中西部地区中小盆地碎屑岩储层特征及含油气性分析

中西部地区中小盆地油气显示丰富，但勘探程度总体较低，油气发现较少。 以碎屑岩储层为研究对象，依据岩心观察、野外地质调查与实验分析，对中小盆地碎屑岩储层特征及含油气性影响因素进行了深入研究。结果表明：①中西部地区中小盆地共发育 5 套碎屑岩储层，分别为处于海陆过渡相沉积环境的石炭系-二叠系和三叠系、处于陆相沉积环境的侏罗系含煤层系和白垩系非含煤层系及处于冲积扇沉积环境的古近系-新近系；②砂岩储层较为发育，但其物性较差，属于低孔、低渗型储层，且含油气饱和度较低；③砂岩储层的矿物成分以石英、长石、黏土矿物、方解石和白云石为主，不同构造背景与沉积环境形成的储层，其矿物成分存在差异；④砂岩储层储集空间类型丰富，主要有粒内孔、粒间孔、微裂缝和有机质孔等 4 种类型；⑤砂岩储层的含油气性主要受沉积相带、岩石矿物组成、储层物性和储集空间类型等因素影响。

Clastic reservoir characteristics and oil-bearing properties within middle and small-sized basins in the central and western regions of China

The oil and gas shows are enriched in middle and small-sized basins in the central and western regions of China, but only few proven reserves were found with low exploration degree. Based on core observation, field outcrop data and experimental analysis, the clastic reservoir characteristics and the controlling factors of oil-bearing properties were analyzed. The results show that: （1） there are developed five sets of clastic reservoirs in the middle and smallsized basins, which are respectively in the Carboniferous-Permian and Triassic strata in transitional facies depositional environment, in the Jurassic coal-bearing strata and Cretaceous non-coal-bearing strata in continental depositionalenvironment, and in the Tertiary strata in alluvial fan depositional environment; （2） the sandstone reservoirs are well developed, but they have poor properties with low porosity, low permeability and low hydrocarbon saturation; （3） the mineral compositions of sandstone reservoir are mainly quartz, feldspar, clay minerals, calcite and dolomite, and different tectonic setting and depositional environment affected mineral compositions of the reservoir; （4） the reservoir space types are rich, including intraparticle pores, interparticle pores, microcracks and organic-matter pores; （5） the oil-bearing properties of sandstone reservoirs are mainly affected by sedimentary facies, rock and mineral compositions, reservoir properties and reservoir space types and other factors.