After a long period of production and development, oil and gas fields will produce many difficult and complicated diseases, the most headache problem is stratigraphic leakage, which will cause safety hazards and environmental pollution. At present, Sinopec Jianghan Petroleum Engineering Shale Gas Extraction Technology Service Company has independently developed a kind of "microbubble" - FAR leak-proof circulatable microbubble workover fluid, which solves the technical problems of low-pressure leakage well workover in China.
To revitalize old oil and gas wells, workover operations are required, during which formation leakage is often encountered, resulting in impurities and dirty water flowing into the wellbore.
"Workover operations in the case of stratigraphic leakage will not only harm the reservoir, but also reduce the capacity of oil and gas wells, and serious leakage may also cause blowouts, bringing danger and pollution." Zhong Tao, director of the Reservoir Transformation Research Institute of The Shale Gas Extraction Technology Service Company of Sinopec Jianghan Petroleum Engineering Company, said.
To prevent stratigraphic leakage, workover fluid is required to plug the gaps, which can be discharged along with the water in the wellbore after the operation is completed. However, at present, the workover fluid on the market can only be used once for a single well, the price is high, and the demand for clean water is also large, and the industry has long hoped that there will be a new workover fluid to replace traditional products. In February 2021, Sinopec Jianghan Petroleum Engineering Company Shale Gas Extraction Technology Service Company established a professional R&D team of FAR leak-proof circulatable microbubble workover fluid to develop an economical and durable workover fluid with better reservoir protection effect.
Microbubbles are small, but they are very effective.
During routine workover operations, the bottom pressure is usually above 30MPa, can the foam resist? "The smaller the foam, the greater the gas pressure inside it." Researcher Yan Xiu explains. In short, large foams are more flexible and smaller foams are stronger. Moreover, the microbubbles in the new workover fluid are "one core, two layers and three membranes" structure, which is equivalent to wearing multiple layers of more solid "protective clothing" for bubbles that are invisible to the naked eye.
"The advantage of the one-core, two-layer, three-membrane structure is that it can greatly increase the strength of the outer membrane of the foam, and even in the face of high-temperature and high-pressure reservoir conditions, the liquid film can also play an effective protective role in its 'microbubble' core, and can be recycled at least three times." Yan Xiu said.
On September 15 this year, during the construction of the Jiao page 28-Z1HF well in Fuling, Chongqing, facing the challenge of the bottom pressure of 24.53 MPa and the bottom temperature of 90.73 °C, this new workover fluid was not only successfully applied, the application results showed that the resistance reduction rate of the system was greater than 70%, which could ignore the bottom pressure of the well to reach the target leak-proof point more smoothly, and after three times of recycling, it could still maintain good stability. According to the company, the workover fluid has reached the domestic advanced level, which is nearly 40% lower than the cost of conventional workover fluid, showing a good market prospect. (Hubei Daily all-media reporter Peng Yiwei correspondent Yan Shiting Li Peng)
Source: Hubei Daily