Does foam work in fractured systems?

Transcription

1 U N I V E R S I T Y O F B E R G E N Department of Physics and Technology Does foam work in fractured systems? Martin A. Fernø Dept. of Physics and Technology, University of Bergen, Norway Complex Fluid Flow in Porous Media Conference Oct 12-14, 2015 Bordeaux, France

2 Department of Physics and Technology Outline of Talk 1. Does foam generate in fractured reservoirs? 2. Does it matter?

3 Department of Physics and Technology What is foam? Foam is defined as a gas dispersion within a continuous liquid phase. The gas phase is discontinuous and gas bubbles are separated by thin liquid films, called lamellae, stabilized by surfactants at the gas/liquid interfaces (Falls et al., 1988; Hirasaki, 1989; Kovscek and Radke, 1994) Oil Surfactant Gas Hirasaki and Lawson, 1985 Rock

4 Department of Physics and Technology Type I What is fractured systems? No rock matrix storage capacity, fractures provide storage capacity and flow paths Type II Rock matrix provides some storage capacity, fractures provide flow paths Type III Rock matrix provides high storage capacity, fractures provide flow paths Type IV Rock matrix provides storage capacity and flow, fractures augment flow Allan and Sun, 2003 Warren and Root, 1963

5 Department of Physics and Technology Why is this important? Large remaining reserves in heterogeneous carbonate reservoirs. Many of these are heavily fractured Oil recovery low due to microscopic and macroscopic - low volumetric sweep efficiency Foam is a proven EOR technique in heterogeneous reservoirs limited usage in fractured reservoirs Will foam be a viable option for mobility control in a fractured reservoir?

6 Department of Physics and Technology Scientific questions investigated a. Can foam generate within the fracture network itself? b. What is the foam rheology in fractures? c. How does foam influence sweep efficiency? Approach d. Can foam be used for EOR (enhanced oil recovery)?

7 Department of Physics and Technology FRACTURE NETWORK Rough-walled fracture surface Surface tension equal to calcite

8 UoB Dept. of Physics and Technology Martin A. Fernø SPE Foam generation and gas fractional flow

9 UoB Dept. of Physics and Technology Martin A. Fernø SPE MRF vs flow rate

10 Department of Physics and Technology Observations (so far..) Foam is consistently generated in situ in rough-walled, calcite fracture networks during co-injections of surfactant solution and gas Gas mobility reduction factors varied from about 200 to more than 1000 consistent with observations of improved sweep. A shear-thinning behavior was observed during coinjection over a range of gas fractions consistent with the rheology of foam.

11 Department of Physics and Technology Does it matter?

12 Department of Physics and Technology Foam in a network of fractures Fracture network properties Length: 31 cm Height: 7 cm Width: 1 cm Matrix porosity: 0 Total porosity: 0.1 Fracture permeability: 170 Darcy

13 Department of Physics and Technology Sweep Efficiency

14 Sweep Efficiency [%] Department of Physics and Technology Sector sweep efficiency Fracture network Co inj SAG CGI Normalized Length

15 Department of Physics and Technology Dual porosity systems Foam influence on fluid transport Pore Level Sweep Efficiency Silicon Wafer Micro Models 25µm constant depth (typical pore size in a sandstone sample) Coordination numbers 1-6 (low pressure models) Initial wetting is water-wet

16 Department of Physics and Technology Dual porosity systems Foam influence on fluid transport CT imaging Fully water saturated fracture and matrix Fractured cylindrical carbonate core plug

17 Department of Physics and Technology Dual porosity systems Oil recovery with N 2 -foam (immiscible with oil)

18 Dual porosity systems Oil recovery with N 2 -foam (immiscible with oil) Department of Physics and Technology NO gas in matrix

19 Dual porosity systems Oil recovery CO 2 -foam (miscible with oil) Department of Physics and Technology

20 Dual porosity systems Oil recovery CO 2 (miscible with oil) Department of Physics and Technology Field of view 10 mm Rock properties Core K: 3.6 md Core Por: 0.45 Fracture K: > 2 D S o = mm

21 Department of Physics and Technology Quantitative analysis with CT 1D profiles <So> with t

22 Recovery factor [frac OOIP] DIFFUSION LENGTH D L [cm] Department of Physics and Technology Diffusion is effective, but size sensitive WHOLE RECTANGULAR 2 VERTICAL CORE PLUG CORE PLUG CORE PLUG BLOCK CORE PLUG CO₂ D L =1.6cm D L =3.2cm D L =11.8cm D L =0cm D L =1.4cm D L =2cm PC14 WHOLE DL=0 Swi=0 PC15 WHOLE DL=0 Swi=0 PC16 OPEN DL=2 Swi=0 PC17 OPEN DL=2 Swi=0 PC14 DL=0cm PC15 DL=0cm PC16 DL=2cm PC17 DL=2cm B2 DL= cm B1 DL= cm 0.6 B1 OPEN DL= Swi=0 0.5 B2 OPEN DL= Swi=0 PC19 OPEN DL=11.8 Swi= PC19 DL=11.8cm Time [h]

