2.2 "Laboratory Measurements as the Ground Truth forShale Classification" - Greg Getz [EN]


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  • Tight Rock Analysis (TRA) is a TerraTek workflow designed to address the Heterogeneic nature of unconventional resources. You could refer to Heterogeneity as “Elephant #1.”
  • From this diagram we can clearly see some of the resolution challenges that seismic faces when compared to other sampling techniques such as logging and core samplingIt becomes clear that seismic cannot go it alone when exploring the heterogeneous nature of this rock (next slide)
  • As you scan your eye across these shale gas logs taken from key shale plays you can seen how some have more calcite while others have more claysYou can also see how they change vertically Note the vertical Heterogeneity with in all these reservoirs
  • The Slide on the left shows the pore structure of a conventional sandstone and we can clearly see the pore structure and mineral frameworkHowever, in when we look at shales under the microscope we have to zoom in much closer to see any type of pore structure, the slide on the RHS has been overlaid onto the slide on the LHS at the same scale to demonstrate the difference in this rock fabricThe pore structure we are used to seeing in the sandstones are lost in the shales and replaced by fossil fragments, kerogen, minerals and clays We cannot simply apply sandstone technology to Shale they are very different and need to be managed differently.
  • Understanding how the rock fabric effects the completion quality is also an essential part of the puzzle Measuring the mechanical properties of the shales in the lab and the field is essential to building this understandingThe variation seen from play to play and even within a few hundred yard can have a dramatic impact on the completion qualityIf stress barriers are not located fractures can easily grow out of zone If we find high stress anisotropy this may produce a completely different result from rock with lower stress contrastIt is not enough to only look at the reservoir quality we cannot expect good results without also evaluating the rock mechanics and completion qualityAt the end of the day it is the rock that matters
  • 2.2 "Laboratory Measurements as the Ground Truth forShale Classification" - Greg Getz [EN]

    1. 1. South Baltic Gas Forum 2011 – Gdańsk, Poland<br />Laboratory Measurements as the Ground Truth forShale Classification<br />Greg Getz<br /> Business Development Manager - Continental Europe<br /> Reservoir Sampling and Analysis<br />TerraTek Core Facility – Warszawa, Polska<br />
    2. 2. © 2011 Schlumberger. All rights reserved.<br />An asterisk is used throughout this presentation to denote a mark of Schlumberger. Measurable Impact is a mark of Schlumberger. Other company, product, and service names are the properties of their respective owners.<br />11-TS-0096<br />
    3. 3. Understanding Shale Classification<br />Scaling and Heterogeneity<br />Unconventional resources are structurally simple yet geologically complex. This complexity is due to extreme variability in rock composition and post-deposition diagenetic processes.All shales are not created equal.<br />Reservoir quality<br />The properties of a source rock that make it amenable to containing significant quantities of hydrocarbons:, porosity, permeability,fluid saturations, total organic carbon (TOC), mineralogy, nature and orientation of natural fractures, thermal maturation, and pore pressure.<br />Scaling & Heterogeneity<br /><ul><li>Pore
    4. 4. Core
    5. 5. Well
    6. 6. Field</li></ul>Reservoir quality<br /><ul><li>Saturation
    7. 7. Porosity
    8. 8. Permeability</li></ul>Completion quality<br /><ul><li>Containment
    9. 9. Fracturability
    10. 10. Rock-fluid interaction
    11. 11. Production management</li></ul>Completion quality<br />The properties of source rock that make it amenable to producing hydrocarbons include fracture complexity and height growth, fracture conductivity, fracturing fluid compatibility, the ability to retain fracture surface area during production, and pressure management during production. <br />
    12. 12. Understanding Shale Classification<br /><ul><li>Scaling & Heterogeneity
    13. 13. Reservoir Quality
    14. 14. Completion Quality</li></li></ul><li>Scaling<br />3. Core Samples<br />2. Logging (GR) – sampling every 15cm<br />1. Seismic – sampling every ~3m (vertically)<br />Next wiggle:<br /> 25m <br />
    15. 15. Heterogeneity<br />
    16. 16. Argillaceous <br />Siliceous/Arg-illaceous <br />Nodules<br />Siliceous<br />Calcareous <br />Mix. Siliceous <br />Argillaceous (R)<br />Geologic Model - Horizontal<br />Heterogeneity<br />Calcareous<br />Argillaceous<br />Siliceous<br />Nodules<br />Siliceous/Argillaceous<br />Siliceous<br />Siliceous/Argillaceous<br />Calcareous <br />Siliceous/Argillaceous<br />Geologic Model - Vertical<br />Geologic simplicity does not imply reservoir simplicity!<br />
    17. 17. Heterogeneity – U.S.<br />Haynesville<br />Barnett<br /> Woodford<br />Fayetteville<br />Eagle Ford<br />Marcellus<br />
    18. 18. Argillaceous<br />Siliceous<br />Calcareous<br />Heterogeneity Matrix Composition and Grain Size - Fingerprint<br />Marcellus<br />Eagle Ford<br />Conventional<br />Grains >4 μm<br />Barnett<br />Increasing silt & sand<br />Matrix Composition<br />Shale<br />Reservoirs<br />
    19. 19. Understanding Shale Classification<br /><ul><li>Scaling & Heterogeneity
    20. 20. Reservoir Quality
    21. 21. Is there a viable reservoir?
