Study On High-temperature Drilling Fluid Of Jidong Oilfield

In order to solve the outstanding problems of high temperature drilling fluid fordeep wells in Jidong Oilfield, the potential damage factors for deep formation werestudied based on analyzing petrological and reservoir space characteristics.The influence of aging temperature, pH value and bentonite content on theproperties of bentonite slurry was analyzed and the mechanisms underhigh temperature conditions were also investigated. The results showed that thethermal stability of the drilling fluid could be obtained under high temperatures intwo aspects, one is avoiding clay deactivation and the other is avoidingcross linking of treating chemical. Surface acting agent A20was optioned toimprove surface activity of clay while sodium sulphite was optioned to improve theoxidation resistance of drilling fluid. Finally the anti temperature drilling fluid oflow fluorescence was formed and was applied in NP282well. The field resultsshowed that the HTHP filter loss of the new system was less than18mL after agingfor72hours, the permeability restoration was higher than93%.