RESERVOIR DISTRIBUTION AND DIAGENESIS IN THE NORTHERN NORTH SEA BASIN
Reservoirs in the northern North Sea Basin range from fractured basement to Eocene deposits.There are five sets of main reservoirs:① the Permian Rottiegeudes aeolian and/or alluvial sandstones;②the Triassic fluvial sandstone;③the Middle and Lower Jurassic fluvial,deltaic and marginal marine sandstone;④the Upper Jurassic shallow marine and deep marine turbidite sandstone and conglomerate;⑤the Upper Cretaceous-Lower Paleocene chalk and Paleocene deep-sea turbidite fan sandstones.It is found that the Paleocene-Eocene sandstone is weak in diagenesis and permeability becomes lower under 3100 m.The dissolution of K-feldspar is a major factor influencing diagenesis and permeability in the shallower part.Then illite becomes the main factor below about 3700 m,and secondary quartz plays a major role in the sequence below 4000 m.Oil and gas accumulation depends on the distribution pattern of reservoirs.