渤海海域旅大16构造沙三段沉火山碎屑岩储层物性及形成机理

渤海海域旅大16构造沙三段沉火山碎屑岩储层受火山碎屑物质和沉积作用双重控制,但优质储层形成机理尚不清楚。综合应用井壁取心、铸体薄片、测井曲线等资料,对沉火山碎屑岩储层致密成因及相对高渗储层主控因素进行了研究。结果表明:临近物源区的储层岩石成分成熟度和结构成熟度较低,成岩过程中形成大量搭桥状伊利石充填了孔隙,富铁、镁的安山岩岩屑蚀变析出细小黄铁矿晶簇,呈星散状密集分布在粒间,储层中毛管束缚水含量高是储层致密的主要成因;沉积期风化淋滤作用及后期成岩作用形成的高岭石对储层起到支撑和保护作用,酸性火山岩岩屑在埋藏过程中生成大量环颗粒分布的雏晶石英,能够起到抗压实和抑制伊利石生长的作用,酸性火山岩岩屑相对易溶蚀而形成次生孔隙,是局部相对高渗储层的主要成因。

PHYSICAL PROPERTIES AND THEIR GENERATING MECHANISMS FOR MEMBER SHA-3 SEDIMENTARY PYROCLASTIC ROCK RESERVOIRS IN STRUCTURE LD-16 OF BOHAI BAY

Member Sha-3 sedimentary volcaniclastic reservoirs in Structure LD-16 of Bohai Bay are both controlled by the volcaniclastic matters and sedimentation,but the forming mechanisms of the high-quality reservoir are still left in the air.Comprehensively integrated with the sidewall coring,cast thin section,well logging data and so on,the compactness genesis and the key origin of the high-permeability reservoir of the sedimentary volcaniclastic reservoir were researched.The results show that the maturities of both the reservoir rock components and the structures quality near the provenances are rather lower,a large number of the bridge-like illite are generated during the diagenesis and fill the pores,the fine pyrite crystals are precipitated by the ferrite/magnesium-enriched andesite debris alteration and densely distributed between the particles,a large number of the capillary irreducible water in the reservoir is the key origin of the compactness;the kaolinite resulted from the weathering and leaching actions during the sedimentation and the diagenesis in the later period possesses the supporting and protecting actions,acidic volcanic cuttings can generate a large amount of the microcrystalline quartz girdling the grain in the process of the burial,and then the anti-compaction and constrained action for the illite development are well displayed,the acidic volcanic cuttings are easily dissolved and developed the secondary pores,and finally become the key origins of the partially relatively higher permeability reservoirs.