新疆风城油田重18井区稠油储集层非均质性定量评价

Quantitative Heterogeneity Evaluation of Heavy Oil Reservoirs in Wellblock Zhong-18 of Fengcheng Oilfield, Xinjiang

新疆风城陆相稠油油田储集层中泥质夹层极为发育,具有极强的不均匀性和不连续性,且层段间差异明显,严重制约了稠油储集层SAGD的有效开发。为了评价此类储集层质量及其改造效果,需要对泥质夹层导致的储集层非均质性进行定量分析。利用洛伦兹曲线法,建立了描述油砂储集层中泥质夹层的非均质性评价模型;提出了几何非均质性系数、数值非均质性系数和综合非均质性系数的概念及其计算方法。应用该方法,定量评价了风城油田重18井区3口SAGD井的渗透率剖面,并将其与CMG数值模拟软件预测的稳产14 a后的采收率进行相关性分析。结果表明,此方法能够区分不同剖面的非均质性差异,且综合非均质性系数和采收率呈现较好的负相关关系,对SAGD区块优选和储集层改造效果评价具有一定的指导意义。

Muddy interbeds are extremely developed and widely distributed in the terrestrial heavy oil reservoirs in Fengcheng oilfield,Xinjiang.The muddy interbeds exhibit serious heterogeneous and discontinuous distribution with distinct differences between intervals,whichsignificantly impacts the effective development of the heavy oil reservoirs by SAGD technology.In order to evaluate the quality and reconstruction effect of the reservoirs,the reservoir heterogeneity caused by the muddy interbeds needs to be quantitatively analyzed.By usingthe Lorenz curve method,the paper establishes an evaluation model to characterize the muddy interbed distribution in oil sands;and presents several concepts about geometrical heterogeneity coefficient,numerical heterogeneity coefficient and composite heterogeneity coefficient and their calculation methods.With this method,the permeability profiles of3SAGD wells are evaluated in Wellblock Zhong-18ofFengcheng oilfield,and their correlations with the recovery after14years of stable production which is predicted by CMG numerical simulation software are analyzed.The results show that the method can distinguish the heterogeneity differences between different profiles and thecomposite heterogeneity coefficient exhibits a good negative correlation with the recovery,which could guide block optimization for SAGDand reservoir reconstruction effect evaluation.