Apparatus and method for logging wells while drilling
First Claim
1. Measurement while drilling apparatus for detecting and communicating information relative to down-hole parameters and/or characteristics of the earth strata via an electrically conductive drill string composed of a plurality of lengths of metallic pipe connected end-to-end in series and through which a drilling fluid is caused to flow and then return to the surface through the well cavity formed between the exterior wall of the drill string and the interior wall of the well, comprising;
- DC voltage supply means for establishing a unidirectional biasing current passing through the electrically conductive drill string, the drill bit and the surrounding earth strata, said biasing current causing a magnetic field to be developed about said drill string;
ferro-fluid means disposed within said drilling fluid and including a colloidal suspension of ferro-magnetic particles cotaed with a non-conductive coating, said ferror-fluid means being carried by said drilling fluid through said well cavity wherein said ferro-magnetic particles are caused by said magnetic field to migrate toward the outer surface of said drill string and to form an insulative coating thereon;
down-hole module means for detecting down-hole parameters and/or characteristics of the surrounding earth strata and for developing a communicative current flow commensurate therewith in said conductive drill string; and
communication means coupled to said drill string at a point remote from said module means for receiving said communicative current flow.
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Accused Products
Abstract
Measurement while drilling apparatus for detecting and communicating information relative to downhole parameters and/or characteristics of the earth strata via an electrically conductive drill string composed of a plurality of lengths of metallic pipe connected end-to-end in series and through which a drilling fluid is caused to flow and then return to the surface through the well cavity formed between the exterior wall of the drill string and the interior wall of the well comprising a DC voltage supply for establishing a unidirectional biasing current passing through the electrically conductive drill string, drill bit and surrounding earth strata, a colloidal suspension of ferro-magnetic particles coated with a non-conductive coating forming a part of the drilling fluid and carried by the drilling fluid through the well cavity wherein the ferromagnetic particles are caused by the magnetic field to migrate toward the outer surface of the drill string and to form an insulative coating thereon, a downhole module for detecting downhole parameters and/or characteristics of the surrounding earth strata and for developing a communication current flow commensurate therewith in the conductive drill string, and a communication electronics coupled to the drill string at a point remote from the module for receiving the communicative current flow.
84 Citations
10 Claims
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1. Measurement while drilling apparatus for detecting and communicating information relative to down-hole parameters and/or characteristics of the earth strata via an electrically conductive drill string composed of a plurality of lengths of metallic pipe connected end-to-end in series and through which a drilling fluid is caused to flow and then return to the surface through the well cavity formed between the exterior wall of the drill string and the interior wall of the well, comprising;
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DC voltage supply means for establishing a unidirectional biasing current passing through the electrically conductive drill string, the drill bit and the surrounding earth strata, said biasing current causing a magnetic field to be developed about said drill string; ferro-fluid means disposed within said drilling fluid and including a colloidal suspension of ferro-magnetic particles cotaed with a non-conductive coating, said ferror-fluid means being carried by said drilling fluid through said well cavity wherein said ferro-magnetic particles are caused by said magnetic field to migrate toward the outer surface of said drill string and to form an insulative coating thereon; down-hole module means for detecting down-hole parameters and/or characteristics of the surrounding earth strata and for developing a communicative current flow commensurate therewith in said conductive drill string; and communication means coupled to said drill string at a point remote from said module means for receiving said communicative current flow. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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Specification