CeREES Petroleum Students starting 2009
Title: Direct and indirect diagenetic effects in igneous affected basins - Constraining diagentic timing, processes and reservoir quality.
Until recently, volcanic dominated sequences have been disregarded as being significant in terms of their potential to act as oil or gas reservoirs. However, recent exploration has identified new play models comprising of siliciclastic sedimentary rocks, intrusions, lavas, and volcaniclastics. But just how problematic are igneous bodies in sedimentary basins? Recent work has started to direct attention to the sediment-lava interface at the base of flood basalt units and at the relationships between intrusions and the host sedimentary basins. This project will combine onshore observations with offshore data provided by Chevron to look at the effects of igneous rocks on diagenesis and the implications for reservoir potential.
Supervisors: Dr Dave Selby
Paul Lillis (USGS)
Mike Lewan (USGS)
Title: Re-Os geochronology of Lacustrine Petroleum systems.
Supervisors: Dave Selby, Paul Lillis (USGS), Mike Lewan (USGS)
PhD research involves applying the Re-Os radioisotope geochronometer to lacustrine sedimentary and petroleum systems. This oil and source rock dating tool has previously only been used in the marine realm and so further research is needed in order to confirm that it can be applied with the same accuracy to lacustrine petroleum systems. This will enable further chronological constraints and oil-source rock correlation in lacustrine basins where plays are becoming increasingly more important.
Alice Du-Vivier
Title: Assessing the use of osmium isotopes as a geochemical proxy accross the late Cretaceous OAE 2 to establish the influence of the ocean-atmosphere system on palaeoclinate and palaeocirculation.
The project aims to understand the mechanisms controlling global ocean anoxia, controls and mechanisms of organic preservation, analogue for future oceanic conditions, and providing a tool to aid in the correlation of dramatic events in the ocean-atmosphere system. Thirty years on from the introduction of the concept of oceanic anoxic events (OAEs) the driving mechanisms for these events remain highly debated. There are three principle mechanisms proposed to be the driving component responsible for the OAE 2; 1) climate change; 2) sluggish ocean circulation; and 3) intense volcanism. The Cenomanian-Turonian boundary oceanic anoxic event (OAE 2) is characterised by abundant organic-rich sediments and a 2 to 4‰ positive δ13Corg excursion that is used for global correlation. My PhD applies high-resolution osmium isotope (187Os/188Os) stratigraphy to address the 187Os/188Os composition of the ocean prior to, during and after the OAE 2, thereby improving our understanding of global ocean anoxia in both the well-studied sites of the proto-Atlantic Ocean and the currently poorly studied sites of the ancient Pacific Ocean.
Title: How do igneous rocks influence diagenetic history? A case study from the Huab Basin NW Namibia
My project is aimed to advance the understanding of the effects of igneous activity (extrusive and intrusive) on petroleum systems. It uses an ideal natural laboratory, the Huab Basin, Namibia, to study in outcrop a siliclastic sediment affected by a large igneous province (the Etendeka Flood Basalts). The project involves field mapping, petrographic and petrophysical analysis. Should these formations be considered as potential reservoirs, given the complexity introduced by igneous rocks?
Title: Reservoir or seal? Porosity, permeability and rock properties in hyaloclastites and associated volcaniclastic facies
Research explores variations in hyaloclastite architecture in different environmental settings, for example, lava entering a standing body of water vs. hyaloclastite material flanking an emergent volcanic system. A key question relates to how lava enters large bodies of water. Lava tubes in pahoehoe sheets transport the bulk of the lava and provide point sources for lava entry. Swtiching between point sources over time can lead to changes in the locus of sedimentation and the development of clinoform morphologies. This paradigm, revealed through field studies challenges the existing simplistic view of lava progradation. This can be seen in areas to the West of Shetland where hyaloclastite deposits form complex packages. Another outcome of this investigation is that both uplift and subsidence plays a large role in facies type and distribution and that variations in architecture occur due to inherent instabilities on volcanic flanks that promote collapse and reworking. Future work will concentrate on facies-specific hyaloclastite rock properties such as porosity/permeability studies to determine the role that hyaloclastite deposits play in petroleum systems. Parameters that lead to pore space reduction such as the formation of clays and authegenic minerals, and both shear and compressive strength estimates, are often facies dependant. This may be an initial depositional effect or result from a number of post depositional diagenetic changes. The emerging picture suggests that current models of hyaloclastite deposits are too insufficient to explain the true range of facies variations and new models are required. This research is sponsored by DONG Energy through the VMRC.