Accumulation factor matching and model of Bozhong 19-6 buried hill gas reservoir, Bohai Sea area

Abstract

The accumulation factors and mechanism of the 100 billion cubic meters gas reservoir in the Bozhong 19-6 buried hill of the Bohai Sea area were studied using geochemical analyses and basin modelling based on a large amount of core, cast thin section, well logging and geochemical data. The results showed the following. (1) The gas generated by the source rocks of the third member of the Shahejie Formation in the Bozhong Sag generally exceeds 5×109 m3/km2. The continuous hydrocarbon supply in the late period provided sufficient material for the formation of the Bozhong 19-6 buried hill gas reservoir. (2) The Indosinian and Yanshanian tectonic movements were the key periods for the formation of structural fractured reservoirs and buried-hill traps, and formed a near-source fault transport system and a far-source unconformity transport system. (3) The thick overpressure mudstone cap rocks of the Dongying Formation and the weak tectonic activity in the late period were beneficial to the preservation of the Bozhong 19-6 buried hill gas reservoir. (4) The time-space matching of the six major accumulation factors of "generation, storage, cap rock, trap, migration, and preservation" ultimately led to the formation of a large gas field of 100 billion cubic meters in the Bozhong 19-6 buried hill. A late accumulation model of multi-depression hydrocarbon supply, multi-directional charging, combined fault and unconformity transport was established in the Bozhong 19-6 buried hill.

Keywords

• bozhong 19-6 buried hill gas reservoir
• accumulation factor coupling
• accumulation model
• bozhong sag
• bohai sea area