准噶尔盆地吉木萨尔凹陷双吉构造带井井子沟组勘探突破及意义

2020—2022年,准噶尔盆地吉木萨尔凹陷双吉构造带多口井在二叠系井井子沟组获得高产工业油流,表明吉木萨尔凹陷二叠系具有良好的常规油气勘探潜力。为深入研究吉木萨尔凹陷及其周缘二叠系常规油气的地质特征及勘探潜力,综合岩心、录井、测井和有机地球化学等分析测试资料,对双吉构造带井井子沟组油气成藏条件进行了系统研究。双吉构造带是受SN向和EW向两组断裂控制形成的断鼻型正向构造,规模储集体发育,砂体展布受古地貌控制,具有"沟槽控砂"特征,具备形成大型构造-岩性油气藏的储层条件。井井子沟组发育"新生古储"型成藏组合,芦草沟组烃源岩生成的油气在生烃超压驱动下,在井井子沟组砂岩储层中聚集成藏,具有"生烃增压驱动、断裂垂向运移、岩性富集高产"的成藏模式。双吉构造带井井子沟组油气勘探突破证实优质烃源岩的下伏储层具备规模成藏的潜力,构造带北部及南部靠近主走滑断裂带,油气运聚成藏条件优越,是拓展吉木萨尔凹陷二叠系常规油气勘探的重点领域。

Exploration breakthrough and its significance of Jingjingzigou Formation in Shuangji tectonic zone of Jimsar sag in Junggar Basin

From 2020 to 2022, many wells in the Shuangji tectonic zone of Jimsar sag in Junggar Basin have obtained high-yield industrial oil flow in the Permian Jingjingzigou Formation, indicating that the Permian reservoirs of Jimsar sag has good conventional oil-gas exploration potential. To deeply study the geological characteristics and exploration potential of conventional oil and gas in Jimsar sag and its surrounding areas, the oil and gas accumulation conditions of Jingjingzigou Formation in Shuangji tectonic zone were systematically studied by comprehensively using the analysis and test data of core, mud logging, well logging and organic geochemistry. Shuangji tectonic zone belongs to fault nose-shaped positive tectonics formed under the control of SN- and EW-trending faults, where large-scale reservoirs are developed and the sand body distribution is controlled by the ancient landform, showing the characteristics of "trench-controlled sand body", and thus it possesses the reservoir conditions of forming large tectonic-lithologic reservoirs. The new bed-generating and old bed-storing accumulation assemblage is developed in Jingjingzigou Formation. Under the drive of overpressure during hydrocarbon generation, the oil and gas generated from the source rock of Lucaogou Formation accumulates in the sandstone reservoir of Jingjingzigou Formation, forming an accumulation mode of "being driven by hydrocarbon generation pressurization, vertical migration along faults, and lithologic enrichment and high production". The breakthrough in oil-gas exploration of Jingjingzigou Formation in the Shuangji tectonic zone proves that the underlying reservoir of high-quality source rock has the potential for large-scale accumulation. The north and south of the tectonic zone are close to the main strike-slip fault zone with excellent conditions for oil and gas migration and accumulation, which are the key fields for expanding the conventional oil-gas exploration in the Permian reservoirs of Jimsar sag.