鄂尔多斯盆地神府地区中低阶煤层气勘探潜力分析

Analysis on exploration potential of mid-low rank coalbed methane in Shenfu Area of Ordos Basin

为了分析鄂尔多斯盆地东缘神木-府谷地区中低阶煤层气的勘探潜力,通过煤岩工业分析,显微组分、Ro,max、热模拟等试验数据的统计、对比,发现8+9号煤生烃能力强于4+5号煤;通过解吸试验可知,研究区东部抬升区煤层气含量低,以吸附气为主,且由于煤层及地下水条件不利于生物气生成,勘探潜力不足;而西部地层缓坡区,特别是背斜发育区,由于中低煤阶煤孔渗相对发育,游离气含量增高,甚至可能超过吸附气。高煤阶煤储层→低煤阶煤储层→常规气藏储层,其含气形式存在以吸附气→吸附气、游离气→游离气为主的变化规律,结合其他煤层气赋存条件,"构造高点"或圈闭是该地区煤层气勘探的有利方向。

In order to analyze the exploration potential of mid-low rank coalbed methane in Shenmu-Fugu Area at east edge of Ordos Ba- sin, though coal and rock proximate analysis, maceral, R heat simulation and other experimental data statistics and eontrastive,it was found that the hydrocarbon generation capacity of No. 8＋9 seam was higher than No. 4＋5 seam. The result of desorption experiments showed that, the coalbed methane content of upraised area at east part of study area was low and was adsorption gas mainly due to the seam and underground water conditions were not suitable to biogas generation and the exploration potential was insufficient. The strata in west of the area were in gentle slope area. Especially in anticline development area, due to the pore permeability of medium and mid-low rank coal relatively developed, free gas content could be increased and could be over the adsorption gas. Based on high rank coal reservoir → low rank coal reservoir → normal gas formation reservoir, and the gas-bearing variation law was adsorbed gas →adsorbed gas and free gas→ free gas, in combination with other coalhed methane deposition conditions, the ＂ structure highs＂ or trap would be favora- ble direction to coalbed methane exploration in the area.