    22. 22. Completion Quality</li></li></ul><li>Reservoir Quality - Core Field Work<br /><ul><li>Taking whole and/or sidewall cores
    23. 23. Handling and marking of core
    24. 24. Canister desorption to determine gas content and gas species
    25. 25. On-site spectral gamma core log
    26. 26. Preservation / Shipping</li></ul>11<br />
    27. 27. Reservoir Quality - Absorbed Gas, Interstitial Gas, and Total Gas Content<br />Total gas<br />Interstitial gas<br />Adsorbed gas<br />The pressure dependence for storing interstitial gas in pores and adsorbed gas in organic surfaces is markedly different.<br />
    28. 28. Reservoir Quality <br />
    29. 29. Reservoir Quality – Tight Rock Analysis (TRA) taken from biscuit (2/3 section)<br />Sample <br />Analysis<br />Core<br />Description<br />TRA<br />Porosity<br />Perm<br />Saturation<br />2/3 Slab<br />1/3 Slab<br />Section for TS, SEM, XRD and TOC<br />SEM<br />TS<br />TOC<br />XRD<br />14<br />
    30. 30. Heterogeneity —“Scratch Testing” <br />Fine-scale heterogeneity is obtained via continuous measurements of unconfined strength along the length of the core. Results provide a profile of rock unconfined compressive strength and its mechanical variability.<br />
    31. 31. 2/3 Section of core – biscuit taken for TRA<br />16<br />
    32. 32. Reservoir Quality - TRA porosity/perm, TS, SEM, XRD, TOC samples<br />17<br />
    33. 33. Reservoir Quality – Core as Ground Truth<br />Unconventional<br />Reservoir Quality<br /><ul><li>Porosity
    34. 34. Permeability
    35. 35. Saturation
    36. 36. Gas (Oil) in Place
    37. 37. Organic Content
    38. 38. Maturity</li></ul>Conventional Reservoir Quality<br />Archie Equation <br />Dacey’s Law - Permeability<br />
    39. 39. Reservoir Quality – Unconventional MicroScale<br />Mineral framework<br />Conventional Sandstone<br />Gas shale<br />Kerogen<br />Pore system<br />700 mm<br />100 mm<br />Free gas in pore space<br />Free gas in pore space<br />Adsorbed gas on kerogen<br />
    40. 40. Reservoir Quality - TRA<br /><ul><li>Effective phi: 4 to ~12 pu
    41. 41. Saturations: Sliquid < 45%
    42. 42. Permeability: > 100 nD
    43. 43. TOC: > 2 wt%</li></li></ul><li>Reservoir Quality – Tight Rock Analysis (TRA)<br />Formation A<br />Formation B<br />
    44. 44. Reservoir Quality – Shale Gas Core/Log Evaluation<br />RHOB<br />RHOM<br />TOCPerm<br />GIPGas-Phi<br />SwPorosity<br />GR<br />Resistivity<br />ECS / XRD<br />Porosity<br />ELAN<br />
    45. 45. Log-Scale Heterogeneity Obtained Through Heterogeneous Rock Analysis (HRA)<br />Log-derived facies<br />…that can be populated with<br />core-measured properties.<br />Each facies represents a container…<br />Log data, <br />e.g., Platform Express* data<br />ECS*/ELAN data<br />Sonic Scanner* data<br />Core data<br />Reservoir quality data<br />Mechanical data <br />Fluid Sensitivity data<br />Petrology<br />Calibrations<br />
    46. 46. Log-scale heterogeneity (stacking pattern of rock classes)<br />Improving reservoir performance, lowering technical risk<br />
    47. 47. Applying Knowledge to Other Wells<br />
    48. 48. Selecting Representative Samples to Test the Variability<br />Sidewall core advisor<br />Automatic sample selection software<br />Whole core sampling<br />
    49. 49. Understanding Shale Classification<br /><ul><li>Scaling & Heterogeneity
    50. 50. Reservoir Quality
    51. 51. Completion Quality
    52. 52. Can the reservoir be produced at economic rates?</li></li></ul><li>Completion Quality<br /><ul><li>Near & Far Stress
    53. 53. Fracture Containment
    54. 54. Mineralogy
    55. 55. Clay Content & Type
    56. 56. Fabric Pattern
    57. 57. Mineral Sensitivity
