鄂尔多斯盆地A油田低渗透储层物性特征及其主控因素

鄂尔多斯盆地A油田长2储层岩性主要为细粒长石砂岩。储层类型为低孔低渗型,平均孔隙度为12.6%,平均渗透率为10.7×10-3μm2。长2储层物性主要受沉积微相、成岩作用、裂缝发育程度与规模控制:辫状河河道砂坝中-细砂岩具有较高的孔隙度和渗透率,天然堤粉细砂岩和细砂岩的孔隙度和渗透率较低;压实作用是导致长2储层砂岩孔隙度降低的主要原因;胶结作用进一步破坏孔隙度,碳酸盐岩是砂岩孔隙度降低的主要胶结物;溶解作用一定程度上改善了长2储层物性,裂缝对砂岩渗透率的提高有重要贡献。

Physical properties and main controlling factors for the low-permeability reservoirs from A oil field in the Ordos Basin

The Chang-2 reservoirs in A oil field in the Ordos Basin dominantly consist of fine-grainded feldspar sandstones which have low porosity and low-permeability,with an average porosity of 12.6% and an average permeability of 10.7 × 10-3 μm2,respectively.The physical properties are mainly controlled by sedimentary microfacies,diagenesis and fissure development and scales.The braided channel bar medium-to fine-grainded sandstones have higher porosity and permeability,while the natural levee siltstones and fine-grainded sandstones have lower porosity and permeability.The mechanical compaction in the early diagenetic phase and cementation of carbonate cements serve as a main cause of the loss of the porosity in the Chang-2 reservoirs.The dissolution may improve the physical properties of the Chang-2 reservoirs.The fissures may contribute to the increase of the permeability of the sandstones.