塔中奥陶系原油的运移方向研究

OIL MIGRATION ORIENTATION OF ORDOVICIAN IN TAZHONG UPLIFT

油气运移方向的确定对油气的进一步勘探具有重要意义。在分析前人资料的基础上,认为塔中隆起在加里东期至海西中期并非存在西北高、东南低的格局,而是总体上表现为东南高、西北低的特征;且塔中存在两个较高部位:一个位于塔中断垒带西段的中1井区附近;另一个为塔中的最高部位,位于塔中断垒带东段的塔中1井附近。油源对比表明,塔中奥陶系的原油大多来自中-上奥陶统的源岩。结合古构造背景的特征,对源自中-上奥陶统原油的充注方向研究表明,塔中北斜坡至少存在两个方向的油气运移:一为从塔中西北部向东南部的较高部位运移充注,二为从塔中西北部向中1井区附近的较高部位运移;塔中南斜坡塔中52井、中4井的油气来自塔中南侧的塘古巴斯凹陷,并经历了相对较短的运移距离,进一步证明了塘古巴斯凹陷中-上奥陶统的烃源岩具有较好的生油气潜力。

Definition of oil migration orientation has great importance to further oil exploration.Based on the previous research,it is found out that it is incorrect that the northwest Tazhong uplift was higher and the southeast uplift was lower from Caledonian to middle Hercynian.In general,southeast part of the uplift is the highest part all along,and there are two relatively higher parts in Tazhong,one is located near well Zhong-1 in west Tazhong horst,the another,the highest part in Tazhong,is located near Tazhong well-1 in east Tazhong horst.The correlation of oil source indicates the crude oil of Ordivician in Tazhong mainly came from the source rocks in middle to upper Ordivician.According to ancient structural setting,the study on filling and accumulating orientation of the crude oil from middle to upper Ordivician shows that there are at least two orientations of oil migration in north Tazhong slope,one is from lower noetheast Tazhong to higher southeast Tazhong,another is from lower northwest Tazhong to higher Zhong well-1block.The oil and gas in Tazhong well-52,Zhong well-4 in south Tazhong slope came from Tanggubasi sag in south Tazhong and migrated a relatively short distance,which further proves the hydrocarbon source rocks in middle to upper Ordivivian in Tanggudasi sag are of good oil and gas generation potential.