含油气盆地深层—超深层碎屑岩油气勘探现状与优质储层成因研究进展

含油气盆地深层—超深层是全球油气勘探的"三新"领域之一，整体低渗-致密背景下相对高孔/高渗的优质储层是深层—超深层勘探的甜点。勘探实践和研究表明，含油气盆地深层—超深层（深度为4~8 km）碎屑岩仍可发育原生孔隙主导型、次生孔隙主导型、孔-缝复合型和裂缝主导型优质储层；在深层—超深层碎屑岩优质储层中，古生界储层以次生孔隙型为主、原生孔隙型为辅，中生界侏罗系—白垩系储层以原生孔隙型为主、次生孔隙型为辅，新生界储层原生孔隙型和次生孔隙型均可大量发育，且中生界勘探突破深度整体深于古生界和新生界。浅层—深层多成因溶解成孔作用控制了深层—超深层储层中次生孔隙的发育，构造作用控制了裂缝的发育，早期胶结作用（绿泥石包壳、碳酸盐胶结壳）、浅层流体超压、烃类早期充注和低时间—温度指数（TTI）型埋藏史—热演化史控制了不同地质背景下储层中孔、缝向深层—超深层的有效保存。深层—超深层优质油气储层的发育是有利的沉积作用、埋藏史—热演化史、流体压力史、成岩史—孔隙演化史—油气充注史等相互耦合的结果，其发育存在：①中—浅层流体超压、中—浅层油气充注主控的原生孔隙主导型，②浅层绿泥石包壳主控、中—浅/深层油气充注的原生孔隙主导型，③早期长期浅埋—晚期快速深埋超压主控、中—深层油气充注的原生孔隙主导型，④地表淋滤成孔、中—浅层油气充注主控的次生孔隙型，⑤多成因溶解主控—晚期烃类充注的次生孔隙型5种典型模式。缺少大规模断裂系统沟通时，埋藏溶解作用增孔量有限，多种类型的"浅成-深保"是深层—超深层优质油气储层发育的关键。碎屑岩油气储层孔隙的保存极限决定了深层—超深层油气勘探下限，深层—超深层油气储层中"烃-水-岩"有机-无机相互作用持续影响储层质量和油气质量演化，高温高压条件下有机-无机相互作用机理及其约束的储层孔隙保存极限深度是下一步研究重点。

Current situation of oil and gas exploration and research progress of the origin of high-quality reservoirs in deep-ultra-deep clastic reservoirs of petroliferous basins

The deep and ultra-deep reservoirs of petroliferous basin are one of the three new fields for global oil and gas exploration.In the context of low permeability and densification on the whole,the high-quality reservoirs with relatively high porosity/permeability are the sweet spots for deep-ultra-deep exploration.Exploration practices and researches show that high-quality reservoirs dominated by primary porosity,secondary porosity and pore-fracture assemblage and fractures can also be developed in the deep-ultra-deep clastic rocks of petroliferous basin(at the depth of 4-8 km);in the deep-ultra-deep high-quality clastic reservoirs,Paleozoic reservoirs are dominated by secondary pores,supplemented by primary pores;Mesozoic Jurassic-Cretaceous reservoirs are dominated by primary pores,supplemented by secondary pores;Cenozoic reservoirs are dominated by the massive development of primary and secondary pores.Moreover,the exploration depth in the Mesozoic reservoir is generally greater than that in the Paleozoic and Cenozoic reservoirs.The development of secondary pores in deep-ultra-deep reservoirs is controlled by shallow-deep polygenetic dissolution pores,the development of cracks is controlled by tectonism,and the effective preservation of pores and fractures in the deep-ultra-deep layers under different geological background condtions is controlled by early cementation(chlorite cladding and carbonate cement crust),shallow fluid overpressure,early hydrocarbon charging and burial-thermal evolution history with low time-temperature index.The development of high-quality oil and gas reservoirs in deep-ultra-deep reservoirs attributes to the inter-coupling of different geological factors,including favorable sedimentation,burial-thermal evolution history,fluid pressure history,diagenetic evolution history-pore evolution history and oil-gas charging history,and are classified into 5 typical types as follows:(1)mainly controlled by fluid overpressure and oil-gas charging in shallow-medium layers,dominated by primary pores;(2)mainly controlled by chlorite cladding in shallow layers and oil-gas charging in medium-shallow/deep layers,dominated by primary pores;(3)mainly under the control of overpressure formed by early long-term shallow burial and late rapid deep burial as well as oil-gas charging in medium-deep layers,dominated by primary pores;(4)mainly controlled by surface leaching poers and oil-gas charging in medium-shallow layers,dominated by secondary pores;(5)mainly controlled by polygenetic dissolution and late hydrocarbon charging,dominated by secondary pores.In the absence of connection between large-scale fracture systems,the porosity increased by burial dissolution is limited,and various types of“shallow accumulation-deep preservation”are the key to the development of deep-ultra-deep high-quality oil-gas reservoirs.In addition,the preservation limit of clastic oil-gas reservoir porosity determines the lower limit for the oil-gas exploration in deep-ultra-deep layers;organic-inorganic interaction of“hydrocarbon-water-rock”in deep-ultra-deep oil-gas reservoirs continues to affect reservoir quality and oil-gas quality evolution;the organic-inorganic interaction mechanism under high temperature and high pressure and the depth limit for the preservation of reservoir pores constrained by it are the focus of further study.