Oil-Based Mud with Low Oil/Water Ratio for Well Jiaoye 54-3HF

During drilling the third interval of the Well Jiaoye 54-3HF, oil-based mud (OBM) was required for its higher plugging and cuttings-carrying capacity. To recover the OBM with high utilization rate, polymer surfactants were used as main emulsifiers to produce a new OBM with desirable stability and rheological property by optimizing the volumes of emulsifier and organic clay, with oil/water ratio of 65/35. The performance evaluation showed that the new OBM has desirable cuttings-carrying and plugging capacities, which can meet the needs of drilling operations. It was determined that the optimal volumetric ratios should be 1:2, i.e. the new low oil/water OBM to the recycled OBM. Drilling fluids characterized by low oil/water ratio and recycled OBM were used in the Well Jiaoye-54-3HF, which featured avolumetric ratio of 1:2, oil/water ratios of 67/33-76/24, emulsion-breaking voltage of 600-1 000 V, and yield point and plastic viscosity ratio of 0.30-0.40. The third interval of the well has a stable sidewall, clean borehole, low friction resistivity and smooth in tripping operations. Thus results indicate that OBM with a low oil/water ratio can meet the demand of drilling horizontal wells for development of shale gas, having good prospects of applications.