Magnetic Referencing and Survey Accuracy for Horizontal Development in the Permian

Transcription

1 Slide 1 of 35 Magnetic Referencing and Survey Accuracy for Horizontal Development in the Permian Wellbore position uncertainty Global and local geomagnetic models Quality control and advanced corrections Tool code and orientation dependent QC thresholds Multi-Station Analysis (MSA) New OWSG tool codes for well planning and AC Stefan Maus, AADE Luncheon, 02/05/2015

2 Positional Uncertainty in MWD Slide 2 of 35 Largest source of lateral error: Magnetic field Accurate geomagnetic models and advanced corrections significantly reduce this error Halliburton

3 Ellipses of Uncertainty Study Slide 3 of 35

4 Uncertainties in West TX Slide 4 of 35 Lateral Uncertainty at TD Well Azim. Lateral Length MWD MWD +IFR1 MWD +IFR1+MS (ft) (ft) (ft) (ft) E (-11%) 173 (-61%) SE (-15%) 160 (-59%) S (-38%) 129 (-50%) Vertical Uncertainty at TD TVD MWD MWD+IFR1+SAG+MS ft 119 ft 71 ft (-40%) 3D Ellipsoids given for 95% confidence interval = 2.79 sigma Error model: ISCWSA OWSG

5 What Does the MWD Tool Measure? Slide 5 of 35 Bx, By, Bz Gx, Gy, Gz Compute Inclination, Magnetic Azimuth, Tool Face True Azimuth = Magnetic Azimuth + Declination

6 Magnetic Elements Given by Model Slide 6 of 35 Zenith South West North East Nadir

7 Main Field Originating in the Earth s Core Slide 7 of 35 European Space Agency, Swarm project

8 Crustal magnetic field as seen by CHAMP satellite Slide 8 of 35 Vertical component of the magnetic field MF7 model Animation by Rother and Maus

9 Omission Error: IGRF Slide 9 of 35 * *IGRF = International Geomagnetic Reference Field

10 Omission Error: BGGM Slide 10 of 35 * *BGGM = BGS Global Geomagnetic Model

11 Latest High Definition Model (MVHD) Slide 11 of 35 For questions about the MagVAR High Definition Model (MVHD) contact

12 Declination Comparison Slide 12 of 35 Main Field MVHD 50 mi x 50 mi

13 Global Model Calculator Slide 13 of 35

14 Global Model Calculator Slide 14 of 35

15 Omission error: MagVAR-IFR Slide 15 of 35 For questions about MagVAR In-field Referencing (IFR) contact

16 Model Comparison Slide 16 of 35 Main Field MVHD MagVAR IFR The most detailed magnetic reference is given by In-Field Referencing (IFR)

17 Permian Basin Aeromagnetic Surveys Slide 17 of 35

18 Slide 18 of 35

19 Slide 19 of 35

20 Declination at 10,000 ft TVD Slide 20 of 35 Main Field MVHD IFR

21 Total Field and Dip anomalies (IFR) Slide 21 of 35

22 MagVAR IFR Calculator Slide 22 of 35 Graphical User Interface provides magnetic reference values and gradients

23 Slide 23 of 35 Export well plan from data base

24 Auto-generated IFR Values for Sections Slide 24 of 35

25 Auto-generated IFR Well Segments Slide 25 of 35 Small magnetic gradients Large magnetic gradients

26 Output File for auto-generated Slide 26 of 35

27 Uncertainties in West TX Slide 27 of 35 Lateral Uncertainty at TD Well Azim. Lateral Length MWD MWD +IFR1 MWD +IFR1+MS (ft) (ft) (ft) (ft) E (-11%) 173 (-61%) SE (-15%) 160 (-59%) S (-38%) 129 (-50%) Vertical Uncertainty at TD TVD MWD MWD+IFR1+SAG+MS ft 119 ft 71 ft (-40%) 3D Ellipsoids given for 95% confidence interval = 2.79 sigma Error model: ISCWSA OWSG

28 QC and Correction of Raw MWD Data Slide 28 of 35 Bx, By, Bz Gx, Gy, Gz Measure 6 quantities get 6 parameters: Inclination, Magnetic Azimuth, Tool Face (use for steering!) Gtotal, Btotal, Dip (use for QC and Corrections!)

29 Examples of Raw Data QC Slide 29 of 35 Raw data (MWD tool code) Raw data (MWD tool code) 3 sigma 3 sigma MD MD 3 sigma 3 sigma MD MD

30 QC Parameter Errors Depend on Wellbore Orientation Example: Contribution of axial bias to error in Btotal Slide 30 of 35 Wellbore parallel to magnetic field (plan view) Wellbore oriented magnetic east (plan view) Axial bias affects Btotal Axial bias not seen in Btotal

31 Computing QC Thresholds for Tool Codes Slide 31 of 35

32 Multi-Station Analysis Correction Slide 32 of 35 Raw data (MWD tool code) IFR and MSA corrected data (MWD+IFR1+MS tool code) 3 sigma 3 sigma MD MD 3 sigma 3 sigma MD MD Note the tighter QC thresholds!

33 Relevant Tool Codes for Well Slide 33 of 35 Planning and Anti-collision Scans Tool Code Magnetic reference model Survey corrections EOU* MWD+IGRF Global IGRF or WMM - +10% MWD Global BGGM or MagVAR MVSD - Standard MWD+HDGM Global HDGM or MagVAR MVHD - -10% MWD+IFR1 Local In-Field Referencing (IFR1) - -30% MWD+IFR1+MS Local In-Field Referencing (IFR1) Multi-Station -50% More Accurate *Approximate values, actual EOU sizes depend on location and orientation of wellbore New set of consolidated error models from the Operator Wellbore Survey Group These are available from Landmark as IPMs for Compass.

34 Importance of Raw Sensor Data Slide 34 of 35 Record and archive the raw 6-axis sensor data With MD, date, time and tool run for each survey Sufficient precision (at least 4 significant digits) The raw data can be read from tool memory - Needs synchronization with MD

35 Conclusions Slide 35 of 35 Wellbore positions have significant uncertainties Uncertainties can be reduced by 50% First step: Produce a local IFR magnetic model Second step: Apply Quality Control and use multistation analysis methods to correct the raw MWD sensor data IFR and survey quality management significantly improve well placement accuracy For questions about the MagVAR High Definition Model (MVHD), MagVAR IFR and the software shown in this presentation please contact maginfo@magvar.com Stefan Maus, AADE Luncheon, 02/05/2015