Published online by Cambridge University Press: 04 March 2021
Total stresses are an important control on pore pressure and fluid flow in sedimentary basins. The magnitude of the total stresses must be known in order to estimate the pore pressure. When pore pressure exceeds the least principal stress, hydraulic fracturing can occur and, if so, fluids are rapidly drained. This can occur naturally or during drilling. I first describe how to estimate the overburden stress, which is commonly assumed to equal the vertical stress and the fracture initiation pressure in a borehole. Zoback (2007) provides an extensive overview of these issues.