Abstract
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Article Information:
Bulk Volume Reduction of the Kimmeridge Clay Formation, North Sea (UK) Due to Compaction, Petroleum Generation and Expulsion
Kenneth S. Okiongbo
Corresponding Author: Kenneth S. Okiongbo
Submitted: 2010 December, 17
Accepted: 2011 January, 20
Published: 2011 February, 20 |
Abstract:
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In this study, the effects of petroleum generation and expulsion on shale porosity is explored by
evaluating the compaction of the Kimmeridge Clay Formation (KCF) within the oil window using log data and
shale samples from the KCF within the depth and temperature range of ~1.5-5.0 km and 90-157ÂșC, respectively.
Petrophysical properties e.g porosity and pore-size distribution were measured, and permeability was calculated
using empirical models based on the measured porosities. Transit-time values from the sonic logs recorded at
depths in the wells were the cores were recovered were calibrated against the porosities determined from the
core samples. Bulk geochemical parameters e.g., Total Organic Carbon (TOC), Hydrogen Index (HI) were
determined. The volume reduction in the KCF within the oil window due to petroleum generation and
expulsion, and compaction due to loss of pore space was determined using the geochemical and log derived
porosity data emplaced into empirical relations. Porosities above the oil window range from ~15-20%, but
decreased to <5% at the end of the oil window. Pore-sizes decrease from ~11 nm to between 6-8 nm at the
depth range of 1.5-5.0 km. Permeability decreased from 4.8 nD to ~0.095 nD. The quantitative estimations of
volume reduction within the oil window indicate that for ~8.0wt% initial TOC sediment, a bulk volume
reduction of 13% of the initial volume is due to oil expulsion, and ~12% is due to loss of pore space.
Key words: Compaction, hydrogen index, mudstone, permeability, pore size distribution, porosity,
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Cite this Reference:
Kenneth S. Okiongbo, . Bulk Volume Reduction of the Kimmeridge Clay Formation, North Sea (UK) Due to Compaction, Petroleum Generation and Expulsion. Research Journal of Applied Sciences, Engineering and Technology, (02): 132-139.
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ISSN (Online): 2040-7467
ISSN (Print): 2040-7459 |
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