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- 1. WORLDWIDE INFORMATION LEADERFOR MARINE BUSINESS, SCIENCE & ENGINEERING REPRINT SEATECHNOLOGY® Facebook.com/seatechnologymag • Twitter.com/seatechnology • www.linkedin.com/company/sea-technology-magazine Evolution of Geologic Models Of Oil, Gas Behavior New Techniques Create 3D Models for a Fuller Picture of Reserves By Robert Chelak SAM SAMPLE REPRIN SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT LE REPRINT
- 2. Geologic modeling, orgeomodeling, has been around since the ‘70s, when it only offered minimal capa- bilities such as 2D cartographic techniques based on contouring and plotting. It wasn’t until the ‘80s and the advent of workstations with 3D graphic cards that geo- modeling software became more user-friendly with better interfaces. These trends continue to evolve today. Geomodeling software can display, edit and calculate oil and gas reserves to help reduce exploration and produc- tion risks and improve reservoir forecasting and oil and gas recovery. Over the last decade, reservoirs have become in- creasingly difficult to characterize due to the complexity of the formations in which they are found. Fortunately, tech- nological advances in software and hardware have yielded the ability to generate earth models more quickly and easily. Geomodeling is commonly used for managing natural resources, identifying natural hazards and quantifying geo- logical processes, with the main applications being oil and gas fields, groundwater aquifers and ore deposits. In the oil and gas industry, for example, realistic geologic models are required as input to reservoir simulator programs, which predict the behavior of the fluids in the rocks under various hydrocarbon recovery scenarios. As a reservoir can only be developed and produced once, selecting a site with poor conditions for development is a very costly and wasteful mistake. Reservoir engineers can use geologic models and reservoir simulation to identify which recovery options offer the safest and most economic, efficient and effective devel- opment plan for a particular reservoir. Originally done manually, reservoirs were mapped by looking at well information, creating a contour map, using a planimeter to compute the area, and then applying an aver- age thickness to compute the rock volume. By evaluating reservoir property details from well log data, a net pay value was computed as a multiplier to determine the number and size of reservoirs. Advances in computing brought methods that have be- come industry practice and are quick ways to predict re- serves and optimize the production of hydrocarbons. For example, 2D mapping is essentially a fast and simple way to identify potential reserves, compute volumes and see the general outline of the play. Limitations include the inabil- Evolution of Geologic Models Of Oil, Gas Behavior New Techniques Create 3D Models for a Fuller Picture of Reserves By Robert Chelak Basic 2D technique (left) shows porosity distributed from well log data across a structural surface. Basic 2D technique in the right-hand image shows a 2D mapped structural surface. SAM SAMPLE REPRIN SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT LE REPRINT
- 3. learn. This isparticularly true for the casual user who con- structs models only occasionally. Today’s tools allow for a multidisciplinary approach, enabling an interoperable and updatable knowledge base about the Earth’s subsurface. All types of users now have detailed 3D reservoir models at their fingertips to effectively plan and forecast the best ap- proaches to produce and deplete assets. These earth models can be used by geoscientists and engineers working closely together. Until recently, this option was met with resistance due to historical ways of working and the misperception that 3D modeling can be performed by only a distinct group of expert users. To address evolving needs, CGG GeoSoftware developed EarthModel FT, a 3D geologic modeling system that meets the needs of a range of different users and their skill levels. Nov- ice modelers and casual us- ers will find the basics they need straight away, as well as advanced features they can use as they become more confident, develop their skills further and re- quire more sophisticated 3D models of complex reservoirs. EarthModel FT is not restricted by any par- ticular geologic scenario, so both onshore and offshore plays can be modeled with the same tool set. Today, more and more people are building 3D reservoir models in EarthModel FT because the tools no longer re- ity to fully identify the areal position of the reservoir and reveal what is re- ally happening within the enclosed structure. This is because data from wells and seismic have been averaged or significantly smoothed to generate results for these maps over a specific vertical interval. While this may be sufficient when the reservoir is thick and uniform vertically, we know that not all reservoirs are like this. Today, larger and more homoge- neous plays are harder to find, and reservoirs that are being discovered can be in thin interbedded heteroge- neous complex formations. In these cases, 2D maps over a thick vertical interval will not do a reasonable job of identifying where the actual reservoir is positioned, as data for the 2D-mapped unit will have results averaged or smoothed. For thinner, more complex reser- voirs, geoscientists and engineers now use more sophisticat- ed ways to characterize the reservoir to determine optimal drilling locations and optimize production scenarios. 2D mapping is no longer sufficient to completely understand the reservoir and create a development plan to effectively extract its hydrocarbons. 3D Modeling Nowadays, mainstream 3D geological reservoir model- ing tools help geoscientists gain a better understanding of reservoir properties. Yet many of today’s modeling systems, with a multitude of available options, can be difficult to (Top) A modern 3D reservoir modeler allows users to con- struct more complex and accu- rate structural interpretations. This image shows a complex faulted structure. (Middle) Structural model displayed with seismic for a more accu- rate representation of a reser- voir. (Bottom) Porosity distri- bution from well data in 3D view (above) and cross-section view (below) offers a more de- tailed understanding of a res- ervoir. SAM SAMPLE REPRIN SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT SAMPLE REPRINT LE REPRINT
