The Impact of SCCO 2 Injection Rate on Recovery efficiency from Gas- Condensate Reservoirs: Laboratory Investigation H. Sidiq, A. Al-bari, R. Amin September 2009 IEA EOR Conference in Canberra 2009

Presentation Outline Purpose Introduction Experimental Work Results and Discussion Conclusions

Purpose To investigate the velocity-dependent relative permeability (VDRP), molecular diffusion and dispersion mechanisms on recovery efficiency from gas-condensate reservoirs.

Introduction The CO 2 associated with natural gas production can be re-injected for enhanced gas-condensate recovery as well as to overcome the problems associated with gas condensation near the production wells. CO 2 injection for enhanced EOR comes as second methods and approximately 300,000 barral/day produced by means of CO 2 injection. SCCO 2 is a promising technology that provides mutual benefits for coupled increased productivity and CO 2 sequestration.

Experimental Work Unsteady state design. Flow rates: 1, 2, 5, 7 and 10 cm/hr equivalent to approx. 0.8, 1.6, 4, 5.5 and 8 ft/day respectively. Flooding pressure: 5900 psi Table 1: Cores petrophysical characteristics

Experimental Work…cont Fig 1: HPHT Coreflooding Schematic Test sequence: 1-Saturating the Cores with brine measuring, Kw. 2-Flooding the Cores with methane or condensate to S wi and measuring wi. 3-Displacing methane or condensate by SCCO 2 at different injection rates measuring methane-CO 2 and condenstate-CO 2 relperm.

Results and Discussion 1-SCO 2 -Condensate

SCCO 2 -Condensate Displacements Figure 2: Condensate Recovery vs. PVI

SCCO 2 -Condensate Displacements…cont Figure 3: Mole % CO 2 Production vs. PVI

SCCO 2 -Condensate Displacements…cont * BT simulation images of air (black) penetrating water (Crandall 2007) A Microscopic Look! 1 cm/s* 5 cm/s*

SCCO 2 -Condensate Displacements…cont Figure 5: SCCO 2 and Condensate Relative Permeability vs. Total Liquid Saturation S wi

Results and Discussion 2-SCO 2 -Methane

SCCO 2 -Methane Displacements Figure 6: Mole % CO 2 Production vs. PVI

SCCO 2 -Methane Displacements…cont Figure 7: SCCO 2 and Methane Relative Permeability vs. CO 2 Saturation at 10 cm/hr

SCCO 2 -Methane Displacements…cont Figure 8: SCCO 2 and Methane Relative Permeability vs. CO 2 Saturation at 1 cm/hr

Conclusions The rate-sensitivity of natural gas and condensate recovery following SCCO 2 injection was investigated. This study showed CO 2 injection rate (velocity) greatly affects the displacement efficiency with it the amounts of CO 2 sequestered. In condensate-SCCO 2 system improved recovery efficiency achieved with decreasing displacement rate. Methane recovery factor at CO 2 breakthrough confirmed that recovery factor increased as injection rate increased until a maximum recovery factor obtained at corresponding field injection rates of 10cm/h

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