Method for reducing pressure and increasing injection through gemini surfactant

Abstract

The invention discloses a method for reducing pressure and increasing injection through a gemini surfactant. The method comprises orderly injecting hydrochloric acid containing an additive, mud acid containing an additive and a gemini surfactant solution into the middle of an oil layer, then injecting water into the oil layer to eject the agents to the stratum after the gemini surfactant is injected, and after well completion, injecting water, wherein the mud acid use amount of each meter of the oil layer is 0.5-2 m<3>, the hydrochloric acid use amount of each meter of the oil layer is 0.8-1.2times the mud acid use amount of each meter of the oil layer, the gemini surfactant use amount of each meter of the oil layer is 4-8 m<3>, the gemini surfactant solution is an ethyldidodecylammoniumphosphate solution and has a concentration of 5.0% to 7.5%. The gemini surfactant realizes pressure reduction and injection increasing of a low-permeability reservoir water injection well and has an effective period longer than the conventional acidification measure. The method can utilizes a water injection pipe column for construction, is free of acid solution returning, orderly injects agents,has simple processes, is easy to operate, has a short construction period and has large economic effects.

Description

Technical field [0001] The invention relates to a method for reducing pressure and increasing injection of a water injection well in a low-permeability oil reservoir, in particular to a method for reducing pressure and increasing injection by using gemini surfactants. Background technique [0002] Efficient development of low-permeability oil and gas fields has become an important way for most oil fields to stabilize their production capacity for a period of time in the future, while low-permeability oil fields are still mainly developed by water injection. Due to the low permeability and low porosity of low-permeability oil fields, the reservoir has low water absorption capacity. In addition, the clay minerals in the oil layer swell with water and the water quality of the injected water is not compatible with the oil layer. The water injection pressure continues to rise. A high-pressure zone is formed near the water injection well. At the same time, long-term high-pressure water...

AI Technical Summary

Problems solved by technology

Due to the characteristics of low permeability oil fields such as low permeability and small porosity, the water absorption capacity of the reservoir is low, and the clay minerals in the oil layer expand with water and the water quality of the injected water is not compatible with the oil layer. The water injection pressure continues to rise, A high-pressure area is formed near the water injection well, and at the same time, long-term high-pressure water injection can easily lead to casing damage, and under-injection of the water well leads to stress-sensitivity effects in the reservoir, which reduces the sweep coefficient and reduces the recovery rate of low-permeability oilfields, which seriously restricts this type of reservoir Effective development of reserves

At present, there are conventional measures such as fracturing, acidification, refilling, layered water injection and other conventional measures for depressurization and injection enhancement. These methods can solve part of the problem of depressurization and injection enhancement, but they have a short effective period and have limited effect on improving the permeability of the near-wellbore zone. And other issues

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