Gaps and Challenges for Light and Tight EOR

Transcription

1 Gaps and Challenges for Light and Tight EOR Williston Basin Petroleum Conference Regina, May 3, 2017 Presented by Kelvin (Kelly) D. Knorr, P. Eng. Operations Manager, Energy Division Saskatchewan Research Council Copyright Copyright SRC SRC 2017

2 Outline Field Locations and SK Production The Road Ahead Challenges in Field Design, Operations and EOR Gaps in Knowledge Gaps in Research Methods and Understanding EOR Mechanisms Challenges & Wishful Thinking for EOR Possible EOR Success Factors and Summary New Approaches and Tools Copyright SRC 2017

3 Quote 1 We have been researching and developing EOR methods for conventional reservoirs for more than 100 years, heavy oils and bitumens for half as long, but we have only been looking at EOR in the very tight and source rocks for a decade we have a lot of work to do! Dr. Norm Freitag, Principle Research Engineer, SRC Energy Division. 3 Copyright SRC 2017

4 Quote 2 It is the early days for this area of EOR research. There is no consensus on which approaches will work best, how much they may cost, what the most pressing challenges are, or exactly when an EOR operation should begin. Our understanding is really small. Dr. Tod Hoffman, Assistant Professor of Petroleum Engineering, Montana Tech University. EOR for Shale, June 2016 SPE Journal of Petroleum Technology (JPT). 4 Copyright SRC 2017

5 Field Locations and SK Production Copyright SRC 2017

6 Tight Oil Plays in Western Canada Source: ERCB 6

7 Saskatchewan Viking Total Oil Wells and Production Production has grown rapidly since 2010, from ~10,000 bbl/d to over 67,000 bbl/d in late 2014, Dec 2016 at 58,000 bbl/d Data source: GeoScout 7

8 Saskatchewan Bakken Total Oil Wells and Production 75,000 3,000 70,000 Oil Production (barrels per day) 2,800 65,000 Producing Well Count 2,600 60,000 2,400 55,000 50,000 45,000 40,000 35,000 30,000 25,000 20,000 2,200 2,000 1,800 1,600 1,400 1,200 1, , , , Jan 04 May 04 Sep 04 Jan 05 May 05 Sep 05 Jan 06 May 06 Sep 06 Jan 07 May 07 Sep 07 Jan 08 May 08 Sep 08 Jan 09 May 09 Sep 09 Jan 10 May 10 Sep 10 Jan 11 May 11 Sep 11 Jan 12 May 12 Sep 12 Jan 13 May 13 Sep 13 Jan 14 May 14 Sep 14 Jan 15 May 15 Sep 15 Jan 16 May 16 Sep 16 Oil Production (barrels per day) Well Count Production has grown rapidly since 2004, from 760 bbl/d to over 70,000 bbl/d in early 2013, Dec 2016 at 43,000 bbl/d Production Month Data source: GeoScout 8

9 The Road Ahead Challenges in Field Design, Operations and EOR Copyright SRC 2017

10 PTAC TOGIN Roadmap Workshop 2015/16 Most important gaps as voted by the participants Reservoir Characterization EOR Fracking and Refracking Water Characterization Collaboration Emissions Guidelines for water disposal 10

11 Tight Oil Development Considerations Rapid Production Decline Low Permeability and Porosity Matrix Fracture contrast Complex geo chemistry Complex geology (can have) Easy to cause formation damage Typical Bakken well production profile 10 fold reduction in 4 years 11

12 Tight Oil Reservoir Characteristics Source: JuneWarren Nickle s Energy Group Source: Canadian Society of Unconventional Resources 12

13 Tight Oil Reservoir Permeability Contrast Matrix 10 nd to 500 µd ( Darcy) Natural Micro Fractures 200 µd to 1 md ( Darcy) Range of Permeabilities can span 7 11 orders of magnitude Makes laboratory and field modelling a challenge Provides many different surfaces for fluid/rock interaction Induced Micro Fractures 500 µd to 10 md ( Darcy) Propped Fractures 1 D to 1 kd ( Darcy) Note micro fractures exaggerated for clarity 13