- 4. ©Copyright 2016 byCompass Publications Inc. Sea Technology (ISSN 0093-3651) is published monthly by Compass Publications Inc., 1600 Wilson Blvd., Suite 1010, Arlington, VA 22209; (703) 524-3136; oceanbiz@sea-technology.com. All rights reserved. Neither this publication nor any part of it may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Compass Publications Inc. quire specialized expertise. Engineers are building first-pass 3D models to estimate rock volumes and perform quick analysis of a reservoir, while all remaining data are being formulated. Armed with a basic understanding and param- eters ready to apply to the complete study, reservoir engi- neers save time once all data are gathered. Fewer iterations are needed to achieve a final result. Geophysicists use EarthModel FT to build 3D models and show low-frequency distributions for detailed seismic inversion studies that help with the management of natural resources, identification of natural hazards, and quantifica- tion of reservoir properties and geological processes. EarthModel FT also saves time through its connection to a central database where users and applications share the latest information. Working with the same well and log data minimizes the need to transfer data and reduces the risk of error. Data are loaded once, shared by everyone and saved centrally. This is important for an asset team collaborating with others and powerful for a single user doing the entire workflow alone. Everyone connected to the database is in- formed of any modifications, additions or deletions. Earth- Model FT has “updateability”, which means it checks for changes from the database and rebuilds the model with the latest information. Automatically kept up to date, the 3D model can be shared with the team and is ready for use in external software packages, including direct export to reser- voir simulators. Modeling Success There are many success stories using these types of 3D modeling techniques. In one particular case, a company was using some basic simple techniques as described earlier in this article. How- ever, they kept drilling wells that were all coming up mar- ginal with respect to reserves that were far from what they expected, and they needed to remedy this.The main reasons for this lack of success was that there were details in the reservoir, in a gas overprint, that were being overlooked be- cause they were just looking at the larger trends. They there- fore decided to employ the techniques from CGG GeoSoft- ware, including EarthModel FT, to model the details within “Mainstream 3D geological reservoir modeling tools help geoscientists gain a better understanding of reservoir properties.” the reservoir, including the use of seismic data to provide data at a distance from the well locations. The 3D model that was constructed was used to plan additional new drill- ing locations, and every well has been a complete success. The new wells intersected the identified reservoirs from the 3D modeling, which resulted in additional reserves, where- as in the initial case the wells did not produce effectively as they did not intersect the reservoirs to optimize recovery. The reserves and production have been on a steady increase after applying these new techniques. This successful application clearly demonstrates the ben- efits of moving from a simple technique to a more robust 3D modeling approach. Conclusion Today’s E&P challenges demand optimum use of tech- nology in order to overcome the most complex subsurface challenges in all types of reservoirs. Software tools are available now to meet the needs associated with geologic complexity and cross-functional collaboration that builds bridges across geoscience disciplines. 3D geologic models provide a better reservoir description and can be generated as easily as creating 2D maps. As new information is discov- ered, models can be updated, made readily available and become part of a daily routine. Raised in a world of video games and advanced 3D graphics, the next generation of geoscientists can readily grasp, and should be encouraged to use, 3D modeling tools to improve their understanding of the Earth and more effec- tively locate, develop and manage its natural resources. ST Robert Chelak is the product manager of reservoir modeling at CGG GeoSoft- ware. He has worked in the oil and gas industry for more than 25 years, focus- ing on reservoir modeling. He began his career in 1986 with Esso Resources in Canada as a technical analyst building 3D models for exploration and ex- ploitation. He later joined Landmark as the key application specialist delivering integrated solutions and played a strategic role in 3D modeling solutions for characterizing reservoirs. From there, he joined Roxar and increased his knowl- edge in reservoir modeling while managing a team of technical support service consultants for the Americas region. Chelak was then appointed a director of reservoir solutions at Knowledge Reservoir to scope and guide reservoir mod- eling projects. He joined CGG three years ago as a subject matter expert and leader for reservoir modeling and integration. 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