Technology for drilling multilateral horizontal wells of Ansai low permeability oilfields

Through analyzing the geological characteristics of the oilfield of low permeability,and the adaptability of the method of developing multilateral wells,as well as the technical characteristics of the method,Well Xingping-1,the first multilateral horizontal well of Ansai Oilfield,is successfully completed,based on the research and application of such techniques as the optimization of multilateral well structure,bit selection,trajectory control,branch hole sidetracking,geosteering,friction and torque analysis.The well is finished with the depth being 5068 m,the horizontal displacement 1574.22 m,the main horizontal section 1203 m long,the ratio of vertical water depth 1.16.With the use of conventional drilling equipment and steering tool,the low-side sidetracking technique is successfully applied to the main horizontal section.As a result,seven branch holes are drilled,which are 2300 m long in total,as well as 3503 meters of target reservoirs are opened.What’s more,reentry into drilling wells is realized for many times.Multiple-well drilling techniques,suitable for the geological characteristics of Ansai Oilfield,have come into being preliminarily.