A DCAMM seminar will be presented by
\nPrincipal Reservoir Engineer Ole Jørgensen
\nMærsk Oil and Gas A/S
\nCopenhagen, Denmark
Abstract:
\n
\nStress-induced elastic anisotropy results in earth materials when moduli are stress dependent and the state of stress is non-hydrostatic. A known example is that of a borehole, where stress concentration effects cause a complex spatial variation of elastic anisotropy. Here the appropriate material model is that of an elastic orthorhombic medium with material axes locally aligned with the principal axes of stress.
\n
\nThe dispersion characteristics of waves propagating along a borehole in a stress-sensitive formation are studied for the purpose of
\ninversion. To include sensitivity to stress in the analysis, a finite-element modeling approach which includes the stress-velocity
\nrelationship, the perturbed stress and velocity field near the borehole, and solutions to the full coupled anisotropic and 3D wave equation
\nis derived.
\n
\nOf particular interest is the phase velocity of the quadrupole wave, which at low frequencies provides an estimate of formation shear-
\nwave velocity. Results indicate that the quadrupole mode dispersion is relatively insensitive to the hoop stress effects around the borehole giving greater confidence to shear-wave estimates made from these modes.
\n
\nThe proposed ring-element formulation, which includes Fourier expansions of the field variables in the direction of the circumference,
\ncan be adapted to include a finite-length borehole. On this note the feasibility of “looking a head of the drill-bit” applications will be discussed.
Danish pastry, coffee and tea will be served 15 minutes before the seminar starts.
\nAll interested persons are invited.
X-ALT-DESC;FMTTYPE=text/html:A DCAMM seminar will be presented by
\nPrincipal Reservoir Engineer Ole Jørgensen
\nMærsk Oil and Gas A/S
\nCopenhagen, Denmark
Abstract:
\n
\nStress-induced elastic anisotropy results in earth materials when moduli are stress dependent and the state of stress is non-hydrostatic. A known example is that of a borehole, where stress concentration effects cause a complex spatial variation of elastic anisotropy. Here the appropriate material model is that of an elastic orthorhombic medium with material axes locally aligned with the principal axes of stress.
\n
\nThe dispersion characteristics of waves propagating along a borehole in a stress-sensitive formation are studied for the purpose of
\ninversion. To include sensitivity to stress in the analysis, a finite-element modeling approach which includes the stress-velocity
\nrelationship, the perturbed stress and velocity field near the borehole, and solutions to the full coupled anisotropic and 3D wave equation
\nis derived.
\n
\nOf particular interest is the phase velocity of the quadrupole wave, which at low frequencies provides an estimate of formation shear-
\nwave velocity. Results indicate that the quadrupole mode dispersion is relatively insensitive to the hoop stress effects around the borehole giving greater confidence to shear-wave estimates made from these modes.
\n
\nThe proposed ring-element formulation, which includes Fourier expansions of the field variables in the direction of the circumference,
\ncan be adapted to include a finite-length borehole. On this note the feasibility of “looking a head of the drill-bit” applications will be discussed.
Danish pastry, coffee and tea will be served 15 minutes before the seminar starts.
\nAll interested persons are invited.
URL:http://www.dcamm.dk/da/Kalender/2014/12/Seminar_No_678 DTSTAMP:20261101T165000Z UID:{0BF98EF2-B6C5-41A3-B6BF-A16224F39C5B}-20141210T140000-20141210T140000 LOCATION: Room 105, Building 404 , DTU, Technical University of Denmark END:VEVENT END:VCALENDAR