The structured gridding implications for upscaling model discrete fracture networks (DFN) using corrected Oda%26apos;s method

作者：Ghahfarokhi Payam Kavousi

来源：Journal of Petroleum Science and Engineering, 2017, 153: 70-80.

DOI：10.1016/j.petrol.2017.03.027

• Oda's permeability tensor
• Fractured reservoirs
• Permeability upscaling
• Grid orientation
• Reservoir simulation
• Discrete natural fractures
• Dual porosity
• Flow-based permeability upscaling

Upscaling of fracture permeability in a field-size discrete fracture network (DFN) for a dual porosity model can be undertaken using Oda's method. It is known that Oda's method usually overestimates equivalent permeability and needs to be corrected by a flow-based numerical method. In this study we show that grid orientation can produce significant differences in single-phase (water) production volumes estimated through flow simulation in dual porosity models (Eclipse 300) when using corrected Oda's method. A five layer synthetic model in a water zone includes thirteen vertical wells. 10 ft by 10 ft structured gridding is performed in six directions: 0 degrees, 15 degrees, 30 degrees, 45 degrees, 60 degrees and 75 degrees counter-clockwise relative to the north. The model DFN used in this study consists of three sets: a dominant, high intensity N76 degrees W set and two lower-intensity sets that strike N28 degrees W and N75 degrees E similar to the fracture sets observed in the Tensleep Formation at Teapot Dome, Wyoming, USA.
The single-phase (water) flow simulation using Eclipse 300 flow simulator for the six synthetic models reveals that the production varies in proportion to the geometric mean of the permeability tensor with grid rotation. The production is at its maximum when the dominant fracture set orients 45 degrees relative to the grid cell principal directions (i, j) and falls to a minimum when the dominant fracture set is parallel to either grid wall (i or j principal directions).
This research reveals a shortcoming of systematic variability of simulated production with grid orientation even though Oda's results are corrected with a flow-based numerical method.

• 出版日期2017-5