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Baker Hughes
11th Annual Global Gas Village Summit 2011
Prague – 11, 12 & 13 April 2011
Evaluating storage capability of r...
Agenda
1. Sub-Surface imperative of UGS
2. Added value of integrated source free approach
3. The challenge of storage capa...
Sub-Surface Imperatives of UGS
3
 Maximize storage capacity
 Maximize deliverability
 Optimize cushion gas volume
 Mit...
Added value of integrated source-free
interpretation approach
4
• Improve the evaluation of storage capability
providing b...
Storage capacity: the first imperative
• The evaluation the storage capacity of reservoir for UGS requires
running porosit...
Evaluating the storage capacity: the challenge
• The traditional approach of evaluation requires running
density and neutr...
Evaluating the storage capability: the solution
• To overcome that, a more advanced approach have
been developed for poros...
NMR vantages
• HSE fully complaint !
• Advanced detailed porosity
description
• Continuous permeability
profile
NMR service
• This evaluation service is available either
– While drilling the well (LWD)
– At end of well drilling in ope...
NMR: what it is measured (a bit of physics)
• NMR logging has the advantage of direct measuring the
hydrogen of fluids in ...
NMR how it works
• NMR logging has the advantage of direct measuring the
hydrogen of fluids in pore space avoiding litholo...
M0 B0
NMR how it works
• NMR logging has the advantage of direct measuring the
hydrogen of fluids in pore space avoiding...
NMR how it works
• NMR logging has the advantage of direct measuring the
hydrogen of fluids in pore space avoiding litholo...
Spins precess in the
B0 field after tipping
by an RF pulse
f =  B0
NMR how it works
• NMR logging has the advantage of di...
NMR how it works
• NMR logging has the advantage of direct measuring the
hydrogen of fluids in pore space avoiding litholo...
Volumetrics porosity distribution in the reservoir
according NMR exploration
0 100 200 300 400 500 600
Time (ms)
Porosity%...
NMR porosity description
• The NMR logging offers a complete overview of
– porosity distribution: total porosity, clay bou...
Where default parameters are: C =10, m = 4 & n = 2
Coates-Timur Model :
MBVI
MBVM
C
k
n
=
m

MPHE
NMR Permeability
Shale indicator from NMR
• CBW: Volume of clay bound water (CBW) represents the
porosity in clay content in a formation ro...
Porosity evaluation in gas bearing beds
• The gas occurrence affect all the
porosity logs
– Lower density: over call densi...
Superior hydrocarbon typing
• Innovative NMR acquisition techniques provide comprehensive NMR data for
fluids analysis
– T...
Porosity evaluation in gas bearing beds
• The accuracy of NMR total porosity in gas-bearing
formations is affected by low ...
Porosity evaluation in gas bearing beds
• However in depleted levels or low pressure reservoir the
correction for HI is de...
Porosity evaluation in gas bearing beds
To overcame this imprecision we suggest to exploit the
vantage of combine the poro...
Acoustic vantages
• HSE fully complaint !
• This evaluation service is available either
– While drilling the well (LWD)
– ...
Porosity from modified Raymer-Hunt-Gardner (1)
• Δt is the measured slowness of wave velocity,
• Δtma is the slowness of t...
Acoustic porosity
• The acoustic measurements respond to lithology and
porosity
• In addition respond to texture consequen...
{
Acoustic porosity calibration
• Calibrate the fitting parameter C
• The Raymer-Hunt-Gardner function is calibrated in a ...
Acoustic porosity calibration
• Calibrate the Δtma, in the shaly sand section
– Using the calibrated C and the NMR porosit...
Acoustic porosity calibration: summary
• The Raymer-Hunt-Gardner function is calibrated using the
NMR total porosity in a ...
Combined NMR log-calibrated acoustic porosity
• These steps let to compute the final porosity using
the correct parameter ...
Example of NMR log-calibrated acoustic porosity
• Example in shaly sand sequences
•
Where and when ?
• This approach is applicable from clean to shaly
sandstones, and carbonate reservoirs
• Necessary data c...
35
Summary
 First UGS imperative: to be able to evaluate the
storage capacity
 Mitigate project risk
 Get information h...
References
• Alberty, M. 1994. The influence of the borehole
environment upon compressional sonic logs. Paper 1994-
S, SPW...
Thank you
Evaluating storage capability of reservoir using an integrated source-free interpretation approach
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Evaluating storage capability of reservoir using an integrated source-free interpretation approach

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The traditional approach of evaluation requires running density and neutron log devices in order to have quantitative estimation of reservoir porosity. Both logs response are affected by lithology and gas presence

NMR log-calibrated acoustic porosity provides more accurate and detailed description of reservoir porosity

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Evaluating storage capability of reservoir using an integrated source-free interpretation approach

