楚雄盆地高成熟煤成烃源岩中原始有机质丰度和原始产烃潜力的恢复

本文对云南楚雄中生代盆地上三叠统煤成烃源层进行了原始有机质丰度和原始产烃潜力恢复的尝试。该烃源层在盆地中具有不均衡热变的特点，南北之间的Ｒ０可由０．８％变化到４．５％不等，东西向的差异也很明显。在各区因排烃量不同而造成有机质残余率不等的情况下，如何恢复其原始有机质丰度和原始产烃潜力，以便进行合理的油气资源评价成为该盆地勘探工作的重要课题。作者通过对生源相近、成煤环境类似而成熟度极低的本区晚第三纪煤系和上三叠统变质最低的华坪煤系样品，按不同温阶进行系统的外加温、外加压生烃排烃模拟实验，从而分别编制出热演化程度与其排烃率（Ｒ０－ＨＣ排）和有机碳损耗率（Ｒ０－Ｃ损）的关系曲线。利用楚雄盆地上三叠统煤成烃源层相同比例尺的残余有机碳平均含量等值线图和平均Ｒ０等值线图叠合，获得两种曲线的若干交汇点。基于各交汇点的Ｒ０值和经过换算的有机碳损耗率，分别从Ｒ０－Ｃ报和Ｒ０－ＨＣ排曲线上求出各交汇点已损失的有机碳百分率和已排出烃类的百分率，从而恢复了各点所在烃源层的原始有机碳丰度和原始产烃潜力。

RECONSTRUCTION OF ORIGINAL ORGANIC MATTER ABUNDANCE AND ITS HYDROCARBON-GENERATING POTENTIALITIES IN A HIGH MATURE COAL-BEARING STRATA IN CHUXIONG BASIN

In this paper, the original organic matter abundance and hydrocarbon-generating potentialities have been reconstructed for the upper Triassic coal-bearing strata in Chuxiong Mesozoic basin, Yunnan, China. The thermal maturity in the coal-bearing strata varies in different location of the basin. The vitrinite reflectance(Ro)is between 0.8% and 4.5% with the northern basin having been more mature than the south. It is an important project in exploration how to reconstruct original organic matter abundance and hydrocarbon-generating potentialities and to evaluate rationally oil and gas resources in case of regionally variable content of remaining organic matter resulting from varing hydrocarbon-expelled content.The relation curves of thermal maturity(Ro)to hydrocarbon-expelled ratio(HC,)and thermal maturity(R,)to organic carbon-consumed ratio (Cc) have been drawn up based on systematic hydrocarbon-generating and hydrocarbon-expelling simulation experiments by external press of temperature and pressure in different temperature stages for the Neogene coals from western Yunnan with biologic source and coal-generating environment similar to the upper Triassic coals and with extreme low maturity. A number of intersection points were obtained by overlaping the isogram of average remaining organic carbon content with the isogram of average vitrinite reflectance in a same scale for the Triassic coal-bearing strata in Chuxiong basin.Based on the vitrinite reflectance (Ro) and the remaining organic carbon content coverted to the ratio of organic carbon-consumed in each intersection point,the percentages of consumed organic carbon and expelled hydrocarbons have been respectively determined in each intersection point from the curves of RO-Cand Ro-HCex, and the original organic carbon abundance and hydrocarbon-generating potentialities have been reconstructed for the coal-bearing strata at each point.