Schlumberger Technology Corporation

Dennis J Pittman

Andrew J Hayman

Philip S Cheung

Abdurrahman Sezginer

Kamal Babour

Richard Bloemenkamp

Henri Denoix

Roel Van Os

Pierre Mouget

Viet Tung Nguyen

Christian B Huau

Xiang Sun

An electrical assembly of a downhole tool utilized within a wellbore extending into a subterranean formation. The electrical assembly includes a housing substantially formed of thermoplastic material, an electronic device sealed within the housing, and an electrode or sensor sealingly embedded within a wall of the housing and electrically connected with the electronic device.

Encapsulated sensors and electronics

The invention concerns an apparatus for investigating the wall of a borehole tilled with non-conductive mud, said apparatus comprising: a pad having an inside face and an outside face for pressing against the wall of the borehole; a set of measurement electrodes mounted on the outside face of the pad, potentials differences being measured between said measurement electrodes in order to provide measured points representative of the resistivity of the formation; both a source electrode and a return electrode adapted to inject current into the formation, the set of measurement electrodes being situated between the source electrode and the return electrode.

Method and apparatus for imaging earth formation

The present invention relates to a method of investigating the wall () of a borehole in a geological formation by means of two injectors () with a potential V being applied between them and in measuring the potential difference &#x3b4;V between two electrically isolated measurement electrodes () situated between the two injectors () and spaced apart from the formation by an insulating layer (), in which the resistivity of the formation is obtained from the measured values of &#x3b4;V, V and I, with corrections being made for the effects due to the nature and the thickness of the insulating layer (). In a first variant these corrections are based on a correction factor obtained from curves of K=Rt.I/&#x3b4;V as a function of the impedance V/I of the injector. In a second variant these corrections are obtained by estimating the current Iactually injected into the formation while taking account of leakage current I, and calculating the resistivity of the formation from the equation (I). The invention also provides an investigation device enabling the values of Iand/or Ito be estimated.

Method and apparatus for investigating the wall of a borehole

The present invention relates to apparatus for a tool for investigating the wall of a borehole in a geological formation, the apparatus comprising: a non-conductive pad having an inside face and an outside face for pressing against the wall; a set of measurement electrodes mounted on the outside face of the pad and means for measuring the potential difference between two measurement electrodes; and both a source electrode adapted to inject current into the geological formation and a return electrode, the set of measurement electrodes being situated between the source electrode and the return electrode for the current; the apparatus being characterized in that the pad comprises an electrically conductive portion covering the entire measurement electrode zone and electrically insulated from the measurement electrodes.

Conductive pad around electrodes for investigating the wall of a borehole in a geological formation

In a well (10) in production or undergoing tests, the recovery of data acquired and stored in a downhole unit (16) located in the lower part of a drillpipe string (12) below a test valve (20) is effected directly in the form of acoustic signals between the downhole unit (16) and an interface tool (24). To this end, acoustic coupling is established between the tool (24) and the drillpipe string (12), and electro-acoustic transducers are provided in the tool and in the downhole unit (16). Commands are transmitted in the opposite direction, also in the form of acoustic signals, in particular to initiate data recovery. The transmission of data and commands between the tool (24) and the surface unit (22) is effected by any known means, for example in the form of electrical signals carried by a cable (26).

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Sorbiers, France

Dennis J Pittman