四川盆地卧新双地区须家河组储层发育特征

Reservoir characteristics of Xujiahe Formation in Woxinshuang area, Sichuan Basin

通过铸体薄片、扫描电镜、X射线衍射及常规物性资料,对卧新双地区须家河组储层的岩石类型、成岩作用特征及储集空间类型进行了研究,并分析了不同成岩作用对储层的影响。结果表明:卧新双地区须家河组储层主要为一套长石岩屑砂岩和岩屑砂岩,具有结构成熟度中等偏高、成分成熟度低的近源快速堆积特点;储层经历了压实-压溶、胶结、溶蚀、交代、破裂和自生矿物充填等成岩作用改造,其中强烈的压实-压溶、方解石胶结和自生矿物充填等作用是导致储层孔渗性变差和致密化的主要原因,绿泥石环边胶结是部分原生粒间孔得以保存的主要原因,溶蚀作用在一定程度上改善了储集性能,破裂作用则更有效地沟通了原生和次生孔隙,极大地提高了储层渗透性。卧新双地区须家河组主要发育特低孔、超低渗裂缝-孔隙型储层,储层孔隙度和渗透率总体相关性较差,但随着孔隙度的升高,孔渗相关性逐渐变好,具有良好的油气成藏条件和一定的勘探开发潜力。

Based on the data of cast slice, SEM, X-ray and normal physical properties, this paper studied the reservoir rock types, diageneses characteristics and reservoir space types of Xujiahe Formation in Woxinshuang area, and analyzed the impact of different diagenese on the reservoir. The result shows that the reservoir lithology is mainly feldspathie litharenite and lithic sandstone with the characteristics of low compositional maturity and medium-high textural maturity, and the provenance is proximal and rapidly accumulated. The sandstone in the study area experienced six diageneses： compaction-pressure solution, cementation, dissolution, replacement, fracturing and authigenic mineral filling. The intensely compaction-pressure solution, calcite cementation and authigenic mineral filling are the main reasons for the degradation of reservoir porosity and permeability and densifieation. The chlorite rim cementation is the main cause for the preservation of some primary intergranular pores. Dissolution to a certain extent, improves the reservoir performance. Fracturing is more effective for communicating the primary pores and secondary pores, and greatlyimproves the reservoir permeability. Xujiahe Formation in Woxinshuang area mainly developed fractured-porous type and extra-low porosity and ultra-low permeability reservoir. The reservoir porosity and permeability is poorly correlated in whole, but with the porosity getting higher, the correlation between porosity and permeability is gradually getting better. The Woxinshuang area has favorable conditions for oil and gas accumulation and has a certain exploration and development potential.