European Unconventional Oil and Gas Assessment (EUOGA) - Development and application of a unified methodology

Over the last decade, various international and national assessments of shale gas and shale oil resources for most EU-countries have been published. Due to methodological differences and in fundamental assumptions related to the quality and quantity of underlying geological information, these results are not comparable and in some cases not reproducible. This presentation focusses on the development and definition of a uniform methodology for estimating (in-place) shale gas and shale oil resources at the pan-European level within the context of the EUOGA study (EU Unconventional Oil and Gas Assessment). The presented methodology is established to determine estimates of GIIP (Gas Initially In Place) and OIIP (Oil Initially In Place) including associated uncertainty bandwidths originating from the various geological input parameters. The method is applied to 81 onshore shale gas or oil formations from 33 thermogenic and two biogenic basins located within the participating European countries. The results of the assessment include a geological description of the basins together with a general chance of success, a ranking of the individual assessment units and the final calculation of GIIP or OIIP for the formations.JRC.C.3-Energy Security, Distribution and Market

European prospective unconventional hydrocarbon shales: a prior approximation for resource assessment parameterisation based on European analogies.

In a European wide project, including Ukraine, 74 shale formations from 30 thermogenic and two biogenic gas bearing onshore basins were studied for hydrocarbon potential. All formations have been mapped and data complied based on information and expert judgments gathered from the respective European National Geological Surveys. Parameters relevant for resource evaluation purposes were gathered for each shale layer according to the current, publically available knowledge. The description also includes a full bibliographic reference database with more than 250 references comprising the current state of the art of scientific research of European shale gas and oil. Average properties for all European shales and for typical Carboniferous and Jurassic shales are presented, applicable as a prior approximation for resource assessment parameterisation based on European analogues. The European shales compare well with prospective North American shales with respect to lateral extent, thickness, TOC content, and maturity. The European prospective shales are, however, dominated by more clay rich rock types than producing North American shales. High clay content is known to pose engineering related difficulties during drilling, completion and production; hence it may pose challenges for successful implementation of North American shale gas and oil technologies to Europe.JRC.C.3-Energy Security, Distribution and Market

Sweet spot identification in underexplored shales using multidisciplinary reservoir characterization and key performance indicators: Example of the Posidonia Shale Formation in the Netherlands

Sweet spot identification in underexplored shale gas basins needs to be based on a limited amount of data on shale properties in combination with upfront geological characterization and modelling, because actual production data is usually absent. Multidisciplinary reservoir characterization and integration of modelling approaches can aid initial site selection for exploratory drilling and de-risk exploration efforts. In this study, the potential of hydrocarbon production across underexplored shale basins is analyzed using key performance indicators. A mean indicator is defined as the harmonic mean of three performance indicators that describe the potential for hydrocarbon generation, storage, and flow stimulation. The performance indicators are based on a limited number of local shale properties, i.e. vitrinite reflectance, porosity, depth, thickness, sorbed gas content and brittleness index. Values for the indicators are calculated relative to prospective North American shales (Marcellus, Bakken, Haynesville and Barnett), so that the mean indicator can be used to rank the prospectivity of an underexplored shale relative to hydrocarbon producing shales. The mean performance indicator is also used to map out the potential for gas production in the underexplored Posidonia Shale Formation in the West Netherlands Basin. The analysis shows that the performance indicator is lower for the Posidonia than for the North American Shales, mainly due to low maturity and brittleness. Local maxima of the indicator correlate with local maxima in vitrinite reflectance and depth. Besides the low potential for flow stimulation, the potential for hydrocarbon generation and storage capacity of the Posidonia are comparable to oil-window thermal-maturity Barnett Shale. Upfront simulations of hydraulic fracture properties and gas production in the Posidonia Shale Formation are in rough agreement with observed average gas flow for Barnett wells in non-core areas that are oil mature. It shows that key performance indicators can be applied to underexplored shales to quantify prospectivity and map out sweet spots across shale basins