Estimation of formation horizontal stress magnitudes using radial profiles of shear slownesses

Abstract

A new inversion algorithm yields estimates of the maximum and minimum horizontal stresses using radial profiles of the three shear moduli referred to an orthogonal set of axes defined by the three principal stress directions. This algorithm inverts differences in the far‐field shear moduli together with two difference equations obtained from the radial profiles of the dipole shear moduli and , and borehole stresses in the near‐wellbore region. Outputs from this inversion algorithm includes the maximum and minimum horizontal stress magnitudes, and an acoustoelastic parameter expressed in terms of two rock nonlinear constants referred to a local reference state. Difference equations in the shear moduli use radial positions away from the borehole surface that do not exhibit any plastic deformation. Results for estimated horizontal stress magnitudes obtained in a Piceance basin well are consistent with the post‐fracture microseismic data suggesting nearly isotropic horizontal stresses in a sand interval.