Impact of sequence-based correlation style on reservoir model behaviour, lower Brent Group, North Cormorant Field, UK North Sea

Abstract

An increasing percentage of remaining reserves in mature Brent Group producing

The use of field analogues in the correlation and static reservoir methodology used in the Tern Field, Northern North Sea, UK

“…Each sequence was between 4 and 7 m in thickness, strongly supporting the modelling methodology. (5) History matching of modelled versus true well behaviour gives excellent results from the resulting model (in contrast to the findings of Wehr and Brasher (1996), who used a clinoform-based model for the adjacent Cormorant Field, and achieved a better match than through a purely lithostratigraphic/tramline correlation model), supporting the robustness of the parasequence-based correlation employed in the present study. The results for the 2000 model and corresponding correlation showed a typical match between modelled and actual well performance of approximately 90% for flow rates, and 60% for the pressure matches (less good, but due mainly to uncertainties in reservoir engineering parameters such as relative permeabilities, i.e.…”

“…Between each of the flooding surfaces, each intervening layer (parasequence) should show a gradual seaward transition from sandy to more muddy deposits, with a consequent decrease in average porosity. Kriging of porosity data from wells will pick this out transition, and this has previously been demonstrated in the Brent and Cormorant Fields (Wehr & Brasher, 1996).…”

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

“…The relationship between structural dip and waterflood direction can also strongly modify the effect of depositional clinoform dip on sweep (Wehr and Brasher, 1996;Howell et al, 2008b;Jackson et al, 2009). The methodology of Jackson et al (2009) was applied to adjust the vertical coordinates of the grid cells in every grid layer to impose a uniform structural dip of 8°that is representative of fluvial-dominated deltaic reservoirs in the Prudhoe Bay (Alaska) field (e.g., Begg et al, 1992) and shallow-marine reservoirs within tilted fault blocks in the North Sea (e.g., Tollas and McKinney, 1991;Wehr and Brasher, 1996;Husmo et al, 2003). For the model of stacked delta-lobe deposits, waterflooding is simulated up structural dip (Figure 4), but each of the delta-lobe deposits in the model has a different azimuthal orientation relative to the waterflood direction, such that some are aligned along depositional dip ( Figure 3A, D) and others along depositional strike ( Figure 3B, C).…”

Three-dimensional modeling of clinoforms in shallow-marine reservoirs: Part 1. Concepts and application

“…Clinoforms are dipping surfaces having geometry that preserves the depositional morphology of the delta-front or shoreface slope; and their distribution reflects the progradation history of the shoreline (Barrell, 1912;Rich, 1951;Gani and Bhattacharya, 2005;Sech et al, 2009) (Figure 1). Clinoforms control aspects of detailed facies architecture within parasequences and can also act as low-permeability barriers or baffles to flow (Wehr and Brasher, 1996;Ainsworth et al, 1999;Dutton et al, 2000;Howell et al, 2008a, b;Jackson et al, 2009;. Therefore, it is important to include clinoforms in models of shallow-marine reservoirs to properly characterize facies architecture and volumes of hydrocarbons in place .…”

“…Few studies have attempted to identify and correlate clinoforms in the subsurface (Livera and Caline, 1990;Jennette and Riley, 1996;Løseth and Ryseth, 2003;Matthews et al, 2005;Hampson et al, 2008) or have built two-dimensional (2-D) (Wehr and Brasher, 1996;Forster et al, 2004) or three-dimensional (3-D) (Howell et al, 2008a, b;Jackson et al, 2009;Sech et al, 2009; flow simulation models that incorporate clinoforms. Previous studies of the Ferron Sandstone Member have incorporated simple clinoform geometries into reservoir models by using either objectbased (Howell et al, 2008b) or deterministic (Howell et al, 2008a) approaches.…”