Design Of Floating Collar And Optimization Of Its Position

With the development of petroleum exploration and development,the directional well and horizontal well drilling technologies are becoming more and more mature,and the technology of extended reach well has been developed at home and abroad.Especially extended reach wells can offer significant commercial advantages and greater drainage coverage of a reservoir is achievable from fewer locations.However,due to the high angle and long horizontal section of the extended reach well,the casing pipe and the tail pipe are hard to be run into the bottom of the well.In order to minimize the frictional resistance of casing,the floating casing technology is widely used at home and abroad.The key to floating casing technology is the reliability of the floating collar and the reasonable calculation of the position of the floating collar.Therefore,it is of great significance to study the floating collar of high reliability and the optimization method of the position of the floating collar.On the basis of the investigation of the structure and working principle of the floating collar at home and abroad,this paper designs a kind of drilling-free floating collar for extended reach wells.The floating collar mainly comprises of a sleeve body,a sliding sleeve,a resistance part,a leather bowl and a sealing ring.In the process of running casing in extended reach wells,the floating collar is placed in the designed installation position.The reliable sealing performance makes the casing section between the supporting ring and floating collar hollow,so the casing in horizontal section is in the middle of the borehole.This can reduce the contact between the casing and borehole,so the sliding frictional resistance is greatly reduced and the casing can be run smoothly to a specified depth.After the completion of the design of the floating collar,the important parts were checked,and the sliding sleeve and the bearing block which are the mainly affected parts by the force are analyzed and checked by the ABQUS software.After analyzing,the floating collar can fully meet the designing and operating requirements.In addition,based on the stress analysis of the casing string of extended reach wells,a model for calculating the frictional resistance of extended reach wells is established based on the rigid rod model.The influence of viscous resistance of drilling fluid,buckling of pipe string and dynamic load on frictional resistance is considered,so the calculation accuracy is improved.Finally,based on the model,the optimization procedure of the floating collar’s position in extended reach well is compiled in the MATLAB.And by comparing the landmark software simulation results and actual results,the accuracy of the model and optimization method is validated.The research results show that the floating collar designed for floating casing pipe in extended reach wells in this paper is reasonable,and it has a good sealing performance and a high reliability,and it can completely meet the actual needs of the drilling site.At the same time,the established model for casing frictional resistance calculation is simple and accurate,the proposed optimization method of floating collar’s position calculation is easy to understand and has a small running time,it can fully meet the needs of floating casing technology for extended reach wells.