Research On Coiled Tubing Operation Technology Of Complex Structure Well

At present,coiled tubing operation has been widely used in workover,acidizing,fracturing,perforating,logging,drilling,well completion,and surface oil and gas pipeline unblocking.It plays a very important leading role in the development of oil and gas resources exploration in China,and the future development prospect is still very big.Compared with the current conventional tubing operation section,the technical advantages of coiled tubing are as follows: 1)high construction efficiency,no need for screw connection,fast tripping;2)high degree of automation,high integration of surface operation equipment,safe and reliable operation;3)less formation pollution,direct operation without well killing,which reduces the pollution of killing fluid on the formation,which is conducive to ensuring the safety of coiled tubing Fourth,it has strong adaptability and can complete the work that cannot be done by ordinary operation,such as highly deviated well,horizontal well and operation under pressure.At present,coiled tubing operation is mainly used in workover,highly deviated and horizontal wells,stimulation measures and auxiliary operations.Coiled tubing workover operations include sand washing,gas lift and other circulation operations;drilling and milling operations in the pipe;wax cleaning and scaling removal under pressure and hydrate plugging removal;fishing of falling objects in the pipe;cutting stuck pipe string;passing through tubing;discharging bottom hole liquid by velocity tube.The operation contents of coiled tubing highly deviated well and horizontal well include horizontal well deviated well perforation,horizontal well deviated well logging,perforation with pressure test,fishing operation,etc.The auxiliary operation of coiled tubing includes high pressure jet radial sidetracking,surface gathering pipeline cleaning,negative pressure operation technology and special treatment technology.The operation contents of coiled tubing stimulation include acidizing,fracturing,squeeze injection through tubing and reservoir treatment.However,due to the fact that it is in the middle and late stage of oil and gas field development,there are many complex wells and difficult wells.Coiled tubing operation is not only constructed in a single operation mode as before,but also requires a combination of various tools and processes,which puts forward new requirements and high standards for coiled tubing construction technology.In view of the increasing difficulty of oil and gas field development and the increasing number of complex wells,the coiled tubing construction is becoming more and more difficult.In this paper,coiled tubing tools,coiled tubing string mechanical analysis and horizontal well coiled tubing acid fracturing technology are studied in detail.And in the actual use of the tool to optimize the matching,so that it can achieve the optimal effect in different processes and working conditions.The successful application of the series of achievements formed by the technical research of coiled tubing operation in complex structural wells has solved the problems of coiled tubing construction in horizontal wells,highly deviated wells and complex well conditions,and achieved economic and technical indicators such as the maximum operation depth of more than 5000 m,and remarkable economic and social benefits.