塔里木盆地地温场对油气成藏过程的控制作用——以古城墟隆起为例

Control effect of geothermal field on hydrocarbon accumulation process in Tarim Basin:a case study of Guchengxu uplift

塔里木盆地是中国海相碳酸盐岩油气勘探的重点区域,近几年中国石油化工股份有限公司在古城墟隆起西段奥陶系天然气勘探获得较大突破,但气藏的高温高压加大了勘探开发难度,且油气性质使得富集规律更为复杂。通过对地温场、油气碳同位素特征以及油气成藏过程剖析,认为古城墟隆起的多期构造活动使得地温异常,平面上具有剥蚀-热事件的差异演化;原油海西中—晚期聚集成藏,经历高温热蚀变,原油组分碳同位素变重;天然气为高成熟度干气,具有一定的原油裂解气的特征,喜马拉雅期聚集成藏;SHN1井成藏过程表征了热液对碳酸盐岩储层的建设作用和对油气的破坏与建设双重作用,使得奥陶系碳酸盐岩层系具有形成大型天然气藏的潜力。

Tarim Basin is a key region for marine carbonate oil and gas exploration in China.In recent years,Sinopec has made a great breakthrough on Ordovician natural gas exploration in the west of Guchengxu uplift.However,the high temperature and pressure of gas reservoir increase exploration difficulty,and the complex oil and gas properties also result in more complicated enrichment laws.Through the analysis on geothermal field,oil and gas carbon isotopic characteristics and hydrocarbon accumulation process,it is considered that the multistage tectonic movement in Guchengxu uplift induced geothermal anomaly,showing the differential evolution of denudation-thermal events at horizontal level.The crude oil accumulated in the mid-late Hercynian,experiencing high-temperature thermal alteration,of which carbon isotopes became heavier.The natural gas is high-maturity dry gas with the characteristics of crude oil cracking gas,presenting accumulation in the Himalayan period.The accumulation process of Well SHN1 represents the constructive effect of hydrothermal fluid on carbonate reservoirs as well as both constructive and destructive effects on oil and gas,thus forming the Ordovician carbonate reservoir with huge natural gas potential.