塔里木盆地草湖凹陷-库尔勒鼻凸烃源岩演化

Source Rock Depositional Evolution in Caohu Sag-Kuerle Nose Salient,Tarim Basin

根据塔里木盆地北部草湖凹陷-库尔勒鼻凸库南1井和满1井的实测烃源岩镜煤反射率Ro数据,结合其他钻井资料,采用Ro梯度与沉积速率相互验证反演沉积埋藏史及生烃史的方法,确定主要烃源岩的“生烃”窗口,并对研究区的地层剥蚀厚度进行恢复.通过3口井的沉积埋藏史,总结出研究区不同构造位置的烃源岩生烃演化的3种模式,即烃源岩的成熟生烃型、被剥蚀破坏型、过成熟型;得出草湖凹陷中下古生界烃源岩演化适中、具有良好的生排烃能力、分布范围附近的圈闭应该成为有效的圈闭的结论.而位于库尔勒鼻凸的下古生界烃源岩,由于海西期的强烈剥蚀,地层缺失严重,所受破坏巨大,已经不能供烃;位于草湖南部满加尔坳陷的满1井下古生界烃源岩演化程度太深,已经失去生烃能力.

Based on R_o data of Kunan-1 well and Man-1 well and other wells in Caohu sag and Kuerle nose salient in Tarim basin, oil-generating window of main source rock was got and erosion thickness of strata in researching area was restored by inversion depositional-burial history and hydrocarbon-generating history.Three models of hydrocarbon generation and evolution in different tectonic areas are established with depositional and burial history of three wells in different areas,which are maturative source rock and hydrocarbon generating,erosed source rock,source rock at over-maturity:① Middle and Lower Paleozoic source rock in Caohu sag was in the moderate evolution degree,which has good ability of hydrocarbon generating and expulsion.The traps near it can be effective. ② Lower Paleozoic source rock in Kuerle nose salient was erosed strongly during Hersynian.The source rock was damaged so tremendously that it couldn't supply hydrocarbon.③ Lower Paleozoic source rock in Manjiaer depression in the south of Caohu sag was at over-maturity evolution stage and loses the ability of hydrocarbon generation.