渤海海域中侏罗统煤系碎屑岩储层主控因素

摘要

The clastic reservoir of Middle Jurassic coal measure in the Bohai Sea area is of strong heterogeneity,which restricts its further exploration severely.In this paper,the Middle Jurassic Haifanggou Formation in Qinan faulted terrace belt was taken as an example.The main factors controlling the clastic reservoirs of coal measure were analyzed by means of test methods,such as thin section analysis,scanning electron microscope,electron probe and carbon/oxygen isotope analysis.It is indicated that the development of quality reservoirs are controlled jointly by sedimentation and diagenesis.Among them,sedimentary facies is the foundation for the formation of reservoirs,and sustainable andconstructive diagenesis is the key to the formation of reservoirs.The cements formed in the early stage of diagenesis (e.g.micritic quartz and iron dolomite) are favorable for the preservation of original pores,and a great number of secondary pores are generated by organic acid denudation and epigenetic weathering and leaching in the deep layers in the middle stage of diagenesis.In the study area,the quality reservoirs are mainly distributed in the area with favorable sedimentary facies and abundant pyroclastic materials,and the favorable exploration targets are the two walls of Haisi fault in Qinan faulted terrace belt,where oil and gas exploration breakthrough is promising.%渤海中侏罗统煤系碎屑岩储层非均质性强,严重制约对其进一步勘探.以歧南断阶带中侏罗统海房沟组为例,利用薄片观察、扫描电镜、电子探针、碳氧同位素分析等测试手段,对煤系碎屑岩储层控制因素进行分析.结果表明:沉积作用和成岩作用共同控制优质储层发育,其中,沉积相是储层形成的基础;保持性和建设性成岩作用是储层形成的关键,成岩早期形成的微晶石英和铁白云石等胶结物有利于原始孔隙保存,成岩中期深部有机酸溶蚀作用及表生期风化淋滤作用形成了大量次生孔隙.研究区优质储层主要分布在有利沉积相带和富火山碎屑物质分布区,有利勘探方向为歧南断阶带海四断裂两盘,油气勘探有望取得新突破.