中亚卡拉库姆盆地油气分布特征与成藏模式

卡拉库姆盆地是世界上仅次于西西伯利亚盆地和波斯湾盆地的第三大富气盆地。本文以获取的最新油气田储量数据为基础，采用石油地质综合分析方法，探讨了该盆地油气的层系和区域分布特征及其成藏模式。受区域盖层控制，盆地内的油气主要富集于两套层系：中侏罗统卡洛阶-上侏罗统牛津阶碳酸盐岩储集层和下白垩统欧特里阶沙特利克组砂岩储集层。前者富集了盆地内68.0%的石油储量、84.0%的凝析油储量和44.2%的天然气储量，后者富集了盆地内36.4%的天然气储量。上侏罗统蒸发岩之下的盐下油气田的区域分布主要受有利储集相带和古隆起构造展布的控制；生物礁和古构造主要发育于盆地东北部的北阿姆河亚盆地，并导致盆地内已发现的盐下油气储量主要分布于此。受蒸发岩区域盖层和深大断裂的控制，盐上油气田主要分布于蒸发岩发育区之外、蒸发岩较薄且主要为硬石膏的地区、以及蒸发岩发育区内的深大断裂附近。蒸发岩之上的盐上层系并非油气特别是天然气勘探的禁区，源自盐下烃源岩的天然气可以在盐上储集层内聚集并形成大气田。

Distribution characteristics and accumulation model for oil and gas in Karakum Basin,Central Asia

The Karakum Basin is the third gas-richest basin in the world next to the Western Siberian and Persian Gulf Basins. Based on the newest reserve data for individual fields, this paper discusses the distribution characteristics and the accumulation model for oil and gas in the basin with an integrated analysis of petroleum geology. Stratigraphic distribution of oil and gas is controlled by regional cap rocks. Oil and gas are concentrated in two reservoir intervals; The Middle Jurassic Callovian-the Upper Jurassic Oxfordiancarbonate rocks and the Hauterivian Shatlyk Formation sandstones of Lower Cretaceous. The former hosts 68. 0% , 84. 0% and 44. 2% of the total proved oil, the condensate and the gas reserves in the basin respectively. The latter reservoirs 36. 4% of the total gas reserves. High quality reservoirs and paleo-high structures are the main controls on the regional distribution of the oil and gas fields in the sub-salt sequences underlying the Upper Jurassic evaporites. The North Amu Darya Sub-Basin where the reef reservoirs and paleo-high structures were well developed, contains bulk of the sub-salt proved oil and gas reserves. The evaporite cap rock and deep-cutting large scale fault zone are the main controls on the regional distribution of the oil and gas fields in the supra-salt sequences. These fields are largely confined to the areas outside the evaporite cap rock, the areas with a thin anhydrite-dominated evaporite sequence and the area near the Large fault zone. The supra-salt sequences are not non-exploration intervals for oil and gas, particularly the latter. Gas derived from the sub-salt source rocks can migrate upwards to form giant gas fields in the supra-salt reservoirs.