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Reservoir Engineering Aspects of Unconventional Reservoirs

Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011. Reservoir Engineering Aspects of Unconventional Reservoirs. Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 t-blasingame@tamu.edu.

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Reservoir Engineering Aspects of Unconventional Reservoirs

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  1. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional Reservoirs Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  2. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsBrief Biography — Tom Blasingame Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  3. Short Bio: Blasingame Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  4. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsStart-Up Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  5. Start-Up: Unconventional Reservoir Systems are DIFFERENT • Flow mechanisms (…nano-scale flow mechanisms) • Fluids are often at critical state (…uniqueness? cause?) • Overpressure is good (…stresses are poorly understood) • Clean-up phase must be managed (…no "choke cowboys") • Shales are generally dessicated (…low water recovery) • Fracture patterns poorly understood (…rock mechanics) • Hydrocarbon liquid production (…artificial lift) • Simultaneous Exploration/Development (…fast track) • "Completions can't Trump Geology" (…but we try) • Unconventional Plays are "Statistical" (…lots of wells) • Stimulation → Multi-Fracture Horizontal Wells (…future?) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  6. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsOverview Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  7. Overview: • Orientation • Nano-Scale Flow Behavior • Time-Rate Analysis: (aka Decline Curve Analysis) • Time-Rate-Pressure Analysis: (aka Production Analysis) • Practical Aspects • Challenge Points for Unconventional Reservoirs • Questions/Discussions Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  8. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsOrientation Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  9. Orientation: Reservoir Engineering Aspects of UR • Where we want to be: (or so we think) • Fit for purpose stimulation (... oil/gas/condensate/geology) • Effective reservoir monitoring (... this is important!) • Early EUR (months? years?) (... prediction/correlation) • Minimum Well Spacing (... geology + PVT + modeling(?)) • How do we get there… • Better understanding of flowback/dewatering (... optimization) • Pressure-dependent properties… (... k, FcD, desorption?) • Understanding of the pore-scale (... what flows/when/how) • Petrophysics (... conventional petrophysics not adequate) • PVT (... oil/gas/condensate/water — HP/HT) • Facts of life… • Analogs (... need to understand uncertainty (very high)) • EUR (... minimum of 12-18 months for high confidence) • IP (... may be uncorrelated with EUR) • Early Productivity (... poor wells don't get better) • Time-Rate Analysis (... not representative? (chaotic operations)) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  10. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsHow Small is Small?(nano-scale pores) Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  11. Pore-Scale: Nelson Pore/Molecule Size Chart • Question(s): • How small are pores in shale gas? Note that the size of the pores is on the order of 5-10 times the size of the fluid molecule. AAPG Bulletin, v. 93, no. 3 (March 2009)Pore-throat Sizes In Sandstones, Tight Sandstones, and ShalesP.H. Nelson, USGS • Perspective: • The concept of pores and pore throats begins to break down at these scales. • The flow path can be as small as 10-20 molecular diameters (or less). • Issues: • How do the fluids move? • Darcy flow? • Dispersion (gases)? • Knudsen flow? • How are the fluids stored? • In the organic matter? • Adsorbed? • Another mechanism? Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  12. Pore-Scale: Shale Pore Space (Barnett Example) • Question(s): • Where is/are the gas/liquid stored? There is porosity, often in the organic materials. • Why is the phase behavior of many shales "near critical"? Nanopores? J. Sedimentary Research, v. 79/12 (2009)Morphology, Genesis, and Distribution of Nanometer-scale Pores in Siliceous Mudstones of the Mississippian Barnett ShaleLoucks, R.G., R.M. Reed, S.C. Ruppel, and D.M. Jarvie Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  13. Gas Flow vy vx Pore-Scale: Petrophysics/Permeability SPE 107954Improved Permeability-Prediction Relations for in Low Permeability SandsF.A. Florence, Occidental Petroleum Corp., J.A. Rushing, Anadarko Petroleum Corp., K.E. Newsham, Apache Corp., and T.A. Blasingame, Texas A&M U. a. Gas Slippage— Kundt, A. and Warburg, E.: "Über Reibung und Wärmeleitung verdünnter Gase, " Poggendorfs Annalen der Physik und Che-mie (1875), 155, 337. c. Microflow model and correlation, "fully implicit" formulation. b. Knudsen "microflow" model (Modified from Karniadakis and Beskok, 2002). Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  14. