Case Studies On Stress Pattern Around Salt Bodies In Deep Water Formations

Shen, X. (Halliburton)


For the 1-dimensional (1D) prediction of the mud-1) pore pressure (PP), overburden gradient (OBG), and weight windoww (MWW), the following input is required: effective stresss ratio and/or Poisson's ratio; 2) cohesive strength (CS), friction angle, (FA) and/or uniaxial compression strength (UCS), and tectonic factor. The first part of the input data is required for the prediction of the upper bound of the MWW, which is the so-called fracture gradient (FG); the second part of input data is used for the prediction of the lower bound of MWW, which is shear failure gradient (SFG). Among these parameters, the effective stress ratio is used in the calculation of minimum horizontal stress (also termed as FG), and the tectonic factor is used in the calculation of maximum horizontal stress. Poisson's ratio is an alternative for the input of the effective stress ratio. In conventional 1D analytical software, such as the Drillworks application [1], the effective stress ratio can be calculated in terms of Poisson's ratio at a point within the formation along the wellbore trajectory.