塔河油田于奇西地区奥陶系洞穴充填程度预测与应用

Filling Degree Prediction of Ordovician Paleocave and the Application in Yuqixi Area of Tahe Oilfield

塔河油田于奇西地区奥陶系碳酸盐岩储层类型以岩溶缝洞型为主,工区中大型洞穴较发育,但由于经历了多期构造运动和岩溶作用,使储层的储集性能遭受破坏,相当部分的洞穴储集空间被充填。洞穴型储层油气产量的高低主要受控于洞穴的充填程度,其中仅中低充填程度的洞穴储集性能较好、油气产量较高。因此,识别、评价预测充填程度较低的岩溶缝洞型储层成为该区寻找高效富集区的关键。本文以洞穴储层发育模式为指导,针对于奇西地区已钻遇洞穴特征,设计不同大小的缝洞体和不同充填程度的地质模型,以波动方程正演模拟为基础,基于属性分析优选出对洞穴大小和充填程度敏感的属性。洞穴充填程度和敏感属性值存在线性关系,通过相关性分析拟合出反映二者关系的曲线量版,以此预测洞穴的充填程度。运用该方法在于奇西地区预测的充填程度结果与实际较吻合,说明该方法在识别未充填和部分充填洞穴型储层中具较好的可靠性,对于奇西洞穴型储层有利区的寻找具积极的推动作用。

The Ordovician carbonate reservoir space is mainly large cave,dissolved pores in Yuqixi area of Tahe Oilfield,middle and large caves are developmental in the work area,but it has experienced multiple tectonic movements and Karstification,it makes the reservoir reconstructed and caves filled seriously.The oil and gas production is mainly controlled by the filling degree of caves in this type of reservoirs,only the middle and low filling degree caves have better reservoir property and higher oil and gas production.Therefore,it is key for the exploration work to identify and evaluate the favorable development zone of karst fracture cave reservoir,which is lower filling degree.This paper is guided by developmental mode of cave reservoir,according to the characteristics of the caves in Yuqixi area,geological model of cave reservoir can be established,which have considered the different size and different filling degree,based on wave equation seismic forward modeling and attribute optimization,the best sensitive seismic attributes for cave reservoir are confirmed.There is a linear relationship between cave filling degree and sensitive attribute value,getting the quantities version by correlation analysis and fitting curve,the filling degree of caves can be predicted.Use this quantities version to predict filling degree of cave in Yuqixi area,the result is consistent with the fact.It shows that the method has good reliability in identifying unfilled and partially filled cave reservoirs,it is positive for finding favorable area of cave reservoir.