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The life cycle of the Netherlands’ natural gas exploration: 40 years after Groningen, where are we now?

The discovery of the giant Permian Groningen Field in 1959 triggered the main phase of gas exploration in NW Europe. This paper deals with the history and future of natural gas exploration in the Netherlands. The aim is to explain the historical exploration process and use the results to predict the remaining part of the exploration life cycle. Data from over 40 years of continuous exploration and production are presented and analysed for relationships between exploration and production (E&P) activity levels (licence area coverage, seismic surveying and drilling rates) and reserves growth. The E&P data are further investigated in terms of the exploration efficiency. After more than 1000 exploration wells drilled, the cumulative reserves growth curve still shows little sign of creaming off. At first sight, this observation would appear to indicate a not very efficient
historical exploration process. The paper will try to explain the impact of the underlying dynamic factors such as added information through time, technology development and infrastructure extensions. Past exploration has revealed part of the total natural distribution of gas accumulations present in the Netherlands subsurface. The best known, i.e. least uncertain, part of the distribution consists of discovered accumulations (although changes in the assessment of this part of the portfolio still occur). Next comes the presently known portfolio of mapped prospects, identified and assessed according to proven play concepts. There is already some of uncertainty as to their actual subsurface volumes. Finally, from the observation that new
prospects have been identified even in recent years, it is proposed that the perceived prospect portfolio will also behave dynamically in the future. Indicators of the maturity level and the estimated ultimate potential of the main play areas are derived. Today’s remaining potential is the source of future exploration. However, the actual outcome of future exploration is not determined by geology alone: business activity levels and exploration efficiency will be shown to be at least as important in the prediction of discovery and production rates.