中国低煤阶煤层气勘探探索——以沙尔湖凹陷为例

DISCUSSION ON LOW RANK COALBED METHANE EXPLORATION IN CHINA——BY TAKING SHA′ERHU SAG AS AN EXAMPLE

近年来低煤阶煤层气在美国粉河、尤因它盆地进行大规模商业性开采 ,引起包括中国在内的许多国家关注。中石油煤层气勘探项目经理部对我国西北、东北、内蒙古、滇黔桂地区中、新生代低煤阶含煤盆地煤层气成藏条件及资源分布进行了研究 ,发现我国低煤阶煤层气资源非常丰富 ,是我国煤层气勘探不可忽视的重要资源。2 0 0 3年优选吐哈盆地沙尔湖凹陷进行了积极探索 ,取得了很好的效果 ,初步分析了低煤阶煤层气成藏控制因素 ,指出低煤阶煤层气藏一般埋藏浅 ,含气量低 ,但煤层渗透性好。勘探目标选择应注意对煤层气保存条件的分析 ,寻找高饱和含气区。另外 ,低煤阶煤层气开发还需要煤层有一定的厚度 ,这样才能保证较高的资源丰度、单井产量 。

A large-scale commercial exploitation of low-rank coalbed methane has been carried out in the Powder River and Uinta Basin of USA in recent years,which has aroused general concern of many countries including China.Through investigating the reservoiring conditions and resource distributions of coalbed methane in the Mesozoic—Cenozoic low rank coal-bearing basins in Northwest China,Northeast China,Inner Mongolia,Yunnan and Guangxi,it was found out that China is much rich in low rank coalbed methane resources which are the important resources not to be ignored in coalbed methane exploration in our country.Sha′erhu Sag in Tuha basin was optimized as the target area in 2003 and good exploration results have been obtained.On the basis of analyzing the control factors of forming low rank coalbed methane reservoirs,it was pointed out that,in general,the low rank coalbed methane reservoirs are of these characteristics,as shallowly burial depth,low methane content and high permeability.The selection of exploration target should pay attention to analyzing the conditions of preserving coalbed methane to survey high methane saturation areas.In addition,the coalbed with a certain thickness is necessary for low rank coalbed methane development,thus being able to ensure the high resource abundance and individual well producing rate so as to obtain a long stable production period.