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The PT Borehole Simulator HEX-B2 Thomas Mgel Thomas Kohl GEOWATT - PowerPoint PPT Presentation

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ENGINE Workshop 4 Drilling cost effectiveness and feasibility of high- temperature drilling July 2 -5 , 2007 The PT Borehole Simulator HEX-B2 Thomas Mgel Thomas Kohl GEOWATT AG Dohlenweg 28, CH-8050 Zrich 03/07/07 ENGINE Reykjavik

  1. ENGINE Workshop 4 “Drilling cost effectiveness and feasibility of high- temperature drilling” July 2 -5 , 2007 The PT Borehole Simulator HEX-B2 Thomas Mégel Thomas Kohl GEOWATT AG Dohlenweg 28, CH-8050 Zürich 03/07/07 ENGINE Reykjavik Drilling Workshop 1

  2. Introduction HEX-B2 Pressure / Temperature are key parameters in reservoir characterization Borehole Measurements are expensive and require a proper data quality control P/T downhole data can be imprecise under EGS conditions 03/07/07 ENGINE Reykjavik Drilling Workshop 2

  3. Accuracy and Risk of Logging HEX-B2 Measurements in Boreholes:  What goals should be achieved?  How can the data be controlled?  What happens during high flow rate experiments?  Is accessibility in boreholes ensured? • High Temperature • Broken Casing • High Mineralization High Costs associated to data acquisition  Logging operation  Cleaning boreholes from cable/squeezed instruments 03/07/07 ENGINE Reykjavik Drilling Workshop 3

  4. New Possibility in Downhole Measurements HEX-B2 Requirements for data extrapolation to downhole conditions  Require P/T information to travel from borehole head to bottom or vice versa  Processes related to fluid density distribution are most critical  Knowledge of • Physical processes in borehole • Geometrical layout of casing / cementing • Rock matrix parameters New technological developments  Make use of use for new computer power 03/07/07 ENGINE Reykjavik Drilling Workshop 4

  5. New pT- Simulator HEX-B2 HEX-B2 HEX-B2 Wellheads GPK2/GPK3 wellhead data borehole model GPK3 03/07/07 ENGINE Reykjavik Drilling Workshop 5

  6. New pT- Simulator HEX-B2 HEX-B2 Model parameters: Input parameters/Physical processes: Dynamic wellhead data 1. Wellhead pressure 2. Injection rate 3. Fluid temperatur Wellhead data: c (1) 4. Fluid NaCl-molality • Initial pressure p(z,t) tmp(z,t) c (2) Dynamic properties and processes implemented p(z,t) Borehole data: • Heat exchange with rock mass tmp(z,t) • Casing diameters • Fluid heat capacity (T, NaCl-mol) • Wall roughness • Fluid density (T, NaCl-mol, p) • MD-TVD • Buoyancy forces in the borehole c (3) • Fluid losses into rock • Friction forces borehole/casing • Initial NaCl-molality • Fluid viscosity (T, NaCl-mol) • Fluid volume (T,p) Resul ults ts Rock mass data: • Thermal conductivity • Specific heat capacity c PT (z,t) Flow Exit • Initial temperature in borehole points c (i) + Injectiv tivity ty Index II (t) 03/07/07 ENGINE Reykjavik Drilling Workshop 6

  7. Features of HEX-B2 HEX-B2 HEX-B2 3 Borehole model: 1 • Arbitrary borehole diameters • Well completion • Rock mass model • Borehole trajectory Processes in borehole: 2 • Navier-Stokes equation • Mass conservation • Pipe friction 1 • Advection (NaCl-mol, T) 2 • Fluid density (NaCl-mol, T, p) 4 • Fluid viscosity (NaCl-mol, T) • Fluid heat capacity (NaCl-mol, T) 3 Radial thermal diffusion (borehole completion and rock mass) 4 40% 20% Exit-/Entry points 4 At production: Inflow of T(t) and NaCl-mol(t) 03/07/07 ENGINE Reykjavik Drilling Workshop 7

  8. Application of HEX-B2 HEX-B2 Possible modes  Reservoir response from measured wellhead data • Pressure/flow rate BC at wellhead • Calculation of injectivity/productivity indices • Improvement of reservoir during stimulation • Variation of downhole temperature during production  Calculation of scenarios from reservoir parameters • flow rate BC at wellhead; Reservoir parameters at bottom • Pressure profile • Production temperature • Failure pressure at shearing events near borehole • Optimization of production scenarios with thermosyphon effect (Buoyancy) • Design of well testing parameters 03/07/07 ENGINE Reykjavik Drilling Workshop 8

  9. Procedure for Application HEX-B2 Calibration of HEX-B2 Model  Provide necessary borehole/rock parameters  Calibrate model on existing dataset Preparatory Phase  Monitoring of wellhead data (pressure, temperature, molality)  Evaluate transient effects from earlier tests Calculation phase  Set reference depth  Calculate injectivity/productivity indices  Perform sensitivity analysis 03/07/07 ENGINE Reykjavik Drilling Workshop 9

