Pravin K Gupta

US Patent:

58549919, Dec 29, 1998

Filed:

Apr 28, 1998

Appl. No.:

/067567

Inventors:

Pravin Gupta - Houston TX
Berthold F. Kriegshauser - Houston TX
Zeljko Jericevic - Houston TX
Otto N. Fanini - Houston TX

Assignee:

Western Atlas International, Inc. - Houston TX

International Classification:

G06F 1900

US Classification:

702 7

Abstract:

A method for determining the 2-dimensional distribution of horizontal and vertical electrical conductivities of earth formations surrounding a wellbore using measurements made by a transverse electromagnetic induction well logging instrument. A model is generated of the axial distribution of the horizontal and vertical conductivities, from induction signals acquired by the instrument using two-frequency alternating current. The model is generated by calculating an initial estimate of the conductivity distribution and axially inverting the estimate with respect to the measurements made using the two-frequency alternating current. Shoulder correction is applied to measurements made by the instrument using single-frequency alternating current. An estimate of the radial distribution of the conductivities is generated from the shoulder corrected induction signals acquired using the single-frequency alternating current. A 2-dimensional model is made of the conductivity distribution from the model of axial distribution and from the estimate of radial distribution.

US Patent:

59998849, Dec 7, 1999

Filed:

Mar 19, 1998

Appl. No.:

9/044741

Inventors:

Berthold F. Kriegshauser - Houston TX
Pravin Gupta - Houston TX
Zeljko Jericevic - Houston TX
Otto N. Fanini - Houston TX

Assignee:

Western Atlas International, Inc. - Houston TX

International Classification:

G01V 338

US Classification:

702 7

Abstract:

A method for estimating axial positions of formation layer boundaries from transverse electromagnetic induction signals. A first derivative is calculated with respect to depth of the induction signals. A second derivative of the signals is calculated. The second derivative is muted. Layer boundaries are selected at axial positions where the muted second derivative is non zero, and the first derivative changes sign. The selected boundaries are thickness filtered to eliminate boundaries which have the same axial spacing as the spacing between an induction transmitter and receiver used to measure the induction signals, and to eliminate boundaries having a spacing less than an axial resolution of the induction signals. In a preferred embodiment, the process is repeated using transverse induction measurements made at another alternating current frequency. Layer boundaries selected in both frequencies are determined to be the layer boundaries.

US Patent:

60443251, Mar 28, 2000

Filed:

Jul 21, 1998

Appl. No.:

9/119926

Inventors:

Srinivasa Chakravarthy - Houston TX
Pravin Gupta - Houston TX
Raghu Chunduru - Webster TX
Berthold F. Kriegshauser - Houston TX
Otto N. Fanini - Houston TX

Assignee:

Western Atlas International, Inc. - Houston TX

International Classification:

G06F 1900

US Classification:

702 7

Abstract:

A method for generating an improved estimate of horizontal conductivity, dip angle, azimuth and anisotropy parameter of an earth formation penetrated by a wellbore from dual-frequency transverse electromagnetic induction measurements, comprising generating an initial estimate of the horizontal conductivity, dip angle, azimuth and anisotropy parameter from the dual-frequency transverse induction measurements made at each one of a plurality of base frequencies. The initial estimates from each of the plurality of base frequencies are input into a primary trained neural network, and the improved estimate is calculated by the trained neural network. The network is trained by generating models of earth formations each having a known value of horizontal conductivity, anisotropy parameter, dip angle and azimuth. Voltages which would be measured by the transverse electromagnetic induction instrument in response to each model are synthesized. Initial estimates from the synthesized voltages are calculated and the initial estimates and known values from each of the models are input to the neural network to cause it to learn a relationship between the initial estimates and the known values.

US Patent:

59998830, Dec 7, 1999

Filed:

Mar 17, 1998

Appl. No.:

9/042982

Inventors:

Pravin Gupta - Houston TX
Berthold F. Kriegshauser - Houston TX
Otto N. Fanini - Houston TX

Assignee:

Western Atlas International, Inc. - Houston TX

International Classification:

G06F 1900
G01V 338

US Classification:

702 7

Abstract:

A method for determining an initial estimate of the horizontal conductivity and the vertical conductivity of an anisotropic earth formation. Electromagnetic induction signals induced by induction transmitters oriented along three mutually orthogonal axes are measured. One of the mutually orthogonal axes is substantially parallel to a logging instrument axis. The electromagnetic induction signals are measured using first receivers each having a magnetic moment parallel to one of the orthogonal axes and using second receivers each having a magnetic moment perpendicular to a one of the orthogonal axes which is also perpendicular to the instrument axis. A relative angle of rotation of the perpendicular one of the orthogonal axes is calculated from the receiver signals measured perpendicular to the instrument axis. An intermediate measurement tensor is calculated by rotating magnitudes of the receiver signals through a negative of the angle of rotation. A relative angle of inclination of one of the orthogonal axes which is parallel to the axis of the instrument is calculated, from the rotated magnitudes, with respect to a direction of the vertical conductivity.