Estimation of the horizontal in-situ stress magnitude and azimuth using previous drilling data

Abstract

Oil exploration and production, well stability, sand production, geothermal drilling, waste-water or CO₂ sequestration, geohazards assessment, and EOR processes such as hydraulic fracturing, require adequate information about in-situ stresses. There are several methods for analyzing the magnitude and direction of in-situ stresses. The evaluation of tensile fractures and shear fractures in vertical oil and gas wellbores using image logs is one of these methods. Furthermore, when image logs are run in boreholes, they can be extremely costly and possibly stop the drilling. The data for this study were gathered from seven directional wells drilled into a strike-slip fault reservoir in southern Iran. Vertical stress, minimum horizontal stress, pore pressure, Poisson's ratio of formations, and 233 mud loss reporting points make up the entire data. This is the first time maximum horizontal stress direction has been calculated without referring to image log data. In addition, the points of lost circulation were categorized into natural and induced fracture. The results revealed that, the maximum horizontal stress direction of the reservoir was calculated at 65° northeast-southwest. The error rate is roughly 10° when comparing the results of this investigation to those obtained from the image log. The maximum horizontal stress direction is calculated precisely. In terms of tensile fracture pressure, the in-situ stress ratio identifies the safest as well as the most critical inclination and azimuth for each well.