  1. 1. Baker Hughes 11th Annual Global Gas Village Summit 2011 Prague – 11, 12 & 13 April 2011 Evaluating storage capability of reservoir using an integrated source-free interpretation approach Fabio Brambilla Senior Geoscientist Baker Hughes Fabio.brambilla@bakerhughes.com
  2. 2. Agenda 1. Sub-Surface imperative of UGS 2. Added value of integrated source free approach 3. The challenge of storage capacity evaluation 4. NMR logging vantages 5. Acoustic porosity 6. Combined porosity 7. Summary 2
  3. 3. Sub-Surface Imperatives of UGS 3  Maximize storage capacity  Maximize deliverability  Optimize cushion gas volume  Mitigate project risk  Well reliability  Profitable project Project Economics Storage Capacity Deliverabilit y Cushion Gas Risk Reliability
  4. 4. Added value of integrated source-free interpretation approach 4 • Improve the evaluation of storage capability providing better porosity knowledge of the reservoir • The continuous permeability profile from NMR service let to understand the deliverability of the well • Avoid any risk about utilization of radioactive sources Project Economics Storage Capacity Deliverability Cushion GasRisk Reliability
  5. 5. Storage capacity: the first imperative • The evaluation the storage capacity of reservoir for UGS requires running porosity logs, in order to have quantitative estimation of space available in your reservoir to accommodate the injected gas
  6. 6. Evaluating the storage capacity: the challenge • The traditional approach of evaluation requires running density and neutron log devices in order to have quantitative estimation of reservoir porosity • Both logs response are affected by lithology and gas presence • Environmental regulations for UGS fields management are more and more limiting the use of chemical radioactive sources • HSE nationals rules tend to made complex the logistic of devices using radioactive sources
  7. 7. Evaluating the storage capability: the solution • To overcome that, a more advanced approach have been developed for porosity determination using source-free tools, combining: 1. Nuclear Magnetic Resonance (NMR) logging 2. Acoustic logging • Both devices rely on a comfortable physics: – NMR: tool contains permanent magnet with magnetic field – Acoustic: deals with acoustic waves • The porosity from that combination is indipendent from lithology and gas presence
  8. 8. NMR vantages • HSE fully complaint ! • Advanced detailed porosity description • Continuous permeability profile
  9. 9. NMR service • This evaluation service is available either – While drilling the well (LWD) – At end of well drilling in open hole (WL) MagTrak MR Explorer (MREX)
  10. 10. NMR: what it is measured (a bit of physics) • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination •
  11. 11. NMR how it works • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination B=0, M=0
  12. 12. M0 B0 NMR how it works • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination
  13. 13. NMR how it works • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination Tool emits radio Frequency RF pulse with field strength B1 Spins are tipped 90 degrees by the RF pulse and then begin to precess in the B0 field f =  B0
  14. 14. Spins precess in the B0 field after tipping by an RF pulse f =  B0 NMR how it works • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination Echoes signal are recorded
  15. 15. NMR how it works • NMR logging has the advantage of direct measuring the hydrogen of fluids in pore space avoiding lithology effect on porosity determination Echoes signal are recorded TE : intercho spacing TE Time 90° x 180° y 180° y 180° y 180° y 180° y Amplitude Echo Signals RF Pulses
  16. 16. Volumetrics porosity distribution in the reservoir according NMR exploration 0 100 200 300 400 500 600 Time (ms) Porosity% 25 20 1 5 10 5 0 Superposition Clay Bound Water Capillary Water Movable Water Light Hydrocarbon 0 1 2 3 4 0.1 PartialPorosity 1 10 100 1000 T2 cutoffs T2 Movable Water Capillary Water Clay Bound Water Light Hydrocarbon
  17. 17. NMR porosity description • The NMR logging offers a complete overview of – porosity distribution: total porosity, clay bound water volume, capillary water volume, mobile fluid volume – a continuous permeability curve. • The knowledge of these values allows: – recognizing the best storage zones of the reservoir – Better understand the deliverability total porosity (ØT,NMR ) Matrix Rock Dry Clay Clay- bound water Free water Capillary trapped water Hydro- carbons BVMCBW e BVI t
  18. 18. Where default parameters are: C =10, m = 4 & n = 2 Coates-Timur Model : MBVI MBVM C k n = m  MPHE NMR Permeability
  19. 19. Shale indicator from NMR • CBW: Volume of clay bound water (CBW) represents the porosity in clay content in a formation rock • From NMR logs, both the fractional porosity from CBW (ØCBV) and the total porosity (ØT,NMR ) are obtained NMRT CBW ,  Vsh = 0 1 2 3 4 0.1 PartialPorosity 1 10 1001000
  20. 20. Porosity evaluation in gas bearing beds • The gas occurrence affect all the porosity logs – Lower density: over call density porosity – Lower Hydrogen index: under call porosity based on Hydrogen Index