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsTime-Rate Analysis Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  15. Time-Rate:Schematic Production Performance Plot = Estimated Ultimate Recovery (EUR) [The area under the hybrid (hyperbolic- exponential rate curves] "Switch Point"from Hyperbolicto Exponential Economic Limit (in rate — qlimit) Logarithm of Rate Hyperbolic Rate Exponential Rate (qlimit) Economic Limit (in time — tlimit) (tlimit) Production Time • Discussion: Schematic Production Performance Plot • The schematic represents the most common approach to EUR. • Used CAREFULLY, this should be valid (other methods needed). Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  16. Time-Rate: Flow Regimes —Multi-Fracture Horizontal Well Discussion: • Very high permeability case (30 md?) → blame graduate student. • Exhibits various flow regimes. • Note square-root time approximation … poor man's EUR (too high). Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  17. Discussion: • 1:2 Slope → b=2 (HIGH fracture conductivity) . • 1:4 Slope → b=4 (LOW fracture conductivity). • This is a schematic, it overly simplifies the system. Time-Rate: Flow Regimes —Multi-Fracture Horizontal Well Formation Linear Flow Regime 1:2 Slope (high FcD) Compound Linear Flow Regime 1:4 Slope (low FcD) Elliptical Flow Regime Logarithm of Production Rate Bilinear Flow Regime Transition Regime Early-Time Regimes are HYPERBOLIC? 1:1 SlopeDepletion(SRV?) Logarithm of Production Time Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  18. Time-Rate:Modified Hyperbolic Rate Relation Modified Hyperbolic Rate Relation: Decline Function: D(t) Hyperbolic Function: b(t) b Function: b(t) b(t) Logarithm of Production Rate, q(t) Logarithm ofD(t) and b(t) b(t) ≈ 2 q(t) 1:2 slope D(t) Logarithm of Production Time Discussion: • qDb functions are DIAGNOSTIC. • D(t), b(t), and b(t) are evaluated continuously (at all points). • This shale gas case exhibits b=2 behavior → q = a√t (Linear Flow). • Appears to be "hyperbolic," but this is just the Linear Flow portion. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  19. b(t) q(t) Logarithm of Production Rate, q(t) Logarithm ofD(t) and b(t) D(t) Logarithm of Production Time Time-Rate:Power-Law Exponential Rate Relation PLE Rate Relation: Decline Function: D(t) Hyperbolic Function: b(t) b Function: b(t) Discussion: • qDb functions are DIAGNOSTIC. • Power-law exponential relation is derived from: • No direct analog to hyperbolic case. • This is a "tight gas" reservoir case. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  20. Time-Rate:Continuous EUR [hyperbolic] [PLE] [qg(t) vs. Gp(t)] c. CEUR governing equations. a. Continuous EUR (CEUR) process plots. b. CEUR hyperbolic, PLE, and q-Gp summary plots. d. CEUR master summary plot (all results). From: SPE 132352 (2009) Continuous Estimation of Ultimate Recovery, S. Currie, D. Ilk, and T. Blasingame, Texas A&M U. Discussion: • EUR is computed at each "time step" (cumulative or incremental). • EUR estimated for each model. • EUR comparison plots probably min/max trends. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  21. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsTime-Rate-Pressure Analysis Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  22. Time-Rate-Pressure: Flowing Material Balance Plot • Question(s): • What is the "Flowing Material Balance" plot? In simple terms, pwf(t)data are "converted" to pavg(t) data using the pseudosteady-state flow equation, then plotted as a straight-line extrapolation function and "solved" for gas-in-place. JCPT (June 1997), 52-55.The 'Flowing' Gas Material BalanceL. Mattar and R. McNeil, Fekete Assoc. "Flowing Material Balance" Plot: • Theory: • Palacio and Blasingame [1993] • Mattar and McNeil [1997] • Agarwal et al [1999] • Advantages: • Straightforward and intuitive. • Shut-in pressures NOT required. • Direct estimation of contacted gas-in-place. • Limitations: • Boundary-dominated flow regime must exist. a. The "Flowing Material Balance" (Normalized Rate-Cumula-tive Function Plot) formulation is derived using the solution for the diffusivity equation during boundary-dominated flow regime. This formulation provides a direct estimate of the contacted gas-in-place using time, flowing wellbore pres-sure, and flowrate data. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  23. Time-Rate-Pressure: Material Balance Time • Question(s): • Can the well-reservoir model be inferred from such data? Yes. • Is diagnosis sufficient? No, we must also be able to model/history match data with a model (complete process). SPE 25909 (1993)Decline Curve Analysis Using Type Curves — Analysis of Gas Well Production DataJ.C. Palacio and T. Blasingame, Texas A&M U. Boundary-Dominated Flow Transient Flow b. "Transformed" data shows fractured well response at early times, very strong evidence of closed system at late times. a. Raw (daily) rate and pressure data — bottomhole pressures are calculated, note the effect of liquid loading. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  24. Time-Rate-Pressure: Flowback Analysis SPE 135607A Comprehensive Workflow for Early Analysis and Interpretation of Flowback Data from Wells in Tight Gas/Shale Reservoir SystemsD. Ilk and S.M. Currie, Texas A&M U., D. Symmons, Consultant, J.A. Rushing, Anadarko Petroleum, N.J. Broussard, El Paso, and T.A. Blasingame, Texas A&M U. a. Crossplot — All wells: qg versus qw. c. Crossplot — All wells: Dp2/qg versus t. b. Crossplot — All wells: pcf versus t. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011) [DI]