    58. 58. Wellbore Placement</li></li></ul><li>Completion Quality – Fractures & Rock Fabric<br /><ul><li> Rock fabric can be very complex
    59. 59. Fractures can be open, healed, drilling induced or reactivated
    60. 60. Clay is usually found in layers
    61. 61. Mud systems need to limit activation of healed systems
    62. 62. All planes of weakness need to be mapped
    63. 63. Regional stress needs to be understood</li></li></ul><li>Completion Quality Varies Dramatically<br />Matrix Composition<br />n<br />n<br />E<br />/E<br />/<br />G<br />/G<br />UCSz/UCS<br />To<br />/To<br />x<br />z<br />yx<br />zx<br />xy<br />zx<br />45<br />x<br />z<br />#<br />Carbonate<br />Calcareous<br />1<br />1.03<br />0.97<br />0.81<br />1.12<br />0.57<br />Mudstone<br />Silty<br />2<br />1.05<br />0.88<br />0.93<br />1.13<br />0.56<br />Mudstone<br />Siliceous<br />Mudstone<br />3<br />1.52<br />1.25<br />1.25<br />1.12<br />0.39<br />Organic/Argillaceous <br />Mudstone<br />4<br />2.06<br />1.47<br />1.32<br />1.43<br />0.27<br />Argillaceous/Siliceous <br />Mudstone<br />5<br />2.49<br />1.34<br />1.76<br />3.23<br />0.14<br />Argillaceous/Calcareous <br />Mudstone<br />Argillaceous<br />6<br />2.99<br />1.60<br />2.03<br />4.55<br />0.63<br />Shale<br />7<br />3.79<br />1.26<br />2.34<br />3.33<br />0.62<br />8<br />4.01<br />2.07<br />2.13<br />4.55<br />0.45<br />
    64. 64. Completion Quality –<br /> Strength and Elastic Anisotropy<br />Testing vessel and sample stack<br />Poisson’s Ratio<br />Triaxial Compression Strength<br />Young’s Modulus<br />
    65. 65. Completion Quality - Proppant Embedment/Fracture Conductivity<br />Evaluate fracture conductivity loss as a function of pressure depletion due to proppant embedment or crushing.<br />Rock softening as a result of rock-fluid interaction might induce this behavior.<br />Goal: Optimize proppant size and concentration.<br />Fracture conductivity, md-ft <br />Closure stress, psi<br />
    66. 66. Completion Quality – Design Application<br />Determine in situ stress contrast. Anisotropy can change this significantly.<br />Supporting measurements:<br />Heterogeneous rock log analysis<br />Anisotropic elastic properties<br />Reservoir pressure<br />Field stress measurements (MDT* modular formation dynamics tester)<br />Fracture conductivity/proppant embedment<br />Modeling provides an estimate of expected fracture geometry<br />
    67. 67. Mapping Completion Quality<br />3D Stress Mapping<br />Complex Hydraulic Fracture Simulations<br />3D DFN Mapping<br />
    68. 68. Integration of Reservoir Quality and Completion Quality<br />Good RQ + Good CQ = Good well<br />Good RQ + Bad CQ = Bad well<br />Bad RQ + Good CQ = Bad well<br />Bad RQ + Bad CQ = Bad well<br />Contour map of <br />Reservoir Quality<br />Contour map of <br />Completion Quality<br />
    69. 69. Mapping RQ And CQ Sweet Spots <br />Region with high RQ and good CQ. These are easy targets.<br />Regions with high RQ and poor CQ. These are engineering challenges.<br />Region with poor RQ and bad CQ. There is no potential (hopeless case).<br />
    70. 70. Understanding Shale Classification<br />“Poland Poised For Productive Shale Development” epmag, map/images courtesy of BNK Petroleum<br />
    71. 71. Reservoir Quality – Baltic Basin<br />Reservoir Quality ???<br /><ul><li>Well A</li></ul>Porosity Range 4% to 6% - Good<br />TOC 1.0% to 2.0% - Low<br />Clay Volume < 30% - Good<br />Perm 175 to 250 nano darcy- Good<br />Thickness 22 Meters – Low<br />Gas In Place - 15 BCF/SQM<br /><ul><li>Well B</li></ul>Porosity Range 2% to 4% - Poor<br />TOC 1.0% to 1.8% - Poor<br />Clay Volume > 50% - Poor<br />Perm 20 to 120 nano darcy - Poor<br />Thickness 80 Meters – High<br />Gas In Place - 20 BCF/SQM<br />Well A<br />Well B<br />
