Tech Division Events

Geomodeling Division

For more information on this Division, please contact the Division Chair, Weishan Ren, ConocoPhillilps, at (403) 233-3428 or via email at weishan.ren@conocophillips.com.

Division Profile

The mandate of the Geomodeling Division is to provide CSPG members with opportunities for education and information related to technical developments in the subject areas of geomathematics and computer technologies as they are used in the pursuit of petroleum exploration and development. As a main contribution of the division, technical luncheon presentations are held once a month, usually on the last Wednesday of the month.

The subjects that are presented in these technical talks include, for example, The latest developments in geomathematical applications, Geological modeling technology, Geostatistical approaches to modeling and risk analysis, Geological case studies using computer technology and the benefits, Digital data organization - storage and retrieval. In addition, ad hoc forums may be organized where members can discuss geomathematical and geological computer issues with experts in the field.The Geomodeling Division does not endorse or promote the use of specific commercial software products, nor does it perform any testing or comparative studies of such products.We do encourage volunteers to present public talks on case histories that illustrate the use of technology and methods.

The success of the Division depends on volunteer participation. CSPG members are encouraged to attend the activities of the Geomodeling Division and to be involved in organizing these activities. Division meetings are held once a month over lunch. If you are interested in joining this committee or if you have suggestions for luncheon talks or other activities, please contact any members of the committee.

Weishan Ren, Chairperson, (403) 233-3428, weishan.ren@conocophillips.com
Peter Boyle, (403) 287-3228, peter_boyle@shaw.ca
Tom Cox, (403) 716-4497, tcox@calgary.oilfield.slb.com
Ned Etris, (403) 296-5729, netris@petro-canada.ca
David Garner, (403) 724-6203, davga@statoil.com
Blair Mattison, (403) 645-2716, blair.mattison@encana.com
Tim McCullagh, (403) 691-2337, tim.mccullagh@shell.com

Division Talks

Fundamental Geostatistics in Reservoir Characterization

Speaker
David Garner,
Statoil Canada Ltd., davga@statoil.com

12:00 Noon
Tuesday, September 7, 2010

ConocoPhillips Auditorium,
3rd Floor- above Plus 15+ level
401 9th Ave SW
Calgary, Alberta

Abstract
The growth in use of geomodeling for subsurface reservoir characterization has accelerated rapidly over the last decade. The 3D geomodels help build a bridge between Geology, Geophysics, Petrophysics and Reservoir Engineering. There is a general acknowledgement of the strength of integration as a positive impact on characterizing petroleum reservoirs for exploration or development. Geomodels can be built without Geostatistics relying on sound geological concepts, the data and the interpretations. As new data are introduced, conceptual models take on added complexity. Uncertainty exists. Geostatistics provides a means to simulate geological variability early; as early as possible.

Figure 1: Geostatistics is used to quantify spatial relationships. For example, these two map images have the same histogram, but a very different look. Classical statistics does not account for these types of differences. We need additional tools to quantify the spatial continuity and heterogeneity of the phenomenon. Use spatial statistics.

Interpolations using mapping algorithms or Kriging yield smooth, best estimates of reservoir parameters. In reservoir property models, flow path distances may be underestimated. Reservoir connectivity may be over-estimated or barriers are interpolated to become overly continuous. Geostatistical simulations are the only methods that yield parameter estimates honouring variability, heterogeneity and thus provide reasonable flow distances. The impact can be significant for reservoir simulation studies, for production forecasting, and for assessing the uncertainties when developing operational strategies or mitigation plans over the development life cycle.

Figure 2: Interpolations give smooth, best estimates, i.e. Kriging. The length, Lk is too short! Stochastic simulations yield estimates honouring variability. The length, Ls, is reasonable for each realization. The analogy to reservoir property models is flow path distances and reservoir connectivity. The impact is significant for reservoir simulation and production forecasting.

The general workflow for geostatistical modeling involves three main elements: the spatial model, the estimation or simulation of parameters, and the statistical post-processing. The spatial model accounts for the correlateablility of the parameters such as facies or petrophysics. The spatial model can describe the relationships between facies, between petrophysical parameters, and can include soft data as trends, all in the structural and stratigraphic framework. The Simulation methods are designed to reproduce the spatial, statistical models, a geologically relevant image, and are conditioned to the input data. Post-processing is a catch-all phrase to say the many realizations are summarized into useful results. Examples are to summarize Probability distributions of the model evaluated resource, or ranking models to select P10, P50, P90 connectivity cases for reservoir simulation and forecasting.

The entire geostatistical workflow is based on sound geological concepts! The Geomodel is a focal point for the integrated subsurface team; it is a direct product of the quality effort to supply the interpretations, of the engagement in feedback and of the team work as a whole. Today, the experience level of practitioners of Fundamental Geostatistics in Reservoir Characterization is diverse and growing. The cumulative modeling experience within the working teams may be a potential ceiling on the whole process as is the incomplete technical capability provided by the commercial geomodeling software we use. Geostatistics training for all is a considerable element to work the solution. Gaps exist and are growing between the well-known academic theories and the technical implementations in commercial software. The main gap is in the lack of focused development by software vendors to provide the tools to efficiently implement best practice workflows for the on-going problems subsurface development teams are tasked to address.

Case Example
SAGD-based recovery in the Athabasca oilsands is a challenge with risks associated with geological heterogeneities. The key objectives of the static geological model are to quantitatively simulate and distribute in 3D the reservoir lithological and petrophysical properties within the structural and stratigraphic framework while honouring the conceptual geological model. The digital model provides images of the reservoir that have similar heterogeneity or variability as the geological phenomenon. The geostatistical approach to reservoir characterization provides the best tools for the integration of diverse data, deterministic and stochastic, for the prediction of spatial reservoir properties and for calculation of post-processed statistics. The static model is used as a rendering of the image into a digital format suitable for input to reservoir engineering simulation software, well placement and forecasting.

Biography
David Garner is Principal Geomodeler for the Heavy Oil Technology Center in Statoil's Calgary office. Before joining Statoil, Garner held the position of Senior Advisor Geologic Modeling for Chevron Canada Resources on the Ells River project. Prior to that, he was with ConocoPhillips Canada on Surmont. He worked on a variety of international reservoir studies applying Geostatistics through TerraMod Consulting over several years.

Garner holds two geophysics degrees, a B.Sc. from Washington and Lee University and a M.Sc. from Cornell University. In 2006 he received a Citation in Geostatistics from the University of Alberta. Garner has actively presented papers at conferences throughout his career. He is an active member of the Canadian Society of Petroleum Geologists where he previously served on the board of directors. He currently serves as a co-chair for the Geomodeling Technical Division Committee and is general chair for the proposed Gussow 2011 conference, "Advances in Applied Geomodeling for Hydrocarbon Reservoirs: Closing the Gap".

Information
There is no charge. Non-members of the CSPG are also welcome. Please bring your lunch. For details or to present a talk in the future, please contact Weishan Ren, ConocoPhillilps, at (403) 233-3428 or via email at weishan.ren@conocophillips.com.