Abstract Water resource management is a major concern in Marquenterre, a maritime plain located in the western part of the Somme department. Water management is particularly indispensable for protecting wetlands in Marquenterre, regulating water usage and avoiding saline intrusion into aquifers. Various approaches including geological modelling and hydrogeological and hydrogeochemical studies were used to prepare a conceptual model of the Marquenterre hydrosystem and to provide better water management in this sector. The conceptual model shows that the chalk aquifer and the various Quaternary deposit aquifers are in hydrogeological continuity. No seawater intrusion has been discovered in groundwater. Salinization discovered at depth is a result of the most recent marine transgressions. Finally, wetlands are primarily supplied by the chalk groundwater or by rainfall. The study results are used to direct policies for surface and subsurface water resource management. The proposed conceptual model may be useful for other coastal aquifers along the English Channel in order to address challenges of managing the chalk groundwater and backshore swamps.

Abstract Exploration drilling activity, discovery history and creaming curves in the offshore UK are analysed for each UK Continental Shelf (UKCS) basin and each play in the North Sea from the earliest wells drilled in 1965 until the end of 2017. Around 52 Bboe of commercially recoverable oil and gas has been discovered, with around half of this volume found in the first 10 years of exploration. UKCS exploration plays are generally at a mature or super-mature stage and the exploration challenges reflect this. Although technical success rates have steadily increased since the 1990s, pool sizes are becoming smaller. In the last 10 years the average commercial discovery size has been 27 MMboe recoverable, and since 2010 only 10% of discoveries have been bigger than 43 MMboe recoverable. The UK Oil and Gas Authority's 6 Bboe mid-case yet-to-find estimate, as published in 2018, would take 40 years to unlock at the current rate of discovery. Future exploration in the mature UKCS is intertwined with prolonging the life of production infrastructure and is increasingly dependent on the development of new low-cost development concepts. Increased focus on the search for subtle traps, and more reliable pre-drill risk and volume estimation through improved benchmarking and calibration will be key to future exploration success.