Reservoir characteristics and development model of Middle Cretaceous Mishrif Formation, Persian Gulf Basin
Gao Jixian1,2, Tian Changbing2, Zhang Weimin2, Song Xinmin2,3, Wang Yuxi1,2, Liu Bo2,3
1. School of Earth and Space Sciences, Peking University, Beijing 100871;
2. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083;
3. Institute of Oil and Gas, Peking University, Beijing 100871
Mishrif Formation is one of the principal carbonate reservoirs in Persian Gulf Basin.The best reservoir conditions occur in rudist-bearing facies,such as rudstone and rudistid packstone/grainstones; other carbonate facies,such as pelagic mudstone/wackestone,bioclastic wackestone and peloidal packstones,are less significant as reservoir rocks.The reservoir spaces are mainly interparticle porosity, intercrystalline, moldic, solution-enhanced porous,fabric selectivity denudation vugs and microporosity.The reservoir is stratified and continuous in lateral,and distribution is controlled by depositional facies boundaries.Tight limestone as flow baffles and barriers distributed within the sequence is the main cause for extremely vertical heterogeneity of the reservoir.Primary deposition,later diagenesis and structural deformation control the porosity development and preservation.The main reservoir facies,such as patch-reefs and rudist shoals,are deposited in carbonate ramp,which distribute directly related to palaeogeomorphology.The cyclicity of the relative sea-level changes controls the migration of reef-shoal facies and diagenetic evolution,which further determine the development of porous layers and tight layers and the feature of significant heterogeneity.The formation of trap well matches the injection of hydrocarbon,which restrains the damages of compaction and cementation to reservoir effectively.