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川东北元坝地区上三叠统须家河组具备良好的探勘潜力,成为近年来油气勘探的重要区块。通过露头剖面实测、钻井资料收集、薄片鉴定、物性分析、沉积相及成岩作用分析等对元坝地区须家河组四段储层特征及主控因素进行了研究。结果表明:研究区须四段储集岩类型以岩屑砂岩、岩屑砂砾岩、岩屑石英砂岩为主;储集空间类型主要是剩余原生粒间孔、粒间溶孔、粒间微孔、粒内溶孔和裂缝。平均孔隙度为2.38%,平均渗透率为0.0661×10-3μm2,为典型的低孔低渗储层。须四段储层主要形成于冲积三角洲平原和冲积扇,胶结作用和压实作用是储层致密化的主要影响因素,而溶蚀作用和破裂作用有效地改善了储层条件。
The Upper Triassic Xujiahe Formation in the Yuanba area of northeastern Sichuan has good prospecting potentials and has become an important block in oil and gas exploration in recent years. Through the outcrop section measurement, drilling data collection, sheet identification, physical property analysis, sedimentary facies and diagenesis analysis, the reservoir characteristics and main controlling factors of No.4 member of Xujiahe Formation in Yuanba area were studied. The results show that the reservoirs in the four sections of Xuchang area are mainly composed of lithic sandstone, crushed conglomerate and lithic quartz sandstone. The main reservoir space types are residual primary intergranular pores, intergranular dissolved pores, intergranular micropores , Intragranular dissolved pores and cracks. The average porosity of 2.38%, the average permeability of 0.0661 × 10-3μm2, is a typical low porosity and permeability reservoir. The reservoirs in the four sections of Es4 are mainly formed in the alluvial delta plain and alluvial fan. The cementation and compaction are the main factors affecting the densification of reservoirs, and the dissolution and fracturing effectively improve the reservoir conditions.