Research On Drilling Fluid For Leak Prevention And Plugging Of Directional Horizontal Well In Double 6 Block

Well loss is an important problem that reduces the speed of drilling,which not only causes a large amount of drilling fluid to be lost,but also causes a series of serious underground accidents such as sticking occurred or well blowout.Well loss is harmful to the drilling,It is important how to deal with well loss on domestic and foreign drilling industry attention.There are many reasons for the leakage of the well and restricting well leakage.How to deal with the different well loss factors has become a technical problem to be solved on the petroleum technology.The double block 6 is located in the Shuangtaizi faulted anticline belt in the western depression of Liaohe fault depression,Shuangtaizi oilfield.The fault basin in the eastern part of the block is a complex fault block structure,which is characterized by complicated and changeable sedimentary facies of fluvial facies.In this paper,the reasons for lost circulation in the double 6 block are analyzed to improve the existing drilling fluid systems.The appropriate ratio of lost circulation while drilling agent to carry out well loss.The experiment found that adding bentonite 4% +1%single blocking agent +2% compound plugging agent +1% in drilling fluid existing in ultrafine calcium carbonate composition drilling plugging agent can effectively seal leakage and micro crack formation,ensure the smooth construction of drilling.In view of the problem that the cementing quality is not qualified in the process of well casing casing casing cementing in the double 6 block well.In this paper it put forward a new type of pressure sealing formula for the double 6 block:Plugging plugging formula of +5% for drilling fluid+2% low permeability plugging agent BST-II +2% cottonseed shell +3% fine grain walnut shell.It is bridging plugging.Improve the formation induced stress and the formation of dense mud cake in the wall to improve bearing capacity.It is used in double block 6 which reduces 5 days.The plugging efficiency is improved,and the requirement of the bearing capacity of the formation is satisfied.