The Effects Of Sedimentary Heterogeneities On Production From A Shallow Marine Reservoir - What Really Matters ?

Abstract

This paper investigates the impact of sedimentary heterogeneities on performance of waterflooding in shallow marine reservoirs. Reservoir simulation models are developed from detailed geological models based on a four-level sedimentary architectural hierarchy ranging from sedimentary structures (wave ripples, hummocky cross-stratification) up to parasequences. Single- and two-phase flow properties are upscaled to capture the effects of small scale heterogeneities on performance. The relative influence of 12 heterogeneity factors is determined using experimental design and analysis of variance. The analysis identified large scale features (parasequence thickness and stacking patterns) to be of primary importance for waterflood performance. These features control the relative proportion of fades belts in the reservoir, which correlates with recovery. Other important, though secondary, heterogeneities include interfingering of facies belts, and small scale bedding.

Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 2. Impact on fluid flow and hydrocarbon recovery in fluvial-dominated deltaic reservoirs

“…Capillary pressure curves are dependent on the facies-association type. These data, as well as oil and water properties, are similar to those documented in many North Sea Brent Group reservoirs and have been widely used in previous modeling studies of shallow-marine reservoirs (e.g., Kjønsvik et al, 1994;Matthews et al, 2008;Jackson et al, 2009). …”

“…As the first part of our analysis, a hierarchy of stratigraphic and sedimentologic heterogeneity in fluvialdominated deltaic reservoirs (modified after the more generic scheme for shallow-marine reservoirs of Kjønsvik et al, 1994) is presented, which provides a framework to identify, organize, and model the heterogeneities observed. The hierarchy classifies six lengthscales of heterogeneity, from the field scale (~10 km [6 mi]) to the pore scale (~10 μm) ( Van de Graaf and Ealey, 1989), and places clinoforms observed in delta lobes (sensu Wellner et al, 2005;Bhattacharya, 2006) in their appropriate context.…”

Reservoir Modeling Methods and Characterization Parameters for a Shoreface Reservoir: What Is Important for Fluid-Flow Performance?

“…In a shallow marine reservoir, the thickness and stacking patterns of parasequences were found to be the most important. 4 Incorporating high-resolution sequence stratigraphic architecture and reservoir quality trends within each parasequence of a reservoir simulation model was found to be significant for improved history match and identifying bypassed oil in a shoreface reservoir. 5,6 For submarine channelized reservoirs, net-to-gross, permeability heterogeneity, mean permeability, mobility ratio, and residual oil saturation were found to be significant factors influencing waterflood performance.…”

Mechanisms of Oil Recovery via Multi-Contact Miscible Gas Injection Process within Lensed Systems

“…Heterogeneity is present at many scales in clastic reservoirs. Small-scale heterogeneities are particularly problematic for all secondary and tertiary recovery processes as they can have a significant effect on recovery [13][14][15] yet cannot be modelled explicitly in fieldscale simulations. One of the most common small-scale heterogeneities found in sandstone reservoirs is lensed system.…”