In-situ or present-day stress direction plays an important role for many science and engineering problems as geology, geophysics, rock mechanics, civil, mining, drilling and petroleum development. It is also a key parameter for engineering decisions in the petroleum exploration and production activities, such as borehole stability, hydraulic fracture stimulation, reservoir characterization and management. To estimate more exactly stress direction in boreholes where the conventional stress measurement techniques are almost impossible, the analysis of borehole failures observed from image logs has been used in the determination of in-situ stress direction.

In this work, we used high-resolution image logs in petroleum wellbores in the Cuu Long basin, offshore Vietnam, to analyze and estimate more properly the direction of in-situ maximum horizontal stresses in the Cuu Long basin. A detailed workflow to estimate the in-situ stress direction based the analysis of borehole failures observed from image logs of petroleum wellbores. The standard circular statistical methods are applied to determine an average maximum horizontal stress direction in each wellbore. These maximum horizontal stresses are oriented approximately North by Northwest - South by Southeast (NNW-SSE). Then, they are also quality ranked according to the World Stress Map (WSM) criteria for borehole failures interpreted from high-resolution image logs. Moreover, the correlation between the stress orientation assessed from borehole failures herein and other studies may provide more reliable information of the in-situ stress direction in the Cuu Long basin, offshore Vietnam.

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