How to Predict Reservoir Performance with Subsurface Uncertainty at Multiple Scales?
Xiao-Hui Wu
ExxonMobil Upstream Research Company
Abstract:
Subsurface uncertainty is one of the main challenges in using reservoir models to predict field performance for development and depletion planning purposes. The importance of reliable characterization of subsurface uncertainty and its impact on reservoir performance predictions is increasingly recognized as essential to robust decision making in the upstream industry, which is especially true for large projects in complex geologic settings. However, despite recent advances in reservoir modeling and simulation, reliable quantification of the impact of subsurface uncertainty remains difficult in practice. Many factors lead to this state of affair; technically, a fundamental difficulty is that reservoir heterogeneity at multiple scales may have strong effect on fluid flows. This lecture presents an analysis of the challenge and possible resolutions. Indeed, relying on computing power alone may not address the challenge. Instead, we must look at reservoir modeling and performance prediction holistically, from modeling objectives to appropriate techniques of incorporating reservoir heterogeneity into the models. We present a goal-driven and data-driven approach for reservoir modeling with the theoretical reasoning and numerical evidence behind them, including real field examples. We show that the proposed approach is driven by the practical limitations inherent in numerical approximations of Darcy flow equations as well as how fluid flow responds to reservoir heterogeneity. The one idea that participants of this lecture should take away is that appropriate parameterization of multi-scale reservoir heterogeneity that is tailored to the business questions at hand and available data is essential for addressing the challenge of subsurface uncertainty.
Tracer Technologies to Assess and Monitor Water, Gas and EOR Projects
Sven Kristian Hartvig
Restrack
Abstract:
Most of the chemical gas and water tracers commonly used today were first field-tested in Norwegian assets, which has been an important driver for the development of today's tracer technology. Inter-well tracer testing is proven as an efficient technology and used extensively to monitor water and gas flooding world-wide. This presentation will review the status of field-demonstrated tracer technology and demonstrate the use and benefit of tracers in off-shore as well as onshore fields.
Significant information can usually be extracted from tracer curves, in addition to the immediate injector-producer communication available upon first tracer breakthrough. Improved tracers, tools and methods is used to quantify how effective water & gas floods displaces water, reveal flow paths and channels and used to assess EOR potential as well as the effect of EOR measures. To exploit existing field's EOR and IOR potential, one challenge is to quantify remaining oil and to evaluate the effect of EOR. One of the proven technologies to estimate the amount of oil in near-well zones is the push-and-pull single well chemical tracer test (SWCTT). SWCTTs exploits the time-lag experienced by oil/water partitioning tracers compared to non-partitioning water tracers. A similar time-lag technique is used in partitioning interwell tracer tests (PITTs), where tracers are injected into injectors and sampled in producers. Lack of PITT-tracers with low-sensitivity detection and unstable partitioning tracers has been challenging for field application of PITTs. New and stable, oil-water partitioning tracers suitable for offshore oil reservoir PITTs have been recently developed and field tested (SPE164059), allowing measurement of remaining oil saturation in inter-well regions. PITTs can therefore now be used to assess inter-well saturations even under harsh conditions and in large reservoirs.
Biography:
Xiao-Hui Wu joined ExxonMobil Upstream Research Company in 1997. His research experience covers geologic modeling, unstructured gridding, upscaling, reduced order modeling, and uncertainty quantification. He is a Senior Earth Modeling Advisor in the Computational Science Function. Xiao-Hui received his Ph.D. in Mechanical Engineering from the University of Tennessee and worked as a postdoc in Applied Mathematics at Caltech before joining Exxon Mobil. He is a member of SPE and SIAM, a technical editor/reviewer for the SPE Journal, Journal of Computational Physics, and Multiscale Modeling and Simulation. He served on program committees of several conferences, including the Reservoir Simulation Symposium.
Sven Kristian Hartvig was appointed COO in the Restrack Company in 2013, following the spin-out of tracer technology services from Institute for Energy technology (IFE). Through 15 years at IFE, Sven was leading major R&D projects for new inter-well tracer technology from the lab scale until operational full field pilot testing. Sven graduated from the University of Oslo in 1997 with M.Sc. in Nuclear and Analytical Chemistry. Sven is member of SPE and EAGE, and has co-authored several SPE papers within utilization of tracer technology.
Program Outline:
17:30 – 18:00 Reception and ice–breaking
18:00 – 18:50 How to Predict Reservoir Performance with Subsurface Uncertainty at Multiple Scales? Xiao-Hui Wu, ExxonMobil Upstream Research Company
18:50 – 19:30 Tracer Technologies to Assess and Monitor Water, Gas and EOR Projects, Sven Kristian Hartvig, Restrack
19:30 – 21:30 Dinner
21:30 – 23:00 Coffee & avec, Networking