The influence of wettability and carbon dioxide injection on hydrocarbon recovery Saif Al Sayari Martin J. Blunt

Objective The influence of wettability on – Electrical resistivity – NMR – Pc – Kr Pore scale modelling Efficacy of CO 2 injection for hydrocarbon recovery – Tertiary HC gas injection – Tertiary WAG injection – Tertiary CO 2 Injection Outline

Evaluate the influence of wettability Compare the results with numerical predictions using pore-scale modelling where the pore space has been imaged using micro-CT scanning. Assess CO 2 injection in carbonate oil fields. Objectives

Sandpack –Porosity ~ 34% –Permeability ~ 35 Darcy Sandstone – Fontainebleau –Porosity ~ 9 % –Permeability ~ 140 mD Carbonate – Middle East –Porosity ~ 28 % –Permeability ~ 7 mD Conventional core analysis

MICP Mercury injection capillary pressure is employed: to describe the pore-size distribution to draw drainage capillary pressure that can be used to compare to other methods such as the porous plate method. Carbonate SN 4

Knowledge of the wettability of a reservoir rock and its influence on petrophysical properties is a key factor for determining oil recovery mechanisms and making estimates of recovery efficiency. We combine in one study the effects of wettability on multiphase flow parameters, looking at capillary pressure, relative permeability, electrical properties and NMR. Influence of wettability

Wettability Influence: Electrical Resistivity Water wetOil-wet n (drainage) n (imb.) n (forced imb.) Carbonate SN 4 - 5

Carbonate sample: Pc (Oil-wet vs. Water wet) Very similar samples (Pore throat distribution) Wettability Influence: Capillary Press.

Steady-state relative permeability for carbonate sample at water-wet condition. The sample is then aged in crude oil and elevated temperature and the relative perm. will be conducted again Wettability Influence: Relative Perm. Carbonate SN 1

CoreMicro-CT Network Rock Properties Porosity Permeability Formation Factor Capillary Pressure Relative Permeability NMR Response Porosity Permeability Formation Factor NMR Response Porosity Permeability Formation Factor Capillary Pressure Relative Permeability NMR Response Relative Permeability, SPE84550Capillary Pressure Pore-scale modeling: - Complementary to SCAL, for the determination of single and multiphase flow properties. - Looking at trends where data is lacking, different rock types, wettability and three-phase flow Laboratory – pore scale

Sand pack - LV60B Sand pack - F42B NMR – Results Sandpacks

Carbonate (2) Comparison of the experimental capillary pressures of carbonate C22 with simulation results from a tuned Berea network. Simulation Parameters Diffusion Coefficient: 2.07x10 -9 m 2 /s (Vinegar, 1995) Bulk Relaxivity: 3.1s (Vinegar, 1995) Surface Relaxivity: 2.8μm/s Number of walkers: 2,000,000 Pores: 12,349 Throats: 26,146 Network: Tuned Berea NMR – Results Carbonats

Carbonate (3) Comparison of the experimental capillary pressures of carbonate C32 with simulation results from a tuned Berea network. Simulation Parameters Diffusion Coefficient: 2.07x10 -9 m 2 /s (Vinegar, 1995) Bulk Relaxivity: 3.1s (Vinegar, 1995) Surface Relaxivity: 2.1μm/s Number of walkers: 2,000,000 Pores: 12,349 Throats: 26,146 Network: Tuned Berea NMR – Results Carbonats

Efficacy of CO2 injection Reservoir condition core flooding test have commenced using a composite core plug from a producing field from the Middle East. Reservoir temp. ~ 250 o F and press. ~ 4000 psi After flooding the sample with brine, vertical flooding sequence has been applied: Tertiary Gas flood. Tertiary Water Alternating Gas. Tertiary CO2 injection.

Oil produced from waterflooding was 42% Efficacy of CO2 injection

Oil produced from gas flooding was 82% Tertiary Gas injection

Oil produced from WAG flooding was 80% Tertiary WAG injection

Oil produced from CO 2 flooding was 96% Injection of CO2 stopped Tertiary CO 2 injection

Comparison between different tertiary flooding methods Efficacy of CO 2 injection

The influence of wettability and carbon dioxide injection on hydrocarbon recovery Saif Al Sayari Martin J. Blunt