二连盆地胜利煤田含煤地层埋藏史及热史分析

Burial and Thermal History of Coal-bearing Strata in Shengli Coalfield,Erlian Basin

根据地层岩性数据及热物理参数,利用50组镜质组反射率数据、46组泥岩声波时差数据以及3个钻孔的地温数据,重建胜利煤田晚白垩世以来的埋藏史、热演化史和生烃史。结果表明:1)胜利煤田表现出"早期沉降伴随抬升,晚期终止"的埋藏特征。阿尔善组至都红木组1段沉积期,研究区处于加速—快速沉降期,其沉积末期发生第一期抬升剥蚀,剥蚀量约410 m;都红木组2段至赛罕塔拉沉积期,研究区再次进入快速沉降期,而后发生第二期抬升剥蚀,剥蚀量约580 m;赛汗塔拉沉积末期至今,研究区处于缓慢—终止沉降期;2)阿尔善期至都红木1段沉积期,研究区地温逐渐升高,在都红木组1段沉积末期地温达到峰值约90℃,随后在第一期抬升剥蚀作用下,地温迅速下降;在赛汗塔拉组沉积期地温迅速升高,沉积末期达到峰值120℃,处于异常高地温状态,而后经过第二期抬升剥蚀作用,地温下降,此后研究区地温处于稳定阶段;3)烃源岩成熟度受控于古地温,阿尔善组和腾格尔组烃源岩处于低成熟—成熟阶段,有一定的生烃潜力,而都红木组和赛汗塔拉组处于未成熟阶段,几乎无生烃潜力。

According to the stratigraphic lithologic data and thermal physical parameters,we use 50 sets of vitrinite reflectance data,46 sets of mudstone sonic slowness data and geothermal data of 3 boreholes to reconstruct the burial history,thermal evolution history and hydrocarbon generation history of the Shengli coalfield since Late Cretaceous period.The result shows:1)The burial characteristics of"the subsidence of the study area was accompanied by uplifting in the early stage and stopped in the late stage"are expressed in the Shengli coalfield.From Aershan period to early Duhongmu period,the study area entered the accelerated rapid subsidence progress,and the first stage of uplifting and erosion occurred at the end of this sedimentary period.The amount of denudation was about 410 m.From late Duhongmu period to Saihantala period,the study area once again entered the rapid subsidence progress,and then it was in the second stage of uplifting,and the denudation amount was about 580 m.Since late deposition of the Saihantala period,the study area was in a slow-ending subsidence period;2)From Aershan period to early Duhongmu period,the geotemperature of the study area gradually increased.At the end of early Duhongmu period,the geotemperature reached a peak value of about 90℃,and then entered the first stage of uplifting,the temperature decreased rapidly.In the Saihantala period,the geotemperature increased rapidly and reached the peak of 120℃at the end of the deposition,in abnormally high temperature state,and then entered the second stage of uplifting,the geotemperature decreased.After that it was in the stable stage in study area;3)The maturity of source rocks was controlled by paleo geotemperature.The hydrocarbons source rocks of the Aershan Formation and the Tenggeer Formation were in a low to medium maturity stage and had a certain potential for hydrocarbons generation.The Duhongmu Formation and Saihantala Formation should be in immature stage and had almost no hydrocarbon generating potential.