Determination of the in-situ stresses direction in the Sarvak formation in one of the West Iranian oil fields

The image logs interpretation from two wells in a fold hosting a west Iranian oil field located in the Dezful Embayment, SW Iran reveal the occurrence of two major systems of natural fractures. In the central part of the fold, the fold-related fractures include two sets of fractures trending N53°E and N34°E. In the eastern and also curved part of the fold, the strike of open fractures varies from N85°E to S85°W with average dip of 63 degrees. Due to operation of the sinistral strike-slip fault, an anticlockwise deflection of fold axis was occurred, which caused to change the orientation and density of fractures in the curved part of the fold. Based on the orientation of the induced fractures and borehole breakouts, the mean present-day maximum horizontal stress orientations varies from N55°E to N30°E in the central and eastern parts of the fold. The SHmax orientations observed in wells located in the eastern and central parts of the fold are nearly consistent with SHmax orientations derived from nearby earthquake focal mechanism solutions and also with the absolute plate motion direction of the Arabian plate in the Dezful Embayment. Due to reactivation of the NE–SW oriented strike–slip faults, the mean shortening direction in the Zagros folds and thrust belt can be changed in the south Dezful Embayment. Drilling of production wells that are highly-deviated or horizontal and oriented approximately towards the present-day stress SHmax are likely to both intersect more hydraulically conductive fractures and reduce wellbore instability problems.