Abstract: Estimating in-situ stress of an interval having drilling response data is described. Estimating involves obtaining drilling response data of a data rich interval with available data. Estimating relative rock strength as a composite value that includes in-situ stress and rock strength. Estimating a Poisson's ratio from the relative rock strength. Generating a stress model that includes uniaxial strain model using the Poisson's ratio. Verifying the stress model with the available data. Applying the stress models in a non-data rich interval.

Abstract: Unconventional reservoirs need hydraulic stimulation in all the wells to enhance permeability for an economic production, which accounts for a large part of the well expenditure. However, lack of accurate stress information leads to incorrect selection of producing intervals, which transforms to under-performance in production. An analytical solution is optimized to determine the principal horizontal stresses by integrating the concept of uniaxial elasticity and frictional equilibrium. The software tool allows estimation of the continuous solutions of stresses based on the frictional strength concept. A more realistic considerations of rock rheology in stress estimation and better estimate principal horizontal stress magnitude in the earth crust help in planning and executing hydraulic stimulation operation. The stress estimate also aids in planning important parameters to drill and complete the wells successfully.

Abstract: This disclosure describes a method for calculating the horizontal stresses that integrate both frictional equilibrium and uniaxial elasticity assumptions. The results are more accurate than either of the assumptions.