Research On The Technology Of Ultra-deep Well Workover In Acid Gas Field

Due to high H2S and CO₂ content, features in super depth, high temperature, high pressure, small wellbore, varieties of well structure and completion strings and complex production process, and a long operation period in YB acidic gas field, many malfunctions, such as the test tool strings and perforation gun broken off, blocking in wellbore, the high temperature degradation or thickening of workover fluid, are occurred, which severely hampered the effective development of YB gas field. Therefore it is necessary to carry out the study of workover technology for the super depth, acidic gas reservoirs in YB gasf ield. In this paper, the technology of fallen fish salvaging, plugging removal and workover fluid were researched for the super deep and acidic gas reservoirs in YB gasfield.1?The salvage of perforating gun ?and its accessories? and special test tool have being deeply researched. It is consist of the formulation of the salvage, the optimization of fish string, the improvement of fishing tools and so on. Finally, the technical specification of fishing the string fish in super deep and acidic gas reservoirs objective of these studies is formed.2?The hydrate blocking and solid blocking are the main block types in YB gasfiled super deep and acidic gas reservoirs. For the different plug types, this study optimizes the broken down scheme, the broken down equipment and the technological process and summarizes the operating parameter of broken down. Ultimately, the plug removing technology of annular heating and coiled tubing in YB gasfiled super deep and acidic gas reservoirs is established.3?The drilling fluid composition is optimized and improved from the several aspects including sedimentation stability of high temperature, resistance to H₂S and CO₂ which are acidic gas, resistance to salt water pollution, bentonite content, reservoir protection and fillers on the YB drilling fluid system basis. At last, the YB acidic gas ultra-deep well workover fluid technology is made.Application field test showed that the YB acidic gas ultra-deep well workover technology has been successfully applied to wells in YB, and has obtained the good effect, ensure the smooth development of the YB gas field and improves the economic benefit.