Offshore oilfield water injection well online one-step-process acidification technology

Abstract

The invention relates to an offshore oilfield water injection well online one-step-process acidification technology, which comprises following steps of (1) preparing one-step acid liquor, wherein the one-step acid liquor consists of following components by weight percent: 20 to 40 percent of industrial acetic acid, 15 to 40 percent of industrial hydrochloric acid, 3 to 15 percent of deposition inhibitor, 5 to 15 percent of discharging aiding agent, 3 to 15 percent of corrosion inhibitor, 5 to 15 percent of antiswelling agent, 5 to 15 percent of iron ion stabilizer and 2 to 10 percent of hydrogen fluoride; (2) storing the acid liquor into an acid storage tank of an injection system, wherein the injection system consists of the acid storage tank, an acid resistant pump, a motor, a frequency converter, a flow sensor, a pressure sensor, a computer, a check valve, a three-way pipe and an acid injection pipe; (3) utilizing the acid resistant pump to pump the acid liquor into the water injection flow; (4) monitoring the variation of the pressure and the flow of the injected acid, and calculating skin coefficients in real time; and (5) keeping the water injection after stopping the acid injection. Due to the adoption of the offshore oilfield water injection well online one-step-process acidification technology, high efficiency, rapidness and large scale in plug removal of an offshore oilfield water injection well can be realized, the water injection pressure can be reduced, and the water injection quantity can be improved.

Description

Technical field [0001] The invention relates to an acidizing technology for water injection wells in downhole operations in offshore oil fields, in particular to an online single-step acidizing technology for efficiently and rapidly reducing wellhead injection pressure and improving water absorption capacity of water injection wells. technical background [0002] Offshore oilfield exploitation platforms have a limited lifespan (generally 20 years). In order to efficiently develop oilfields, as much formation crude oil as possible should be recovered within the lifespan of the platform, and water injection development methods should be adopted to increase the recovery rate and shorten the development time. [0003] With the increase of water injection time, the water injection wells in offshore oilfields gradually become clogged near the wellbore, resulting in a decrease in the water absorption capacity of the formation, an increase in the injection pressure, and a decrease in...

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Problems solved by technology

[0007] However, under the circumstances that the water injection wells in offshore oilfields are currently clogged on a large scale near the wellbore and the injection pressure is too high, the existing construction process of "injecting pre-fluid → injecting treatment fluid → injecting post-fluid → injecting displacement fluid" is exposed. Some disadvantages of poor adaptability to offshore oilfields: 1) The acid system is complex, there are many acid tanks and other auxiliary equipment, occupying a lot of space on ships and platforms, troublesome relocation, time-consuming and labor-intensive; 2) The construction process is relatively complicated and labor-intensive High; 3) The operation is highly exclusive, and other operations cannot be carried out during the acidification operation, that is, cross-operation cannot be implemented; 4) It is difficult to optimize the design of the scale of the treatment liquid, and an inappropriate scale selection may easily lead to incomplete plugging removal effect or waste of acid liquid; 5 ) It is difficult to implement large-scale acidification and plugging removal operations; 6) High operating costs

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