东营凹陷民丰北带古近系砂砾岩体孔隙度量化表征

综合运用钻井岩心、录井等相关资料,结合镜下薄片观察,总结了东营凹陷民丰北带沙河街组储集层的沉积特征,根据高孔隙度发育的主要控制因素建立了民丰北带不同岩性、不同油-水层砂砾岩体的现今孔隙度量化表征图版,即不同分选和不同胶结物含量的孔隙度量化表征曲线。另外,通过对近岸水下扇各沉积亚相、微相的分选性、含油性及胶结物含量统计,按照现今孔隙度量化表征图版的应用条件,将近岸水下扇砂体分成5类,各类储层依据不同的特征对应着不同的孔隙度量化表征曲线。利用该方法预测的结果表明:扇根、扇缘及扇中辫状水道间砂体基本为无效储层,而扇中辫状水道砂体也并非全为有效储层,靠近泥岩层0.35 m以内的部位为致密胶结带,这一区域为无效储层,若砂体上、下均为泥岩层,则砂体厚度必须大于0.7 m才有可能成为有效储层,否则为无效储层。

Quantitative characterization of porosities of Paleogene glutenites in the northern Minfeng sub-sag of Dongying sag

Through comprehensive application of the drilling and logging data and other analytical tests in combination with microscopic observations, this paper summarized the deposition characteristics of reservoirs in Shahejie Formation of the northern Minfeng sub-sag of Dongying sag. According to the major controlling factors for high porosity, quantitative characterization of current porosities of the glutenites with different lithologies in various oil-water layers was conducted. Specifically, corresponding curves were established for the porosities of glutenites with different sorting coefficients and cementation contents. Based on the sorting features, oil potential and cementation contents of sedimentary subfacies and microfacies, the sand bodies of nearshore subaqueous fan were divided into five categories according to the application of quantitative characterization curves. Various types of reservoirs with different characteristics correspond to different curves. The results show most invalid sand reservoirs are found in fan root and fan edge, or between braided channels of the middle fan, while not all reservoirs in braided channel are valid. Reservoirs are invalid in the tight cementation zone, which is located 0.35 m away from the mudstone layer. If both the upper and lower of sand body are mudstone, valid reservoirs can be only found when its thickness is greater than 0.7 m.