New (? Logging) Developments in Reservoir Monitoring

Transcription

1 New (? Logging) Developments in Reservoir Monitoring Reservoir Monitoring Consortium (RMC) Seismicity Annual Review meeting University of Southern California October 21, 2014 Alan Sibbit, Senior Research Advisor, Schlumberger-Doll Research

2 New Developments in Reservoir Monitoring - Overview What do we mean by reservoir monitoring? Changes in fluid in the reservoir (What can we measure?) Pulsed neutron capture and spectroscopy Nuclear magnetic resonance Seismic and temperature Gravity Uncertainty (Can we measure accurately, enough?) Some words on the micro-seismic business 2

3 What is Reservoir Monitoring? Monitoring production-induced changes in reservoir properties Changes in fluid saturations (time-lapse resistivity, pulsed neutron, seismic ) Changes in pressure (well testing) Compaction (seismic, gravity, precise depth measurements, ) Fault and fracture activation (micro-seismic, ) Reservoir compartmentalization (fluid sampling, )

4 Saturation Monitoring Techniques Techniques depending on presence of carbon Carbon/Oxygen logging (Pulsed Neutron Spectroscopy) Techniques depending on density contrast Density/neutron, density/nmr, differential gravity, pressure etc. Techniques depending on compressibility contrast Acoustic techniques V p /V s (Array acoustic tools / seismic) Techniques depending on water salinity Chlorine logging (Pulsed Neutron Spectroscopy) Capture cross-section, S (Pulsed Neutron Capture) Resistivity Other techniques dielectric properties and dispersion nuclear magnetic resonance properties (diffusion depends on viscosity) pulsed neutron count-rates and ratios thermal properties, 4

5 Sensitivity and required precision The expected dynamic range is the fluid property multiplied by the fluid volume Fluid density, r f (water ~ g/cc, oil ~ 0.6 1g/cc, gas ~ g/cc) Hydrogen density/index (water/oil ~ 1, gas ~ 0.2, CO2 ~ 0 ) Fluid compressibility (water GPa -1, oil GPa -1, gas GPa -1 ) Magnetic Resonance Diffusion Constant ( gas ~ 10 x water > 10 x oil) Carbon density (water 0, light oil ~ 0.85r h, gas ~ 0.75r h ) Fluid resistivity (oil/gas ~, water W.m) Capture cross-section, S f (oil ~ 22cu, gas ~ 6cu, water ~ cu) Relative dielectric constant, r (oil ~ 5, gas ~ 2, water ~ 80) 5

6 Pulsed Neutron Logging Inelastic Scattering Elastic Scattering Thermal Capture 6

7 What about uncertainty? (precision can be measured) Repeat Analysis S precision s S ~0.22 cu Precision in saturation S w s S (S w S h ) measurement precision dynamic range

8 Gas injection monitoring SPE time-lapse passed with pulsed-neutron, S, and neutron porosity Gas breakthrough and upward migration can clearly be seen and quantified

9 Cased Hole Pulsed Neutron Tool Adding further, deeper detectors does not necessarily improve the measurement. A longer source detector spacing can improve dynamic range but at the cost of poorer statistics. When there is liquid in the borehole signal to noise becomes worse.

10 Depth of investigation of pulsed neutron tools Water filled borehole Gas (CO2) filled borehole Deep Far Near Inelastic Capture Inelastic Capture

11 Measure Point Schlumberger Public 3D Pulsed Neutron Tool 175degC 15K PSI Deep (YAP) Far (LaBr3) Near (LaBr3) PNG + CNM 1.72 OD 18.3Ft long NACE Compliant 9 ft Measurements Hydrogen Index, Sigma, Inelastic Gas (GSH) Challenging Cased Hole Environments Gas Borehole Complex Completions Carbon/Oxygen, Capture Spectroscopy (IC) Cased Hole Spectroscopy High Temperature C/O C/O Logging Time Reduced Water flow, 3-Phase Holdup Key Technologies High Output Smart-PNG LaBr 3 and Deep Detectors Compact Neutron Monitor (CNM) Schlumberger Confidential

12 RST Base log with water in borehole Water Schlumberger Confidential

13 RST time lapse log after gas injection started Problem: Gas in borehole affects formation porosity (TPHI) Unable to identify gas in the reservoir Schlumberger Confidential Gas Water

14 PNX time lapse log after gas injection started Gas in borehole does not affect PNX formation porosity (TPHI-red) Can identify gas in the reservoir Schlumberger Confidential Gas Water

15 Field Test Example (Oil Producer - CO2 Injection) Sigma-Lithology 1000ft/hr in 5.5" OD casing 17lbs/ft Schlumberger Confidential OH Data 2010 Lithology data PNX 2014 Sigma Mode data PNX 2014

16 Quantifying liquid and gas with Magnetic Resonance Field measurement, Magnetic Resonance Fluid Typing Diffusion constant, D, changes by an order of magnitude T 2 s may be similar 1 gas, 2 oil filtrate, 3 residual, 4 bound Precision is a function of statistics, processing Sandstone, ~ 5400m, ~ 18 percent porosity 16

17 Magnetic Resonance Fluid Typing Sandstone, ~ 5400m, ~ 18 percent porosity Diffusion constant, D, changes by an order of magnitude T 2 s may be similar 1 gas, 2 oil filtrate, 3 residual, 4 bound Precision is a function of measurement statistics and processing Unrestricted Diffusion Restricted Diffusion

18 Miscible Gas Monitoring by Time-Lapse NMR Diffusion Schlumberger Public

19 Concluding remarks on saturation monitoring Many physical principles can be used to quantify changes in fluid saturations especially gas-liquid fractions. These include density and/or hydrogen contrast, compressibility, and NMR. Pulsed Neutron techniques are well proven and versatile, however they are shallow and sensitive to near-borehole effects. Good precision is vital for reservoir monitoring. Monitoring programs have to be carefully designed and planned, to ensure that their objectives can be met.

20 Some words on Micro-seismic Image Hydraulic Fracture Mapping Interpret Integrate Completion Effectiveness Reservoir Optimized Completions Hydraulic Fracture Geometry Survey Design and Acquisition Processing Visualization Moment Tensor and Failure plane solution Comprehensive Geoscience and Engineering Workflows Survey Design, Sensors, Processing, Visualization Advanced Answer Products Field Development Decisions

21 Imaging - Acquisition Surface Shallow Grid Surface line/patch Survey options: 4 1. Downhole vertical 2. Downhole horizontal 3. Shallow hole grid 4. Surface lines or patch Downhole Single well vertical or horizontal Multi-well, multi-array

22 Response [V/g] Schlumberger Public Accelerometers rather than geo-phones GAC GEO While most geophones are optimized for high sensitivity in the Seismic band (<100 Hz), the GAC maintains its sensitivity over the entire microseismic frequency range. This allows recovery of higher and lower frequency signals and clear identification of P- and S- wave arrivals in microseismic data sets. Note the amplification of low frequency noise recorded by a conventional geophone in the velocity domain GAC GEO Frequency [Hz]

23 Microseismic Services Hydraulic Fracture Mapping 1. Treatment well 2. Hydraulic fracture stages 3. Microseismic events 4. Downhole monitor well vertical 5. Downhole monitor well horizontal 6. Shallow well monitor 7. Shallow well grid 8. Surface monitor lines 9. Surface monitor patch 10. Well site communications 11. Real-time remote processing 12. Visualization and Interpretation 13. Advanced answer products 14. Modeling and integration Thank you