The petrophysical properties of deformation bands in relation to their microstructure

Ogilvie, SR Glover, PWJ

Sr. Ogilvie et Pwj. Glover, The petrophysical properties of deformation bands in relation to their microstructure, EARTH PLAN, 193(1-2), 2001, pp. 129-142

34

INGLESE

Article

Earth Sciences

EARTH AND PLANETARY SCIENCE LETTERS

0012-821X → ACNP

193

1-2

2001

129 - 142

ISI

0012-821X(20011130)193:1-2<129:TPPODB>2.0.ZU;2-4

Deformation bands are significant discontinuities in reservoir sandstones p roviding baffles to the migration of fluids and acting as seats for hydroca rbon accumulations. Their contribution to these processes is dependent upon a range of inter-related factors including lateral continuity, relative di splacement, reservoir geohistories and rock microstructure. Deformation ban ds have millimetre-scale displacements, which are smaller than the seismic resolution, and hence the study of their microstructure from reservoir core s is a necessary tool in the prediction of their fault seal potential. The latter is only achieved if detailed petrophysical measurements of fault mic rostructure are carried out using techniques, which are suitable for measur ement of very low permeability fault rock at the relevant scale. Convention al techniques of fault rock porosity and permeability determination invite host rock bias in measurement and inevitably underestimate the potential of these structures as fluid barriers. Pressure decay probe permeametry used in this study has the advantage of measuring small volumes of rock at Finer spatial resolutions and detailed permeability distributions around common types of deformation bands are obtained. Together with supporting data prov ided by conventional core analysis techniques, these measurements show that the greatest differences in petrophysical properties relative to host rock occur in those bands, which have experienced cataclasis, These results pro vide valuable input into reservoir simulation models and help reduce much o f the uncertainty regarding the role of different types of deformation band s in fault seal. (C) 2001 Elsevier Science B.V. All rights reserved.