The Hydrocarbon Generation Potential And Assessment On Source Rock In The Qiketai Formation In The Taibei Sag In Turpan-Hami Basin

The second member of the Qiketai Formation in the Shengbei Subsag is the potential horizon for the exploration of tight oil,in which the source rock is dominated by dark-colored mudstone with low maturity and reservoir mainly contains carbonates-bearing mudstone.For clarifying geological and geochemical characteristics of source rock with low maturity and evaluating its hydrocarbon generation potential and resources,based on organic geochemical analysis and by establishing sequence stratigraphic framework,analyzing of genetic environment,oil-source correlation,evaluation of effective source rock,and research on hydrocarbon generation potential,the hydrocarbon generation potential and resources of lowly-mature source rocks in the second member of Qiketai Formation were comprehensively analyzed.It is indicated in the study that this horizon is dominated by lacustrine sediments and can be divided into4 layers.Among them,the fourth and third layers were in the deposition stage and in the shallow-semi-deep sedimentary facies.The depositional water column is slightly reduced and saline that is most favorable for the development of effective source rock.The J₂q₂⁴ contains the highest organic matter abundance and the best organic matter type,namely Type I-II₁.J₂q₂³ is the secondary and the organic matter is represented as Type II₁-II₂.The comparison between geochemical characteristics of source rocks in different lithologies shows that the dark-colored mudstone contains the highest organic matter abundance and better organic matter type.It is mainly distributed in the fourth layer,followed by carbonate-bearing mudstone and siltstone.Oil-source correlation also demonstrates that the oil in the J₂q₂² is sourced from this set of mudstone in the bottom of second member of Qiketai Formation.The development of effective source rock is mainly subject to sedimentary environment.The effective source rock in the second member of Q iketai Formation was mainly developed in shallow-semi-deep sedimentary facies.The fourth layer contains the thickest effective source rock and represents two thickness centers on plane.In Shengbei 6-Taican 2–Shengbei 5–Shengbei 7 well vicinities,the Shengbei7-Shengbei 10 well vicinities reach the maximum thickness which can be 80m;in the Shengbei Subsag,the oil generating amount of second member of Q iketai Formation is predicted to be 2.3×10⁸t.And the favorable distribution areas of tight oil are in the Lianbei well vicinity,Shengbei 11-Shengbei 5-Taican 2 well vicinities,and Susha-Shenghuo areas.