  21. 21. Superior hydrocarbon typing • Innovative NMR acquisition techniques provide comprehensive NMR data for fluids analysis – T1, T2 & Diffusion data acquired simultaneously while logging • 2D NMR plots identify and quantify hydrocarbons – Available from all hydrocarbon typing Objective Oriented Acquisitions – Acquired as continuous logs (NOT stationary measurements!) PoroPerm + Gas PoroPerm + Oil PoroPerm + Heavy Oil 2 32 512 T2,app (ms) 16 4 1 T1/T2,app T2,int (ms) e-8 e-9 e-10 e-11 D(m2/s) 2 128 1024 T2,int (ms) e-8 e-9 e-10 e-11 e-12 D(m2/s) 162 128 102416 Gas CBW BVI Water Oil Heavy Oil Water
  22. 22. Porosity evaluation in gas bearing beds • The accuracy of NMR total porosity in gas-bearing formations is affected by low Hydrogen Index (HI) • Thanks to hydrocarbon typing analysis we can correct for the HI effect ,
  23. 23. Porosity evaluation in gas bearing beds • However in depleted levels or low pressure reservoir the correction for HI is definitively an improvement but still an estimate due to uncertainty of HI estimation Porosity & HI correction 0 1 2 3 4 5 6 7 8 0 50 100 150 200 250 300 350 BAR HI 0 5 10 15 20 25 30 35 40 Porosity
  24. 24. Porosity evaluation in gas bearing beds To overcame this imprecision we suggest to exploit the vantage of combine the porosity from NMR service with the porosity from the acoustic service NMR Acoustic
  25. 25. Acoustic vantages • HSE fully complaint ! • This evaluation service is available either – While drilling the well (LWD) – At end of well drilling phase (WL) in open hole and cased hole (CH) SoundTrak XMAC F1
  26. 26. Porosity from modified Raymer-Hunt-Gardner (1) • Δt is the measured slowness of wave velocity, • Δtma is the slowness of the dry matrix. – Constant in clean reservoir (Δtma,clean ) – it changes with shale presence: type, distribution, and percentage of shale (Δtma) • C is the fitting parameter C t tt ma acoustic   = (1 ) Alberty, M. 1994
  27. 27. Acoustic porosity • The acoustic measurements respond to lithology and porosity • In addition respond to texture consequently acoustic porosity is an indirect measurement based on semi- empirical models, which often requires calibration of parameters • The Raymer-Hunt-Gardner function can be calibrated using the NMR total porosity and NMR shale volume
  28. 28. { Acoustic porosity calibration • Calibrate the fitting parameter C • The Raymer-Hunt-Gardner function is calibrated in a clean water zone using the NMR total porosity • (ØT,NMR ) = (ØT,Acoustic ) • Calibrate Δtma,clean – Complex matrix C t tt cleanma NMRT   = , , C t tt a cleanmaa NMRTa   = , , C t tt b cleanmab NMRTb   = , , cleanma t tt C NMRT , ,  =  0 1 2 3 4 0.1 PartialPorosity 1 10 100 1000
  29. 29. Acoustic porosity calibration • Calibrate the Δtma, in the shaly sand section – Using the calibrated C and the NMR porosity • A correlation can be established between Δtma and Vsh • The matrix slowness is back-calculated over all the shaly zones t C tt NMRT ma = , GRvstma . dt_ma vs GR 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 GR (gAPI) dt_ma(us/ft) )(gAPIGR tma(s/ft) GRvstma . dt_ma vs GR 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 GR (gAPI) dt_ma(us/ft) )(gAPIGR GRvstma . dt_ma vs GR 0 10 20 30 40 50 60 70 80 0 20 40 60 80 100 GR (gAPI) dt_ma(us/ft) )(gAPIGR tma(s/ft) GR (gAPI) tp,ma(µs/ft) Vsh % Δtma
  30. 30. Acoustic porosity calibration: summary • The Raymer-Hunt-Gardner function is calibrated using the NMR total porosity in a clean water zone. • Subsequently using the shale volume, computed from the clay bound water volume, the matrix slowness is back- calculated over all the shaly zones • The function, with the calibrated parameters is run over the reservoir
  31. 31. Combined NMR log-calibrated acoustic porosity • These steps let to compute the final porosity using the correct parameter over the whole interval. Compute Vsh,NMR Calibrate Δtma Calibrate C NMR logging Acoustic logging Using modifies R-H-G function Compute NMR-calibrated Acoustic Porosity Permeability
  32. 32. Example of NMR log-calibrated acoustic porosity • Example in shaly sand sequences •
  33. 33. Where and when ? • This approach is applicable from clean to shaly sandstones, and carbonate reservoirs • Necessary data can be gathered either using LWD at drilling phase and or at wireline measurements phase
  34. 34. 35 Summary  First UGS imperative: to be able to evaluate the storage capacity  Mitigate project risk  Get information helping to maximize the deliverability  NMR log-calibrated acoustic porosity provides more accurate and detailed description of reservoir porosity  Data can be acquired either while drilling or post drilling phase. Project Economics Storage Capacity Deliverability Cushion GasRisk Reliability
  35. 35. References • Alberty, M. 1994. The influence of the borehole environment upon compressional sonic logs. Paper 1994- S, SPWLA 35th Annual Logging Symposium • Raymer, L.L., Hunt, E.R., and Gardner, J.S. 1980. An improved sonic transit time to porosity transform. Paper 1980-P, SPWLA 21st Annual Logging Symposium • Chun Lan, Songhua Chen, Freddy Mendez, Rex Sy, 2010. Sourceless Porosity Estimation in Gas Reservoirs Using Integrated Acoustic and NMR Logs, SPE ATCE SPE 133487
  36. 36. Thank you

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