Turpan-Hami Basin And Its Surrounding Carboniferous-Permian Source Rock Characteristics And Formation Environment

Due to the deep burial of Carboniferous-Permian source rocks in the Turpan-Hami Basin,fewer exploration wells and poor quality of seismic data,the distribution of related source rocks in the basin is still unclear,which restricts the exploration of Carboniferous-Permian.In this paper,representative field outcrops and exploratory well core samples of Carboniferous and Permian source rocks were collected,combined with regional geological,seismic,drilling and logging data,mineral analysis,thin section observation,and logging identification methods were used to identify Carboniferous-The lithology and lithology combination of the Permian strata are predicted,and the lithology and distribution characteristics of potential source rocks are preliminarily clarified.At the same time,based on the evaluation of the geochemical characteristics of the source rocks,the TOC of each source rock interval was calculated by theΔLog R method,and the source rock development intervals were identified by combining the classification criteria of the effective source rocks,and the Carboniferous-Permian hydrocarbon source was clarified.The distribution range and formation environment of rocks.The research shows that the Middle Permian source rocks are dominated by dark pure mudstone,while the Carboniferous and Lower Permian source rocks are dominated by tuffaceous mudstone and dark pure mudstone.The Permian Taodonggou Group source rocks have the highest organic matter abundance,followed by the Lower Permian source rocks,and the Carboniferous source rocks have the lowest organic matter abundance.The overall Carboniferous-Permian source rock types are mainly type II₂-III,among which the source rocks of Taodonggou Group have the best organic matter type,mainly type II₂,and a small amount of type II₁.The Middle Permian source rocks are generally in the mature stage from low maturity to a large amount of oil generation,the Lower Permian source rocks are in the mature stage as a whole,and have reached the over-mature stage in the Tanan sag;the Carboniferous source rocks are generally mature stage,and some have reached the over-mature stage.The Middle Permian source rocks are mainly distributed in Tainan,Taipei and Toksun sags,and a small amount in the Dananhu sag,among which the source rocks are thicker in the Tainan sag;The Lower Permian source rocks are mainly distributed in the northern Turpan sag,Tainan sag,and Tanan sag,and may also be distributed in the northeastern Hami Depression.Carboniferous source rocks are widely distributed in the basin.The formation environments of the Middle Permian and Lower Permian source rocks are both weak oxidation-weak reduction,and the water body of the Lower Permian is more reducible.The Permian is brackish water-salt water;The formation environment of Carboniferous source rocks is a partial reduction environment,the water body has high salinity,and the characteristics of salt water are obvious.Carboniferous-Permian source rocks are mainly developed in the Middle Permian Tallang Formation,and there are two source rock development modes:one is the organic matter enrichment mode under partial reducing conditions,and the other is the partial oxidation condition.The enrichment pattern of organic matter.