沁水盆地成庄区块煤层气成藏优势及富集高产主控地质因素

成庄区块是沁水盆地煤层气开发最为成功的区块之一。为了指导相似地质条件的煤层气区块的勘探开发，基于大量的勘探开发实践数据，利用数理统计、室内实验、测井解释、构造解析、数值模拟及递减分析等方法，系统开展了该区块煤层气成因、成藏条件及产气规律等方面的研究。研究表明：该区具备构造简单、煤层展布稳定、埋藏深度浅、有机热成因气、含气量高、渗透率高等优越的成藏条件；该区高产井比例高（占总井数47%），具有单井平均产量高（介于4 000~7 000 m³/d）、采收率高（预计采收率为55.1%）等产气特征。进一步分析了富集、高产主控因素的控气作用机理，结果认为：构造热事件提高生气能力，改善了物性，封盖条件与水动力优势配置，利于煤层气富集；张性水平应力分布区及煤矿卸压应力释放区的煤储层渗透率高，利于储层高产。

Favorable and major geological controlling factors for coalbed methane accumulation and high production in the Chengzhuang Block,Qinshui Baisn

As one of the most successful blocks of coalbed methane (CBM) development in Qinshui Basin,the exploration and development in Chengzhuang coal block can provide useful guidance for the development of other CBM blocks with geologically similar backgrounds.In combination of plenty of practical data on exploration and development and methods such as mathematical statistics,laboratory experiment,wire line logging interpretation,structure analysis,numerical modeling,decline analysis,we analyzed the genetic mechanism,accumulation conditions of CBM,and patterns of gas production,in the Chengzhuang Block.The study indicates that:(1) the Chengzhuang Block is characterized by favorable accumulation conditions with its simple structure,extensive reservoir distribution,shallow burial depth of coal reservoir,organic thermogenic gas,high gas content and high permeability;(2) the high productivity wells account for 47% of the total wells of the block,with high average production of 4 000~7 000 m³/d per well and high expected recovery of 55.1%.Furthermore,we analyzed the controlling mechanisms for CBM gas accumulation and high production,and concluded that (1) the tectonic thermal events would boost gas generation,reservoir quality,seal-capping capacity and optimal distribution of hydrodynamic force,which would be beneficial for CBM accumulation;(2) the coal reservoirs with horizontal extensional stress and in the coal mine pressure relief zone are of high permeability,favorable for CBM production.