Abstract: Methods and apparatus for acoustic velocity well logging. Methods may include estimating a property of an earth formation, including estimating a depth-dependent lateral tectonic strain profile for the earth formation by generating a linear-to-linear transformation constrained to map a first value of a shear wave velocity parameter of the formation to an estimated minimum value of lateral tectonic strain in at least one direction corresponding to at least one principal horizontal stress of the formation, and map a second value of the shear wave velocity parameter of the formation to an estimated maximum value of lateral tectonic strain in the at least one direction, wherein the strain values may be estimated using closure pressure. The first value of the shear wave velocity parameter may be a minimum value of shear wave slowness and the second value of the shear wave velocity parameter is a maximum value of shear wave slowness.

Abstract: Methods and apparatus for acoustic velocity well logging. Methods may include estimating a property of an earth formation, including estimating a depth-dependent lateral tectonic strain profile for the earth formation by generating a linear-to-linear transformation constrained to map a first value of a shear wave velocity parameter of the formation to an estimated minimum value of lateral tectonic strain in at least one direction corresponding to at least one principal horizontal stress of the formation, and map a second value of the shear wave velocity parameter of the formation to an estimated maximum value of lateral tectonic strain in the at least one direction, wherein the strain values may be estimated using closure pressure. The first value of the shear wave velocity parameter may be a minimum value of shear wave slowness and the second value of the shear wave velocity parameter is a maximum value of shear wave slowness.

Abstract: A method of obtaining a hardness profile of a formation is disclosed. A testing surface in a wellbore impacts the formation to obtain a measurement of formation hardness. A lithological property of the formation is measured and used in determining the rock strength of the formation from the formation hardness. The testing surface may be propelled at the formation a plurality of times to obtain a profile of rock hardness measurements with distance into the formation, including at a surface layer of the formation. Alternatively, the testing surface can be propelled at the formation at multiple energies to obtain formation properties at a plurality of depths into the formation, including at a surface layer of the formation. The rock strength may be used with measurements of geomechanical stress and pore pressure to build a model of the formation in order to develop the formation.

Abstract: A method and apparatus for estimating a rock strength profile of a formation is disclosed. A tool having a testing surface is conveyed into a wellbore in the formation. The testing surface is propelled to impact the formation at a plurality of depths in the wellbore. A measurement of hardness of the formation is obtained from a rebound of the testing surface from the formation at the plurality of depths. The rock strength profile of the formation is estimated using the obtained measurements of hardness at the plurality of depths. A parameter for drilling the wellbore can be affected using the estimated rock strength profile.

Abstract: A method for validating earth formation data for input into a geophysical model includes: determining a lithology of the earth formation; receiving measurement data for a plurality of different properties of the earth formation rock; plotting data points for a first property versus a second property in a cross-plot using the received measurement data; plotting an expected correlation between the first property and the second property on the cross-plot for rock of the determined lithology; establishing an acceptance criterion for validating the data points related to the first property and the second property with respect to the expected correlation; determining which of the plotted data points fall within the acceptance criterion to provide validated data points related to the first property and the second property; and inputting the validated data points related to the first property and the second property into the geomechanical model.

Abstract: A method and apparatus for estimating a rock strength profile of a formation is disclosed. A tool having a testing surface is conveyed into a wellbore in the formation. The testing surface is propelled to impact the formation at a plurality of depths in the wellbore. A measurement of hardness of the formation is obtained from a rebound of the testing surface from the formation at the plurality of depths. The rock strength profile of the formation is estimated using the obtained measurements of hardness at the plurality of depths. A parameter for drilling the wellbore can be affected using the estimated rock strength profile.