14 PTAC TOGIN Roadmap Workshop 2015/16 Focus on Reservoir Characterization and EOR Reservoir Characterization EOR Fracking and Refracking Water Characterization Collaboration Emissions Guidelines for water disposal 14

15 EOR Types What is Being Considered? Sharp depletion during primary recovery What s next? Gas Flooding Water Flooding Thermal? CO 2 flue gas produced gas natural gas formation brine modified brine surfactant Multiple Contact Miscible? Compatibility? IFT & Wettability? 15

16 Gaps in Knowledge Copyright SRC 2017

17 Gas Flooding CO2 Nitrogen C1 C4 Advantages Injectivity Miscibility (some) Conformance (WAG) Potential Gaps in Knowledge Gravity override effects Viscous fingering effects Limited rich gas availability? Miscibility pressure too high? Matrix dissolution a problem? 17 Copyright SRC 2017

18 Gas Flooding Typical miscibility and reservoir pressures in some SK reservoirs Pressure, MPa > < 1 CH4 C2H6 C3H8 CO2 Typical reservoir pressures Bakken Weyburn Viking 18

19 Gas Flooding Saturation of Bakken core plugs with carbonated 20 MPa and 88 C for four months. Grain of feldspar dissolved by CO 2 Permeability increase from carbonate dissolution can be offset by decrease due to clay precipitation and fines migration. Precipitation (likely Kaolinite) 19 Copyright SRC 2017

20 Water Flooding Advantages Wide availability of water Possible Imbibition into tight rock if water wet Initial Producers Infill Producers Conversion to Injectors Initial Producers Later Infill Producers Still later Still Later Conversion to injectors Potential Gaps in Knowledge Injectivity and permeability contrast effects? Compatibility with reservoir rock and brine? Clay swelling and migration? Water saturation blocking effects? One Section Pattern Shown Initial well Infill well Converted to injector 20

21 Water Flooding Water Saturation Blocking Results in low effective permeabilities to all fluids over large saturation ranges in the reservoir. 1 Effective Permeability k e = k abs x k r k ro k rw Low k r Matrix Part Saturation Dependent Part % Water/Brine Saturation Should we continuously vary wettability to avoid saturation blocking? 21

22 Chemical Flooding Advantages Low capital requirements add to waterfloods Target residual oil trapped in tight rock Potential to improve injectivity by increasing (apparent) effective permeability Potential Gaps in Knowledge High surfactant adsorption Compatibility with reservoir rock, brine Complex design (wettability, IFT, phase behavior) Oil trapped due to capillary forces 22

23 Chemical Flooding Can Reduce Water Saturation Blocking and improve Effective Permeabilities and Injectivity (laboratory observations) Addition of surfactants reduce IFT and can shift the relative permeability curves up reduces range of most severe saturation blocking 1 k ro k rw However, excessive adsorption may lead to poor economics Low k r % 23 Slide 23

24 Gaps in Research Methods and Understanding EOR Mechanisms Copyright SRC 2017

25 Gaps in EOR Research Methods Physical Modeling Need to consider all permeability flow regimes: Matrix Micro fractures Propped macro fractures Pressures gradients of 10 MPa/m in lab experiments on the matrix. 2 cm 3 /hr brine injection into a cm (L) 3.84 cm (D) core stack. Pressure drop reaches 3 MPa!!! EOR process physical modeling challenging with 1D core systems! 25

26 Gaps in EOR Research Methods Physical Modeling (continued) 1 Core preparation and testing with ultralow permeability matrix. Resaturation to initial conditions not possible with core displacement. Can be a %PV lower initial oil saturation (S oi ) even with 100 s of PV injected. 0 k ro True False k rw 0 100% Water/Brine Saturation 26

27 Gaps in EOR Research Methods Fluid Characterization in immature reservoirs with high TOC In situ Bubble Point Pressure (P bp ) can be kpa less than P bp measured in the lab. In situ Critical Temperature (T c ) can be changed by C 27

28 Gaps in Understanding EOR Mechanisms Wettability Image source: W. Adallah et al., Fundamentals of Wettability. Oilfield review. 28

