鄂尔多斯盆地东缘煤层气有利区块优选

鄂尔多斯盆地东缘经过20 a的勘探开发,煤层气仍然没有实现产业化。随着勘探资料的不断丰富,有必要对该区进行煤层气有利区块的优选和重新认识。在前人研究基础上,首先将鄂尔多斯盆地东缘埋深1 500 m区域分为6个区块,选取煤层厚度、含气量、构造条件、水文条件、煤体结构、含气饱和度、储层压力梯度、渗透率和临界解吸压力与储层压力比9个参数作为区块优选指标,结合国内外及研究区实际情况制定了相应的评价临界值。将上述参数作为评价指标集合,以评价单元作为对象集,以有利、较有利和不利作为评级等级集合,然后运用模糊数学综合评判方法得到各评价单元的不同评价参数对评价等级的隶属度,并运用层次分析法确定了各指标的相对权重,最后得到了评价单元对评价等级的隶属度。根据最大隶属度原则,吴堡-柳林属于有利区,大宁-吉县和韩城属于较有利区,准格尔、府谷、河曲-临县属于不利区,吴堡-柳林的煤层气可采性好于大宁-吉县和韩城。因此,建议将吴堡-柳林、大宁-吉县和韩城定为研究区煤层气优先开发区块。 

Selection of the favorable coalbed methane(CBM) blocks in eastern Ordos basin

After 20 year exploration and development, the CBM industrialization hasn't been realized in eastern Ordos basin. With the enrichment of CBM exploration data, it is necessary to select favorable blocks. In this paper, firstly, in combination with previous research, the area shallower than 1500m in eastern Ordos basin may be divided into six blocks, and 9 parameters were chosen as selecting index, such as coal seam thickness, gas content, tectonic condition, hydrologic condition, coal structure, gas saturation, reservoir pressure gradient, permeability and the ratio of critical reservoir pressure to the reservoir pressure; secondly, the corresponding critical evaluation value was determined. The above 9 parameters are set as the evaluation index aggregate, evaluation unit as the object aggregate, favorable, sub-favorable and unfavorable as rating level aggregate. Then by using the fuzzy mathematics comprehensive evaluation method, the membership degree to the evaluation grades of the evaluation parameters for each evaluation unit was obtained, and by using hierarchy analytic process, the relative weight of every index was obtained. Finally, the membership degrees to the evaluation rating was obtained. According to the maximum membership degree principle, Wubao-Liulin was sorted as favorable area, Daning-Jixian and Hancheng as sub-favorable areas, and Zhungeer, Fugu, Hequ-LinXian as unfavorable areas, the CBM recovery in Wubao-Liulin is higher than that in Daning-Jixian and Hancheng, and Wubao-Liulin, Daning-Jixian and Hancheng were proposed as CBM priority development blocks in eastern Ordos basin.