STOR EOR Macro and Micro Displacement EOR PDF

Displacement Efficiency (Micro and Macro) Secondary and Tertiary Oil Recovery 1 Microscopic Displacement Efficiency 2 Fundamentals • Entrapment and mobilization of residual oil • The influence of recovery mechanism in residual oil 3 Trapping mechanism • Pore structure of the porous medium...

Displacement Efficiency (Micro and Macro) Secondary and Tertiary Oil Recovery 1 Microscopic Displacement Efficiency 2 Fundamentals • Entrapment and mobilization of residual oil • The influence of recovery mechanism in residual oil 3 Trapping mechanism • Pore structure of the porous medium • Fluids/rock interactions related to wettability • Fluid/fluid interactions reflected by IFT 4 Trapping in a single capillary • Known as ‘Jamin effect’ • The static pressure difference, pB – pA must be overcome to initiate flow. • For part (a); • For part (b); 5 Trapping in a single capillary • For part (a); • For part (b); • For part (c); 6 Trapping with fluid bypassing • Due to channel geometry. • Based on experimental study by Arriola et. al.(1983) • Water bypassed oil drop (nonane) at the corners of the capillary. • At the constriction of the capillary, the oil drop became trapped by the Jamin effect. • Balance of capillary force and viscous force. 7 Pore doublet model • Oil is trapped when the displacement proceeds faster in one pore than the other. • Pores are assumed to be water-wet. • Viscosities and densities of oil and water phases are assumed to be equal. 8 EOR process efficiency  Displacement Efficiency (microscopic) • Capillary forces • Viscous Forces • Capillary Number – Calculation – correlation  Volumetric Efficiency (macroscopic) • Mobility Ratio – Basic principles – Calculation – Correlation • Viscous Gravity Ratio – Influencing factors – Calculation 9 Capillary Number • A method of correlating experimental data of different conditions and parameters to the yield residual saturation of the displaced phase. • Using dimensionless groupings of variables involving the ratio of viscous to capillary forces. 10 Correlation of Nca/cosθ with oil saturation in core at water breakthrough (Moore and Slobod, 1956; and Abrams, 1975) 11 Correlation of Nca term with residual oil saturation (Abrams, 1975) 12 Correlation of Nca(µw/µo)0.4 with residual oil saturation (Abrams, 1975) 13 Correlation of Nca(µw/µo)0.4 with residual oil saturation for different rocks (Abrams, 1975) 14 Correlation of Nca,m in a single capillary with a constriction (Arriola et al., 1983) 15 Effect of wettability on relative permeability curves 16 Effect on residual oil of changing capillary or viscous forces at the front and behind the front (Moore and Slobod, 1956) 17 Correlation of recoveries of residual phases as a function of Nca (Stegemeier, 1977) 18 Sketch the movement and trapping Sketch the movement of oil showing the entrapment using a pore doublet model in (a) Water wet system (b) Oil wet system Exercise 20 Macroscopic Displacement Efficiency 21 Macroscopic Sweep Efficiency The volume of reservoir contacted by the injected fluid Fraction of PV invaded by the injected fluid Is a function of time E = EV ED Controlling Factors Properties of the injected fluids Properties of the displaced fluids Properties and geological characteristics of the reservoir rocks Geometry of the injection and production well pattern Volumetric Displacement Efficiency and Material Balance Areal and Vertical Displacement Efficiencies Consider a reservoir with uniform porosity, thickness and hydrocarbon saturation, but consists of several layers EV = EA EL  EA is the area swept divided by the total reservoir area  EL is the pore space invaded by the injected fluid divided by the pore space enclosed in all layers behind the location of the leading edge of the front EV for Real Reservoir Porosity, thickness and hydrocarbon saturation vary areally EA is replaced by Ep (pattern sweep efficiency) Ep is the hydrocarbon pore space enclosed behind the injected fluid front divided by the total hydrocarbon pore space in the pattern or reservoir Note: EA and Ep typically are not independent Mobility Ratio 28 Parameters affecting displacement Viscous/Gravity Ratio Exercise