塔里木盆地顺南地区奥陶系高压气藏成藏过程分析

Analysis of accumulation process of gas reservoir with high pressure in Ordovician in south of Shuntuoguole Uplift,Tarim Basin

根据测试数据、声波时差、流体包裹体均一温度资料,采用古压力恢复及数值模拟方法,研究塔里木盆地顺南地区奥陶系油气藏特征、成藏期压力及成藏过程。结果表明:塔里木盆地顺南地区奥陶系油气藏是以过成熟裂解气为主的高温超压型干气藏。第一期油气充注发生于海西晚期,以来自寒武系烃源岩的原油和湿气为主;第二期油气充注发生于喜山期,以寒武系过成熟的干气、气侵改造及原油裂解形成的干气藏为主。顺南地区南部现今超压气藏主要是由喜山晚期油气充注和高温下原油裂解形成的,超压形成期与油气充注成藏期基本一致,深层超压有利于顺南地区晚期大型天然气藏保存。该结果为塔里木盆地顺南地区油气藏勘探开发提供依据。

The characteristics,paleopressure and accumulation process of oil and gas reservoirs in Ordovician Shunnan Area of Tarim Basin were studied by test data,acoustic time difference,homogenization temperature of fluid inclusions and paleopressure recovery.The results show that the Ordovician hydrocarbon in Shunnan Area of Tarim Basin are mainly high temperature and overpressure dry gas reservoirs dominated by over-mature cracked gas.The first period of oil and gas charging occurred in the Late Hercynian,mainly from the Cambrian source rocks of crude oil and wet gas;the second stage of hydrocarbon charging occurred in the Himalayan period,mainly caused by the Cambrian over-mature dry gas,gas invasion transformation and crude oil cracking leading to dry gas reservoirs.The present overpressure gas reservoirs in the southern part of Shuntuoguole low uplift are mainly caused by hydrocarbon charging in the late Himalayan and crude oil cracking at high temperature.The overpressure formation period is basically consistent with the hydrocarbon charging and accumulation period.Deep overpressure is conducive to the preservation of large natural gas reservoirs in the late Shuntuoguole low uplift.The results provide a theoretical basis for the exploration and development of oil and gas reservoirs in Shunnan Area of Tarim Basin.