Anisotropy and Maximum In-situ Stress Determination Using DSI Log

Document Type : Research Paper

Authors

1 Anisotropy and Maximum In-situ Stress Determination Using DSI Log

2 Department of Earth Science, Faculty of Geology, Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Research Institute of Petroleum Industry (RIPI), Tehran, Iran

Abstract

Anisotropy is defined as the variation of the properties of a medium in different directions. The accurate determination of anisotropy is very important in exploration geophysics studies, reservoir geophysics, the detection of appropriate drilling direction and the prevention of sand problems .The DSI tools measure shear waves slowness in two directions perpendicular to each other and parallel to the well axis. Anisotropic zones and the maximum in situ stress can be determined by using DSI log and mathematical method of Alford Rotation. The large difference between the maximum and minimum values, especially when the minimum energy is low, shows zones with significant anisotropy. In this study, the anisotropy of a carbonate reservoir was studied and the maximum in situ stress was determined. In the interval discussed, isotropic and anisotropic zones were separated. The maximum in situ stress from DSI has been determined to N30E direction, which is in agreement with the direction resulted from FMI (N19E) and the maximum stress in Zagros.

Keywords


[1]. Armstrong P., Ireson D., Chmela B., Dodds K., Esmersony C., Miller. D., Hornby B., Sayers C., Schoenberg. M., Leaney. S., and Lynn. H., The Promise of Elastic Anisotropy., Oilfield Review Vol. 6, No. 4, pp. 36-47, 1994.##
[2]. Winterstein D. f., “Velocity anisotropy terminology for geophysicists”, Geophysics, Vol. 55, pp. 1070-1088, 1990.##
[3]. Schlumberger, Fractured reservoir characterization using seismic anisotropy, 2003.##
4. Helbig K. and Thomsen L., “75-plus years of anisotropy in exploration and reservoir seismics: A historical reviewof concepts and methods”, Geophysics, Vol. 70, No. 9-23, 2005.##
[5]. Thomsen L., “Weak elastic anisotropy”, Geophysics, Vol. 51, pp. 1954-1966, 1986.##
[6]. Alford R. M., “Shear Data in the Presence of Azimuthal Anisotropy”, Dilley, Texas, 56th SEG Annual International Meeting, Houston, pp. 476-479, 1986.##
[7]. خوشبخت، ف،. ارزیابی ناهمسان‌گردی یک مخزن کربناته با استفاده از لاگ دو قطبی- برشی DSI، مجموعه مقالات سی‌امین گردهمایی علوم زمین، سازمان زمین‌شناسی و اکتشافات معدنی کشور، 1390.##
[8]. Brie A., Endo T., Hoyle D., Codazzi D., Esmersoy C., Hsu K., Denoo S., Mueller M.C., Plona T., Shenoy R., and Sinha, B., “New Directions in Sonic Logging”, Oilfield Review, Vol.4, No.1, pp. 40-55, 1998.##
[9]. Brie A., Endo T., Johnson D. L., and Pampuri F., “Quantitative formation permeability evaluation from Stoneley waves”, SPE Reservoir Eval. Eng, Vol.3, No.2, pp. 109–117, 2000.##
[10]. Esmersoy C., Kane M., Boyd A., and Denoo S., “Fracture and stress evaluation using dipole-shear anisotropy logs”, Transaction of the SPWLA 36th Annual Logging Symposium, Paris, France. 1995.##
[11]. Schlumberger Wireline and Testing, DSI Dipole Shear Sonic Imager. Houston, Texas, USA, 1995.##