Lan Fengjuan1, Qin Yong1,2, Chang Huizhen1, Guo Chen1, Zhang Fei1

Funding project: Funded by the National Natural Science Foundation of China Key Project (40730422).

About the first author: Lan Fengjuan, born in 1986, female, doctoral candidate, coalbed methane geology, 13151981375, lanfj11986@126.com.

(1. School of Resources and Earth Sciences, China University of Mining and Technology, Xuzhou, Jiangsu 221116; 2. Key Laboratory of Coalbed Methane Resources and Accumulation Processes, Ministry of Education, Xuzhou, Jiangsu 221008)

Abstract: General Generally speaking, the concentration of heavy hydrocarbons in coalbed methane is less than 3% to 5%. However, in some areas, the concentration of heavy hydrocarbons in coalbed methane exceeds the norm and appears abnormal. The chemical composition of coalbed methane contains extremely rich information on its origin. Research on the causes of abnormal heavy hydrocarbons can deepen the understanding of the origin of coalbed methane and promote the improvement and development of basic research on coalbed methane geochemistry. This article summarizes the distribution and characteristics of heavy hydrocarbon anomalies in coalbed methane at home and abroad, as well as the many explanations currently provided by scholars for the causes of heavy hydrocarbon anomalies. The author puts forward his own opinions on these explanations, providing a basis for in-depth research on the causes of heavy hydrocarbon anomalies. As an idea and entry point, it is believed that further research needs to be conducted based on specific regions and comprehensive consideration of multiple factors.

Keywords: Causes of abnormal distribution characteristics of heavy hydrocarbons

Distribution Characteristics of Abnormal Heavy Hydrocarbon in Coalbed Methane and its causes

LAN Fengjuan1 QIN Yong1,2 CHANG Huizhen1 GUO Chen1 ZHANG Fei1

(1. The School of Resource and Earth Science, china university of Mining and Technology, Xuzhou, Jiangsu 221116, china 2. Key Laboratory of CBM Resources and Reservoir Formation Process, Xuzhou, Jiangsu 221008, China)

Abstract: Generally speaking, concentration of heavy hydrocarbon of CBM is between 3%～5%, however, it is more than normal in somewhere. There is abundant genetic information in chemical composition of coalbed methane (CBM) . The research about its origin will deepen our understanding of origin and geochemistry of coalbed gas. This article summarizes the distribution characteristics of abnormal heavy hydrocarbon domestic and overseas and scholars' explanations for its causes at present, giving the author's own opinion which provides a starting point for the further research of the causes. It is thought that it still needs further study taking many factors into account in some definite area.

Keywords: abnormal heavy hydrocarbon; distribution characteristics ; causes< /p>

Introduction

Coalbed methane is mainly composed of CH4, the minor components are heavy hydrocarbons (C2+), N2 and CO2, and the trace components include Ar, H2, He, H2S, SO2, CO et al (Tao Mingxin, 2005).