Research And Application Of New Formation Protection Drilling And Completion Fluid System In Dagang Oil Field

Because of the positive pressure differential casued by drilling fluid, it is hard to avoid formation damage during the drilling process. In order to decrease the damage degree,and eventually achieve zero damage drilling, researches on formation protection drilling and completion fluid are carried out.In the last twenty years, formation protection technologies have made a great progress and wide application and dissemination.Especially the broadspectrum"oil film"temporary plugging drilling fluid system,which could plug many kinds of formation using the same system. But field conduct shows that this temporary plugging agent GPJ can be improved and especially the compatibility with existing drilling fluids. Based on the laboratory experiments ,a favorable cation loss control agent is selected to combine with GPJ at a optimum proportion. Then we get a new agent named FPA. This paper evaluates basic properties and properties in base mud of this agent, place stresses on its compatibility with many kinds of mud systems used in field and formation protection ability. Results of laboratory experiments show that add this agent FPA to existing mud at a proper proportion,then can convert the initial mud to the new formation protection mud. Field experiments of four wells in Dagang Oil Field demonstrate that this new mud system has perfect formation protection effect, and should be popularized and applied widely.Meanwhile, this paper proposes a new formation protection methode which is called cooperation synergism that new formation protection drilling fluid cooperates with common shielding temporary plugging technology. And preliminary laboratary experiments were carry out. Results show that this principle is hopeful to achieve the zero damage drilling goal.