• Talk title: Shale Gas in the Posidonia Shale, Hils Area, Germany
• Authors: Brian Horsfield(1), Ralf Littke(3), Ulrich Mann(2), Sylvain Bernard(1), Tiem T. Anh Vu(1), Rolando di Primio(1), Hans-Martin Schulz(1)
• Institutions: 1. GFZ German Research Centre for Geosciences, Potsdam, Germany; 2. Research Centre Juelich, Juelich, Germany; 3. Institute of Geology and Geochemistry of Petroleum and Coal, RWTH Aachen, Aachen, Germany.
• Time and location: April 14th, 2010, 1:40 PM to 2:00 PM, Location: 353/354/355.

Shale gas is a self-sourced resource in which thermogenic or biogenic hydrocarbon gases are contained within a fine grained, organic-rich, low permeability matrix, occurring in free, adsorbed and dissolved states. While no commercial shale-gas enterprises are currently known outside North America, many parts of Europe contain prime targets for shale gas exploration. One of these is the Posidonia Shale (Lias ε) of northern Germany. The Posidonia Shale in the Hils Syncline is approximately 35m thick and subcrops at relatively shallow depth over a 500 sq km area. It displays a threefold stratigraphic subdivision: lower marlstone, middle calcareous shale with bivalve shells, and upper calcareous shale. It is organic-rich, and lateral variations in its maturity have been related to deep burial or the effects of the Vlotho Massif, a purported deep seated igneous intrusion. We have analysed a total of 300 whole core pieces and core plugs from 6 research boreholes, which completely penetrated the Posidonia Shale of the Hils Syncline, covering the maturity range Rm = 0.48 – 1.45%. The two fundamental components of gas shales, namely the origin/occurrence of in-situ gas and the nature of the rock matrix, have both been studied. Only at very high maturity levels (>1.4% Ro) does the Posidonia Shale fulfil the empirical organic geochemical criteria which label it as a gas shale candidate. The Posidonia Shale originally contained Type II kerogen of Petroleum Type Organofacies Low Wax P-N-A in all boreholes. Geochemical logging revealed that vertical heterogeneity in richness and quality is significant in single wells, in part related to depositional facies. However, maturity variability between locations is responsible for much larger shifts in TOC, S1 and S2 values. The relative amounts of the different clay mineral groups remain constant with increasing levels of thermal maturity, though porosity and pore size are reduced. Heterogeneities in bitumen, kerogen and mineral abundances at the nanometre scale occur in overmature samples. Gas retention efficiencies for the represented maturation stages were calculated as a function of Transformation Ratio using mass balance models. Because the Posidonia Shale displays similarities to the Barnett Shale we conclude that it represents a potentially productive gas shale in Germany.

• Horsfield et al.: Shale Gas: an unconventional hydrocarbon resource in South Africa? Some preliminary observations

• di Primio et al.: Validation of Compositional Kinetic Predictions
• Horsfield et al.: Shale gas potential of the Posidonia Shale, Hils Syncline, Germany

• Talk title: Petroleum System Modelling of the Vlaming Sub-Basin and Mentelle Basin, Offshore South- Western Australia
• Authors: Volkmar Neumann(1); Rolando di Primio(3); Brian Horsfield(3); Irina Borissova(2); Chris Nicholson(2); Andrew Krassay(2)
• Institutions: 1. GeoS4 GmbH, Michendorf, Germany. 2. Geoscience Australia, Canberra, ACT, Australia. 3. GFZ-Potsdam, Potsdam, Germany
• Theme E: Gondwana and Pangean Petroleum Systems: Exploration, Development and Production—Emerging Plays, Lessons and Analogs;
• Session title: Exploration, Development and Production Successes in South-East Asia, October 29, 2008

Basin evolution of the Vlaming Sub-basin and the deep-water Mentelle Basin, both located offshore on the southwest Australian continental margin, were investigated using 2D and 3D petroleum system modelling. In the Vlaming Sub-basin has a proven petroleum system. Exploration activity in this area is limited and has mainly focused on structural highs/tilted fault blocks. The deep-water Mentelle Basin represents frontier exploration acreage but is assumed to have sedimentary facies and source poten-tial similar to the Vlaming Sub-basin.

