Technology and application of acid fracturing for efficient stimulation of deep and ultra-deep reservoirs

Deep and ultra-deep reservoir is one of the most important developing fields of oil and gas industry in the world, and oil and gas exploration and exploitation of China constantly approaches this field, so that oil and gas of deep and ultra-deep reservoir has been the main strategic succeeding region for the development of Chinese oil and gas industry.The exploration and exploitation technology of deep oil and gas had been classified as the prior developing theme and an important strategic task by the National middle & long-term science and technology development plan and the National innovation driven development strategy program respectively, and the exploitation technology innovation of deep oil and gas also had been listed as a key task by the National Revolutionary innovation action plan of energy technology. It’s the objective of this technology that the depth limit of the exploration and exploitation of oil and gas can be more than 8000m, and a mature practical and theoretical system for effectively exploiting the reservoir of 6000-7000m can be established, while this technology can reach international advanced level.

Acid fracturing stimulation technology is one of the four core technologies of the exploration and exploitation for deep and ultra-deep oil and gas. Deep and ultra-deep reservoirs can’t be exploited efficiently unless stimulated by acid fracturing to build the “highway” for oil and gas flowing. However, there are four world problems that must be overcome when applying acid fracturing into deep and ultra-deep reservoirs, which are high and ultra-high temperature,ultra-high fracture pressure, ultra-high closure pressure and serious leak-off based on an abundance of fractures and holes. To overcome these problems, the effective acid fracturing stimulation technology aimed at deep and ultra-deep reservoirs has been established in this project, which leading an indispensable stimulation technology spanning from the depth of 4000m to the ultra depth of 7000m.This technology has been a trump card to explore and exploit deep and ultra-deep reservoirs, promoting China in the areas of exploring and exploiting deep and ultra-deep reservoirs ascend the best in the world. Depending on the project, many achievements had been reached last three years.200 million ton of oil and gas equivalent had been ascertained.7.86 million ton of oil and gas had been increased.32 invention patents and 11 software copyright had been authorized and 172 papers included by SCI and EI had been published.