Forward Stratigraphic Modelling, Deterministic Approach to Improve Carbonate Heterogeneity Prediction; Lower Cretaceous, Abu Dhabi

Abstract

This paper discusses the results of an innovative methodology using Dionisos 4D forward stratigraphic modelling of Middle Eastern carbonate reservoirs on a field scale. Traditional stochastic techniques do not sufficiently capture carbonate reservoir heterogeneities, reducing the accuracy of static and dynamic models. The methodology applied to three Lower Cretaceous UAE reservoirs, uses a deterministic approach that aims to define carbonate heterogeneity and provides a structure to develop a more accurate and usable static and dynamic model for field development. Dionisos uses a predefined sequence stratigraphic scheme as a framework. A reference case model is manually calibrated to environmental parameters, followed by automated multi-realisations that generate several other plausible calibrated models. A sensitivity analysis provides an indication of the influencing environmental parameters controlling facies and texture distribution.The calibrated forward stratigraphic models resulted in the generation of 14 carbonate textures for the three reservoirs using a 200x200 m grid size and a 50 kyrs time step. Carbonate lithology production (mud, fine, coarse, bioconstructions) varies between 0 and 350 m/Ma, wave direction is SW (200 -260°); wave action depth 7-18 m while wave energies vary between 0 and 140 kW/m. Sediment diffusion coefficients by wave transport range from 0.1 (mud) to 0.0008 km 2 /kyr (bioconstructions) while gravity driven transports from 0.1 to 0.001 km 2 /kyr. The lower part of Reservoir A is characterised by low angle TST sequences dominated by algal boundstones-floatstones. Deposition continued with the development of a low relief margin with aggradational to progradational architectures comprising rudist shoals. This defined a topographic split into platform, slope and basin with lateral texture heterogeneities showing a northward deepening trend. The successive clinoform top sets (Seq4a, b) are rich in rudist boundstones-floatstones with lower slope dominated by packstones-wackestones.Reservoir B and C are isopach with strong lateral variability in carbonate texture as evidenced by well data. The overall architecture of the sedimentary systems consists of low relief interconnected algal boundstone-floatstone mounds separated by gentle depressions dominated by fine grained sedimentation. The numerical simulation of these systems was driven by a carbonate production law as a function of the substratum energy and bathymetry under dynamic subsidence/uplift conditions. The innovative workflow applied at field scale allowed the modelling of complex carbonate geometries and associated textures honouring lateral and vertical heterogeneities observed at wells. The application of this workflow as alternative/complement to stochastic methodologies brings further insights on the proposed sequence stratigraphic framework allowing the confidence and predictability of static and dynamic facies models to be increased.

Forward stratigraphic modelling of sediment pathways and depocentres in salt‐influenced passive‐margin basins: Lower Cretaceous, central Scotian Basin

“…In this study, stratigraphic modelling was conducted using DionisosFlow ™ , a diffusion‐based forward stratigraphic modelling software that simulates basin infill over geological time scales (Granjeon, ). Produced models are then analysed using CougarFlow ™ to assess the impact of various simulation parameters, and determine regions of increased sensitivity (Agrawal et al, ; Hawie et al, ). Models are calibrated against reference wells and seismic surfaces with the goal of reproducing the overall trends of sediment distribution in the basin.…”

“…CougarFlow ™ is a statistical software used to evaluate the sensitivity of stratigraphic models generated using DionisosFlow ™ (Hawie et al, ). It uses Response Surface Modelling (RSM), in which multiple models are run.…”

Quantitative controls on the regional geometries and heterogeneities of the Rayda to Shu'aiba formations (Northern Oman) using forward stratigraphic modelling

“…We propose that applying Dionisos 4D forward stratigraphic modelling to a broader set of subsurface data in Oman could be used to: (1) complement stochatic modelling and (2) to enhance the predictability and confidence level on reservoir models (Hawie et al, 2015). This is because complex carbonate sedimentary geometries (i.e.…”

“…rudist shoals, algal mounds, development of clinoforms, aggradation and progradation of carbonate platforms) require a broad multi-disciplinary dataset integration and understanding of various geological processes. For example, a calibrated forward stratigraphic model was generated for the three Lower Cretaceous reservoirs located on onshore oil field in Abu Dhabi (Hawie et al, 2015). A 200x200m grid size and a 50 kyrs time step were used to simulate these reservoirs, supported with sensitivity analysis (Hawie et al, 2015).…”

“…For example, a calibrated forward stratigraphic model was generated for the three Lower Cretaceous reservoirs located on onshore oil field in Abu Dhabi (Hawie et al, 2015). A 200x200m grid size and a 50 kyrs time step were used to simulate these reservoirs, supported with sensitivity analysis (Hawie et al, 2015). These models consider in situ production and transport by waves, gravity and water influx (Hawie et al, 2015).…”