Research And Application Of Sealing By Pressurization In Drilling Fluid

Lost circulation is often happened during oil drilling process. It not only influences the normal drilling operations, but also derives other types of buttonhole complicated accidents, such as well collapse; stuck pipe and even blowout accident if it’s serious, meanwhile causes a substantial increase in the drilling costs. It has been a technical topic to solve lost circulation and recover the normal drilling operations as soon for many years, with the continuous development of drilling industry.The project in this paper is for the problem of lost circulation, which caused by some buttonhole complicated since it been researched and tested in field, such as the reduction of formation pressure in Liao He oilfields; the coexistence of multiple sets of formation pressure in long open hole section, and the method to complete cementing work while the well always meets the problem of lost circulation caused by the low reservoir pressure, such as Shuang6 well and Liu Zhuang gas storage.Analysis the characteristics of stratum in the leakage block and the reasons of lost circulation. Forming a leak proof and plugging drilling fluid system. Improving the plugging and bearing capacity of formations efficaciously, Ensure wellbore stable, the normal construction of long open hole section and cement slurry can be returned to the ground when conduct cementing operations in Liu Zhuang gas storage.R & D optimized a new high fluid loss acid soluble plugging agent, through the analysis and research about the vicious lost circulation in the southern block of Sulige.Overcoming the problems about improper collocation of particle size of the existing conventional plugging formula, easy to fracture the formation pressure when the pressure hold block, plugging slurry easy taking, easy erosion failure. Optimizing leak-proof and plugging process in the southern block of Sulige, solving the vicious lost circulation problem in the southern block of Sulige.