海上特稠油超临界蒸汽驱物模数模一体化研究

Physical-Numerical Simulation Integration of Super-Critical Steam-Flooding in Offshore Extra-Heavy Oil Reservoir

针对超临界蒸汽驱的增产机理和效果预测缺乏定量研究的问题,运用物模数模一体化的方法,在增产机理实验数据的基础上,开展了超临界蒸汽驱增产机理的数值模拟等效表征研究,并分析了驱替过程中原油热裂解和岩石溶蚀作用分别引起的原油组分和储层渗透率变化规律。结果表明:特稠油在超临界蒸汽热裂解作用下黏度下降,约为原始值的26%,沥青质与胶质在一维驱替初期开始热裂解为轻、中质组分,并伴随焦炭沉积于产出端附近;岩石在超临界蒸汽溶蚀作用下渗透率最大增幅为22%,一维驱替过程中注入端附近温度在亚临界区与超临界点范围内,是溶蚀效应发生的主要区域;特稠油油藏超临界蒸汽驱开发较常规蒸汽驱开发可提高驱油效率达15. 9个百分点。该研究可为海上特稠油油藏超临界蒸汽开发可行性论证及方案设计提供技术支持。

Physical-numerical simulation integration was adopted to quantitatively characterize the enhancing mechanism and performance of super-critical steam flooding. An equivalent characterization with numerical simulation for the super-critical steam-flooding was carried out based on the experiment data of enhancing mechanism. It also presents the effects of thermal cracking and rock dissolution on the crude oil composition and reservoir permeability. Research indicates that the extra-heavy oil viscosity was reduced to 26% of the original value by the thermal cracking effect of super-critical steam. Asphaltene and colloid begin to thermally crack into light and medium components in the early stage of one-dimensional displacement,which deposits near the outlet end. The permeability was maximally increased by 22% under the effect of super-critical steam dissolution. The inlet temperature is within the range of the sub-critical and super-critical points,which is the major area for active dissolution effect. The supercritical steam-flooding in extra-heavy oil reservoir can improve the displacement efficiency by 15. 9 persentage points comparing with that of conventional steam-flooding treatment. This research could provide certain technical reference for the feasibility demonstration and program design of supercritical steam-flooding development in offshore extra-heavy oil reservoir.