23 Department of Physics and Technology CO 2 foam accelerates and improve oil recovery

24 Department of Physics and Technology Present study part of an ongoing multi-scale approach for mobility control in heterogeneous and fractured reservoirs during CO 2 EOR CO 2 injection for EOR Project status o 4 confirmed onshore field pilots in the USA o Field characterization on 2 field ongoing o 5-spots patterns identified o CO 2 injection started o Surfactant for CO 2 foam identified o 4 PhD hired by 2015 o 10+ academic institutions o 8 oil and service companies and independent operators o Project manager: Prof. Arne Graue, UoB

25 Department of Physics and Technology Acknowledgements Reservoir Physics Group Dept. of Physics and Technology Faculty Prof. Arne Graue Assoc. Prof. Geir Ersland PhD and Post docs (current employment) Jarand Gauteplass (UoB) Lars Petter Øren Hauge (Perecon) Øyvind Eide (Perecon) Marianne Steinsbø (UoB) Bergit Brattekås (University of Stavanger) Åsmund Haugen (Statoil) Organizers and Sponsors of Complex Flow in Porous Media 2015

26 Department of Physics and Technology References Haugen, A., N. Mani, S. Svenningsen, B. Brattekas, A. Graue, G. Ersland, and M.A. Fernø, Miscible and Immiscible Foam Injection for Mobility Control and EOR in Fractured Oil-Wet Carbonate Rocks. Transport in Porous Media, (1): p DOI: DOI /s Fernø, M.A., M. Steinsbø, Ø. Eide, A. Ahmed, K. Ahmed, and A. Graue, Parametric Study of Oil Recovery during CO2 injections in Fractured Chalk: Influence of fracture permeability, diffusion length and water saturation. Journal of Natural Gas Science and Engineering In Press. DOI: /j.jngse Eide, Ø., G. Ersland, B. Brattekås, Å. Haugen, A. Graue, and M.A. Fernø, CO2 EOR by Diffusive Mixing in Fractured Reservoirs. Petrophysics, (1 (Feb.)): p DOI: Steinsbø, M., B. Brattekås, G. Ersland, K. Bø, I. Opdahl, R. Tunli, A. Graue, and M.A. Fernø, Foam as Mobility Control for Integrated CO2-EOR in Fractured Carbonates in EAGE IOR th European Symposium on Improved Oil Recovery. 2015: Dresden, Germany. Fernø, M.A., O. Eide, M. Steinsbø, S. Langlo, A. Christophersen, A. Skibenes, T. Ydstebø, and A. Graue, Mobility control during CO2 EOR in fractured carbonates using foam: laboratory evaluation and numerical simulations Journal of Petroleum Science and Engineering, DOI: /j.petrol Haugen, A., M.A. Fernø, A. Graue, and H.J. Bertin, Experimental Study of Foam Flow in Fractured Oil-Wet Limestone for Enhanced Oil Recovery. Spe Reservoir Evaluation & Engineering, (2): p Fernø, M.A., J. Gauteplass, M. Pancharoen, Å. Haugen, A. Graue, A.R. Kovscek, and G. Hirasaki, Experimental Study of Foam Generation, Sweep Efficiency and Flow in a Fracture Network, in SPE Annual Technical Conference and Exhibition. 2014, Society of Petroleum Engineers: Amsterdam, The Netherlands.

27 U N I V E R S I T Y O F B E R G E N Department of Physics and Technology BACKUP SLIDES

28 Slide 28 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Why Use CO 2 for Enhanced Oil Recovery? 60% of anthropogenic CO 2 from fossil energy Stepping stone for CCS CCUS for more sustainable fossil energy production CO 2 for EOR Miscible at relatively low pressure Decreased oil viscosity Oil swelling Storage potential in the North Sea Fractured chalk reservoirs

29 Slide 29 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Experimental Approach Supercritical CO 2 (40 C and 10 Mpa) imaged using CT First contact miscible CO 2 and oil Single component oil

30 Slide 30 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Experimental Approach Supercritical CO 2 (40 C and 10 Mpa) imaged using CT First contact miscible CO 2 and oil Single component oil 3D CT image with spacer POM spacer

31 Slide 31 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Rock Properties and Porosity Distribution Core ID Length [cm] Radius [cm] Por [%] Matrix K [md] Fracture K [md] S WI [%] RC# > Narrow pore size distribution Fracture omitted from histogram

32 Slide 32 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE CO 2 Diffusion during Injection

33 Slide 33 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Development in oil saturation during CO 2 Injection Oil saturation profiles Average oil saturation 33 of 13

34 Slide 34 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Calculation of diffusion coefficient

35 Slide 35 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Numerical Model Semi-circular model Peng-Robinson EOS Reproduced experimental conditions in the matrix Straight line relative permeability and no capillary pressure in the fracture First contact miscible CO 2 and decane modelled as single phase due to lack of mechanical mixing in fractured reservoirs

36 Slide 36 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Numerical Simulation

37 Slide 37 of 13 UoB Dept. of Physics and Technology Martin A. Fernø SPE Conclusions II An effective diffusion coefficient of m 2 s was calculated based on saturation profiles in a homogeneous chalk sample at 10.7 MPa pressure, and 40 C. It is also shown that care should be taken when laboratory tests are used to predict field performance and also highlights the importance of including diffusion as a production mechanism in some fractured reservoirs.