Digital Outcrop Models of Hydrocarbon Reservoir Analogues: An example from Alderley Edge, Cheshire

Date: Thursday, 20th February 2014

This presentation will take place at the Royal Cambrian Academy headquarters in Crown Lane, Conwy at 6.30pm.  Refreshments from 6.00pm.

Speaker Overview:

Dr David Hodgetts – Senior lecturer in Petroleum geology and Reservoir Modelling.  Basin Studies and Petroleum Geoscience Group.

David received an honours degree in Geology from Durham, followed by a Computing in Earth Science MSc from Keele University where he stayed on to undertake a PhD in 3D numerical modelling of continental lithospheric deformation. After a short post doctoral research position at Keele working on 3D structural restoration algorithms he moved to Liverpool to join the Strat Group, working on a diverse range of projects both subsurface and fieldwork related. He joined the University of Manchester in 2003, and is currently a Senior Lecturer in Petroleum Geology and Reservoir Modelling.

David has 18 years’ experience of working on petroleum industry projects ranging in scope from forward modelling, geological software development, seismic interpretation, field mapping and reservoir modelling primarily focussing on siliciclastics. His research over the past 10 years has focussed on the application of digital data acquisition techniques, in particular terrestrial laser scanning (lidar) to field geology. This research has focussed on outcrop description and extraction of geostatistical data to assist in subsurface reservoir characterisation. In order to achieve this he has developed software called VRGS (Virtual Reality Geological Studio) to facilitate the processing, interpretation and modelling of lidar and other digital outcrop data types.

Abstract:

Lidar mapping is rapidly becoming a regular addition to the field geologists toolkit. Using Lidar data it is now easy to make photorealistic models which involve producing a triangulated irregular network (TIN) or mesh of the point cloud, and then texture mapping digital images onto the mesh via projective texturing techniques. This approach produces visually pleasing models which are easy to interpret, however this is only the case if the features of interest are clearly visible in the digital photograph, which in rocks of fairly uniform colour may not always be the case.

The high resolution nature of lidar derived digital outcrop models facilitates the generation of surface attributes (such as curvature, co-planarity and roughness for example) which may be used to highlight features not easily seen in the photo-realistic model. These surface attributes not only make manual interpretation of the data easier, but facilitate the development of more automated mapping and tracking tools, which are essential in the large datasets provided by terrestrial and airborne laser scanning. 

The Sherwood Sandstone Formation (SSF) is an important economically in the UK as both aquifers and hydrocarbon bearing reservoirs.  In this study digital outcrop modelling approaches integrated with traditional fieldwork aims to shed new light on this important geological group.  Lidar data collected from extensive mine workings in the Alderley Edge are used to build digital outcrop models allowing accurate mapping and measurement of key stratal surfaces, structure and sedimentology, with a focus on understanding fault geometry, and fracture distribution in relation to those faults and to the mechanical stratigraphy of the SSF.

The Alderley Edge Mines themselves are distributed over an area of 1.5km x1.0 km approximated with around 16km of passages and caverns down to a depth of 60m. The mines (originally used for minerals such as copper, lead and cobalt) are cut through the Sherwood Sandstone offering exceptional and unparalleled 3D exposure of the Sherwood sandstone.

1 An view of a Lidar data based model from the Alderley Edge Mines. The image colour shows the reflection intensity of the laser. Several scans are merged together to form this model.

Recent Publications

• Hodgetts, D., in press. Laser Scanning and Digital Outcrop Geology in the Petroleum Industry: A review. Marine and Petroleum Geology.
• Rarity, F., van Lanen, X.M.T., Hodgetts, D., Gawthorpe, R.L., Wilson, P., Fabuel  Perez, I., Redfern, J., 2013. Quantifying depositional elements: LiDAR-based digital outcrop datasets for integrated sedimentological analysis, in: Martinius, A.W., Howell, J.A., Good, T. (Eds.), Sediment-Body Geometry and Heterogeneity: Analogue Studies for Modelling the Subsurface. Geological Society of London.
• Seers, T.D., Hodgetts, D., 2013. Comparison of digital outcrop and conventional data collection approaches for the characterization of naturally fractured reservoir analogues, in: Spence, G.H., Redfern, J., Aguilera, R., Bevan, T.G., Cosgrove, J.W., Couples, G.D., Daniel, J.-M. (Eds.), SP374 Advances in the Study of Fractured Reservoirs. Geological Society, London, Special Publications.
• Fabuel-Perez, I., Hodgetts, D., Redfern, J., 2010. Integration of digital outcrop models (DOMs) and high resolution sedimentology – workflow and implications for geological modelling: Oukaimeden Sandstone Formation, High Atlas (Morocco). Petroleum Geoscience 16, 133-154.

