Assessing the effect of geological uncertainty on recovery estimates in shallow-marine reservoirs: the application of reservoir engineering to the SAIGUP project

Abstract

Reservoir management is a balancing act between making timely operational decisions and the need to obtain data on which such decisions can be made. There is a further problem: estimates of recovery for prospective development plans are subject to uncertainty because of the uncertainty of the geological description within the simulation model. The SAIGUP project was designed to analyse the sensitivity of estimates of recovery due to geological uncertainty in a suite of shallow-marine reservoir models. However, although it was generic, it had the hallmarks of active reservoir management, because those members of the team responsible for deriving the notional development plans for individual models via reservoir simulation, and computing the recoveries, had to work in parallel with others under time and budget constraints. This paper describes the way the reservoir engineering was carried out to achieve these objectives, the assumptions made, the reasoning behind them, and how the principles could be used in other studies. Sample results are also presented, although the bulk of the results are presented in other papers in the project series. One surprising result was that faults that impede flow can improve recovery. The underlying physical explanation for this behaviour is provided.

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). …”

Faults in conventional flow simulation models: a consideration of representational assumptions and geological uncertainties

“…Production is simulated for up to 30 years, subject to minimum well-specific and field-wide oil production rate cutoffs. Further details of sedimentological, structural and reservoir engineering aspects of the models are given by Howell et al (2008), Manzocchi et al (2008b), Matthews et al (2008) and Stephen et al (2008).…”

“…Ringrose et al 1993;Manzocchi et al 1998Manzocchi et al , 2002Rivenaes & Dart 2002;Al-Busafi et al 2005;Berg & Øian 2007). The example reservoirs used in this study -although synthetic -contain scales, rates, fluids and pressures representative of real reservoirs (Manzocchi et al 2008a, Matthews et al 2008 and are, therefore, a good test of whether two-phase fault rock properties may, indeed, be of practical significance. The workflow used to allow routine inclusion of two-phase fault rock properties in the simulation models is described below, and the results for three different input assumptions discussed.…”

Impact of Geological Heterogeneity on Early-stage CO2 Plume Migration

“…To this end, we have selected four parameter spaces of geological variations from the SAIGUP study [2,3,4]. The parameters span realistic intervals for progradational shallow-marine depositional systems with limited tidal influence.…”

“…Within oil recovery, the impact of geological uncertainty on production forecast has been thoroughly investigated in the SAIGUP project [2,3,4] focusing on shallow-marine reservoirs. To study different factors, synthetic realistic models were made and several thousand cases were run for different production scenarios.…”