Title
Multidisciplinary approach for detailed characterization of shale gas reservoirs, a Netherlands showcase
Author
Zijp, M.H.A.A.
Nelskamp, S.
Schavemaker, Y.A.
ten Veen, J.H.
ter Heege, J.H.
Publication year
2013
Abstract
The success of shale gas exploration and production in the United States has triggered other countries around the world to look into possibilities of producing gas from different shales. As it turns out, one of the main difficulties when looking for shale gas is obtaining an in depth understanding of the shale formations and interpret where the sweet spots for gas production will be. This is mainly caused by the large differences in properties of shale formations. To improve our understanding of the vertical and lateral property changes that determine high and low productivity zones in shales, TNO has proposed a workflow including well log interpretation, mud log interpretation, depth modeling, organic geochemistry, basin modeling, palynology, electron microscope analyses, mineral typing and porosity identification and characterization. This method serves as a solid basis for sweet spot determination and proper resource estimates. The proposed method has been applied to the two main possible shale gas reservoirs in the Netherlands; the Lower Jurassic Posidonia Shale Formation (PSF) and the Carboniferous (Namurian) Epen Formation. The latter is of particular interest as it contains the highly organic basal Geverik Member (GM). For the two formations detailed and accurate depth maps have been produced. Research on the PSF shows that a number of areas are expected to have reached gas maturity, together around a fifth of the total area of the formation. Besides shale gas there appears to be potential for shale oil. High productivity zones within these shales are expected in the deepest part of formation and orientated along the distribution axis within the West Netherlands Basin. In the multidisciplinary workflow a 3D faciesmodel of the formation is created using palynology and organofacies to detect prospective layers within the formation. This faciesmodel is then used in combination with log-interpretaion, seismic interpretation and sedimentological interpretation to detect most prospective zones and areas. FIB-SEM microscopy shows that coccoliths present in the formation can have large favourable effects on the porosity and permeability providing for a micropermeability pathway for oil and gas when interconnected. When the proposed workflow is applied to the Geverik Member, a correlation between silica content and Total Organic Carbon (TOC) is found, i.e. log-derived TOC is in general close to 10% when the dominant mineral type is silica. Geomechanical analysis of rock properties shows that the lower zone of the Geverik Member is the favourable layer to target, i.e. the layer is dominantly build up of quartz and silica suggesting preferential conditions for hydraulic stimulation.
Subject
Earth & Environment
PG - Petroleum Geosciences
EELS - Earth, Environmental and Life Sciences
Geological Survey Netherlands
Geosciences
Energy / Geological Survey Netherlands
Petroleum prospecting
Porosity
Productivity
Quartz
Well logging
Electron microscope analysis
Hydraulic stimulations
In-depth understanding
Multi-disciplinary approach
Sedimentological interpretations
Seismic interpretation
Total Organic Carbon
West netherlands basins
Shale
To reference this document use:
http://resolver.tudelft.nl/uuid:8c901dfe-29a6-4191-aa95-84bb1f4a620e
TNO identifier
485051
Source
Offshore Technology Conference Brasil, Rio de Janeiro, Brazil, 29-31 October 2013, 1-10
Article number
OTC-24383-MS
Document type
conference paper