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Breakout analysis using Fullbore Formation MicroImager images. Ágnes Bőgér. Department of Geophysics and Space Sciences Eötvös University, Budapest bogeragnes@gmail.com. ISZA 2012 Tatabánya. 1. Overview. Aims Theoretical background The Fullbore Formation MicroImager (FMI) equipment
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Breakout analysis using Fullbore Formation MicroImager images Ágnes Bőgér Department of Geophysics and Space Sciences Eötvös University, Budapest bogeragnes@gmail.com ISZA 2012 Tatabánya 1
Overview • Aims • Theoretical background • The Fullbore Formation MicroImager (FMI) equipment • Data Processing • Interpretation • Results • Conclusions 2
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
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
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
Borehole deformations • The Borehole Breakout (BO) and the Drilling induced tensile fracturesare special kinds of drill-hole failures • Compressive borehole breakouts form in the area of maximumcircumferential stress, which in vertical wells is found at the azimuthof Shmin • Tensile failure forms90° from borehole breakouts in thedirection of the maximum horizontal stress (SH max) 6
BO analysis method • Instruments • Dipmeter • Acoustic Televiewer • FMI 7
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
Data processing RAW data PROCESSED data Schlumberger- Techlog Software • Speed correction • Pads image creation • Buttons harmonisation • Histogram equalisation • Image processing 9
Sedimentological features Depth (m) 0.5 m Fractured zone Vuggy rock Bedding surfaces Bőgér, Á., in prep., 2012. 10
Borehole breakouts Depth (m) 1 m Not covered by the pads Well visible BO Bad contact Bőgér, Á., in prep., 2012. 11
Drilling induced fractures Depth (m) Zoback, M. D. et al., 2003. Bőgér, Á., in prep., 2012. 12
Maximum horizontal stress directions Well A, SHmax 101°, s.d. ±16° 1.44-1.55 km Well C, Shmax 157°,s.d. ± 13° 2.41-2.16km Well B, SHmax 14°, s.d. ±11° 3.11-3.22 km 13
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
Rock mechanics parameters from sonic measurements Compressional (Vp) and Shear (Vs) velocities Formation density • Young modulus (E) • Shear modulus (μ) 15
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
Acknowledgement • Dr. László Balázs • Dr. Tamás Tóth and the Geomega Ltd. for providing FMI data References • .Bőgér, Á., Oláh, P., 2012. 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, 2012. Poster • Dövényi, P., 1994. 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., 2003. Determination of stress orientation and magnitude in deep wells.International Journal of Rock Mechanics & Mining Sciences 40 (2003) 1049–1076 18
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