Seismic Interpretation – Ten Ways to be wrong

Date: Thursday, 21st November 2013

This presentation will take place at the Royal Cambrian Academy headquarters in Crown Lane, Conwy at 6.30pm.  Refreshments from 6.00pm.

Speaker Overview:

Dr Andrew Hopkins is an independent seismic interpretation consultant based in London, where he is currently working on the Carboniferous of the Southern North Sea. Andrew received his BSc from Imperial College in 1980, and has worked for various oil companies, contractors and consultants, including Enterprise Oil, Endeavour Energy, Horizon Exploration, and Helix-RDS, on seismic data from many of the world’s hydrocarbon provinces. In 2007 he completed a PhD at Cardiff University on the seismic interpretation of Cretaceous and Cenozoic contourites in the Walvis Basin, offshore Namibia. Before becoming freelance, Andrew was Chief Geophysicist at African Petroleum.

Abstract:

The last several decades have seen the dynamic growth of a global database of high-quality seismic reflection data, both 2D and 3D, which has been almost entirely driven by hydrocarbon exploration. Consequently, seismic data now provide the pre-eminent means we have of investigating sub-surface geological phenomena which would otherwise be inaccessible. Indeed, seismic interpretation has been the key component of many of the significant advances in structural geology and stratigraphy in recent years. These include for example, major developments in our understanding of fault dynamics, salt tectonics, fluid-rock interactions, igneous and sedimentary intrusions, not to mention the creation of the entire field of seismic and sequence stratigraphy. Although the mechanics of the process of seismic interpretation have been extensively dissected and reviewed in textbooks, courses and on the internet, this talk will propose that a valuable set of insights may yet be gleaned from a little-known and under-appreciated text book, now more than 20 years old. While the subject of “To Interpret the Earth” (1991) by Stanley Schumm, is geomorphology rather than seismic interpretation, its wisdom has relevance across all the earth sciences. Schumm sub-titled his book “Ten Ways to be Wrong” and he identified a series of problems of interpretation by which the unwary geoscientist may be led astray. He placed these problems into three broad classes, scale and place, cause and effect, and system response. The talk will attempt to transpose these “ways to be wrong” from their original geomorphological context into the milieu of the seismic interpreter. Numerous examples from the literature and from the speaker’s experience will be presented.

Directions to the venue:

RCA, Crown Lane, Conwy, LL32 8AN

The North Wales Geology Association proudly presents

“A Journey to the Burgess Shale, British Columbia, Canada”

This meeting to be held at the University of Chester, Large Lecture Theatre: Binks Building, Parkgate Road, Chester. Tea and coffee served from 7PM. Talk will commence at 7:30PM.

Dr Jacqui Malpas of NEWRIGS, Geodiversity Wales and former Post-Doctoral Research Student at the University of Chester.

Since discovering geology as an Open University undergraduate I have dreamt of visiting the most famous fossil site in the world; The Burgess Shale.  This trip was my 60th birthday present.

The Burgess Shale was discovered as the result of two decisions.  The first was Canadian Pacific Railway chose to run their line through the Rockies via Kicking Horse Pass; the second was that the Geological Survey of Canada sent their most experienced geologist, Richard McConnell, to map the geology on either side of the line. Thus in 1886, McConnell was the first geologist to find and collect from the Burgess Shale of Mt. Stephen, which overlooks the village of Field, British Columbia.  McConnell’s report attracted the attention of Charles Walcott a palaeontologist with the United States Geological Survey.  Walcott eventually found the Phyllopod Bed Fossil Ridge, between Wapta Mountain and Mount Field, the main Burgess Shale site, in 1909, 23 years later.  Charles Walcott’s diary of 31st August 1909 reads:

‘Out with Helena and Stuart collecting fossils from the Stephen Formation.  We found a remarkable group of Phyllopod Crustaceans.  Took a large number of fine samples to camp.’

The Burgess Shale, with its remarkable preservation of a diverse fauna with soft-body as well as skeletal parts was previously unknown.  This site and its fossils provide a unique insight into animal life of the early Cambrian Period.

This talk will illustrate some of the history of the site and an overview of the fossils and how they changed the way the evolution of animal life of the Cambrian Period is understood and interpreted.

The Cretaceous and Cenozoic stratigraphy and palaeoclimate of southern coastal Tanzania: results from a decade of fieldwork and scientific drilling

Date: Thursday, 17th October 2013

This presentation will take place at the Royal Cambrian Academy headquarters in Crown Lane, Conwy at 6.30pm.  Refreshments from 6.00pm.

