Hydrocarbon Generation Potential Evaluation of Upper Paleozoic Limestone in Ordos Basin

Han Wenxue; Ma Weijiao; Tao Shizhen; Yao Jingli; Liu Xinshe

Abstract：There is little research on whether hydrocarbon generation from limestone in the transitional phase of the Upper Paleozoic in the Ordos basin can be made,and on how much the hydrocarbon can be.Using rock pyrolysis,determination of TOC,carbon isotope of kerogen,organic maceral and Ro experiment,we analyzed the limestone source rocks and characteristics of hydrocarbon generation and expulsion.The results show that:(1)The source rocks from Benxi Formation,Shanxi Formation and Taiyuan Formation is poor,poor-fair,and fair-good respectively according to organic matter abundance.(2)The organic matter type of Benxi Formation,Taiyuan Formation and Shanxi Formation is Ⅲ,Ⅱ 2-Ⅱ and Ⅲ mixed with a small quantity of Ⅱ 2 respectively.(3) The maturity of source rocks from Benxi Formation is mature-high mature stage,and Taiyuan Formation and Shanxi Formation is high mature stage.According to hydrocarbon expulsion threshold theory,we consider large amount of natural gas generated when Ro is above 1.6 ％.Considering the particularity of limestone source rocks,maturity and characteristics of hydrocarbon expulsion,we comprehensively consider that the limestone of Taiyuan Formation can be the effective source rocks of natural gas.