Research On Anti-high Temperature And Clay-free Drilling Fluid In Salt Water

The current drilling fluid requirements of high temperature deep drilling process: betterborehole purification; fluid-loss control and micro-cracks dropout; maintain wellbore stability;reduce the damage to the oil and gas reservoir. Because of the presence of clay in traditionalclay drilling fluid system, sub-micron particles become more, the hydrocarbon layerprotection become ineffective, drilling speed is reduced. In connection with these deficienciesin clay drilling fluid, the polymer is selected to provide the basic properties of the drillingfluid, its less solid play a very good role in the protection of hypotonic oil and gas reservoir.The advantages of scouring the bottom of the well, carrying the debris and reducing drillingresistance in clay-free drilling fluid are also improved drill speed. the paper is based on theresearch of additives selecting in clay-free drilling fluid, anti-high temperature salt clay-freedrilling fluid system is developed.The paper evaluate weak gel WG-1through the synthetic additives in ZhongyuanOilfield, WG-1had better performance in the water and bentonite slurry, and had the obviousfunction of increasing viscosity and improving shear; the weak gel WG-1had bettertemperature resistance up to17℃0; WG-1had better effect on increasing viscosity andimproving shear after aging on170℃in alkaline salt water, and it can be applied to anti-hightemperature salt clay-free drilling fluid.Through contrast some traditional additives of improving shear in domestic and abroad.The paper preferred the program of increasing viscosity and improving shear in anti-hightemperature salt clay-free drilling fluid. The synthesis weak gel WG-1was sensitivity toalkaline at high temperature, the complex program of Na2CO3and NaOH were preferred asthe alkaline adjusting agent. The paper selected blocking fluid loss additive by synthesizingby Zhongyuan Oil field, which had excellent performance in reducing water loss. At the sametime，through selecting the appropriate weighting agent and anti-sloughing agent，it formedanti-high temperature salt clay-free drilling fluid， which had resistance to temperature effect up to170℃, which provided the better solution of viscosity reducing low-cut problemcaused by the degradation of the polymer in clay-free drilling fluid under high temperature;this fluid had better anti-bentonite pollution，at the same time anti-collapse resistance andlubricity meet the requirements of deep well drilling fluid，which can effectively reducedownhole accidents; anti-high temperature clay-free drilling fluid system can be maintainedbased on drilling fluid design, which was easily to control the properties of drilling fluid.