辽河坳陷鸳鸯沟地区成岩相分析与异常高孔带预测

Diagenetic Facies Analysis and Anomalously High Porosity Zone Prediction of the Yuanyanggou Area in the Liaohe Depression

岩心的实测孔隙度、普通薄片和铸体薄片资料表明,鸳鸯沟地区新生界储层发育3个异常髙孔带。为了预测异常髙孔带的横向展布,选取对成岩作用反应敏感的、成岩阶段划分常用的成岩指标古地温、镜质组反射率、甾烷C29S/R+S、伊/蒙混层中蒙皂石层的含量和自生石英含量这5项参数,分别在时空领域内进行单项成岩作用的数值模拟,预测了鸳鸯沟地区成岩阶段和成岩相的横向展布。异常髙孔带内的储层主要发育于河口坝、辫状分流河道以及心滩沉积微相,处于早成岩阶段B期晚成岩阶段A1期,发育溶蚀成岩相,所以通过叠合成岩相图与沉积相图即可预测异常髙孔带的平面展布。沙三段的异常髙孔带主要分布在鸳鸯沟地区中部的斜坡带,其延伸方向大致平行于辽河西斜坡的走向。

The measured porosity data and the observations of the thin sections and blue epoxy resinimpregnated thin sections show that there exist three anomalously high porosity zones vertically in the Cenozoic reservoirs in the Yuanyanggou area, Liaohe Depression, Bohaiwan Basin. To predict the lateral distribution of anomalously high porosity zones, the diagenetic stages and diagenetic facies has been predicted by digital modeling of the diagenetic parameters,＂ e. g. paleotemperature, vitrinite reflectance, sterane isomerization rate, smectite and authigenetic quartz concentrations in space-time, respectively. The chosen diagenetic parameters are sensitive to diagenesis and applied to divide diagenetic stages commonly. The anomalously high porosity zones are dominantly formed in the channel mouth bar, braided channel and channel bar deposits in the early diagenetic stage B period to late diagenetic stage At period, and developed dissolution diagenetic facieses. Therefore, the anomalously high porosity zones in the reservoirs could be blocked out by superposing the diagenetic facies maps on the microfacies maps.The anomalously high porosity zone of the Shasan member is mainly located in the middle slope part of the Yuanyanggou area, and extends along the western slope of the Liaohe Depression.