Schlumberger Technology Corporation

David Hoyle

Jahir A Pabon

Hitoshi Sugiyama

Hitoshi Tashiro

Frank Morris

Kazumasa Kato

David Leslie

Benoit G Froelich

Hiroshi Hori

Alain Brie

Akira Otsuka

A formation logging tool having a substantially continuous central mandrel with regularly spaced mass blocks disposed thereon, at least some of the mass blocks carrying sensors such as receivers. By adopting this structure, the tool can be made to behave as a mass-spring structure and its flexural and extensional behaviour controlled such that its dispersion curve does not extend into the dispersion curve of the formation to be logged. The structure can be applied to the whole of the logging tool or just to the receiver section and/or any spacer section between the receiver and the transmitter section.

Sonic logging tool including receiver and spacer structure

A sleeve for an acoustic logging tool has a structure with a window section having fewer bars than a conventional sleeve separated by a slotted region with thin circumferential slots which are stress-relieved at the ends (&ldquo;dumb-bell&rdquo; shaped). Steel receiver mounts are provided for hydrophone pressure sensors and this, together with the axially oriented hydrophones makes the tool less susceptible to interfering vibration.

Acoustic logging tool

A sleeve for an acoustic logging tool having a structure with a window section having fewer bars than a conventional sleeve separated by a slotted region with thin circumferential slots which are stress-relieved at the ends (&ldquo;dumb-bell&rdquo; shaped). Steel receiver mounts are provided for hydrophone pressure sensors and this, together with the axially oriented hydrophones, makes the tool less susceptible to interfering vibration.

A logging tool having a tool body, which can be positioned in a fluid-filled borehole, including a receiver section and a dipole transmitter; wherein the dipole transmitter includes a transducer with a shell having a reaction mass and a motor located therein, the motor operatively connecting the shell and the reaction mass such that only an outer surface of the shell is in contact with the fluid in the borehole. This new type of dipole source for well logging involves shaking all or part (axially) of a dipole tool body to produce a pure, broadband acoustic dipole signal while at the same time coupling as little energy as possible into the tool body. Important variations on this idea include a linear phased array of shaker sources, and active cancellation of tool borne noise.

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Slependen, Norway

David Hoyle