1. Breakout analysis using Fullbore Formation MicroImager images
Ágnes Bőgér
Department of Geophysics and Space Sciences
Eötvös University, Budapest
ISZA
2012
Tatabánya 1

2. Overview Aims Theoretical background
The Fullbore Formation MicroImager (FMI) equipment
Data Processing
Interpretation
Results
Conclusions 2

3. Aims Processing of raw FMI data Interpretation of borehole images
Determining the maximum horizontal stress (SH max) direction from borehole breakouts (BO) and drilling induced tensile fractures (DIF)
Compare the new data with the former SH max directions
Calculate the rock mechanics parameters 3

4. Why the knowledge of the stress field is important?
Hydraulic fracturing of unconventional HC reservoirs
Monitoring the well to maintain its stability
Tectonic researches 4

5. Methods applied to determine the stress field
„In situ” methods
Borehole deformation
Overcoring
Hydraulic fracturing
Methods based on geological observations
Focal mechanism
Fault mechanics
Volcano lineaments 5

6. Borehole deformations
The Borehole Breakout (BO) and the Drilling induced tensile fractures are special kinds of drill-hole failures
Compressive borehole breakouts form in the area of maximum circumferential stress, which in vertical wells is found at the azimuth of Sh min
Tensile failure forms 90° from borehole breakouts in the direction of the maximum horizontal stress (SH max) 6

7. BO analysis method
Instruments
Dipmeter
Acoustic Televiewer
FMI 7

8. The Fullbore Formation MicroImager (FMI) instrument
Electrical method used in boreholes to image bedding and fractures around the perimeter of the borehole
Measure the borehole size
Measurement in the water-based drilling fluid
High resolution picture based on resistivity
contrasts from the borehole wall
Vertical resolution, 5 mm
Pad
Flap 8

9. Data processing Schlumberger- Techlog Software Speed correction
RAW data
PROCESSED data
Schlumberger- Techlog Software
Speed correction
Pads image creation
Buttons harmonisation
Histogram equalisation
Image processing 9

10. Sedimentological features
Depth (m) m
Fractured zone
Vuggy rock
Bedding surfaces
Bőgér, Á., in prep., 2012. 10

11. Borehole breakouts Well visible BO Not covered by the pads Bad contact
Depth (m) m
Well visible BO
Not covered by the pads
Bad contact
Bőgér, Á., in prep., 2012. 11

12. Drilling induced fractures
Depth (m)
Zoback, M. D. et al., 2003.
Bőgér, Á., in prep., 2012. 12

13. Maximum horizontal stress directions
Well A, SHmax 101°, s.d. ±16° km
Well C, Shmax 157°,s.d. ± 13° km
Well B, SHmax 14°, s.d. ±11° km 13

14. Maximum horizontal stress directions in Hungary
The lines show the maximum horizontal stress (SHmax) directions established by BO analysis (from dip logs and images logs). The red lines show the former data (Dövényi 1994, and Bőgér, Oláh 2012), and the blue lines depict the directions presented in this study. 14

15. Rock mechanics parameters from sonic measurements
Compressional (Vp) and Shear (Vs) velocities
Formation density
Young modulus (E)
Shear modulus (μ) 15

16. Rock mechanics parameters from sonic measurements16

17. Conclusions
I processed the FMI data of three wells and I created FMI images
I interpreted BO and DIF on these images
I determined the SH max directions
I compared the new SH max directions with the former data. They are in agreement with each other
I started to investigate the relationship betwen borehole deformations and rock mechanics parameters 17

18. Acknowledgement Dr. László Balázs
Dr. Tamás Tóth and the Geomega Ltd. for providing FMI data
References
.Bőgér, Á., Oláh, P., Determination of the stress directions in the Earth~s crust in Hungary based on borehole breakout analysis made on borehole images (CBIL, FMI), ISZA, Tatabánya, Poster
Dövényi, P., Geophysical investigations for the understanding of the evolution of the lithosphere of the Pannonian basin. Candidate theses, Department of Geophysics, Eötvös Loránd University, Budapest, 120 p
Zoback, M. D. et al., Determination of stress orientation and magnitude in deep wells. International Journal of Rock Mechanics & Mining Sciences 40 (2003) 1049–1076 18

19. Thank you for your attention!19

20. Conclusions
I processed the FMI data of three wells and I created FMI images
I interpreted BO and DIF on these images
I determined the SH max directions
I compared the new SH max directions with the former data. They are in agreement with each other
I started to investigate the relationship betwen borehole deformations and rock mechanics parameters 20