    72. 72. Completion Quality – Baltic Basin<br />Completion Quality ???<br />Well A<br />Closure variability 0.15 psi/meter - Good<br />Clay Volume < 25% - Good<br />No ductile clay - Good<br />Well B<br />Closure variability - ?<br />Clay Volume > 50% - Poor<br />Some ductile clay – Poor<br />
    73. 73. Completion Quality – Baltic Basin<br /><ul><li> Static Young’s moduli derived from sonic measurements (dynamic) using Zimmerman’s correlation (Marcellus shale) are lower than those measured in the laboratory (Track 2)
    74. 74. Given the low total porosity (< 10%, Track 1) dynamic moduli compare better with laboratory measurements (Track 3)
    75. 75. Poisson’s ratios should be refined (Track 4), although lab measurements and model predictions are in good agreement in the isotropic sections (see ~ 1000 m MD)
    76. 76. Predicted anisotropic FG at perforation depths using static moduli from sonic logs and tectonics (Ex=0.3 Ey=0.8) are (Track 6)</li></ul> 0.65 psi/ft @ 1000 m MD<br />0.85 psi/ft @ 1500 m MD <br />
    77. 77. Building Regional Models<br />Extending to seismic volume<br />Mapping reservoir potential<br />Basinwide heterogeneous rock analysis model<br />
    78. 78. Natural Gas for Europe http://naturalgasforeurope.comMonday, September 05, 2011 <br /> “BNK Updates on Saponis Baltic Basin Shales”<br />…The TOCs in the Lebork S-1 well ranged from 0.14 to 1.50, averaging 0.8 by percent weight for the Lower Silurian, 0.04 to 6.04, averaging 2.2 by percent weight for the Ordovician and 5.0 to 9.2, averaging 7.2 by percent weight for the Cambrian.<br />Also received were the Porosity values of the 148 meter thick Lower Silurian interval which ranged from 1.0 to 9.6, averaging 3.9% in the Lebork S-1 well…<br />BNK also announced that the Starogard S-1 …There were 107 meters of whole core recovered from the well and a full suite of logs was run. In addition, 100 sidewall cores were taken above the whole cored interval where good gas shows and preliminary log analysis indicate potential.<br />
    79. 79. Reservoir Heterogeneity can be measured and scaled up<br /> Reservoir Quality can be quantified and mapped<br /> Completion Quality can be quantified and mapped<br /> “Ground Truth” core data provides a reliable foundation for determination of unconventional shale Reservoir Quality and Completion Quality<br />An integrated workflow is required to characterize shale reservoirs<br />Higher understanding means less risk and more productivity<br />Conclusions<br />
    80. 80. Technology <br />Commercial <br />Challenges - Teamwork<br />Market<br /><ul><li>Structure
    81. 81. Pricing mechanism
    82. 82. Access to infrastructure</li></ul>Geosciences & Resource Characterization<br /><ul><li>Advanced logging tools
    83. 83. Core sampling & measurement
    84. 84. Better ‘sweet spot’ identification</li></ul>Partnering<br /><ul><li>Types (super major, boutique)
    85. 85. Non-traditional (e.g. Utilities, gov’t)</li></ul>Modeling<br /><ul><li>Full 3D predictive models</li></ul>Regulatory<br /><ul><li>Land access
    86. 86. Water management</li></ul>Drilling<br /><ul><li>Slim hole hot tools
    87. 87. Efficient drilling systems</li></ul>Supply chain<br /><ul><li>Footprint
    88. 88. Available capacity</li></ul>Completions & Stimulation<br /><ul><li>Fracture fluids
    89. 89. Alternative to stimulation
    90. 90. Environment</li></ul>Operating model<br /><ul><li>Low cost
    91. 91. Flexible to adjust for reservoir heterogeneity</li></ul>Surface Infrastructure<br /><ul><li>Water Management
    92. 92. Footprint and number of sites
    93. 93. Environmental impact</li></li></ul><li>Questions?<br />