非均质超稠油油藏SAGD快速启动技术界限——以风城油田侏罗系齐古组超稠油油藏为例

Limits of SAGD Fast Start-Up Technology for Heterogeneous Super Heavy Oil Reservoirs:A Case Study of Super Heavy Oil Reservoir of Jurassic Qigu Formation in Fengcheng Oilfield

以风城油田侏罗系齐古组非均质超稠油油藏为例,利用室内岩石力学实验结果,建立耦合应力场的数值模型,进行SAGD快速启动扩容过程的数值模拟分析,描述了风城超稠油油藏储集层的扩容特征,结果显示:在快速启动结束时,近井筒地带孔隙度提高2%,渗透率增加10%～100%,体积扩容率最大为1.74%,储集层可实现有效扩容。在此基础上,分别研究了水平井轨迹、储集层岩性、物性变化对快速启动技术的影响,得到SAGD快速均匀启动技术界限。研究结果表明:沿水平段无大段泥岩发育,水平段渗透率级差小于3,SAGD上下井轨迹垂向偏移小于1 m或平面偏移小于2 m的井组均适合采用快速启动,现场可针对SAGD井组及油藏实际情况选择性实施快速启动技术。

Taking the super heterogeneous heavy oil reservoir of Jurassic Qigu formation in Fengcheng oilfield and using indoor rock mechanics experimental results, the paper establishes numerical models of coupled stress field, carries out numerical simulation analysis onSAGD fast start-up expansion process, and describes expansion features for the super heavy oil reservoirs. The results show that when thefast start-up ends, the porosity and the permeability in near-wellbore zones increase by 2% and 10%~100%, respectively, and the volumeexpansion rate can reach 1.74%, indicating the reservoir can be effectively expanded. Based on which, the influences of horizontal well trajectory, reservoir lithology and physical property on the fast start-up technology are studied, and the limits of SAGD rapid and uniform startup technology are obtained. The study results reveal that the well groups with the following conditions can satisfy the fast start-up technology: no large mudstone section is developed along the horizontal section, the order differential of the permeability in the horizontal section isless than 3 and the vertical deviations between the upper and lower trajectory in the SAGD well are less than 1 m or the horizontal deviationis less than 2 m. The fast start-up technology should be implemented according to the actual situations of SAGD well groups and reservoirsduring field practices.