Drilling Fluid Used for Gangshen-78 Well

Gangshen 78 well is an important wildcat well in shallow sea area of Dagang Oil Field. A special drilling fluid is developed for it in order to suit its formation and to prevent wall sloughing. Sea water polymer drilling fluid system is used in drilling upper formation, and KCl sea water polymer drilling fluid system is used in drilling down formation. It is shown that KCl sea water polymer drilling fluid system can meet the needs of preventing wall sloughing, and it has also good inhibitive property, suitability to temperature and lubricity. When it is drilled to 4420m, the well obtains the crude of 542.58m 3/d and the gas of 9.05×10 4m 3/d.