  25. Time-Rate-Pressure: Time-Rate Diagnostics SPE 135616Hybrid Rate-Decline Models for the Analysis of Production Performance in Unconventional ReservoirsD. Ilk and S.M. Currie, Texas A&M U., D. Symmons, Consultant, J.A. Rushing, Apache, and T.A. Blasingame, Texas A&M U. a. b-derivative — Holly Branch Wells. b. b-derivative — "Shale Gas Field C" Wells. c. b-derivative — All Models (Holly Branch Well). Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011) [DI]

  26. Time-Rate-Pressure: Integration of Results SPE 140556 (2011)Integration of Production Analysis and Rate-time Analysis via Parametric Correlations — Theoretical Considerations and Practical ApplicationsD. Ilk, DeGolyer and MacNaughton, J.A. Rushing, Apache, and T.A. Blasingame, Texas A&M U. Horizontal well with multiple vertical fractures: "Shale Gas Field C" a. Correlation plot — kcal versus kmeas. Power-Law Exponential Relations: "Shale Gas Field C" b. Correlation plot — EURcal versus EURmeas. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  27. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsPractical Aspects Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  28. Practical Aspects: Stimulation "You only produce from what you frac …"Anonymous Individual Fractures fromIndividual Perforation Clusters Complex Fractures fromIndividual Perforation Clusters Project Rulison (1971)Stimulation using Atomic Weapons Discussion: • Maximizing SRV (Stimulated Reservoir Volume) • Build Complexity → Slickwater • Build Conductivity → Hybrid/Gel Systems • Future Stimulation Challenges: • Can we "rubblize" the reservoir? • Can we "pulverize" the reservoir? • Can we do this with little or no water? Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  29. 10-3 1:2 slope Formation Linear Flow (very high fracture conductivity) Total Fluid Productivity Index, STB/D/psi 10-4 Clean-up Behavior 10-5 100 101 102 103 Total Fluid Material Balance Time, days Practical Aspects: Clean-Up Discussion: • Build choke profile slowly (2/64ths every 2-3 days). • Hold choke constant once rates peak. • For HPHT systems, start at 10-12/64ths, build to 12-16 64ths. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  30. Dimensionless Pressure Dimensionless Time Practical Aspects: Pressure Transient Analysis Nearby well is being stimulated. 1:4 Slope Nearby well is being stimulated. Apparent 1:4 slope for pressure drop and pressure drop derivative functions  LOW CONDUCTIVITY VERTICAL FRACTURES. Discussion: • Multiple BHP pressure transient test data sets (5 wells). • Apparent 1:4 slope → low conductivity vertical fractures. • Data are "normalized" (dimensionless) in pressure drop and time. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  31. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional ReservoirsChallenge Pointsfor Unconventional Reservoirs Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 — t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  32. Challenge Points: "What Keeps Me Up at Night…" • What we REALLY know… • Tight gas is relatively easy (... vertical wells, HP/HT, PVT) • Gas shales are technically viable as a resource (… economics?) • Horizontal multi-fractured wells (… (now) taken for granted) • What we THINK know… • The fracture geometry is (... planar? complex? who cares?) • The phase behavior (… can be extremely complex) • The ptf to pwf conversion(s) (... early-time heavy water load?) • What we may NEVER know… • Distribution of natural fractures (... impossible?) • Transport of gas/liquids in shales (... via organic matter?) • What we SHOULD KNOW in the near future… • Duration of data required for EUR (... more is always better) • Better understanding of phase behavior (... not "conventional") • Optimal well spacing/orientation/placement (... do this early!) