The Effect of Fault Plane on the Horizontal In Situ Stresses Orientation: a Case Study in one of Iranian Oilfield

Document Type : Research Paper


Research Institute of Petroleum Industry


Knowledge of the orientation of horizontal in situ stresses is important to some areas of oil and gas field development plans. Borehole breakouts observed in image logs and drilling-induced fractures are the main parameters for the determination of the stresses’ directions in situ.
In this work, the orientations of borehole breakouts were investigated as a function of depth in oil wells A and B in Lali oilfield, in the Southwest of Iran. Borehole breakouts were detected from FMI logs. By the statistical analysis of the borehole breakouts’ orientation in the foregoing two wells, it was found that, while a mean orientation of minimum horizontal stress in well A is NE-SW, the azimuth of breakout in well B is different with a mean azimuth of 312˚±10˚. The result reveals that the orientation must be different in these two wells due to some geological abnormality. Therefore, accurate and reliable geomechanical analyses are crucial steps toward minimizing the costs of drilling and completion programs and mitigating borehole instability problems.


Prensky S., “Borehole Breakouts and In Situ Rock Stress: a Review,” The Log Analyst, 1992, 33, 304-312.
Bell J. S. and Gough D. I., “Northeast-Southwest Compressive Stress in Alberta: Evidence from Oil Wells,” Earth and Planetary Science Letters, 1979, 45, 475-482.
Zoback M. D., Moos D., Mastin L. G., and Anderson R. N., “Well Bore Breakouts and In Situ Stress,” Journal of Geophysical Research, 1985, 90, 5523-5530.
Plumb R. A. and Hickman S. H., “Stress Induced Borehole Elongation: a Comparison between the Four-arm Dipmeter and the Borehole Televiewer in the Auburn Geothermal Well,” Journal of Geophysical Research, 1985, 90, 5513–5521.
Peska P. and Zoback M. D., “Compressive and Tensile Failure of Inclined Borehole and Determination of In Situ Stress and Rock Strength,” Journal of Geophysical Research, 1995, 100, 12791–12811.
Asquith G. and Krygowski D. “Basic Well Log Analysis”, AAPG Methods in Exploration, 2004, Series 28, 244.
Ekstrom M. P., Dahan C. A., Chen M. Y., Lloyd P. M. et al., “Formation Imaging with Microelectrical Scanning Arrays,” Log Analyst, 1987, 28, 294-306.
Hung J. H., Ma K. F., Wang C. Y., Song S. R., et al., “Subsurface Structure, Fault Zone Characteristics and Stress State in Scientific Drill Holes of Taiwan Chelungpu Fault Drilling Project,” Scientific Drilling, No 1, 2007, 55–58.
Barton C. A. and Zoback M. D., “Discrimination of Natural Fractures from Drilling Induced Wellbore Failures in Wellbore Image Data Implications for Reservoir Permeability,” Paper SPE 58993, Presented at the SPE International Petroleum Conference and Exhibition in Mexico, Villahermosa, Mexico, 2000, 1–3 February., The World Stress Map (WSM) Project, 2008.
Ghorbani Ghashghai I., “Geological Study a Static Model Construction of Asmari Reservoir in Lali Oilfield,” 2008, NISOC, 6409.
Brudy M., and Kjoholt H., “Stress Orientation on the Norwegian Continental Self-derived from Borehole Failures Observed in High-resolution Borehole Imaging Logs,” Tectonophysics, 2000, 337, 65–84.
Yaghoubi A. and Zeinali M., “Determination of Magnitude and Orientation of the In Situ Stress from Borehole Breakout and Effect of Pore Pressure on Borehole Stability: Case Study in Cheshmeh Khush Oil Field of Iran,” Journal of Petroleum Science and Engineering, 2009, 67, 116-126