渤南洼陷沙四上段非均质性储层“二步建模”方法及应用

The approach of two-stage modeling and its application in the study of heterogeneous reservoir of Upper Member 4 of Shahejie formation in Bonan subsag

渤南洼陷沙四上段油气储层非均质性明显,砂层薄且与泥质间层分布,储层分布规律和空间叠置关系复杂。储层主要受深水盐湖、扇三角洲、滑塌浊积扇、近岸浊积扇、远岸浊积扇五类沉积相控制。利用先进的GridStrat建模软件,采用特殊的"二步建模"处理方法,根据不同沉积相的储层参数分布规律,进行井间插值或随机模拟,建立了沉积相、岩性、孔隙度、渗透率和产能系数模型。沉积相模型显示出扇三角洲及浊积扇是砂体分布的主体,且分布范围广;岩性模型显示出不同岩类的分布受沉积相带、构造位置及不同物源控制。孔、渗模型显示沉积相带和岩性是决定储层孔隙度与渗透率发育程度的主控因素。孔隙度决定了储油气空间的数量,渗透率决定了储层产能系数的大小。产能系数模型显示出产能潜力区为浊积扇和扇三角洲的叠合分布区。研究结论对油田开发部署起到积极指导作用。

The heterogeneity of oil gas reservoir is obvious in the Upper Member 4 of Shahejie formation in Bonan subsag. The sand layers are very thin and are interlayered with shale bands. The distribution and spatial superposed relation of the reservoir are very complicated. The reservoir was mainly controlled by five kinds of sedimentary facies, that is, the deep-water salt-lake, the fan-delta, the fluxoturbidite fan, the coastal turbidite fan and the remote turbidite fan. By use of the advanced GridStrat software that provides a special approach of two-stage modeling, and according to the distribution of reservoir parameters, we established the sedimentary facies model, the lithology model, the porosity model, the permeability model and the formation productivity model by data interpolation or stochastic simulation. The sedimentary facies model shows that the fan delta and the turbidite fan are the main distribution of sandstone and are widely distributed. The lithology model shows that the type of rocks was controlled by sedimentary facies, structure location and the distance from the sedimentary province to the source area. The porosity model and the permeability model show that the porosity and the permeability were mainly controlled by sedimentary facies and lithology, and that the hydrocarbon pore volume was controlled by the porosity and the formation productivity was controlled by the permeability. The formation productivity model shows that the prospective productivity will be offered from the superposed area of the turbidite fan and the fan-delta. The study results may provide active instruction for the deployment of oilfield exploitation.