GENETIC TYPES AND DEVELOPMENT CHARACTERISTICS OF GAS CHIMNEYS IN THE QIONGDONGNAN BASIN AND THEIRCONTROL ON HYDRATE ACCUMULATION

Gas chimney is an important channel for vertical movement of hydrocarbon in deep waters. Its formation and evolution are closely related to hydrocarbon migration and accumulation. Since Miocene, the Qiongdongnan Basin has been characterized by strong hydrocarbon generation and fluid activities, which lead to the wide distribution of gas chimneys. It is of great significance to study the development characteristics and genetic types of the gas chimneys in the Qiongdongnan Basin for the establishment of oil and gas migration and accumulation channel systems, the analysis of oil and gas hydrate migration and accumulation conditions, and providing guidelines for oil and gas (hydrate) evaluation, exploration and deployment. Based on the seismic data from the Qiongdongnan Basin, this paper starts with the description of the seismic reflection characteristics of gas chimneys in the study area, the scale of gas chimneys and the genetic classification of gas chimneys. Combined with the depth of the bottom of gas chimneys, the energy strength and the bottom environment, the genetic types of gas chimneys in the deep water area of Qiongdongnan Basin are classified as follows: shallow low energy fault-fissure-controlled gas chimneys, shallow high energy and low-rise-controlled gas chimneys, middle medium energy and low-rise-controlled gas chimneys, middle high energy and low-rise-controlled gas chimneys. We believe that gas chimneys not only act as channels and indicator of hydrate migration and accumulation, but also have multiple characteristics of the destruction of hydrate deposits. On this basis, we further analyzed the distribution and formation patterns of gas chimneys in the Qiongdongnan Basin.