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  33. Challenge Points: "Conventional Wisdom…" • Estimated Ultimate Recovery (EUR)? • Early EUR? (... can this be meaningful?) • EUR = f(t)? (... how do we incorporate this?) • Well Spacing? (... is this really the holy grail?) • QUANTIFYING reservoir properties? • Pressure Transient Analysis (... ultra-low k ... issues?) • Production Analysis (... ptf may not be sufficient) • Petrophysical analysis (... theory ≠ application) • Liquids-Rich Systems? • Fluid-Flow Mechanisms (... what is really flowing where?) • PVT (... near-critical fluids are not trivial) • Improved Recovery (... we all know this is coming) • Fit-for-Purpose Stimulation (... higher FcD, more complexity) • Artificial Lift (... fact of life) • Recovery (... low to extremely low primary recovery?) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  34. Challenge Points: "Everybody Has An Opinion" • Never-Ending Arguments… • SRV (... what is it, really?) • Desorption (... significance? timing? relevance?) • Stimulation Fluids (... where does it go? does it matter?) • Microseismic (... crystal ball, roulette wheel, or roadmap?) • Pressure-Dependent Whatever (... so what?) • Natural Fractures (... if/when/why/what?) • Dual Porosity/Dual Permeability (... what about the physics?) • Well Placement/Effect of Layering (... when does it matter?) • Things that SHOULD help… • Production Logs (... but just a snapshot in time) • Optimal Proppant Design/Placement (... obvious, but) • Stimulation Stages/Perforation Clusters (... geology + logs) • Things that DEFINITELY WOULD help… • Measured pwf (... yes, this is my favorite song) • Downhole Fluid Sampling (... sooner or later) • Horizontal Core (... why not?) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  35. Challenge Points: "My Crystal Ball Tells Me…" • EUR: • Time-Rate Analyses (... may not be sufficient) • Time-Rate-Pressure Analyses (... requires reservoir model) • Constraints (... e.g., 15 years seems reasonable) • Reservoir Modeling: (i.e., simulators) • Present (... conventional models with modifications) • Near-Future (... fundamental flow kinetics, complex geometries) • Distant-Future (... pore-scale phenomena, nano-scale PVT, ?) • Reservoir Engineering Tools: • Material Balance Methods (... not applicable at reservoir-scale) • Pressure Transient Tests (... surprisingly good in cases [need k]) • Production Analysis (... very good in cases [need good ptf data]) • Reservoir Fluids (... very complex, near-critical liquids) • EOR (... not sure where to start — CO2, lean gas, ???) • Ad-hoc Tools (... e.g., Linear flow analysis — lack resolution) Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

  36. Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects ofUnconventional Reservoirs End of Presentation Tom BLASINGAME Department of Petroleum Engineering Texas A&M University College Station, TX 77843-3116 (USA) +1.979.845.2292 t-blasingame@tamu.edu Presentation at SPE GCS Reservoir Study Group Houston, TX (USA) — 27 October 2011 Reservoir Engineering Aspects of Unconventional Reservoirs Tom Blasingame — Texas A&M University (27 October 2011)

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