A vertical well is drilled to a depth of 4000 ft in an oil field. By considering the data given in Table, a) Calculate the in-situ stress values (vertical and horizontal) for rock formations located around the bottom of the wellbore. b) Calculate the normal and shear stresses at the bottom of the wellbore wall in a Cartesian coordinate system. (Give all calculation steps) Unit weight (kN/m') Biot's Poisson's Pore pressure gradient (psi/ft) constant ratio 22.5 1 0.25 0.40