煤层气成藏条件及开采特征

doi:10.11743/ogg20120409

摘要/Abstract

摘要：

根据煤层气的存储状态及煤层所处的构造位置,将煤层气划分为自生自储吸附型、自生自储游离型和内生外储型3种成藏模式,不同成藏模式的富集高产机制不同。基于沁水盆地、鄂尔多斯盆地东缘、阜新及铁法盆地不同层位煤层气甲烷含量及甲烷碳同位素分布研究,煤层气成藏期可划分为早期成藏、后期构造改造成藏和开采中二次成藏3个时期,特别指出了开采中窜位和窜层引发二次成藏的条件。利用沉积相分析厚煤层的层内微旋回,细划分出优质煤层富含气段;进一步利用沉积相探索成煤母质类型及其对煤层气高产富集的控制作用,阐述了构造应力场及水动力对煤层气成藏的作用机理。最后,总结了煤层气的开采特征,指出煤层气井开采中包含阻碍、畅通和欠饱和3个开采阶段,欠饱和阶段可划分为多个阶梯状递减阶段;并认为由构造部位和层内非均质性的差异形成了自给型、外输型和输入型3类开采特征。

关键词: 成煤母质, 高产富集, 成藏模式, 开采特征, 煤层气

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

中图分类号:

TE132.2

赵庆波,孔祥文,赵奇. 煤层气成藏条件及开采特征[J]. 石油与天然气地质, 2012, 33(4): 552-560. doi: 10.11743/ogg20120409 Zhao Qingbo,Kong Xiangwen,Zhao Qi. Coalbed methane accumulation conditions and production characteristics[J]. Oil & Gas Geology, 2012, 33(4): 552-560. doi: 10.11743/ogg20120409

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