  10. Examples of HEX-B2: Soultz GPK3 Stimulation 2003 HEX-B2 HEX-B2 HEX-B2 calculation of injection 03/07/07 ENGINE Reykjavik Drilling Workshop 10

  11. Examples of HEX-B2: Soultz GPK3 Stimulation 2003 HEX-B2 HEX-B2 Comparison with downhole data  pT-probe shifted from 4544 MD to 4244 MD  good fits with measured data  reconstruction of failed pressure data at 4544 MD Data correction High Accuracy! 03/07/07 ENGINE Reykjavik Drilling Workshop 11

  12. Examples of HEX-B2: Soultz GPK3 Stimulation 2003 HEX-B2 HEX-B2 DEMO 03/07/07 ENGINE Reykjavik Drilling Workshop 12

  13. Examples of HEX-B2: Soultz GPK4 Stimulation 2004 HEX-B2 Completion of downhole PT-data 03/07/07 ENGINE Reykjavik Drilling Workshop 13

  14. Examples of HEX-B2: Synthetic GPK2 Production Test HEX-B2 HEX-B2 Calculation of production without additional inflows  Tdh = 190°C  NaCl-mol = 5 03/07/07 ENGINE Reykjavik Drilling Workshop 14

  15. Examples of HEX-B2: Synthetic GPK2 Production Test HEX-B2 HEX-B2 Calculation of production with assumed inflows  Tdh = 190°C  NaCl-mol = 5  inflows at -2200 MD  inflows at -4500 MD 03/07/07 ENGINE Reykjavik Drilling Workshop 15

  16. Examples of HEX-B2: Failure Pressure of Fractures HEX-B2 Near-borehole microseismicity GPK2 (2000): GPK3 (2003): Easting Easting 150 -350 -350 100 300 Northing 300 Northing 0 50 -100 -200 -400 -400 0 -300 200 200 Northin Northin -400 -50 100 100 -450 -450 0 0 -4500 -4500 -500 -500 -100 -100 -4550 -4550 -550 -550 -4600 -4600 -4650 -4650 -4500 -4500 -4700 -4700 -4600 -4600 -4750 -4750 -4800 -4800 -4700 -4700 -4850 -4850 -4900 -4900 -4800 -4800 -4950 -4950 -5000 -5000 -4900 -4900 -5000 -5000 First 24 h First 24 h r < 25 m r < 25 m r : 25 - 50 m r : 25 - 50 m r > 50 m r > 50 m 03/07/07 ENGINE Reykjavik Drilling Workshop 16

  17. Examples of HEX-B2: Failure Pressure of Fractures HEX-B2  Near-borehole microseismicity  Downhole pressure history GPK2 (2000): GPK3 (2003): Whole ole open hole section activated immediately Top-to to-down activation of open hole section Failure pressure of all intersecting fractures Failure pressure of intersecting fractures immediat ediately ly exceeded was exceeded slowly ly 03/07/07 ENGINE Reykjavik Drilling Workshop 17

  18. Examples of HEX-B2: Failure Pressure of Fractures HEX-B2 Fracture failure pressure for GPK3 GPK3 (2003): Easting 150 -350 -350 100 50 -400 -400 0 Northin Northin -50 -450 -450 -4500 -4500 -500 -500 -4550 -4550 -550 -550 -4600 -4600 Depth + Time -4650 -4650 -4700 -4700 -4750 -4750 -4800 -4800 of near-borehole -4850 -4850 -4900 -4900 -4950 -4950 -5000 -5000 events + HEX-B2 Calculation of corresponding downhole pressures • Failure pressure from 52 - 60 MPa with TVD • Reflects depth-dependency of stress field • Range at a given depth: fracture orientation?! • Gradient of failure pressure: 5-10 10 MPa/400m 03/07/07 ENGINE Reykjavik Drilling Workshop 18

  19. Examples of HEX-B2: Sensitivity Calculations HEX-B2 Steady-state pressure vs. Molality vs. productivity index Productivity Index 5 mol = 0% mol = 10% 4 mol = -10% PI [l/s/MPa] 3 2 1 0 150 160 170 180 190 200 T CS [°C] 03/07/07 ENGINE Reykjavik Drilling Workshop 19

  20. Conclusions HEX-B2 HEX-B2 was used for interpretation of Soultz testing data Most useful features:  Comparability of downhole pressure data • Different tests during exploration phase at variable flow rates • Extrapolation to arbitrary levels • Comparability of data  Calculation of injectivity/productivity indices  Correction and reconstruction of pT-data gaps  Sensitivity calculation  Scenario analysis for production temperature (heat loss in well, effect of inflow temperature,...)  Accounting for effects of leaks in the casing (injection and production) Cost reduction for pT-downhole measurements 03/07/07 ENGINE Reykjavik Drilling Workshop 20

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