Interaction between NTI and MRI for Numerical Analysis

Interaction between NTI and MRI for Numerical Analysis of Core Floods for Enhanced Oil Recovery Visit from DONG Energy Åsmund Haugen, Bergen, 9 jan. 2012

Introduction Porosity + Permeability+ Oil Rock Water Wettability Oil Water Strongly Neutrally wet Oil-wet water-wet

Introduction – Fractured Reservoirs

Objective �Study impact form wettability on oil recovery from fractured reservoirs �Suggest ways to improve oil recovery

Method of Approach Controlled laboratory experiments on simplified systems Larger Sample 2 D NTI 3 D MRI Smaller core with fracture 2 D MRI of Core Numerical Simulations Sensitivities 2 D MRI of Fracture EOR

Experimental – NTI - Vertical Flow Rig �Nuclear Tracer Imaging �Radioactive isotopes are added to fluids �Each isotope emmits defined γ-energies �Intesity of each energy is detected by germanium detector �Intesity related to amount of fluid phase present Co 60 Rock Sample

Experimental – NTI - Vertical Flow Rig �Nuclear Tracer Imaging �Radioactive isotopes are added to fluids �Each isotope emmits defined γ-energies �Intesity of each energy is detected by germanium detector �Intesity related to amount of fluid phase present Rock Sample Injection Pump Detector

Differential Pressure �Nuclear Tracer Imaging �Radioactive isotopes are added to fluids �Each isotope emmits defined γ-energies �Intesity of each energy is detected by germanium detector �Intesity related to amount of fluid phase present Injection Pump Experimental – NTI - Vertical Flow Rig Collimated Germanium Detector Rock Sample

Experimental – MRI Electronics Samples are Loaded Here Computer Sample Coils 2. 0 T Superconducting Permanent Magnet

Experimental – MRI �MRI to image in-situ saturation development � Non destructive method � Sensitive to hydrogen density (similar in oil and water) � D 2 O (heavy water) as it does not reveal any signal in the MRI �No magnetic materials close to MRI magnet � Epoxy coated rock sample � Relatively low pressures MRI Transducer Pump

Experimental – Schedule 1. 2. 3. 4. 5. 6. 7. • • • Coated block with epoxy Measure rock properties Saturate with water Porosity Permeability Drained with oil multidirectionally to Swi Waterflooded with imaging Drained back to Swi Cut and reassembled with fracture network Waterflooded with fractured network with imaging 9 cm A C B 5 cm 15 cm

Simulation - History matching �History matching the waterfloods �Production profiles

Simulation - History matching �History matching the waterfloods �Production profiles Capillary Pressure Relative Permeabilites

Simulation - History matching �History matching the waterfloods �Production profiles �In-situ fluid saturation development �Matching Procedure �Match production/saturation for whole block �Adjust relative permeability curves and capillary pressure �Use as input for fractured block

Simulations – The Numerical Model � Grid: 100 x 17 � Honour porosity/permeability distribution � Additional layers in outlet and inlet (boundary) � 99. 9% porosity � 10 000 m. D � Pc = 0 � 100% initial oil saturation � Wells connections Porosity distribution chalk Porosity distribution limestone

Simulations – The Numerical Model � Grid: 100 x 17 � Honour porosity/permeability distribution � Additional layers in outlet and inlet (boundary) � 99. 9% porosity � 10 000 m. D � Pc = 0 � 100% initial oil saturation � Wells connections � Fractures � 99. 9 % porosity � 10 000 m. D � Pc = 0 � Straight relperm curves � 100% initial oil saturation � Width of 0. 01 cm → 0. 1 mm

Nuclear Tracer Imaging

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Pc = 0 in fracture Experiment Simulation

Simulation – Capillary Contact A C B

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Simulation – Capillary Contact Pc = 0 Capillary Contact

Magnetic Resonance Imaging

Simulation – Strongly Water-Wet Chalk Experimental 0. 05 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 10 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 13 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 17 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 19 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 22 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 26 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 28 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 31 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 35 PV Numerical

Simulation – Strongly Water-Wet Chalk Experimental 0. 44 PV Numerical

Simulation – Summary SSW case �Recovery mechanism � Capillary dominated imbibition �Large influence of fractures � Block-by-block displacement �Excellent reproduction of experiment SSW Recovery [%OOIP] Exp. Num. Whole 50. 0 48. 7 Fractured 46. 6 48. 6

Simulation – Oil-Wet Limestone Experimental 0. 00 PV Numerical

Simulation – Oil-Wet Limestone Experimental 0. 05 PV Numerical

Simulation – Oil-Wet Limestone Experimental 0. 10 PV Numerical

Simulation – Oil-Wet Limestone Experimental 0. 13 PV Numerical

Simulation – Oil-Wet Limestone Experimental 0. 16 PV Numerical

Simulation – Oil-Wet Limestone Experimental 0. 19 PV Numerical

Simulation – Oil-Wet Limestone Experimental 1. 15 PV Numerical

Simulation – Summary OW case �Recovery mechanism � Viscous displacement �Large influence of fractures � Reduced sweep – low recovery � No apparent fluid transport to matrix �Excellent reproduction of experiment OW Recovery [%OOIP] Exp. Num. Whole 70. 0 71. 1 Fractured 15. 7 16. 4

Weakly oil-wet Strongly water-wet Fractured Blocks - Simulation Experimental Numerical

Conclusions �Matching both production and in-situ fluid distribution gave higher confidence in simulations �Fractures were explicitly represented in the numerical model and confirmed to have significant impact on recovery and fluid flow dynamics. �Capillary contact across fractures may impact recovery �Fracture permeability had large effect on recovery and sweep for oil-wet conditions.