准噶尔盆地滴南凸起石炭系火山岩气藏岩相结构

Lithofacies Structures in Carboniferous Volcanic Gas Reservoir in Dinan Swell,Junggar Basin

准噶尔盆地滴南凸起石炭系是该区油气勘探的重点层系,目前已发现滴西10、滴西14、滴西17及滴西18井区等4个较大规模的气藏,据最新钻探资料分析,该区还可能有较大规模气藏。通过对目前石炭系主要钻探成功及失利井单井垂向上岩相组合分析,以及主要井区气藏连井剖面岩相结构特征的井震剖析,认为控制该区油气成藏的因素很多,但主要还是以岩相为主,提出一定要以"岩相体"的概念分析识别有利岩相。预测上序列火山岩有利目标主要集中在滴西17气藏外围及斜坡带零散分布的安山岩、玄武岩中;下序列火山岩有利目标主要分布在3处:靠近滴水泉西断裂的斜坡带上零散分布的火山岩;滴西21井以西的安山岩、玄武岩及角砾状凝灰岩为主;滴西33井以东沿滴水泉西断裂附近零散分布的火山岩。这些有利相带的共同特征是火山岩体被风化淋滤时间长,靠近断裂分布。

The Carboniferous in Dinan swell of Junggar basin is a major sequence for petroleum exploration in this area.At present,four bigger gas reservoirs have been found,namely Dixi-10,Dixi-14,Dixi-17 and Dixi-18 gas reservoirs.The latest drilling results show that there are other large-scale gas reservoirs to be found.Based on current vertical lithofacies structural analyses of successful and unsuccessful wells drilling into the Carboniferous,integrated with well logs and seismic data analysis of the lithofacies structural characteristics of well fence profile in gas reservoirs in main well block,it is suggested that the hydrocarbon accumulation control factors are lot,but of which lithofacies is dominant.So the concept of ＂lithofacies body＂ should be used to identify the favorable lithofacies in this area.In the upper sequence volcanic rocks,the favorable targets mainly include the andesite and basalt which are scattered in distribution outside the Dixi-17 gas reservoir and slope area of,while in the lower sequence volcanic rocks,the targets could be in scattered volcanic rocks on slope area near the Dixi fault,in andesite,basalt and rubble tuff in the west of Dixi-21 well,and in scattered volcanic rocks along the Dixi fault mainly in the east of Dixi-33 well.The common features of these favorable lithofacies zones are that the volcanic rock mass weathering and leaching time was long and distributed near the fault.