Paleobiology as a Driver In Exploration and Production Activities: Two Examples of Enhanced Exploration Potential from the Dutch “Upper Jurassic” Offshore

(Best of EAGE)

Abbink, Oscar A.¹, Harmen F. Mijnlieff¹, Dirk K. Munsterman¹, Roel M.C.H. Verreussel¹ (1) TNO-NITG, Utrecht, Netherlands

The Upper-Jurassic – Lower Cretaceous strata have been a target for the oil and gas exploration in The Netherlands for several decades. During the initial stages of the Dutch offshore exploration history, various oil fields and some gas fields were discovered. Only the F3-FB field proved to be economic. However, in recent years, new biostratigraphic techniques and newly-acquired stratigraphic data have renewed interest in the uppermost Middle Jurassic (Callovian) – lowermost Cretaceous (Ryazanian) strata of the Central Graben and Terschelling Basin (Dutch Northern Offshore). The geology of thess non-marine to shallow marine strata is complex. The combination of lateral facies changes, repetitive log and facies characteristics in time, sea-level and climate changes, salt tectonics, and structural differences complicate seismic interpretation and log correlation.

New biostratigraphic techniques and newly-acquired stratigraphic data have led to the identification of a series of events which can be related to the tectonic, climatic, environmental and stratigraphic development of the “Upper Jurassic”. Three tectono-stratigraphic sequences (1, 2, and 3) are recognized. These insights have direct impact on the exploration potential. For sequence 1, stratigraphic traps in the deeper part along the basin axis are formed within paralic and fluvial deposits. In sequence 3, sponge reefs, growing due to special paleoenvironmental conditions, form reservoir units along the basin edges and on intra-basinal highs within structural traps. In these two examples, the existence of only one economic oil field and the (mis)placement of exploration wells will be explained. The paleoenvironmental understanding is essential for future exploration potential.