In this report the results are presented of the ‘Improved Sweet Spot Identification and Smart Development Using Integrated Reservoir Characterization’ project. The aim of the project was to characterize the shale gas reservoir properties of the Posidonia Shale Formation (PSF), present in the Dutch subsurface. Particularly, the project aimed at characterizing and quantifying lateral and vertical shale heterogeneities and their expressions in conventional well logs. In order to achieve this goal, an age-equivalent outcrop analogue to the PSF was selected and studied in detail. The selected outcrop analogue was the informal ‘Jet Rock’, part of the Whitby Mudstone Formation, cropping out in coastal cliff sections in Yorkshire, Northern England. The analytical results from the Whitby outcrop study were then applied to the PSF in the West Netherlands Basin. In support of the analogy, it could be concluded that the ‘Jet Rock’ is very similar to the PSF with respect to overall thickness, depositional environment, mineralogy, and to a certain extent also in the TOC distribution. This suggests that on a trend parallel to a paleo-shoreline of the northwestern part of the Tethys Ocean, the PSF is laterally homogeneous over large distances (>50 km). It is expected that the PSF is less homogenous over large distances on a trend perpendicular to the paleo-shoreline.
In contrast to mature shale gas plays, for which extensive exploration drilling is and was possible, exploration in the Netherlands is very challenging in the absence of dedicated exploration wells. This project therefore aimed at developing and applying a methodology for shale gas exploration that builds on the synthesis of existing information and data from vintage wells in addition to analyses of outcrop analogues and core material in order to identify the most promising targets for shale gas presence and production. The "Sweet Spot 2" project showed that it is possible to identify promising shale gas targets or areas of superior source-rock quality from available exploration data. A better understanding of processes that lead to the deposition of organic-rich shales helps in understanding and predicting the distribution and quality of these areas and thus reducing the need for extensive exploration drilling in order to identify shale gas targets. This report compiles the results of the second phase of the project entitled “Improved Sweet Spot Identification and Smart Development Using Integrated Reservoir Characterization”. Data and results from the first phase were incorporated and extended in this study.
In this report, the results are presented of a stratigraphic study on the Upper Jurassic to Lower Cretaceous of the Step Graben, Broad Fourteens and offshore West Netherlands Basins. In addition a composite stable isotope reference curve for the Upper Jurassic to Lower Cretaceous for the Dutch offshore is presented. The data underpinning the geological model presented here, are primarily derived from palynological and stable isotope analyses, while seismic cross-sections are used to illustrate the stratal relationships. The general aim of the project was to improve the Upper Jurassic and Lower Cretaceous stratigraphy of the Dutch offshore. More in particular, it was aimed to develop a tectono-stratigraphic framework for the studied interval, with special interest in the distribution of reservoir sandstones.
The FOCUS project investigated the Upper Jurassic and Lower Cretaceous in the Eastern part of the Dutch offshore in order to provide new insights on the regional and local stratigraphic, depositional and syn-depostional settings. Despite having numerous known reservoirs, this stratigraphic interval still holds key remaining questions regarding its depositional environments and the preservation of sandy strata. The local and regional correlation of these strata across the main structural provinces required new analysis and insights that this project offers. The study area encompassed the three main structural provinces and five platforms. The main stratigraphic interval of interest was the Upper Jurassic and Lower Cretaceous. The project included sedimentological, biostratigraphic, geochemical, stratigraphic and structural analysis of subsurface data including cores, cuttings, wireline logs and seismic data. The results obtained from the combination and integration of these various analytical techniques were used to produce a new stratigraphic and tectono-stratigraphic model for the Upper Jurassic and Lower Cretaceous in the northern and eastern part of the Dutch offshore.