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Comparison of Residual Saturations of an Unconventional Reservoir Rock Measured by Different Capillary Pressure Laboratory Methods
N. Schleifer(1), Alexandra Amann-Hildenbrand(2), Jim Bell(3), Philipp Aurin(1) and Roman Scheliga(2)
(1) Wintershall Holding GmbH, Central Laboratory, Germany; (2) RWTH Aachen, Institute of Geology and Geochemistry of Petroleum and Coal, Germany;(3) Advanced Rock Properties Group, Core Laboratories (U.K.) Ltd
This paper was prepared for presentation at the International Symposium of the Society of Core Analysts held in
Vienna, Austria, 27 August - 1 September 2017
Abstract:
An extensive Special Core Analysis study was carried out on an unconventional gas reservoir from the Carboniferous sandstone. As the ambient porosity of the rocks is below 12 % and Klinkenberg corrected permeability is ranging in between 0.001 and 1 mD the laboratory study took almost two years. Saturation measurements were near the detection limit of all applied techniques while running the experiments following best practice procedures.
After finalizing the study the question arose whether such time consuming and cost expensive programs running at the limit of accuracy are appropriate for a proper reservoir characterization or whether a different “more easy” approach is required to deliver data, which would rather give trends and reduce measurement uncertainty by found statistics. Accordingly a research program was started to compare the existing results with a different approach. Advanced core analysis capillary pressure methods as ultracentrifuge, porous plate and mercury injection (MICP) at overburden stress were compared to cost effective methods like ambient MICP, vapor desorption and adsorption as well as counter current imbibition (CCI) delivering a large amount of data, however at ambient conditions.
The paper shows the results of the different approaches under the consideration of accuracy and the governing physical principles/processes. However, their comparison is not straightforward as each method covers different pressure ranges and partially involve usage of non-reservoir fluids, which requires the transfer to representative wettability conditions. The results of this study show the advantages and disadvantages of characterizing such low porosity reservoir rocks and tries to define a complementary laboratory program delivering valuable results within acceptable time for a proper reservoir characterization.
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About the Society of Core Analysts
Objectives
The name of this organization is the Society of Core Analysts (SCA) and was founded in 1986. This organization is a Chapter-at-Large of The Society of Petrophysicists and Well Log Analysts (SPWLA) and is established with two objectives:
- To promote the aims, purposes, and membership of the SPWLA which is a non-profit scientific organization.
- To serve the interests of all persons who use or obtain reservoir evaluation information from rock and core samples.
As a guide for fulfilment of the first objective, this Chapter stands responsible to, and subject to, the rules and regulations of the SPWLA.
As a means toward the second objective this Chapter will sponsor technical speakers, projects, and presentation of papers dealing with formation evaluation. This Chapter will hold membership open to all core analysts, log analysts, geologists, geophysicists engineers, service company personnel and all others interested in the study of rocks and their interstitial fluids. This Chapter will also actively encourage membership and participation in the activities of the SPWLA.
Website: www.scaweb.org
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