Source-rock Evaluation and Hydrocarbon-expulsion Characteristics of Bayingebi 2 Member,Chagan Depression

In this paper,the source rock of Cretaceous Bayingebi 2 Member in Chagan Depression,is evaluated,including its thickness,organic-matter abundance,type and maturity.In addition,not only the hydrocarbon-expulsion characteristics are studied by means of a method of hydrocarbon-generation potential,but also the hydrocarbon-expulsion intensity is also evaluated.Results show that (1) the source rock is featured by large thickness,high abundance and better type of organic matter,however,bigger difference existing between west and east subdepressions;(2) the expulsion threshold and peak are 1,600m and 2,700m,respectively;(3) the average expulsion efficiency is 55%, the maximum of 80%; and (4) the average expulsion intensity is 200 × 104t/km2 .All these characteristics indicate that there is a better exploration potential.