Reservoir Engineering Courses – K. Madaoui - 2004 145 Reservoir Engineering Courses – K. Madaoui - 2004 ENHANCED OIL RECOVERY PROCESSES CONTENTS -1-INTRODUCTION EOR world potential- -2-THERMAL PROCESSES - Steam injection –Air injection -3-CHEMICAL METHODS -Polymers and Surfactants -4-GAS INJECTION as a promising EOR process - Specificities,Mechanisms,Efficiencies,Selection criteria,Ratios,Methodology to conduct a GI project -5-CONCLUSIONS: EOR vs R&D 146 Reservoir Engineering Courses – K. Madaoui - 2004 Typical Oil Field Performances Time Years Field Oil Rate Aband. Rate WATER-CUT NATURAL DEPLETION (30%) WATER INJ. (+ 15%) N P DN P Diagnosis 3 rd TYPE EOR (+ 10%) IRM (+ 5%) 147 Reservoir Engineering Courses – K. Madaoui - 2004 Ultimate Reserves and Recovery mechanism sequence N pu =N 1 +N 2 +N 3 at economical abandonment conditions =N 1 +(N i -N 1 )[E d xE vol ] water +(N i -N 1 -N 2 )[E d xE vol ] gas How to optimise N pu ?How to combine N 1 ,N 2 ,N 3 ? Main parameters? N 1 (nat.depl.) :identification-limitations-duration N 2 (water inj.) :limitations-implementation-duration N 3 (EOR) :process selection-implementation 148 Reservoir Engineering Courses – K. Madaoui - 2004 Tertiary Recovery Objectives PRODUCE-ECONOMICALLY- PART OF OIL LEFT BY CONVENTIONAL RECOVERY METHODS – Improvement of displacement efficiency decreasing Sorw miscible or near miscible gas injection chemical flood-surfactants increasing gravity forces oil vaporization – Improvement of volumetric sweep efficiency lowering mobility ratio by increasing m w chemical flood - polymers reducing m o thermal flood 149 Reservoir Engineering Courses – K. Madaoui - 2004 Microscopic and Volumetric Sweep Efficiencies Example of Five Spot Injection Pattern- Cross section Water flooded zone - Intermediate status Water flooded zone - Final status Injector Producer Injectors Producers Soi Sorw 150 Reservoir Engineering Courses – K. Madaoui - 2004 Pore Level Mechanisms - Microscope Efficiency · Competition between viscous and capillary forces capillary number: · Competition between gravity and capillary forces Dombrowski Brownwell number: 1.0 0.5 0.0 10 -6 10 -4 10 -2 10 0 Capillary number, N c Microscopic displacement eff., Em WATER-WET SYSTEMS PORE SIZE DIST'N WIDE AVERAGE NARROW s m U N c = s Dr gk N b = E m for N b > 10 -5 151 Reservoir Engineering Courses – K. Madaoui - 2004 Water Injection Efficiency Water-flood efficiency = Areal sweep efficiency x Vertical sweep efficiency xDisplacement efficiency Limitations: Ed<1 Eareal<1 Evertical<1 f(pattern,mobility ratio) vs.layer contrast Sorw = 0 152 Reservoir Engineering Courses – K. Madaoui - 2004 Limitations of conventional methods- Recovery by conventional methods= Natural depletion +Water injection recovery =N 1 +N 2 =N 1 +(N i -N 1 )xEdispl.XEvol. Ed= Oil left in swept zones Evol<1 ~0.4 to 1 Oil left in unswept zones S oi -S orw 1-S wi <1 ~60% 153 Reservoir Engineering Courses – K. Madaoui - 2004 Enhanced Oil Recovery Methods Enhanced Oil Recovery IMPROVEMENT OF VOLUMETRIC EFFICIENCY Evol IMPROVEMENT OF DISPLACEMENT EFFICIENCY Ed INCREASE WATER VICOSITY OIL VISCOSITY REDUCTION REDUCE INTERFACIAL TENSION INCREASE GRAVITY FORCES OIL VAPORIZATION HEAVY OIL STEAM INJECTION IN-SITU COMBUSTION POLYMER SURFACTANT GAS INJECTION MISCIBLE NEAR MISCIBLE HC,CO2,N2,AIR,… Lean gas injection (HC,N2,CO2,AIR, ) Stable displacement IMMISCIBLE LEAN GAS INJECTION STEAM INJ.(LIGHT OIL) [...]... Injection Mechanisms FLUE GAS Air + Oil + Water N2 + Oil Oil Stripping Hc Gas + Stripped Oil + N2 LTO Co, Co2 + others O2 + Oil Oxydation Temperature Oil Vaporization (Oil Composition HTO and Res Temp.) WATER STEAM Reservoir Engineering Courses – K Madaoui - 2004 174 Co, Co2 + others Air Injection F Oxygene Oil Reactivity vs Reservoir Temperature F Possible Spontaneous Oil Ignition and Complete Comsumption... Legend O2 + flue gas + heavy ends Thermal front (water + oil vaporisation + oxydation Ù CO + CO2 + LTO (alcool, aldehyde, ester) + some visbreaking Flue gas (N2 + CO + CO2 + HC) Steam + vaporised oil + flue