GEOMODELING DIVISION
Upcoming Division Talk

Practical Facies for Digital 3D Models

Speaker: David Garner, TerraMod Consulting

Location: Husky Conference Room A, 3rd Floor, +30 level, South Tower, 707 8th Ave SW, Calgary, Alberta

March 28th, 2019 | 12:00 Noon 

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ABSTRACT:
A key impact on success in reservoir studies is a sound strategy around facies for modeling. The modeled facies provide local geological features, patterns and properties. Facies are derived from many sources with varied definitions and purposes. Classically, facies are a visual interpretation of the face of a rock driven by concepts. For example, from outcrops, we derive an understanding of depositional architecture and stacking patterns.  In petroleum reservoirs, we commonly use these surface observations of analogues in addition to sparse subsurface information to determine facies logs. Is this adequate? 

Figure 1. Visually interpreted depo-facies inputs are not consistent with logs. Electrofacies results provides consistency necessary for geomodeling processes. Figure is from Martinius, et al., 2017


Figure 2. Permeability based on electrofacies and micromodeling illustrates non-linear relationships and a percolation effect. Electrofacies can provide petrophysical distinctness. (Garner et al., 2014; Manchuk et al., 2015).

For modeling purposes, the input facies each represent consistent statistical properties across a study area. Visually interpreted facies must be checked for petrophysical consistency, i.e. the distinctness of petrophysical distributions which is not guaranteed. Application of electrofacies, a multivariate classification can improve consistency and is beneficial for the hierarchy of modeling workflows (Figure 1; Martinius et al. 2017). The result of electrofacies is to enforce the lithological characteristics based on distinct rock properties measured and to be distributed in models (Figures 2 and 3; Garner et al., 2014; Manchuk et al., 2015). A brief discussion of five assumptions underlying an application of electrofacies provides practical guidance on checking and improving useful facies inputs (Davis, 1986; Nivlet, et al., 2001).

There are rules and checks for sampling facies logs and associated properties into discrete grids to maintain model fidelity. The bigger the scale, the greater the uncertainty on individual facies and the more mixed the properties become. Across larger scales, facies probabilities and proportions are introduced, similar to the concept of net-to-gross for two categories. 

Trends, both vertical and lateral, must be taken into account to fairly represent the large scale reservoir features and connectivity in local areas of the 3D model. Seismic attributes sample from a relatively large scale, yield facies probabilities and can be introduced to update spatial trends for facies proportions. Fluid distributions as well as flow and mechanical properties are dependent on the characterization by each facies. Accounting for known physical behavior, percolation and capillarity, when distributing properties facilitates reasonable physical responses in flow models. 

Modeling strategy strongly benefits and depends on questions to be addressed mainly by reservoir engineering, from well understood to complex systems. Additional criteria derive from availability of data from multiple disciplines e.g. petrophysics, geophysics, geomechanics. Resource extraction for a mature reservoir waterflood generally requires a different type of model than a thermal gravity-driven extraction, i.e. SAGD-based. The scale of geological features, spatial trends, physical properties, size and architectural arrangement are all significant in the modeling process and are derived from the modeled facies. Handling facies digitally from concept to engineering is one of the most critical foundations of a successful reservoir study using geomodels. A number of techniques and examples will be noted to establish context.

Figure 3. Water saturation trends for each electrofacies are illustrated using conditional expectation curves. This captures the capillary effect of the variable grain sizes. An empirical irreducible water saturation, Swirr, can be estimated from each curve for the reservoir simulator. (Garner, et al., 2014)

BIOGRAPHY:

David Garner is an internationally recognized consulting advisor in applied geostatistics and geomodeling with more than 35 years of diverse technical experience in the hydrocarbon industry. He has taught numerous public and private courses in various countries during his career. He is currently an associate of Geovariances in Fontainebleau, France and TerraEX Group in Denver. He has over 23 years of work directly in geostatistical studies in petroleum and mining. He has published and presented numerous papers, many of which were peer-reviewed. 

Previously Mr. Garner held positions in applied R&D with Halliburton and Statoil, as a hands-on geomodeling advisor for Chevron and specialist at ConocoPhillips. He was president of TerraMod Consulting for 6 years applying geostatistics and geomodeling techniques mainly for large international reservoir studies and mining resources. As an active volunteer, Mr. Garner currently serves as a co-chair for the CSPG Geomodeling Technical Division committee. He was chairman/convener for the 2018 Gussow conference entitled Closing the Gap III - Advances in Geomodeling for Hydrocarbon Reservoirs, and was the chair for the CSPG 2011 and 2014 Gussow conferences, co-editor of the special edition December 2015 BCPG on Geomodeling Advances and the 2013 CSPG Memoir 20.  

Mr Garner is registered as a Professional Geophysicist (P.Geoph) through the Alberta’s Association of Professional Engineers and Geoscientists (APEGA).

REFERENCES
- Davis, John, 1986. Statistics and Data Analysis in Geology, 2nd Edition, New York, John Wiley & Sons, 646 pages.
- Garner, D., A. Lagisquet, A. Hosseini, K. Khademi, B. Jablonski, R. Strobl, M. Fustic, and A. Martinius, 2014. The Quest for innovative technology solutions for in-situ development of challenging oil sands reservoirs in Alberta, WHOC14-139, 2014 World Heavy Oil Congress
- Manchuk, J.G., Garner, D.L., C.V. Deutsch, 2015. Estimation of permeability in the McMurray formation using high resolution data sources, Petrophysics, Vol. 56, No. 2. 
- Martinius, A.W., M. Fustic, D.L. Garner, B.V.J. Jablonski, R.S. Strobl, J.A. MacEachern, S.E. Dashtgard, 2017. Reservoir characterization and multiscale heterogeneity modeling of inclined heterolithic strata for bitumen-production forecasting, McMurray Formation, Corner, Alberta, Canada, Marine and Petroleum Geology, Vol. 82, pages 336–361.  
- Nivelet, P., F. Fournier, and J.J. Royer, 2001. Propagating Interval Uncertainties In Supervised Pattern Recognition For Reservoir Characterization, SPE 71327, presented at the SPE Annual Technical Conference and Exhibition, New Orleans, USA, 30 September - 3

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.

Committee Members

Weishan Ren | Chairperson         Tom Cox                      Hayley Silberg             
David Garner | Co-chair              Sasan Ghanbari           Darcy Novak

Olena Babak                               Damien Thenin             Eric Niven  

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 via email at renws2009@gmail.com