塔里木盆地顺托果勒地区超深层油藏保存及影响因素:来自流体包裹体的证据

Preservation and influence factors of ultra-deep oil reservoirs in Shuntuoguole area,Tarim Basin:evidence from fluid inclusions

超深层领域油气相态和成藏模式是勘探研究关注的热点问题。以塔里木盆地顺托果勒地区中—下奥陶统储层包裹体为研究对象,开展了详细的包裹体岩相学、油气充注古温压恢复、流体成分、拉曼光谱等系统分析,结合油气藏地质条件,探讨顺托果勒地区超深层油藏的保存途径和影响因素。奥陶系储层发育含固体沥青烃包裹体、气液烃包裹体和干气包裹体3种类型,其中跃进—顺北地区发育含固体沥青烃包裹体和气液烃包裹体,顺南地区发育含固体沥青烃包裹体和干气包裹体。包裹体古温压恢复研究表明,顺托果勒地区至少经历两期油气充注,早期充注的原油在藏内热演化成轻质油和晚期轻质油的充注这两种途径共同决定了顺北地区超深层油藏的保存,该区经历的最高古地温(大于150℃)持续时间较短是控制油藏保存的主要因素,油藏介质环境对原油的热演化起到了一定的抑制作用,这也利于液态烃保存。

Oil and gas phase and accumulation model in the ultra-deep field are hot topics in exploration and researches.Taking reservoir inclusions in Middle-Lower Ordovician in the Shuntuoguole area of the Tarim Basin as research object,the detailed systematic analyses have been carried out,such as inclusions petrography,restoration of paleo temperature and pressure during oil and gas charging,fluid composition,Raman spectrum and so on.Combined with the geological conditions of oil and gas reservoirs,the preservation mechanism and influence factors of ultra-deep oil reservoirs in the Shuntuoguole area are discussed.There are 3 types of inclusions in the Ordovician reservoirs,namely solid bitumen bearing hydrocarbon inclusions,gas liquid hydrocarbon inclusions and dry gas inclusions.Solid bitumen bearing hydrocarbon inclusions and gas liquid hydrocarbon inclusions are developed in the Yuejin-Shunbei area,and solid bitumen bearing hydrocarbon inclusions and dry gas inclusions are developed in the Shunnan area.Research of paleo temperature and pressure restoration of inclusions shows that,there are at least 2 stages(early and late)of oil and gas charging in the Shuntuoguole area.The early-charged crude oil transformed into light oil through thermal evolution in the reservoirs.In the late stage,light oil was charged in the reservoirs.These two ways together determined the preservation of ultra-deep reservoirs in the Shunbei area.The short duration of the maximum paleo temperature(greater than 150°C)in this area is the main control factor of ultra-deep reservoir preservation.The medium environment of the reservoirs has a certain inhibiting effect on the thermal evolution of crude oil,which is also conducive to the preservation of liquid hydrocarbons.