鄂尔多斯盆地上三叠统延长组储层致密史恢复

Recovery of compact history of Yanchang reservoir in Upper Triassic, Ordos Basin

郭正权 齐亚林 楚美娟 程党性

Guo Zhengquan Qi Yalin Chu Meijuan Cheng Dangxing

中国石油长庆油田分公司勘探开发研究院, 西安, 710018 2. 低渗透油气田勘探开发国家工程实验室, 西安, 710018

Exploration and Development Institute of Changqing Oilfield, PetroChina, Xi'an, Shaanxi 710018, China 2. National Engineering Laboratory of Low-Permeability Oil and Gas Field Exploration and Development, Xi'an, Shaanxi 710018, China

针对鄂尔多斯盆地延长组储层低渗透—特低渗透特征,通过对延长组砂岩铸体薄片显微镜和扫描电镜观察鉴定,识别出延长组低渗砂岩储层主要经历了压实、胶结、溶蚀、烃类侵位等成岩作用,并明确了各种成岩作用的先后序次,搞清了三角洲砂岩与重力流砂岩的成岩序列的差异,前者绿泥石膜较发育,压实作用相对较弱,后者不发育绿泥石膜,压实作用较强烈。通过对各种成岩作用的定量计算,恢复了孔隙演化史,表明早期压实作用和晚期胶结作用是孔隙度降低的主要原因;经过早期压实作用之后,储层未致密,而晚期胶结作用之后,储层孔隙度降至12%以下、渗透率1×10-3μm2左右,变为特低—超低渗透储层。这些认识对寻找预测相对高渗储层进而发现油田有重要的指导作用。

Microscopy and scanning electron microscopy identifications of cast thin sections of sandstones from the Yanchang Formation of the Ordos Basin have been made in view of the characteristics of low and ultra-low porosity and permeability.Diagenesis effects such as compaction,cementation,dissolution and hydrocarbon emplacement have been proved in the sandstone reservoir of the Yanchang Formation and the diagenesis sequence has been made clear.The difference of diagenesis sequence between delta sandstone and gravity flow sandstone has been studied.Chlorite membrane is well-developed in delta sandstone and the compaction effect is weak.In gravity flow sandstone,chlorite membrane does not exist and the compaction effect is severe.Through the quantitative calculation of diagenesis,the evolution history of porosity has been restored.Early compaction and late cementation lead the decrease of porosity.After the early compaction,reservoir is not tight.And after the late cementation,porosity has decreased to below 12% while permeability is about 1×10-3μm2,both referring to extra-low and ultra-low permeability reservoir.These perceptions have an important guiding significance in predicting relatively high permeability reservoirs and discovering oil fields.

国家科技重大专项“鄂尔多斯盆地大型岩性地层油气藏勘探开发示范工程”(2011ZX05044)资助

https://doi.org/10.11781/sysydz201206594