THE CHALLENGE

FCMG CHAIR CARBONATE RESERVOIR SIMULATION

SIMULATING IOR AND EOR IN CARBONATES – SELECTED RESEARCH EXAMPLES

• Carbonate reservoirs hold over 60% of the world’s remaining oil reserves and account for over 30% of the world’s oil production. • Recovery factors from carbonate reservoirs are often low (10 to 20%) due to their multi-scale heterogeneity and complex wettability. • A small (1-2%) increase in recovery will impact global hydrocarbon resources. • Advances in flow prediction and recovery will be among the most significant developments for the oil and gas industry in the next decade. • A key challenge is to understand – from pore- to field-scale – where residual oil is located and to predict how it can be mobilised best.

OUR VISION AND MISSION KEY OUTPUTS 2012/2013

S. Geiger1,2, S. Agada1, M. Ahmed1, N. Akhimiona1, R. Annewandter1, S. Chandra1,2, M.I.J. van Dijke1,2, C. Fricke1, Z. Jiang1,2, H. Kouevi3, L. de Lima1,2, C. Maier1, A. Mangione1,2, T. Pak2, J. Shaw-Stewart2, D. Stone3

1Institute of Petroleum Engineering, Heriot-Watt University, U.K. 2International Centre for Carbonate Reservoirs 3Department of Mathematics, Heriot-Watt University Email: sebastian.geiger@pet.hw.ac.uk Web: http://comphg.wikidot.com

• To develop innovative and practical solutions that provide a step-change in carbonate reservoir modelling and simulation. • To work interdisciplinary and bridge gaps between disparate scientific fields. • To form strategic industry-academic alliances that ensure efficient knowledge transfer. • To train a new generation of world-leading carbonate reservoir engineers.

Typical multi-scale and sub-grid heterogeneity encountered in a carbonate reservoir. Fracture picture courtesy of H. Boro, Amsterdam. Pore-scale picture from Cantrell & Hagerty (1999).

Many carbonate reservoirs are now considered for EOR (e.g. WAG). We develop digital rock physics tools to estimate two- and three-phase flow properties in multi-scale carbonates with arbitrary wettability and demonstrate how they can be used in field-scale reservoir simulations.

• Graduated 1 PhD student (current employer PDO). • Supervised and graduated 9 MSc students. • Published 11 peer-reviewed papers (1 in press). • Published 12 conference papers (SPE and EAGE). • Launched the Rapid Reservoir Modelling (RRM) Consortium with Drs. Mario Costa Sousa, Leonardo Guimaraes, and Matt Jackson (Imperial College) • Launched the UK-wide industry-academic research network “Porous Media – Processes and Mathematics”

A major outreach activity of the FCMG Chair in 2012 was the joint AAPG-SPE-SEG Hedberg Research Conference. It was chaired by Dr Susan Agar (ExxonMobil) and Sebastian Geiger and attended by 87 scientists from industry and academia.

Carbonate reservoirs contain highly complex geological structures. We use high-resolution outcrop analogues to analyse which geological features have the greatest impact on a given IOR or EOR scheme and develop new reservoir characterisation approaches such as near-wellbore modelling to capture these heterogeneities at the field-scale.

Most carbonate reservoirs contain fractures, which are the primary pathways for fluid flow. We have previously shown that upscaling discrete fracture networks (DFN) can introduce an error that is larger than the geological uncertainty. Here we demonstrate that this error cannot be corrected using state-of-the-art assisted history matching approaches and physically informed transfer functions are key to model fracture-matrix fluid exchange accurately.

DFN model ∆x = ∆y = 100 ft

∆x = ∆y = 200 ft

High

Medium to High

Low to Medium

Low

Model of the matrix properties of the Teapot Dome oil field (A fractured dolomite and sandstone reservoir in Wyoming)

Fracture intensity models at Teapot Dome

Assisted history matching of liquid and water rates

∆x = ∆y = 100 ft ∆x = ∆y = 200 ft

Best-case fracture permeability after history matching

kx ky kx ky

Physically informed multi-rate dual-porosity models

Few small matrix blocks

Uniform matrix

Few large matrix blocks

WAG - Empirical Model (Stone I) WAG - Empirical Model (Stone II) WAG - Network model

Multi-scale carbonate

Single-scale carbonate

kro

krg

krw

Complex small-scale structures Outcrop analogue