Study On Surface Excellent And Fast Drilling Technology In Zhaotong Block

Zhaotong block is an important area for shale gas exploration and development in China.There are complex strata with multi-stage collapse and leakage coexisting on the surface of this area.Conventional drilling technology can not effectively solve this complex stratum,and the successful drilling experience of adjacent blocks can not be simply copied in this block.There are technical problems with long surface drilling cycle and high risk of sticking,which seriously restrict the speed and efficiency of shale gas well drilling.Aiming at the problem of Zhao tong surface drilling,this paper takes the new surface excellent and fast drilling technology,casing reaming bit and drilling parameters as the research object,and carries out the research on Zhao tong surface excellent and fast drilling technology by combining theory,numerical simulation and field test,mainly including:(1)This paper summarizes and analyzes the difficulties of surface drilling in Zhaotong block and the principle,scope of application,advantages and disadvantages of existing drilling process technology,designs a new process method suitable for excellent and fast surface drilling in Zhaotong block,and deeply analyzes the principle and advantages of this process.(2)The drilling conditions of casing reaming bit and the relationship between bit size and casing are analyzed and summarized,and the overall structure and design parameters of casing reaming bit are determined;The cutting structure of casing reaming bit is optimized,and an outer diameter is designed φ 385 mm,inner diameter φ 320 mm casing reaming bit,and its rock breaking stress analysis and strength check.(3)ABAQUS software is used to simulate the dynamic drilling process of casing reaming bit,analyze the influence law of different WOB and speed combination on bit footage displacement,average reverse torque and drilling acceleration,and obtain the theoretical reference range of drilling parameters of the new surface excellent and fast drilling process: wob 20-40 k N,speed 30-50 rpm.(4)The field application of 20 wells in Zhaotong block summarizes the optimization criteria of field drilling parameters,and carries out the comparative analysis of application effects.The analysis results show that the average drilling cycle of a single well is saved by 32.1d,and the overall speed increase effect is 68.3%.There is no downhole complex situation,which effectively ensures the safety of surface drilling,and the speed increase and efficiency effect is obvious.It provides a new technical method for optimal and fast drilling in this kind of difficult drilling formation.