Abstract:With the continuous development of oil industry and the continuous widening of the exploration and development field in the world, the direction of exploration and development has gradually transformed to“exploring deep deposit”. The increase of the proportion of high-risk wells, deep wells and ultra-deep wells has put forward higher requirements for drilling technology and drilling fluid technology. Especially since 2014, the drilling environment of Dongsheng gas field changed significantly, due to the application and extension of drilling fluid recovery technology, a lot of used drilling fluid is involved in the circulation after simple treatment, large amount of submicron in such drilling fluid makes the maintenance and treatment difficult. For infill wells construction in old blocks, especially the exploited blocks, the permeability of drilling fluid during the pre-drilling process reduced the mechanical strength of strata rocks and changed the stress distribution of rocks, which makes the formation pressure can not be accurately predicted on the basis of the original geological data, the borehole instability problem is more prominent. Therefore, scientific management and fine management are also necessary for drilling construction, and simulation analysis is more necessary to accurately determine the performance range of drilling fluid for wall stability. The paper discusses the borehole instability of Dongsheng gas field in recent 2 years, a set of borehole stability technology is formed by the combination of drilling fluid and engineering measures to deal with the increasingly complicated borehole conditions.
