The Study Of Drilling Fluid For Reservoir Protection In Wuqi Area

The low permeability reservoir is easily polluted and damaged by drilling fluid during drilling operation.Once it is damaged,permeability of low permeability reservoir is more difficult to recover than that of high permeability reservoir.Taking Wuqi oilfield as the research object,by lab study and evaluation of field drilling fluid,this paper finds out that content of the field drilling fluid treatment agent is less,especially the content of inhibitor,which causes a large loss of water,and a large loss of water causes damage of water sensitivity and water block of the core,making the hole roar smaller.All of these lead to more pollution and plugging,and the flow conductivity is greatly reduced.This paper targets to study the excellent drilling fluid formulation to protect the reservoir on the basis of fully understanding of the geological features in Wuqi area,reservoir sensitivity,field drilling fluid reservoir damage and compatibility.First,start from inhibition evaluation of single agent used commonly,select those single treatment agent with better inhibition,and make the excellent drilling fluid formulation system under normal temperature through synergistic combination of treatment agents.Then,by surface active agent selection and compound experiment,optimize drilling fluid waterproof lock combination,and by scale inhibitor and lager dose,reduce plugging caused by incompatibility of drilling fluid filtrate and formation water.In the end,comprehensively evaluate the characteristics of salt resistance,temperature resistance,and anti pollution of the drilling fluid system.Determine reservoir protection drilling fluid system suiting for Wuqi area.The experiment shows that the recovered permeability value of core from this system is high,which is benefit to reservoir protection.