gas + fuel oil (heavy) Oil Vaporized oil + flue gas + condensed water + fuel oil Steam Condensed oil + flue gas + condensed water + fuel oil Water Oil rim + flue gas Sorw + flue gas Sorw Reservoir Engineering... Combustion F Effect Reduction of oil viscosity due to heating effect Reservoir Engineering Courses – K Madaoui - 2004 161 Heavy Oil : a mix of heterogeneous denominations Confusing heterogeneous denominations : - Heavy Oil, Extra Heavy Oil, Oil Sands, Tar Sands, Bitumen, … è need for a simple classification 4 Classes based mainly on downhole viscosity : 0 A Class : Medium Heavy Oil 25°> d°API > 18° 100 cPo...Production Mechanisms Order of magnitude of recovery factor Mechanism I- Oil reservoirs Natural depletion only 5 to 20 %OOIP ND+Water depletion 30 to 50 %OOIP ND+WI +Enhanced oil recovery 50 - 65 %OOIP II- Gas reservoirs 60 - 90 % OGIP Natural depletion Reservoir Engineering Courses – K Madaoui - 2004 154 EOR contribution in the world oil production ESTIMATION* YEAR 2000 THERMAL 1.0 to 1.5... Engineering Courses – K Madaoui - 2004 158 ENHANCED OIL RECOVERY Reservoir Engineering Courses – K Madaoui - 2004 159 Heavy oils qoi= High viscosity a kakro(Swi+g) h moBo[Lnre/rw +s-0.75] Low PI x (Pr-Pwf ) = PIx (Pr-Pwf ) Low or Uneconomical oil rate Reservoir Engineering Courses – K Madaoui - 2004 160 Fundamentals of Reservoir Engineering Thermal Flood HEAVY OIL( °API 106... Extra Heavy Oil 20°> d°API > 7° 10 000 cPo >m > 100 cPo , mobile at reservoir conditions 0 C Class : Tar Sands and Bitumen 12°> d°API > 7° m > 10 000 cPo, non mobile at reservoir conditions 0 D Class : Oil Shales Reservoir = Source Rock, no permeability Mining Extraction only Reservoir Engineering Courses – K Madaoui - 2004 162 Heavy Oil (excluding Oil Shales) : 3 Main Categories Heavy Oil Classification... zon zone r apo dens V Co n Oil bank Schematic Representation of in Situ Combustion Process and the Various Zones as Formed in the Oil Reservoir Reservoir Engineering Courses – K Madaoui - 2004 172 Air Injection Mechanisms : Oil + Flue Gas F Reservoir Pressure Maintenance / Repressurization F Gravity Stable Displacement F Oil Swelling F Miscibility - Flue Gas / Reservoir Oil Reservoir Engineering Courses... *: 1000 billion stb (for an initial oil in place of >3500billion stb) 1% recovery factor improvement~35 billion stb ! UNCONVENTIONAL RESERVES: Deep offshore:100 billion stb Heavy oil :600 billion stb *onshore+offshore( less than 300 meters water depth) Reservoir Engineering Courses – K Madaoui - 2004 157 TENTATIVE ESTIMATE of EOR POTENTIAL CASE of MATURE or AGEING OIL FIELDS (more than 20 years old... and the Various Zones as Formed in the Oil Reservoir Reservoir Engineering Courses – K Madaoui - 2004 167 Fundamentals of Reservoir Engineering Thermal Methods Cyclic Steam Injection Process Scheme Steam injection Soak period Produced fluids Viscosity Steam Steam Viscous oil Heat Heat Cond water Viscous oil Reservoir Engineering Courses – K Madaoui - 2004 168 Low oil Water Fundamentals of Reservoir Engineering... 2004 170 Fundamentals of Reservoir Engineering Thermal Methods In Situ Combustion F Oil is Ignited around Well Bore F Burning Front Sustained by Continuous Injection of Air F A Small Portion of the Oil is Burned F The Heat Generated · Reduces Oil Viscosity · Produces Miscible Fluids · Increases Sweep Efficiency · Reduces Oil Saturation F Continuous Air Injection Develops Efficient Gas Drive Mechanisms . Madaoui - 2004 Enhanced Oil Recovery Methods Enhanced Oil Recovery IMPROVEMENT OF VOLUMETRIC EFFICIENCY Evol IMPROVEMENT OF DISPLACEMENT EFFICIENCY Ed INCREASE WATER VICOSITY OIL VISCOSITY REDUCTION REDUCE. 2004 145 Reservoir Engineering Courses – K. Madaoui - 2004 ENHANCED OIL RECOVERY PROCESSES CONTENTS -1-INTRODUCTION EOR world potential- -2-THERMAL PROCESSES - Steam injection –Air injection -3-CHEMICAL. INJ.(LIGHT OIL) 154 Reservoir Engineering Courses – K. Madaoui - 2004 Production Mechanisms Mechanism I- Oil reservoirs Natural depletion only ND+Water depletion ND+WI +Enhanced oil recovery II-