Deriving field-based statistical relationships to characterize the geometry, heterogeneity and permeability of faults in mixed sand-shale sequences : a new tool for upscaling flow properties

Fault zones can strongly affect fluid flow in the subsurface. Faults can act as (partial) barriers to flow, as conduits and as combined conduit-barrier systems. Understanding the relationship between faulting and fluid flow has many practical applications, including hydrocarbon exploration and production, mineral exploration, groundwater management, radioactive waste disposal, geothermal energy and carbon sequestration. This study is primarily focussed at the applications in the hydrocarbon industry. For hydrocarbon exploration, faults are important because they can act as long term barriers (fault sealing), in which case they can be part of structural traps. Faults acting as conduits also need to be considered, hydrocarbons moving vertically along a fault can either migrate into a reservoir, or the hydrocarbons can leak out of the reservoir along the fault. For hydrocarbon production also the short term effect of faults needs to be considered, as faults can block or baffle flow towards a well. For all these scenarios it is currently diffcult to reliably predict the behaviour of the fault deep underground. The research presented in this thesis aims to improve this prediction. Several studies have shown that fluid flow along and across fault zones is strongly affected by the heterogeneity of the fault zone and the presence of connected high permeability pathways. Both heterogeneity and high permeability pathways cannot be detected or predicted using currently available hydrocarbon industry tools. Therefore this study uses extensive field studies of faults exposed at the earth's surface, to characterize these features in detail. For this study 12 fault exposures have been studied in SE Utah and the western Sinai in Egypt. The faults are mapped with mm to cm-scale detail and samples are taken for petrophysical analysis. These data are further analyzed by numerical modelling of fluid flow through the fault zones. By combining fieldwork and flow modelling, the features that most strongly affect fluid flow (key flow controls) can be identified. Key flow controls provide a tool for efficient collection of data that allow the statistical characterization of fault zones. Statistical characterization of fault zone fluid flow properties can be used to improve hydrocarbon industry workflows.This study has revealed a wide variety in fault architectures for faults in sand-shale sequences. None of the faults studied here is dominated by a single homogenous gouge of mixed sand and shale, as is assumed by many current workflows for predicting (upscaled) fault permeability. With such a wide variety of fault architectures, it is impossible to define a simple rule for the fluid-flow characteristics of faults. For successful prediction of fault sealing and fault permeability it will be necessary to successfully predict fault architecture. Predicting fault architecture will require the detailed evaluation of host rock stratigraphy, fault structureand the deformation, fluid flow and thermal history.

Advisor / supervisor

Shipton, Zoe
Lunn, Rebecca

Resource Type

Doctoral thesis

Note

This thesis was previously held under moratorium from 31st March 2015 until 31st March 2017.

DOI

10.48730/jtt4-sd92

EThOS ID

uk.bl.ethos.667572

Date Created

2014

Former identifier

9912173843402996

Beziehungen

Objekte

Titel	Hochladedatum	Sichtbarkeit	Aktionen
Appendix_A_Database.zip	2021-07-02	Öffentlich	Herunterladen
Appendix_B_FlowModels.zip	2021-07-02	Öffentlich	Herunterladen
Appendix_C_Matlab.zip	2021-07-02	Öffentlich	Herunterladen
PDF of thesis T13966	2021-07-02	Öffentlich	Herunterladen