Reservoir geology, structural framework and petrophysical aspects of the Wijk gas field

Abstract

The De Wijk gas field is situated near the town of Meppel in the Dutch province of Drenthe. It produces gas from Carboniferous, Triassic and Tertiary. The largest gas accumulation is contained within a system of Triassic reservoirs and is trapped in a broad salt induced structure some 10 by 11 km. Within this structure Triassic sediments, ranging from the Lower Muschelkalk Member in the east to the Main Claystone Member in the west, subcrop with marked angularity on the Late Kimmerian erosion surface. Vertical sealing is provided by Lower Cretaceous shales and marls which unconformably overlay the Triassic sediments. So far economic gas production has been established from the shallow Basal Dongen Tuffite Member in the lower part of the Tertiary, from the Triassic Rogenstein oolite, Volpriehausen Sandstone and Lower Muschelkalk members, as well as from a small Carboniferous reservoir. The fact that gas is produced from the Basal Dongen Tuffite, Rogenstein oolite and Lower Muschelkalk makes the De Wijk field unique among Dutch gas fields; nowhere else in The Netherlands are any of these reservoirs gas productive. The reservoir properties of the Triassic reservoirs are due to diagenetic effects; in particular to leaching of anhydrite during the Kimmerian erosional phases.