Detailed Near-Well Modeling and Upscaling in Condensate Systems
Abstract/Contents
- Abstract
- In gas condensate reservoirs, when the pressure falls below the dewpoint, condensate liquid appears. Because pressure is typically the lowest around production wells, this liquid drop out occurs first in the near-well region. This phenomenon often leads to reduced gas production because the condensate causes a decrease in gas relative permeability. This so-called condensate blockage can be difficult to capture in standard reservoir simulation models because well blocks are typically too large to resolve the pressure and saturation variations that lead to this localized effect. In this thesis, unstructured grid models, which include high resolution in the well and near-well region, are constructed and used to simulate condensate systems. The well completion components, such as tubing, gravel pack and perforations, are represented in detail. Simulations involving various completion strategies (open-hole, cased-hole with di erent types of perforations) are performed to quantify the impact of completion type on well productivity. As would be expected, open-hole completions are shown to provide greater productivity than cased-hole completions, and longer perforations result in higher production rates than shorter perforations. The unstructured grid simulations are, however, very computationally demanding. For this reason, single-phase and two-phase near-well parameter upscaling procedures are applied to coarsen the unstructured ne-scale descriptions to coarse structured models. The single-phase upscaling provides coarse-scale well indices and well-block transmissibilities, while the two-phase upscaling generates coarse-scale well-block relative permeability functions. Both upscaling techniques determine the coarse-scale parameters through use of optimization procedures that minimize the mismatch in flow results between fine and coarse-scale simulations over a near-well region referred to as the local well model. Comparison of global coarse-model solutions to the reference fine-scale results demonstrates that the models that use only upscaled single-phase flow parameters provide a reasonable degree of accuracy when only gas is owing, though less accurate results are observed when both gas and liquid are owing. The additional use of upscaled well-block relative permeabilities is shown to improve the accuracy of simulation results when two phases are owing. Thus the overall upscaling procedure provides a means for generating coarse-scale models that capture the detailed interaction between the well completion and the near-well reservoir region.
Description
| Type of resource | text |
|---|---|
| Date created | December 2009 |
Creators/Contributors
| Author | Kim, Hyung Ki |
|---|---|
| Primary advisor | Durlofsky, Louis J. |
| Degree granting institution | Stanford University, Department of Energy Resources Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
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Preferred citation
- Preferred Citation
- Kim, Hyung Ki. (2009). Detailed Near-Well Modeling and Upscaling in Condensate Systems. Stanford Digital Repository. Available at: https://purl.stanford.edu/jv967qq2258
Collection
Master's Theses, Doerr School of Sustainability
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