Seismic Characterisation of Carbonate Platforms and Reservoirs
In October 2018 the Geological Society of London hosted a conference focused on seismic characterisation of carbonate platforms and reservoirs, with strong attendance from industry and academia.
The programme consisted of two days of talks and posters, with a variety of themes, covering topics such as:
- Seismic investigations of platform architecture and development
- Seismic data in frontier exploration for carbonate plays
- Extracting geological features using seismic attributes and blends
- Seismic insights into carbonate diagenesis and fluid flow
- Seismic workflows and advances in inversion and modelling
- Seismic characterisation of south Atlantic pre-salt carbonates
- Seismic geomorphology and seismic facies applied to carbonate depositional processes and products.
It was generally agreed that a conference with this theme was sorely overdue. All the participants were actively engaged in the Q&A sessions either directly after the talk, or during the discussion time at the end of each session. The conversations didn’t stop during the breaks, or at the end of the first day. At the conclusion of day 1 the registrants were treated to a “hot fork buffet”- a term new to many in attendance.
Two Focus Areas
In a general sense, the themes can be grouped into two broad focus areas:
- General approaches to geomorphology, interpretation workflows, and maximising attribute analysis – a good source of methods to apply to our own data
- Applications to specific assets and exploration areas that were of interest to a broad cross-section of attendees.
There were four keynote speakers, each of whom managed to showcase innovative ways to approach carbonate seismic interpretation.
James Bishop from Chevron discussed the integration of image log bed dips to validate the clinoform orientations and platform architecture, while Shell’s Manuel Poupon gave a retrospective view of workflows developed to capture the complex morphology of carbonate depositional systems. The Total perspective on improved imaging and interpretation of carbonates for exploration and development was given by Jeroen Kenter, and the final keynote talk came from Lars Reuning of RWTH Aachen University, who discussed the identification of ooid ‘dune fields’ in 50-300m of water, currently located downdip from the relict platform margin.
However, the content of the remaining talks was equally compelling, and the organisation of the thematic sessions was easy to follow. Authors presented studies from many key areas of the world where there is either active exploration, or reservoir development (i.e., Pricaspian, Barents Sea, Middle East, Caribbean, Brazil, and broader ‘Australasia’), or where regional-scale seismic volumes allowed us to develop high quality analogues, where non-productive carbonates have been imaged and analysed. In this latter case we saw several talks which utilised publicly available datasets from north-western Australia that provide phenomenal reservoir architecture analogues.
The Way Forward
At the end of the technical sessions the conveners asked Paul Wright and Imelda Johnson to chair a closing session to capture input from the audience and frame the “Way Forward.”
Johnson engaged with the audience to frame both the positive points (the ‘plusses’) and the key learnings that could be incorporated at a similarly themed future conference (the ‘deltas’). We will briefly summarise the outcome of that session in the below.
Positive Feedback on Content as Presented (Plusses)
- Lots of exploration examples! A general thank you was offered for the companies who agreed to show data from frontier areas;
- Availability of public domain data (NW Australia Shelf especially);
- Availability and power of imaging and interpretation software;
- Seismic atlas discussions (increased confidence in ability to discriminate carbonates, at least some types of carbonate build-up/platform);
- Lacustrine / pre-salt session: new concepts;
- Visualisation power of seismic methods for geological interpretation (e.g. spectral decomp., inversion methods, attribute combinations);
- Kudos for sharing examples of exploration ‘failure’ – important learnings for future success;
- Value of integrated multidisciplinary studies (sum > parts).
- Increase in ‘comfort level’ of interpreters regarding basic concepts for carbonates;
- Direct application / validation of ‘things we are seeing’ in our data.
Potential areas for Addition/Modification of Content, or ‘Learnings’ in General (Deltas)
- Would have been good to see more on rock physics and on QI (AVO/EEI) in carbonates. The question(s) asked were: (1) When does it work? (2) Is it viable without well data?
- Lots on results but less detail on workflows behind them. Adding an open discussion specifically on workflows was suggested;
- Likewise, dedicated session on integrated workflows (beyond geophysics) would be useful (chemostratigraphy was suggested);
- A thematic session on how to de-risk carbonates in volcanic provinces: not just volcanoes vs. isolated build-ups, also lava deltas vs. platform clinoforms, etc.;
- No discussion on seismic signature of hydrothermal alteration of carbonates;
- The paucity of presentations using seismic data in unconventional carbonates and fractured carbonates;
- Importance of critical evaluation – don’t take seismic on ‘face value’; explore alternative models, iterative hypothesis testing, validate with well data.
GENERAL (often beyond an interpreter’s control):
- The importance of involving interpreters (and geologists) in survey design and parameterisation prior to acquisition, was addressed. If the orientation of a trend is known from earlier 2D or 3D, then this should be factored into the acquisition design when a new survey is planned.
In conclusion: as the first event in a number of years to showcase this theme, this was a very well attended conference, with strong representation from academia and industry. It is hoped that there will be an appetite to host something similar in the future.
Further Reading on Carbonates in Petroleum Geology
Some recommended GEO ExPro articles related to, or similar in content to, carbonate reservoirs in petroleum geology.
Carbonate Hydrocarbon Reservoirs
The 2006 discovery at Tupi, offshore Brazil, opened up a new chapter for petroleum reservoirs: lacustrine carbonates capable of producing hydrocarbons at extremely high rates.
This article appeared in Vol. 15, No. 4 - 2018
Mediterranean Carbonate Potential: Lessons from Existing Discoveries
Raffaele Di Cuia and Alberto Riva, GEPlan Consulting
The opening of new areas and the changing regional political and economic situation, together with innovative technologies, new seismic data and improved imaging, have revitalised exploration activity in the Central and Western Mediterranean. Analysing the characteristics of previous carbonate discoveries can help future exploration activity.
This article appeared in Vol. 13, No. 1 - 2016
Back-Reef to Basin Depths
Situated adjacent to the very prolific Permian Basin is one of the earth’s greatest and most studied carbonate depositional systems, the Permian Reef Complex of New Mexico and west Texas.
This article appeared in Vol. 9, No. 6 - 2013