作　　者： ; ; ; ; ; ; (冯圣）;

机构地区： 中国矿业大学北京

出　　处： 《天然气工业》 2011年第2期34-38,123,共5页

摘　　要： 乌审旗地区是鄂尔多斯盆地的重要含煤区，也是近几年低煤阶煤层气勘探的热点地区。但该区前期煤层气钻探总体效果并不理想，迫切需要认清该区煤层气富集规律，以便有效开展煤层气勘探及开发利用。为此，对该区煤层分布特征、聚煤期沉积环境、煤岩特征及储层物性、煤层含气性等地质条件进行了分析，发现该区煤岩演化程度低，以低堞阶长焰煤为主，煤层厚5～30n3，大部分地区煤层埋深小于1000m且分布稳定，具有一定的煤层气勘探潜力。但煤层气钻井揭示该区煤层含气性变化大，煤层含气量介于0．19～6．7m^3／t，部分地区煤层气组成中CH4含量小于25％，说明煤层早期成岩时生成吸附的甲烷已被破坏逸散。进一步分析影响该区煤层气富集的主控因素后认为：在煤层直接盖层为砂岩、保存条件差的地区，煤层含气性差，反之，则含气性好，如果有后期生物气的补充，则可以富集成藏。最后指出：该区北部的乌审召区块和南部的纳林河区块，煤层气保存条件好、含气量高、勘探潜力大，可作为下一步煤层气勘探的有利目标区。 The Jurassic coal seams in the Ordos Basin are rich in low-rank coalbed methane resources which is about 5.28 trillion m3 and accounts for 36% of the total low-rank coalbed methane resources(14.7 trillion m3) in China.Wushenqi,an important Jurassic coal-bearing area in the Ordos Basin,is also the focus of low-rank coalbed methane gas exploration in recent years.Although many projects of coalbed methane gas drilling and exploration in this area have been substantially performed by the PetroChina,local governments and many other enterprises,no satisfactory results have been achieved yet.Therefore,there is an urgent need to find out the rules of the CBM enrichment in this area in order to effectively explore and exploit more CBM methane gas resources here.Through an analysis of geological conditions of CBM in the Wushenqi area,it is discovered that this area is of low degree of evolution and is dominated by low-rank long-flame coals with the thickness of coal seam at the range from 5 to 30 m;in most parts the burial depth of coal seams are less than 1000 m with a stable distribution and a potential for coalbed methane gas exploration.However,the CBM drilling result reveals that the gas-bearing property of the coal seams in this area varies greatly with gas contents from 0.19 to 6.7 m3/t,and in some parts of this area,the CH4 content is even less than 25% in the components of the CBM gas,which demonstrates that the methane gas generated and adsorbed in the early diagenetic period of coal beds has escaped or has been destroyed.Further studies show that if there is poorer preservation condition with sandstone as the sealing rocks,the gas-bearing property in coal beds will be worse;while,on the contrary,the gas-bearing property will be better,and in this case if there is additional later biogas,the gas will be accumulated to be reservoirs as a result.In the end of this paper,it is also pointed out that the northern Wushenzhao and the southern Nalinhe have great potential of CBM gas exploration with high methane gas cont

关 键 词： 鄂尔多斯盆地 乌审旗 低煤阶 含气性 次生生物气 保存条件 油气富集 水文地质

领　　域： [天文地球] [天文地球]