Multidisciplinary exploration strategy in the northeast Netherlands Zechstein 2 Carbonate play, guided by 3D seismic

Abstract

The Nederlandse Aardolie Maatschappij has actively pursued the exploration of the Zechstein 2 Carbonate play over the last 40 years. The effort concentrated largely on the SE Drenthe area. It has resulted in the discovery of 20 gas fields with cumulative reserves of some 57 x 109m3. The Zechstein 2 Carbonate Member is part of the Basal Zechstein Unit which developed mainly as an anhydrite platform at the southern fringe of the Southern Permian Basin. The facies within the member reflect platform, slope and basinal settings. The subsurface data collected in the exploration and development of the Zechstein fields have led to a detailed sedimentological model for the member.Prospects in the member are seismically defined as structural highs at Top Zechstein 2 Anhydrite level. However,as exploration moves towards the search for more subtle traps, 3D seismic becomes indispensable. Basal Zechstein isochore maps based on 3D seismic, display the topography of the Basal Zechstein platform. These maps are used to assess reservoir potential and gross reservoir thickness. Variations in reservoir parameters, especially porosity, of the Zechstein 2 Carbonate Member are reflected in the seismic response. Quantitative studies based on 3D seismic allow spatial prediction of specific reservoir parameters. Detailed fracture studies in gas fields have demonstrated a relationship between seismically detectable fault patterns and core-scale reservoir enhancing fracture patterns. The Collendoornerveen exploration well demonstrates the successful integration of the various disciplines.