Optimization Of Drilling Fluids In The Chuanxi Gas Reservoir In Western Sichuan

Because the Xujiahe Formation five sections gas reservoir buried deeply in the west of Sichuan, the geologic structures are complicated, fracture development, the rock is dense,the grinding is strong, wells leakage,wellbore instability, sticking pipe, reaming and other complex cases is easy to occur during drilling,low drilling speed and long drilling cycle, which seriously affected the development of oil and gas exploration and development,and not adapted to the growth of the national economy.Drilling fluid as "drilling blood",so it is necessary to drill fluid optimized for the Xujiahe Formation five sections gas reservoir in western Sichuan,further improve the drilling speed,shorten the drilling cycle.By analyzing and summarizing the theoretical influence factors of drilling fluid on the drilling speed,it is concluded that the main drilling fluid affecting the mechanical drilling speed is the density of drilling fluid in the deep section before,the second is the solid content of drilling fluid.The main influence factors of mechanical drilling speed are the rheological property and viscosity of drilling fluid when the well depth is more than Xujiahe Formation. After comparing the real drilling data of CX568 well and X201 well,is proposed to drill fluid measures for enhances drilling speed the Xujiahe Formation five sections gas reservoir in western Sichuan.The low solid drilling fluid based optimization system should be used in the shallow layer of the middle shallow layer acceleration,optimization of polysulfonate drilling fluid system should be taken into consideration cooperate with drilling speed in the deep well section. Through a lot of experiments,the drilling fluid was optimized from two aspects:the inhibition and rheology,and according to the construction experience and indoor results,the application limit of polymer drilling fluid is put forward.The optimization and strengthening of the anti-collapse plugging of the polysulfonate drilling fluid were carried out,and puts forward the targeted anti collapse blocking system.And the shallow and deep plugging technology optimization.In the X504 well and X503 well,the field test was successfully carried out,through the middle shallow layer low solid polymer drilling fluid with raising speed technology?deep layer polysulfonate anti collapse drilling fluid technology?application of leakage protection and sealing technology,compared with the non test wells average penetration rate increase of 57.73%,the average drilling period is shortened by 18.11%,while caving,lost circulation etc. complex situations are both to improve, to achieve the desired purpose.