Geochemical characteristics of kerogen in Yanchang Formation source rocks,Xifeng area,Ordos Basin

Abstract

The kerogen's maceral,elements and carbon isotopes in the Chang 7 and Chang 8 source rocks of the Yanchang Formation,Xifeng area,southwestern Ordos Basin,suggest that the organic matter types in the Chang 7-2 and Chang 7-3 are good,containing sapropel and sapropel-humic kerogens,which are formed in a deep lake with a reducing environment and indicate algae input in productive period.The Chang 7-3 source rocks contain many terrestrial plant remnants due to turbidite sediments.The Chang 8 source rocks have worse organic matter type,mainly mixed type,formed in a shallow lake,with both terrestrial plant remnants and some algae input.Because of the difference of the sedimentary and preservation environments,the Chang 8 source rocks at some wells have mainly humic kerogen.The source rocks of the Chang 7-2 and Chang 7-3 have good potential for oil and gas,and are probably the main source for the oil reservoirs.