利用地表甲烷氧化菌异常勘探天然气藏

EXPLORING FOR GAS RESERVOIRS BY APPLYING THE ANOMALIES OF SURFACE METHANE OXIDIZING BACTERIA

用最大或然数(MPN)微生物计数法测定油田深度为1.0～1.5 m地表土壤样品的甲烷氧化菌数量,结合气相色谱法测定土壤中甲烷氧化菌消耗甲烷的速率,来分析供试地区甲烷氧化菌的异常,推断地下天然气藏的分布.甲烷氧化菌的数量与其活性具有正相关性,但不具有明显的规律特征.甲烷氧化菌的数量明显高于背景值.供试油田土壤的湿度、pH值和岩性对甲烷氧化菌的数量与活性影响不明显.通过对油田20个测点土壤中甲烷氧化菌数量及相关井位的研究,结果表明甲烷氧化菌的数量可以作为指示天然气藏分布的指标.试验油田东部及东南部为有利气勘探区.该方法作为天然气勘探的一种辅助手段,具有快速、低成本的优点.

Through measuring the quantity of methane oxidizing bacteria (MOB) in the surface soil samples with burial depths of 1. 0 - 1. 5 m in one oilfield by use of the most probable number (MPN) microbiological counting method) in combination with the gas chromatogram-measured rates of consuming methane by MOB in soil, the distribution of gas reservoirs could be predicted on the basis of analyzing the anomalies of MOB in the oilfield. The quantity of MOB was positively correlated to their activity, which hadn' t obvious law. The quantity of MOB was much higher than the background value. The influence of the humidity, pH and lithology of the soil on the quantity and activity of MOB was unnoticeable in the oilfield. According to the study results of the quantity of MOB in 20 soil samples and the relevant well locations, it was indicated that the quantity of MOB may be regarded as the criterion of showing the distribution of gas reservoirs and the east and southeast parts of the oilfield are the favourable areas of exploring for gas. This method may be taken as an auxiliary means of natural gas exploration, being of the advantages of high-speed and low-cost.