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通过天然气沉淀水合物的动力学模拟计算,研究了墨西哥湾GC185区BushHill海底天然气渗漏系统的演化特征及对水合物沉淀的影响。渗漏早期,天然气渗漏速度大(q>18.4kg/m2a),海底沉积以泥火山为主,渗漏天然气具有与气源天然气几乎一致的组成,形成的水合物具有最重的天然气成分。渗漏晚期,天然气渗漏速度很慢(q<0.55kg/m2a),在海底附近没有水合物沉淀,主要以冷泉碳酸盐岩发育为主,水合物产于海底之下一定深度的沉积层中。介于二者间的渗漏中期(q:0.55～18.4kg/m2a),海底发育水合物、自养生物群为特征,渗漏速度控制了水合物和渗漏天然气的组成及沉淀水合物的天然气比例。BushHill渗漏系统近10年的深潜重复采样显示,渗漏天然气和水合物天然气的化学组成在时空上是多变的,相对应的渗漏速度在时间上的变化约为3倍,在空间上的变化近2个数量级。
Based on the kinetic modeling of natural gas hydrate precipitation, the evolution characteristics of the natural gas leakage system in the Bushill sea floor of GC185 in the Gulf of Mexico and its effect on hydrate precipitation were studied. In the early stage of the seepage, natural gas leakage rate was high (q> 18.4kg / m2a). Most of the seafloor sediments were mud volcanoes. Leaking gas was almost the same composition as gas source gas and the hydrate formed had the heaviest natural gas composition. In the late stage of leakage, the seepage rate of natural gas is very slow (q <0.55kg / m2a). There is no hydrate precipitation near the seafloor, which is mainly dominated by cold spring carbonate rocks. Hydrates are produced in sediments of a certain depth under the seafloor . Between mid-term leakage (q: 0.55 ~ 18.4 kg / m2a), marine hydrophytes and autotrophs are characterized by the rate of leakage controlling the composition of hydrate and seepage natural gas and the rate of precipitation of hydrates Natural gas ratio. The BushHill seepage system for nearly 10 years showed that the chemical composition of natural gas leakage and hydrate gas was variable in time and space, and the corresponding leakage rate was about 3 times change in time. In the space The changes on the nearly 2 orders of magnitude.