ANALYSIS OF THE GAS HYDRATE MIGRATION AND ACCUMULATION MODEL IN THE DEEP WATER AREAS OF QIONGDONGNAN BASIN

Natural gas hydrate is one of the focuses nowadays in hydrocarbon resource researches. Physical and chemical properties, reservoir forming factors and gas hydrate migration and accumulation mechanisms have been carefully studied in previous references. However, there still remain different opinions and discrepancies on the migration and accumulation process of gas hydrate. Systematic induction and summarization are required. In order to better understand the migration and accumulation model of gas hydrate, which is critical to the exploration and evaluation of gas hydrate and the optimization and prediction of favorable enrichment zones, this paper, taking the reservoir forming types of gas hydrate in the Qiongdongnan Basin as the research focus, made a comprehensive analysis of 3D seismic data and geological research results based on the previous studies. According to the differences in gas source supply, migration and accumulation mode and occurrences of gas hydrate, the migration and accumulation modes of gas hydrate in the Qiongdongnan Basin are systematically classified, and also analyzed and discussed are the distribution pattern and their control factors. According to the difference in gas source and reservoir models, the hydrate accumulation in the Qiongdongnan basin can be divided into three types: the type of lower generation and upper storage, the type of self generation and self storage and the type of compound and mixed genesis. The former two types are further divided into five subtypes, of which the type of lower generation and upper storage includes four subtypes: gas chimney dominated subtype, mud diapir dominated subtype, micro-cracks dominated subtype and fault dominated subtype; and there is only one subtype under the type of self generation and self storage, i.e. the type of shallow in-situ deposits.