Improvement of mud displacement from the annular space of the borehole in terms of the criterion of selecting washing fluids and pre-flushes
Keywords:washing fluids, pre-flushes, mud displacement, sealing the wellbore, washing time
One of the most important steps in drilling the well is cementing the annular space between casing and rock formations. This process is significant because of the stabilization of the well and effectively separation of the consecutive rock horizons. It is required that cementing ensures durable and effective insulation of the rock mass. The complete displacement of the drilling fluid from the annular space is particularly important due to a number of negative phenomena related to its insufficient extrusion. The cement slurry pressed through the annular space displaces the mud but is not able to sufficiently thoroughly remove the residue left behind. The subject of the laboratory research was to check how selected washer affect the efficiency of displacing drilling fluid from the annular space of the borehole. In addition, the tests included the determination of the optimal washing time and the optimal pumping rate of the washing fluid. Moreover, the tests included the determination of the optimal washing time and the optimal pumping rate of the washing fluid.