烃源岩油气藏的圈层效应特征、差异成藏机制与有序分布模式

近源找油、进源勘探是未来油气勘探的方向。目前近源找油、进源勘探还面临很大的风险，主要原因是对烃源岩附近，尤其是烃源岩内的油气成藏条件、成藏机理、分布规律认识不到位。重新定义了烃源岩系统和烃源岩油气藏的概念，认为一个烃源岩系统就是一个独立的油气成藏单元，而烃源岩油气藏为赋存于烃源岩系统内的油气聚集。划分出常规油气藏与非常规油气藏两大类，泥岩裂缝油气藏等6种烃源岩油气藏，受构造控制，造就了它们独有的形成机制和特定的分布规律，形成了横向并列成圈、纵向有序成串、上下分层过渡、常规与非常规差异机理成藏和有序共生的圈层结构特征：即从内圈的深湖相页岩油气藏、浊积砂岩性油气藏，到中圈的半深湖相的致密油气藏，再到外圈的浅湖-半深湖过渡相的岩性尖灭油气藏分布序列。成藏机制上，也形成了内圈的页岩油气藏以原地连续性“滞留”与微运移“停留”,中圈的致密油气藏以大面积初次运移“停留”、外圈的岩性尖灭油气藏以浮力二次运移“截流”为特征的有序成藏机理序列。明确了页岩油气藏甜点区位于深盆区内圈前三角洲相带的具有“优势组构-滞留烃超越效应”的区域；致密油气藏甜点区位于深盆区中圈三角洲前缘相带的具有“优势孔缝耦合”的区域；...

Source-rock reservoirs: Ring structure characteristic,differential accumulation mechanism and ordered distribution pattern

The future direction of oil and gas exploration is to find oil near or inside the source-rock area. However, this type of operation is still risky due to lack of understanding of source-rock properties, mainly its hydrocarbon accumulation conditions, mechanisms and distribution laws. This paper redefines the ‘source-rock system’ and ‘source-rock reservoir’ concepts—it considers the source-rock system is an independent hydrocarbon accumulation unit, and source-rock reservoir is hydrocarbon accumulation within the source-rock system. Hydrocarbon reservoirs are divided into two categories: conventional and unconventional reservoirs. There are six types of hydrocarbon source-rock reservoirs, including mudstone fractured reservoir, lithologic reservoir, shale oil and gas reservoir, and tight oil and gas reservoir. Under structural control, each reservoir type has its unique formation mechanism and specific distribution law and together they form a ‘horizontal parallel ring’ structure, as the source-rock system—with vertical sequence formations, upper and lower stratification transition, differential formation mechanism (conventional vs. unconventional), and ordered symbiosis—developed from deep lacustrine shale and turbidite sandstone reservoirs in the inner circle, to semi-deep lacustrine tight reservoirs in the middle circle, then to shallow lacustrine and semi-deep lacustrine transition facies in the outer circle. The source-rock system is formed by orderly, sequential accumulation mechanism, where the shale reservoirs formed in the inner ring via in situ continuing accumulation and micro migration interruption; the tight reservoirs formed in the middle ring via large-scale primary migration interruption; and the lithologic pinch-out reservoirs formed in the outer ring via buoyancy secondary migration closure. This paper determines that the shale reservoir “sweet spots” are located in the predelta facies belt of deep basin inner circle with “dominant fabric and superior hydrocarbon retention”; for tight oil and gas reservoirs the “sweet spots” are located in the “dominant pore-fracture coupling” region of delta front facies belt in the middle circle of deep basin; and for lithologic pinch-out reservoirs the favorable distribution areas are located in the trap area with dominant migration channel along convergent ridge in delta plain facies belt outside the deep basin. There are variety of source-rock reservoirs with huge oil and gas resources potentials, and their exploration, development and utilization has just begun.