普光地区嘉陵江组沉积相及储层特征

Sedimentary facies and reservoir characteristics of Jialingjiang formation in Puguang area

普光地区位于四川盆地东北部,由于对该区嘉陵江组沉积及储层特征认识不清,制约了油气高效勘探。综合运用测录井资料及薄片鉴定、物性测试、压汞分析等方法,对该地区嘉陵江组沉积相及储层特征开展分析。结果表明:嘉陵江组主要发育开阔台地、局限台地和蒸发台地三类沉积相,并进一步可划分为滩间海、台内滩、局限潟湖、局限潮坪、蒸发潟湖和蒸发潮坪等六个亚相和相应若干微相。其中,台内滩亚相和局限潮坪亚相中的云坪微相为储层发育有利相带。沉积相控制了储层发育带,嘉陵江组储层主要分布于嘉陵江组二段,储层岩石类型主要为颗粒云岩、其次为晶粒云岩,部分样品孔隙度小于2.00%,大部分样品孔隙度为2.00%~10.00%,平均为2.00%;渗透率为0.001×10–3~1.000×10–3μm2,平均为0.230×10–3μm2,总体属低孔、低渗储层,以Ⅲ类储层为主。

Puguang area is located in the northeast of Sichuan basin, due to the unclear understanding of the sedimentary and reservoir characteristics in this area, the efficient exploration of oil and gas is restricted. The sedimentary facies and reservoir characteristics of Jialingjiang formation in this area are analyzed by means of core, thin section identification, physical property test, mercury injection analysis and logging. The results show that Jialingjiang formation is mainly composed of open platform, limited platform and evaporation platform, and it can be further divided into six sub-facies and corresponding micro-facies, including inter beach sea, intra platform beach, restricted lagoon, limited tidal flat, evaporation lagoon and evaporation tidal flat. Among them, Yunping micro-facies in platform beach sub-facies and limited tidal flat sub-facies are favorable facies belts for reservoir development. The sedimentary facies controls the reservoir development zone, and the reservoirs of Jialingjiang formation are mainly distributed in the second member of Jialingjiang formation. The main reservoir rock type is grainstone dolomite, followed by crystalline grain dolomite. The distribution range of porosity is 2.00%~10.00%, and the permeability is 0.001×10–3~1.000×10–3 μm2, and the average value is 2.00% and 0.230×10–3μm2 respectively. Generally they are low porosity and low permeability reservoirs, mainly of class Ⅲ reservoirs.