Key factors controlling reservoir forming and accumulation model of coal-derived gas in eastern part of Linqing depression

Linqing depression is regarded as an important oil-gas exploration and study area in Bohai Bay basin. Low exploration level and big potential made research work to be significant in this area. The paper studied main factors controlling reservoir forming in different aspects including typical reservoir analysis, and summed up accumulation models for coal-derived gas in Linqing depression. Main source rocks in Linqing depression are coal and dark mudstone, among which coal bed was classified as type-III kerogen inclined to generate gas, and mudstone of II2-III-type kerogen apt to generate oil as well as gas. Hydrocarbon migration is mainly featured by short connecting passages. Development of coal-derived gas reservoir is mainly controlled by trap evolution, gas migration, assemblage of source rock, reservoir bed and cap rock, as well as distribution of good source rock. Research indicated that there are two types of coal-derived gas accumulation models namely reservoir model of the interior of source rock and the exterior of source rock. Among them, reservoir model of the interior of source rock is main targets of exploration henceforth, while the I-type of reservoir model is to be studied further.