Baker Hughes Corporation

Wallace H Meyer, Jr

Macmillan M Wisler

John W Harrell

Andrew G Brooks

James V Leggett, Iii

Larry Wayne Thompson

Jian-Qun Wu

Herbert W Beimgraben

MacMillian M Wisler

Daniel C Minette

Ronald Deady

Bernard G Hubner

Ronald J Deady

An arrangement of two closely spaced transmitters and two spaced apart receivers symmetrically disposed about the transmitters in a measurement while drilling tool avoids the effects of mutual coupling between the receivers. In one method of operation of the transmitters, each transmitter is sequentially activated while the other transmitter is decoupled to eliminate mutual coupling, and the recorded signals processed to take advantage of reciprocity relations. In another method of operation, both transmitters are operated simultaneously with one relative polarity and then with another relative polarity, to eliminate the effects of mutual coupling and to take advantage of reciprocity relations.

Method and apparatus for avoiding mutual coupling between receivers in

The present invention provides a measurement-while-drilling (MWD) system having a downhole computer and multiple downhole sensors. Relatively large amounts of basic or 'raw' data are measured by downhole sensors, and these data are processed within a downhole computer to be reduced to parameters of interest, which may be utilized to control the drilling operation by downhole devices, stored downhole, telemetered to the surface, or both. The measurements may be correlated downhole with stored reference data thereby providing additional information pertaining to the drilling operation. Downhole depth correlation between downhole measured parameters may be made by utilizing surface determined or downhole determined borehole depth.

Drilling system with downhole apparatus for determining parameters of

The current invention is directed toward the use of a downhole computer and downhole storage within a measurement-while-drilling (MWD) downhole subassembly to process data from the response of a plurality of sensors of different classes or one or more sensors of the same class which exhibit different measure points and vertical resolutions. Classes or types of sensors applicable to the invention include, but are not limited to, electromagnetic, acoustic, and nuclear. Sensor measurements are made essentially simultaneously. In combining downhole responses from one or more sensors to obtain parameters of interest, a critical prerequisite is downhole depth correlation and vertical resolution matching of all sensor responses prior to combination. Methods and apparatus are disclosed for performing these critical functions within the limits of telemetry and downhole storage capacities of current MWD systems, Alternate embodiments of the invention include wireline operations in which telemetry band width is limited by components such as single conductor logging cables employed in logging wells under high pressure.

Downhole depth correlation and computation apparatus and methods for

A wave propagation measurement-while-drilling system is used to determine selected formation and borehole properties. One or more transmitter-receiver pairs are utilized with the transmitter components operating at one or more frequencies to provide a measured data set. A model relating the borehole instrument response to a wide range of formation and borehole conditions is also utilized. Inversion techniques are employed to determine selected formation and borehole parameters of interest and to simultaneously correct the selected formation parametric measurements for the adverse effects of the borehole and formation bed boundaries thereby avoiding serial type corrections which can yield erroneous results in certain frequency ranges.

Multiple depths and frequencies for simultaneous inversion of

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Spring, TX, United States of America

Wallace H Meyer, Jr