Speaker Overview:

Paul Pearson is a micropalaeontogist and palaeoclimatologist at the School of Earth and Ocean Sciences, Cardiff University.  Paul received a BA in geology at Oxford University and a PhD on the evolution of planktonic foraminifera at Cambridge University.  He worked as a postdoctoral research fellow at Cambridge and Bristol before moving to Cardiff in 2003. Paul is interested in biostratigraphy, evolution and palaeoclimate, focusing mainly on the Cenozoic era.  He has helped develop palaeoclimate proxy methods such as oxygen isotope palaeothermometry and boron isotope pCO₂ reconstruction.  Paul has sailed twice with the Ocean Drilling Program and has conducted fieldwork in many places including Tanzania, Mozambique, Java, New Zealand and Trinidad.  He has directed onshore scientific drilling projects in Tanzania and Java.

Abstract of talk:

The Late Cretaceous to Oligocene Kilwa Group of southern coastal Tanzania is a thick succession of hemipelagic clays with accessory siliciclastic and limestone inter-beds. It is renowned for the spectacular preservation of its carbonate microfossils (forams, calcareous nannoplankton and others) which are important for taxonomy, stratigraphy, and the application of palaeoclimate proxies. A campaign of shallow coring using small mobile rigs at 40 sites distributed over about 100 km of strike has allowed us to recover about half of the stratigraphy in core, including important new records through the Paleocene / Eocene and Eocene / Oligocene transition intervals.

This work has been augmented by offshore piston coring and seismic surveying. Detailed study has resulted in over 35 peer-reviewed publications so far, including a new appreciation of tropical climate evolution since the Cretaceous, and insights into the structural geology and hydrocarbon potential of the area. There is still much potential for further discovery: A new deep cored reference section is planned onshore by the International Continental Drilling Project, with scientific aims linked to a planned offshore drilling expedition by the Integrated Ocean Drilling Program.

Directions to the venue:

RCA, Crown Lane, Conwy, LL32 8AN

Integrated petroleum systems & play fairway analysis in a complex Palaeozoic basin: Ghadames – Illizi Basin, North Africa

Date: Thursday, 19th September 2013

This presentation will take place in the Royal Cambrian Academy headquarters in Crown Lane, Conwy at 6:30pm.  Refreshments from 6:00pm.

Speaker Overview:

Dr Richard Dixon is a geologist with BP Exploration based in the London area where he is part of BP’s Exploration Assurance Team. Richard received his BSc & PhD from University College Cardiff. He then joined Robertson Research in 1985 as a sedimentologist working for them in North Wales & Aberdeen until 1988 when he joined BP. Richard spent 8 years working the North Sea & Faeroe – Shetland Basins mainly in development & appraisal roles, before moving to international exploration in 1996. For the last 17 years Richard has worked regional exploration projects across the globe, including the North Slope, North Africa, East Siberia, Sakhalin, Trinidad & Venezuela, India East Coast, West Africa (Angola & Gabon) & Brazil. For the last 3 years Richard has also been involved in teaching the Petroleum Geoscience MSc class at the University of Manchester and was appointed as visiting professor (Basin Analysis & Petroleum Geoscience Group) earlier this year.

Abstract:

The Ghadames–Illizi Basin is a highly productive petroleum province with a long exploration history in Algeria, Libya and Tunisia (from the late 1950s to present day). Ongoing exploration success in all three countries suggests that it will continue to provide attractive exploration targets in the future. The basin has a long and complex geological evolution characterized by multiple phases of subsidence punctuated by significant regional uplift events. Two ‘world-class’ petroleum source rocks of different geological age are present (Lower Silurian and Upper Devonian) with similar depositional environments and geochemical characters. Both source horizons have generated significant volumes of oil and gas. Petroleum migration is strongly influenced by the stratigraphic architecture of the basin fill, notably distribution of regional seals and the complex patterns of subcrop and onlap across regional unconformities. Multiple reservoir–seal combinations are presented by Late Ordovician glaciogenic sediments and younger Silurian through to Carboniferous paralic sequences. Integrating the stratigraphic relationships with the complex burial history of the basin (timing of uplift, degree of tilting, amount of section removed by erosion) is not a trivial task, but is key to exploration success in such a complex basin. With the aid of 3D basin reconstruction and fluid flow modelling software, we can attempt to capture the stratigraphic and structural complexity and make exploration predictions. If basin modelling techniques are to be optimally applied in such settings, a fully integrated and geologically realistic approach involving biostratigraphers, sedimentologists, structural geologists, geophysicists and geochemists is required. A modelling approach, workflow and some results will be presented.

This talk was presented in 2010 at the Barbican Conference. The paper is published – Petroleum Geology Conference series doi: 10.1144/0070735 Petroleum Geology Conference series 2010, v.7; p735-760 and available through the Lyell Collection.