渤海是海上异常高温高压低渗油藏高效开发的试验区,沙二段为其主力储集层,查明该区的低渗储层特征及成因对油田高效开发具有重要意义.综合利用温压测试、岩矿分析、物性分析等资料,对低渗储层特征及成因机制进行系统分析.结果表明:渤海海域X油田沙二段储层属中孔低渗储层,不同沉积作用形成的储层结构组分特征各异,从而导致储层原始物性存在差异;成岩作用是形成低渗储层的关键因素,成岩早期压实作用、胶结作用强烈,成岩后期溶蚀增孔作用有限,成岩晚期胶结作用持续加剧储层低渗进程,同时高温高压条件下对压实作用抑制较弱,对溶蚀作用影响有限,胶结作用增强,以上因素综合导致沙二段储层低渗;该成果深化了该区低渗储层的认识,为后期勘探开发中有利储层的优选提供了依据.%Bohai X oil field is a pilot area of high efficiency development of offshore abnormally high temperature and high pressure low permeability reservoirs.The Sha 2 member is the main reservoir.It is important to find out the characteristics and causes of the low permeability reservoirs in the area.The data of temperature and pressure test,rock-mineral analysis,reservoir physical property analysis were used to analyze the characteristics of temperature and pressure,the feature of low permeability reservoir characteristics of the Sha 2 member in Bohai X oilfield.The results show that the Sha 2 member mainly developed mesopore and low permeability reservoirs,the sedimentary difference,which leads to different primary geophysical properties because of different material composition,grain size and sort,is the primary cause of low permeability.The diagenesis is the vital cause of low permeability.The compaction and cementation in early diagenetic stage,the dissolution in later diagenetic stage and continuous cementation in late diagenesis.Meanwhile,The abnormally high temperature and pressure environment has a lesser effect on compaction and dissolution,but cementation show a better reinforcement effect.The above factors have combined to form the low-permeability reservoirs finally.The results deepen the understanding of the low permeability reservoir,and provide the basis for the selection of favorable reservoirs in the late exploration and development satge.
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