|Publisher||International Petroleum Technology Conference||Language||English|
|Content Type||Conference Paper|
|Title||Improving Reservoir Modeling with Global Scale-up|
X.H. Wu, S.S. Ghai, M.T. Stone, R.R. Parashkevov, and S.L. Lyons, ExxonMobil Upstream Research Company
International Petroleum Technology Conference, 4-6 December 2007, Dubai, U.A.E.
2007. International Petroleum Technology Conference
|6 Reservoir Description and Dynamics
In this paper, we present a new global scale-up technology for calculating effective permeability and/or transmissibility and its applications to reservoir modeling. This technology involves using global flow solutions on the fine-scale model to improve scale-up accuracy and reusing them to improve scale-up efficiency for re-gridded coarser models.
Global scale-up was initially proposed about 20 years ago . Its potential benefits have been demonstrated for simple models in the literature. Until now, significant technical challenges associated with applying global scale-up to real reservoir models have prevented its adoption by the industry. Real reservoir models are often characterized by complex geometry and connectivity, caused by faults, pinch-outs, and flow barriers. Here, we present industry's first commercial global scale-up technology that overcomes these difficulties.
Our studies show that the new global scale-up technology leads to significant improvements in scale-up accuracy. Our global scale-up method preserves complex fine-scale connectivity much more accurately than the industry-standard, local scale-up methods. Moreover, the reuse of flow solutions makes it very efficient to scale-up a fine-scale reservoir model to different coarse-scale models. These advantages enable us to build more accurate reservoir models at different scales and optimize these models for different business objectives. Several applications of global scale-up to the reservoir modeling are presented.
In most reservoirs, rock properties are heterogeneous over many spatial scales and therefore, they are scale dependent. This makes it difficult to consistently incorporate rock property data measured at 0.01~1 meter scale into reservoir models with cell sizes of 50 to 100s of meters. Therefore, an accurate scale-up is required to bridge this wide gap. Often, scale-up needs to be performed recursively at intermediate scales before fine-scale data can be brought into coarse-scale models (see e.g., [2-4]).
Permeability, a key rock property which directly affects the flow, is particularly challenging to model since coarse-scale permeability relates to fine-scale permeability through Darcy's flow and cannot be accurately calculated using simple averages of the fine-scale permeability. Therefore, flow-based scale-up has been widely used in the industry for modeling permeability at different scales. Simply put, the procedure entails solving flows in a volume of interest, e.g., a gridblock, and using the flow solutions to calculate the "effective" permeability of that volume, see  for a recent review of development in this area.
In the following, we present an overview of a global scale-up technology, we recently developed , and its applications to reservoir modeling.
|File Size||1,357 KB||11|