长江沿岸某区浅层天然气特征及其对工程建设的影响

在详细分析研究地质地貌的基础上,依据长江演化历史和沉积构造特征,得出长江口某区为典型河口湾相沉积环境.根据天然气成分分析和CH4碳同位素资料,论证了该区天然气为浅层天然气.根据第四系泥质层中有机碳的含量,得出全新世第2次海浸期的河口湾相沉积层是气源层,其中的砂质透镜体、薄砂层以及粘土质砂层为主要储气层.通过生、储、盖的条件分析,该区具备自生、自储、自盖的生储盖组合,而生盖条件相对较好,储层条件欠佳,从而对其在工程建设中的影响作了初步评价,提出防、堵、排三结合,以排为主的措施.

Character and effect on the engineering construction of shallow layer natural gas in an area of Yangd River coastwise

Preliminary assessment of shallow layer natural gas in engineering construction is a new topic.Based on the laboring of geology topographic features and Yangtze River evolutionary history and sedimentary structure characteristic,it is determined that this area is a typical river estuary sedimentary facies.According to analysis of natural gas ingredient and CH_4 carbon isotope,it is proven that the natural gas of this area is superficial.According to the organic carbon content of the quaternary sedimentary,it is found that the gas source level is the river estuary sedimentary facies of the second sea to soak in Holocene.The main gas-bearing reservoir is the gritty lens,thin sand and clayey sand.The analysis of living,storing up and covering suggests that this area has the combination of autogeny,storing up and covering by itself.The condition of autogeny and covering by itself is comparatively good and out of condition to store up.Thus we get their preliminary assessment in engineering construction and give the measure which joins the defending,stopping and drainage together and gives priority to drainage.