29 Gaps in Understanding EOR Mechanisms Wettability and Relative Permeability Relative permeability, fraction Crosses at > 50% Water saturation, fraction PV Relative permeability, fraction Crosses at < 50% Water saturation, fraction PV (a) Water-wet rock (b) Oil-wet rock 29

30 Gaps in Understanding EOR Mechanisms Contact angle of a Bakken core in reservoir brine Wettability and Capillary Pressure Capillary pressure and wettability play crucial roles in controlling fluid flow and distribution in tight/shale reservoirs. Knowing formation wettability is extremely important in design of an effective enhanced oil recovery processes. Wettability differences for three surfactants on a shale sample 30

31 Gaps in Understanding EOR Mechanisms Controlling Capillary Pressure Imbibition How to manage IFT and wettability to maximize oil recovery? P c =4/DxIFTxcos(θ) IFT cos(θ) P c Surface Tension Part Wettability Part Surface active chemicals have various functional groups and structure. Novel chemicals for wettability alteration volatile surfactants for gas injection? Need to continuously vary wettability to maximize oil recovery? 31

32 Challenges and Wishful Thinking for EOR Copyright SRC 2017

33 Challenges Limited Reservoir Knowledge Reservoir fluid proper es limited database Petrophysical proper es limited database Geomechanical proper es effects on natural/induced fractures Geochemistry how injec on fluids interact with forma on rock & fluid Vertical and horizontal heterogeneity across Viking and Bakken reservoirs adds more complexity 33

34 Challenges & Wishful Thinking for EOR EOR POTENTIAL SIDE VIEW LESS MORE MOST Propped fractures Induced microfractures Natural microfractures Near Connections Normal spacing and micro fractures Closer spacing Closer + more micro fractures Note micro fractures exaggerated for clarity 34

35 Challenges & Wishful Thinking for EOR FLUID IMBIBITION & OIL DRAINAGE Micro Fracture Oil Brine Imbibition Zone Fracture Surface Propped Fracture Oil Brine Oil wet pore Brine wet pore Note micro fractures exaggerated for clarity Target specific minerals in pores to alter wettability 35

36 Possible Success Factors and Summary Copyright SRC 2017

37 Possible EOR Success Factors Propose: All fractures are good fractures for EOR. Surfactant performance optimizes with soak time & maximum surface contact area. Then: Refracs and more stages are good higher fracture density and surface area. Earlier injection for pressure maintenance establish flow paths for chemicals. Earlier chemical injection longer residence time and more surfaces contacted. Frequent or continuous altering of wettability to avoid saturation trapping and maximize oil recovery? Copyright SRC 2017

38 Summary Lots of work to do! Need to close gaps in Knowledge, Methods and Understanding Mechanisms. Some immiscible gas and water injection for pressure maintenance has been started. Possible that immiscible gas flooding can lead to higher oil production rate at the beginning of injection process, but ultimately recovers less oil than water flooding. Possible that miscible gas injection likely best recovery scheme WAG? Possible that volatile surfactants can maximize gas injection recoveries. Copyright SRC 2017

39 New Approaches and Tools for EOR Research Coreless Injectivity Method for fluid compatibility. Injectivity without reservoir cut cores use drill cuttings. Duel Porosity Permeability 3D physical test model Flow between matrix and fractures. Geo chemical interactions with synthetic matrix. High Speed Centrifuge Resaturate cores to initial reservoir saturations. Determine relative permeability curves and capillary pressure together. Copyright SRC 2017

40 Connect With Us Kelvin (Kelly) D. Knorr, Operations Manager, Energy Division Phone: Regina Research Drive Toll free info@src.sk.ca Copyright SRC 2016 SRC 2017

41 Challenges & Wishful Thinking for EOR How to maximize reservoir access to displacing fluids? How to maximize fracture density to improve surface area for chemicals? How are the macro and micro fractures distributed? How accurately do we need to model the reservoir to estimate EOR performance? Need full length wells? Need fully tuned fracture performance? Need full geo model details? Need full petro physical details? 41