Experimental study on the critical initiation of reservoir fluid mud motions

Abstract

Reservoir fluid mud is the stagnant or near-stagnant suspension distributed at the bottom of a reservoir after variable-density flows. It consists of fine particles that flocculate easily, and its thickness can be maintained unchanged over a long time period. Because the formation and the movement of reservoir fluid mud are affected by various factors, and given that measured data relevant to the dynamic conditions of the reservoir fluid mud are lacking, current results can hardly explain scientific questions that have to be resolved. These include the development of reservoir fluid mud and its response mechanisms to subsequent floods. In this study, a pressurized sealed water flume is employed to simulate deep-water conditions and to facilitate the conduct of experiments on the initiation of reservoir fluid mud motions. The results demonstrate that the critical shear stress required for the initiation of motion of fluid mud increases exponentially as a function of the volumetric weight of fluid mud and water depth. The critical shear stress is much smaller than the Bingham yield stress and the two are associated according to a power-function relationship. The findings provide technical support for the utilization of the reservoir fluid mud and the optimization of reservoir operations.