The Permian-Cenozoic Vlaming Sub-basin contains siliciclastic fluvial-deltaic and marine rocks reach-ing up to 14 km in thickness. The Mentelle Basin, formed during the break-up of eastern Gondwana, contains more than 8 km of sedimentary section.

Compositional kinetics, determined on the main source sequences, were used to predict timing of hy-drocarbon generation and migration as well as GOR evolution and phase behaviour in our 2D and 3D basin models. The main phase of petroleum generation in the Vlaming Sub-basin occurred at 150 Ma and ceased during following inversion and erosion episodes. Only the areas which experienced later burial have generated additional hydrocarbons during the Tertiary and up to present day. Our results indicate the likely generation and trapping of light oils for the Jurassic intervals for a variety of struc-tural traps. It is these areas that are of greatest interest from an exploration point of view.

The 2D numerical simulations in the Mentelle Basin indicate the presence of active hydrocarbon gen-erating kitchen. Burial histories and generalized petroleum history will be presented.

• Talk title: Gas Generation and Retention in the Bakken Shale, Williston Basin
• Authors: B. Horsfield, G. P. Muscio, K. Grice, R. di Primio, P. Kuhn, E. Maslen
• When: Wednesday morning oral sessions at 10.25

• Talk title: New insights into Jurassic - Early Cretaceous rifting of the Southwestern Australian margin, Basin evolution magmatism and Petroleum system elements
• Authors: Borissova, C. Nicholson, A. Krassay, V. Neumann, R. di Primio and C. Boreham

The northwest trending Perth Basin (172, 300 km2) and the deep-water Mentelle Basin (36, 400 km2) are part of the southwest Australian extensional terrain. The complex architecture of this margin is the result of NE–SW extension in the Permian followed by predominantly E–W extension in the Middle Jurassic to Early Cretaceous. During both extensional phases the segmentation of the margin was strongly influenced by N–S and NW–SE oriented basement structures such as the Darling Fault and Proterozoic shear zones. This has produced a series of N–S to NW–SE trending depocentres separated by shallow basement highs. The Mesozoic extension culminated in the breakup between Australia and Greater India in the Valanginian. It was associated with voluminous volcanism on the Gascoyne-Cuvier margin and significantly less magmatic output on the Perth margin. However, farther west in the Mentelle Basin and on the Naturaliste Plateau, there was significant breakup-related volcanism.

The Vlaming Sub-Basin is a major Jurassic-Early Cretaceous depocentre in the southern Perth Basin. It contains more than 12 km of sediments, the bulk of which are syn-rift section. A new tectonostratigraphic framework for the Vlaming Sub-basin produced during recent Geoscience Australia studies redefined the stratigraphy and key source rock intervals. This information, together with seismic grids generated for the main sequence boundaries, were used for 3D burial history modelling. Modelling results indicate the presence of an active petroleum system with oil being generated from several stratigraphic intervals. For Jurassic and Early Cretaceous source rocks the main phase of petroleum generation started at about 150 Ma, however depending on the initial depth of burial and the amount of the breakup related erosion, it continues to a lesser extent today. This creates favourable conditions for charging potential traps. A number of accumulations were modelled in the eastern and southern parts of the basin indicating significant undiscovered potential.

The Mentelle Basin is a frontier basin lying in 500 to 3300 m water depths which has never been explored. Structural restoration of the margin has shown that major tectonic and accommodation cycles in the Mentelle Basin are similar to those in the Vlaming Sub-basin. Seismo-stratigraphic correlations are made to the DSDP well 258 on the Naturaliste Plateau and to the exploration wells in the Southern Vlaming Sub-basin for the Late Cretaceous to Recent part of the section. Ages of the syn-rift sequences have been interpreted using the new Vlaming Sub-basin tectonostratigraphic framework. Seismic facies analysis was then used to define potential source rock intervals and correlate them to the known source rocks in the Vlaming Sub-basin.

2D burial history analysis has been performed for three transects testing different scenarios for source rock properties. Modelling results indicate potential for hydrocarbon accumulations generated by Jurassic source rocks. The main risk is the presence of good quality seals at the right stratigraphic level. Current seismic coverage in the Mentelle Basin is insufficient for the detailed structural interpretation needed to define potential plays. Provided suitable structures are found in the Mentelle Basin, it may be potentially prospective frontier basin.