Reservoir Heterogeneity in Upper Carboniferous Tight Gas Sandstones: Lessons Learned From an Analog Study
- P. Wuestefeld (RWTH Aachen University) | C. Hilgers (RWTH Aachen University) | B. Koehrer (Wintershall Holding GmbH Germany) | M. Hoehne (RWTH Aachen University) | P. Steindorf (RWTH Aachen University) | K. Schurk (RWTH Aachen University) | S. Becker (RWTH Aachen University) | P. Bertier (RWTH Aachen University)
- Document ID
- Society of Petroleum Engineers
- SPE/EAGE European Unconventional Resources Conference and Exhibition, 25-27 February, Vienna, Austria
- Publication Date
- Document Type
- Conference Paper
- 2014. Society of Petroleum Engineers
- 1.14 Casing and Cementing, 4.1.2 Separation and Treating, 5.1.2 Faults and Fracture Characterisation, 4.3.4 Scale, 7.3.1 Exploration and Appraisal Strategies, 5.1.3 Sedimentology, 5.3.4 Integration of geomechanics in models, 5.8.1 Tight Gas, 1.2.3 Rock properties, 4.1.5 Processing Equipment, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.1.5 Geologic Modeling, 5.1.1 Exploration, Development, Structural Geology, 5.5.2 Core Analysis
- structural diagenesis, tight gas
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Upper Carboniferous sandstones in NW-Germany consist of thick successions of cyclothems and are major tight gas reservoirs. This study presents the heterogeneity exposed in a large quarry near Osnabrueck, Germany, which contains faulted and jointed third-order coarse- to fine-grained tight sandstone cycles separated by anthracite coal seams. First, we characterize the rocks and the lateral variation of rock properties such as porosity, diagenesis and structural inventory. Than we test whether the quarry may act as a reservoir analog to better constrain input data for reservoir modelling.
The tight sandstones are intensely compacted and cemented with quartz and generally characterized by low matrix porosities < 8 % (He-pycnometry on plugs and cuttings) and very low permeabilities (<0.01 mD). Porosity is generally secondary, formed by detrital and authigenic carbonate dissolution and dissolution of feldspars. Matrix porosity significantly increases up to 25% in corridors around faults. Rock types can be distinguished by spectral gamma ray in the quarry. Fluid flow within and around faults is indicated by quartz veins and fault mineralizations. Normal faults show and bands of clay smear and gouge, forming compartments. Fractures were analyzed in a 50 x 50 m section of the quarry wall using Lidar laser scanning. This digitized quarry face also allows the characterization of the lithology and quantitative measurement of bedding, fracture and fault orientation data in inaccessible areas.
Our high resolution field analog enables a better understanding of unconventional reservoir properties and reservoir quality at a subseismic scale, considering both the change of porosity during diagenesis and the formation of structures. Results may be used to develop data-driven exploration strategies and improved development options for similar subsurface tight gas reservoirs.
|File Size||11 MB||Number of Pages||10|