Determination of anisotropic moduli of earth formations
AssigneeSchlumberger Technology Corporation
InventorsBikash K. Sinha, Colin Michael Sayers, Takeshi Endo
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Abstract
A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, including measuring sonic velocity properties in formations surrounding the substantially vertical section of the wellbore; measuring sonic velocity properties in formations surrounding the deviated section of the wellbore; and determining, from the measured velocities, all of the transverse isotropic elastic constants of the region.
Claims21
A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, comprising the steps of:
- measuring sonic velocity properties in formations surrounding the substantially vertical section of said wellbore;
- measuring sonic velocity properties in formations surrounding the deviated section of said wellbore;
- and
- determining, from the measured velocities in said substantially vertical and deviated sections of the formations, all of the transverse isotropic elastic constants of said region.
A method for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having a deviated section therethrough, comprising the steps of:
- measuring sonic velocity properties in formations surrounding said deviated section of said wellbore;
- determining the ratio of axial to radial components of polarization associated with quasi-compressional or quasi-shear waves in formations surrounding said deviated section of said wellbore;
- and
- determining, from the measured velocities and said determined ratio in said deviated sections of the formations, all of the transverse isotropic elastic constants of said region.
A method for determining properties of a region of earth formations that is transverse isotropic, traversed by a wellbore having a substantially deviated section therethrough, comprising the steps of:
- measuring compressional velocity in formations surrounding said substantially deviated section of wellbore;
- measuring two orthogonally polarized shear velocities in said formations surrounding said substantially deviated section of wellbore;
- and
- determining three elastic parameters of the formations surrounding said substantially deviated section of wellbore.
A method for determining properties of a region of earth formations having orthorhombic or monoclinic symmetry with respect to a wellbore traversing said region of formations, comprising the steps of:
- measuring two orthogonally polarized shear velocities in formations surrounding said wellbore in said region;
- measuring the tube wave velocity in formations surrounding said wellbore in said region;
- and
- determining, from said measured shear velocities and tube wave velocity, three shear moduli referred to the wellbore axis, of said region of formations.
Apparatus for determining properties of a transverse isotropic region of earth formations traversed by a wellbore having substantially vertical and deviated sections therethrough, comprising:
- means for measuring sonic velocity properties in formations surrounding the substantially vertical section of said wellbore;
- means for measuring sonic velocity properties in formations surrounding the deviated section of said wellbore;
- and
- means for determining, from the measured velocities in said substantially vertical and deviated sections of the formations, all of the transverse isotropic elastic constants of said region.
Dependencies are inferred from the claim text.