Bureau of Economic Geology, The University of Texas at Austin (www.beg.utexas.edu).
AAPG Annual Convention, Houston, Texas, April 9–12, 2006
Insights into Reservoir Characteristics of Sinuous
Deep-Water Channel Fills from Outcrop Analogs—Part 2: Testing Production
Scenarios Using Outcrops as Templates for Geologic and
Moderate to low net-to-gross sinuous slope-channel turbidite reservoirs, imaged by 3D seismic data, are extremely common in offshore W. African fields. Early production information and 4D seismic monitoring data from these fields indicate heterogeneities near and below seismic resolution are important in controlling fluid flow. These heterogeneities are poorly understood and difficult to represent in geologic and reservoir simulation models, resulting in, for example, poor predictions of water and gas breakthrough.
We describe the use of outcrop studies to understand production performance of these reservoirs. Outcrops of deep-water channel-fills provide stratigraphic and sedimentologic information at much higher resolution than even the highest quality seismic images of subsurface reservoir elements. Therefore, geologic models of outcrop analogs can potentially be used to test the impact of fine-scale heterogeneities on field development and production concepts.
We have built 3D geologic models of deep-water channel complexes from the Capistrano Fm. (CA.) and the Brushy Canyon Fm. (W. TX.). Fluid flow simulation experiments tested various stratigraphic scenarios believed to be important in determining the production behavior of W. African fields. Specifically, we have investigated: 1) low transmissibility drapes on channel margins; 2) high permeability gravel "lags" in channel axis positions; and 3) impact of thinly bedded reservoir in off-axis to overbank positions. These high-resolution, outcrop-based simulation experiments confirm the critical need for proper representation of the 3D distribution of strong permeability contrasts in both geologic and reservoir simulation models of deep-water channel complex reservoirs.