南苏门答腊盆地构造演化对沉积演化及成藏条件的控制

南苏门答腊盆地是新生代弧后裂谷盆地,盆地的构造演化明显地控制了沉积演化和成藏条件。早始新世—早渐新世为同生裂谷早期,地堑和半地堑发育,以陆相沉积为主,前三角洲页岩为重要的烃源岩,冲积扇和辫状河砂砾岩为主要储层;晚渐新世盆地处于同生裂谷后期的早期,西南方的海侵使盆地中央为海相沉积,边缘为三角洲和河流相沉积,三角洲中的含煤页岩为主要烃源岩和重要盖层,河流—三角洲相砂岩是重要储层;早中新世为同生裂谷后期末,盆地以海相沉积为主,深海—半深海泥页岩、泥灰岩是重要烃源岩和区域性盖层,而储层主要是滨浅海的碳酸盐岩滩和生物礁灰岩;中中新世—上新世,盆地遭受挤压,发生海退,海相、陆相和海陆过渡相同时发育,滨浅海的海退砂岩是良好的储层,而三角洲相泥页岩是好的烃源岩和盖层。

Control of tectonic evolution on sedimentary systems and hydrocarbon accumulation, South Sumatra Basin, Indonesia

The South Sumatra Basin is the typical backarc rift basin of Cenozoic. The tectonic evolution controls the distribution of sedimentary systems and source rock, reservoir and seal from Eocene to Holocene. From early Eocene to early Oligocene, the South Sumatra Basin is in the early syn-rift stage and developed a set of grabens and half grabens with terrestrial facies, in which the prodelta shale is the main source rocks, and glutenites in the alluvial fan and braided river are the main reservoir rocks. During Late Oligocen,the South Sumatra Basin is in the early syn-rift later stage when there is the marine facies in the middle of the basin caused by the transgression from southwest, and delta and fluvial facies existed at the edge of the basin. The coal-bearing shale in the delta is the main source rock and the important cap rock, while the sandstones in the fluvial and delta facies are the important reservoir rocks. During the early Miocene, the South Sumatra Basin is in the last syn-rift later stage when the basin is deposited mainly as the marine facies, in which the mud shale and muddy limestone in the abysmal-bathyal facies are the important source rocks and regional seals,while the carbonate bank and biohermal limestone in the shore-shallow marine are the main reservoirs. From the middle Miocene to Pliocene, the South Sumatra Basin experienced the compaction and regression causing the development of marine, terrestrial and transitional facies at the same time. The regressive sandstone in the shore-shallow marine is the favorable reservoir, and the mud shale in the pre-delta is the good source and seal rocks. Definition of the evolution of the sedimentary system and the corresponding distribution of source rock, reservoir and seal in the South Sumatra Basin will provide the scientific foundation to establish the database of sedimentary system and hydrocarbon system in the petroliferous basins all over the world.