Breakout analysis using Fullbore Formation MicroImager images

Report
Breakout analysis using Fullbore
Formation MicroImager images
Ágnes Bőgér
Department of Geophysics and Space Sciences
Eötvös University, Budapest
[email protected]
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 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
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
Pad
• Vertical resolution, 5 mm
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
Well visible BO
Not covered by the pads
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°
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, 14
Oláh 2012), and the blue lines depict the directions presented in this study.
Rock mechanics parameters from sonic
measurements
Compressional (Vp) and Shear (Vs) velocities
Formation density

Vs 

2
V
p

Young modulus (E)

3
2
E
Shear modulus (μ)
  Vs2

15
Rock mechanics parameters from sonic
measurements
16
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
Thank you for your
attention!
19
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

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