This paper presents a comparison of several methods that can be used to obtain in-situ stress field data in an oil/gas well. In an offshore well recently drilled in the Arabian Gulf, the following techniques were used to acquire data used in the design of hydraulic fracture treatments for the well:
Microfrac pressure analysis yielded information about the magnitude of the minimum principal stress.
A borehole extensometer used during the microfrac testing gave additional information: the in-situ shear modulus, the orientation of the principal stress axes, the actual orientation of the created fracture, and the width of the fracture.
Anelastic strain recovery (ASR) was employed as a secondary method to determine the orientation of principal stress axes.
Oriented coring after microfrac testing was used to recover a portion of the actual microfrac and determine the orientation.
A borehole scanning record was used to determine the orientation of natural fractures.
A multi-arm caliper log was used for wellbore ellipticity evaluation, while borehole breakout was used as an indicator for the orientation of principal stress axes.
The results obtained are compared and discussed based on general knowledge of the regional stress field variations as obtained from geological surveys. In addition, rock properties obtained from core sample tests and from processing of an acoustic wireline record were compared with the data calculated from the wellbore extensometer. A comparison of the various methods for determining the magnitude and orientation of the in-situ stress field demonstrate the relative reliability, for this case, of the individual methods. This paper demonstrates the necessity of using several methods to obtain reliable in-situ stress data.