准噶尔盆地侏罗——白垩系煤系与非煤系储层成因模式与孔隙定量预测

Diagenetic Patterns of Jurassic – Cretaceous Coal Measure and Non-coal Measure Reservoirs and Porous Quantitative Prediction in Junggar Basin

根据煤或碳质泥岩发育程度,将准噶尔盆地侏罗—白垩系划分为煤系储层(八道湾组、西山窑组)和非煤系储层(三工河组、头屯河—齐古组、吐谷鲁群)。文章从储层基本特征描述、储层性质的主控因素分析、储层成因模式的建立和储层性质评价与预测等四个方面,对重点地区侏罗—白垩系储层展开研究。认为侏罗—白垩系相对优质储层均为剩余原生粒间孔隙发育型储层,而成岩压实作用强弱是决定粒间孔隙保存的关键因素,由于煤系与非煤系储层物理与化学成岩作用模式与进程有明显差异,其压实作用的表现形式也不同,并导致储层原生孔隙的保存条件有明显差异。同时,煤系储层溶蚀作用主要是对颗粒的溶蚀,并不能有效改善储层的孔隙结构,对渗透率贡献小,甚至在一定条件下起负作用,溶蚀作用产生的副产物对储层的渗透性能也有较大的负影响,从而揭示了非煤系储层三工河组、头屯河组和吐谷鲁群的物性普遍优于煤系储层八道湾组和西山窑组的原因。在明确储层性质控制因素和控制机理的基础上,建立了三大类储层的成因—演化模型,并在此基础上分地区和分层位进行了储层评价和预测,指出了不同渗透率储层的深度界线及相对优质储层的平面分布。

Jurassic – Cretaceous System in Junggar Basin can divided into coal measure reservoirs (Badaowan Formation and Xishanyao Formation) and non-coal measure reservoirs (Sangonghe Formation,Toutunhe-Qigu Formation,Tugulu Group).The study is made on the key areas of Jurassic – Cretaceous reservoirs on the basis of description of basic reservoir characteristics, analysis of main controlling factors for reservoir properties, establishment of reservoir diagenetic patterns and assessment and prediction of reservoir properties. It is considered that the relatively high-quality reservoirs of Jurassic – Cretaceous are the ones of remaining original intergranular porous evolution type.The strength of diagenetic compaction is the key factor to determine the existence of intergranular pores.The compaction took different forms owing to the apparent difference in physical and chemical diagenetic patterns between coal measure reservoirs and non-coal measure reservoirs, thus causing the obvious difference in the keeping conditions for the original pores of reservoirs. Meanwhile, the dissolution effect of coal measure reservoir was made mainly on particles and could not effectively improve the porous texture of reservoir. The dissolution made little contribution to permeability and even exerted negative effect under a certain condition. The by-product caused by dissolution also exerted negative in?uence on the permeability of reservoir. That is why the physical properties of Sangonghe Formation, Toutunhe Formation and Tugulu Group of non-coal measure reservoir are generally better than those of Badaowan Formation and Xishanyao Formation of coal measure reservoir. Based on clari?cation of the controlling factors and controlling mechanism of the reservoir properties, the diagenesis-evolution model is established for the reservoirs of three major categories. Then, reservoir assessment and prediction is made according to the different zones and levels, pointing out the depth boundaries of the reservoirs with the different permeability and plane distribution of relatively high-quality reservoirs.