precipitation. Poor physical properties, deep polluted reservoirs are difficult to effectively remove plugging, even through acid fracturing and other methods, it is difficult to effectively develop, the effective period is short and the construction cost is high

Images