Application of Coal Petrographic Methods in Petroleum and Natural Gas Exploration

摘要

The relationship that exists between coalification and the formation of liquid petroleum and natural gas depends entirely upon the temperature in the earth's crust and the duration of heating. The degree of coalification can be determined by reflectivity measurements on very small vitrinitic (huminitic) inclusions in sedimentary rocks, because a satisfactory correlation has been established between mean reflectivity (R/sub m Oil/) and different parameters of chemical rank using 900 vitrites of different rank. This paper reports the considerable experience obtained with this method using cores and cuttings from boreholes of the German oil industry. Subsequently, examples from other countries are described which confirm the applicability of the method. Results obtained so far suggest that oil deposits may occur when the reflectivity (R/sub m Oil/) of the vitrinite lies between 0.3 and 1.0% (brown coal to high-volatile bituminous stage), whereas economic gas deposits may be found when R/sub m Oil/ extends from 0.7 to 2.0% (high-low volatile bituminous stage). (ERA citation 04:025378)