Oil & Gas Geology ›› 2012, Vol. 33 ›› Issue (4): 552-560.doi: 10.11743/ogg20120409

Previous Articles     Next Articles

Coalbed methane accumulation conditions and production characteristics

Zhao Qingbo1, Kong Xiangwen2, Zhao Qi3   

  1. 1. Langfang Branch Department, PetroChina Research Institute of Petroleum Exploration and Development, Langfang, Hebei 065007, China;
    2. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China;
    3. China University of Geosciences, Beijing 100083, China
  • Received:2011-03-15 Revised:2012-07-05 Online:2012-08-28 Published:2012-09-11

Abstract:

Based on the occurrence status of coalbed methane and structure setting of coal beds,the accumulation models of coalbed methane are divided into three types:self-source and self-reservoir adsorbed gas,self-source and self-reservoir free gas,and inside-source outside-reservoir gas.Coalbed methane enrichment and production mechanisms vary with various accumulation models.According to methane content and δ13C1 distribution in different coalbed methane accumulation in Qinshui Basin,eastern margin of Ordos Basin,Fuxin Basin and Tiefa Basin,three coalbed methane accumulation stages are indicated as early accumulation stage,late structural-reworking accumulation stage and secondary accumulation stage during production.The secondary accumulation is induced by inter-zone and inner-zone flow during production.Micro-cycles within thick coal beds are analyzed based on sedimentary facies and the coal bed intervals with high coalbed methane content are identified.Furthermore,the types of coal-forming parent materials and their control on coalbed methane enrichment and productivity are studied based on analysis of sedimentary facies.This paper also discusses tectonic stress field and hydrodynamic force influencing coalbed methane accumulation.Finally,this paper summarizes the production characteristics of coalbed methane.The production of methane well can be divided into three stages including blocked,unblocked,and unsaturated stages.The unsaturated stage is subdivided into several step-like declining stages.Structural positions and inner-layer heterogeneity result in three types of self-supporting,exporting and importing production characteristics.

Key words: coal-forming source, high production and enrichment, accumulation model, production characteristics, coalbed methane

CLC Number: