Optimization of Replacement Techniques in Dip Reservoir After Steam Flooding

The large-dip-angle (>10º) region accounts for a large proportion of the steam flooding test area in Qi40 block of Liaohe oilfield. As this area has entered the late stage of development, the production continues to decline and production cost continues to rise. Optimization study on the steam flooding follow-up development scheme in the typical high dip angle well group in Qi40 block was carried out. Four typical well groups in Qi40 block were chosen as the research target, the 3-D geologic model was constructed by Petrel and the numerical analysis model was built by CMG-STARS. Simulation results indicate that the producing degree of Lian I oil layer is high; while the producing degree of Lian II is low, with a remaining oil saturation of over 0.6, and there is little distribution difference in the high and low structural parts. Based on the characteristics of remaining oil saturation distribution in Lian I and Lian II oil layers, the stratified steam injection technology can be considered at the late production stage. Simulation result indicates the oil recovery can be enhanced by 4% with this method. In addition, the optimization on steam flooding follow-up development technologies in large dip reservoir indicate that the oil recovery can be enhanced by 5.2%, the maximum degree, with the intermittent steam flooding; secondly 4.6% with continuous steam flooding; and a relative small range with hot water flooding or steam and air compound flooding. The intermittent steam flooding has a higher Lian I producing degree than the continuous steam flooding, and a higher oil-steam ratio than the steam air compound flooding and the steam-water alternate flooding. Comprehensively, the intermittent steam flooding technology is recommended as the follow-up process to produce the large dip reservoir after steam flooding.