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Title: Understanding the processes governing the origin of clay coated sand grains and sediment heterogeneity in petroleum reservoirs : insights from a modern marginal marine system
Author: Wooldridge, L. J.
ISNI:       0000 0004 7428 6507
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2018
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The main cause of porosity- and permeability-loss in sandstone reservoirs during prolonged burial and heating, after compaction, is the growth of authigenic quartz cement (Walderhaug 1996; Worden and Morad 2000). Much research has been focussed on factors that inhibit quartz cement since they may lead to anomalously high porosity sandstones deep in sedimentary basins (Bloch et al. 2002). Clay-coated sand-grains are the principal reported cause of the inhibition of the porosity-occluding quartz cements and thus preservation of anomalously high porosity in ancient, deeply-buried sandstone reservoirs (Ajdukiewicz and Larese 2012; Bloch et al. 2002; Dowey et al. 2012; Ehrenberg 1993; Heald and Larese 1974; Storvoll et al. 2002). Despite the potential fundamental importance of clay-coated sand-grains in governing the economic viability of many deeplyburied sandstone reservoirs and almost five decades of research, there remains no credible capability for making predictions about grain coat coverage in ancient and deeply-buried reservoir rocks (Dowey et al. 2012; Pittman and Lumsden 1968; Wooldridge et al. 2017b). The research reported in this thesis can be summarised as series of related studies focused on answering the following three fundamental questions; 1. What processes govern the origin, distribution, and mineralogy of clay-coated sand grains? 2. How can the presence of clay-coated sand-grains be predicted? 3. How do sediment biofilms influence the reservoir quality of marginal marine sediments? The principal aim of this research was to constrain the origin and distribution of clay-coated sand-grains in a modern marginal marine system which can, by analogy, be applied to help prediction of anomalously high porosity in ancient, deeply-buried sandstones. The second aim was to assess the role of biological activity on sediment heterogeneity. A summary of the research questions that are addressed in this study and the collected data sets is given in Figure 1.1. This study addressed the above stated research questions by focussing on the Ravenglass Estuary, Cumbria, UK.
Supervisor: Worden, Richard Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral