Electrical connectors – Combined with nonelectrical feature
Reexamination Certificate
2002-05-31
2003-11-04
Patel, Tulsidas (Department: 2839)
Electrical connectors
Combined with nonelectrical feature
C439S950000, C439S038000, C166S242600
Reexamination Certificate
active
06641434
ABSTRACT:
TECHNICAL FIELD
The present invention relates to apparatus and methods used in oil well drilling and oil well operations for transmitting measurement data to a surface station from locations in a borehole.
BACKGROUND OF THE INVENTION
Measurement While Drilling (MWD) and Logging While Drilling (LWD) systems derive much of their value from the ability to provide real-time information about conditions near the drill bit. Oil companies use these downhole measurements to make decisions during the drilling process, and sophisticated drilling techniques, such as the GeoSteering system developed by Schlumberger, Ltd. Such techniques rely heavily on instantaneous knowledge of the formation that is being drilled. The industry continues to develop new measurements for MWD/LWD, including imaging type measurements with high data content.
These new measurement and control systems require telemetry systems having higher data rates than those currently available. As a result, a number of telemetry techniques for use with measurement while drilling have been tried or proposed.
The industry standard is mud pulse telemetry that uses the drill pipe to guide acoustic waves in the drilling fluid. Currently, using mud pulse telemetry, data is sent to the surface at bit rates in the range of 1-6 bits/second. Such a slow rate is incapable of transmitting the large amounts of data that are typically gathered with an LWD string. In some cases (e.g., foamed drilling fluid), mud pulse telemetry does not work at all. Normally, some or all of the data is stored in downhole memory and downloaded at the end of the bit run. This delay significantly reduces the value of the data for real-time applications. Also, there is a significant risk of data loss, for example, if the tool is lost in the hole.
Electromagnetic telemetry via earth path has been tried with limited success. Even at very low data rates, it works only to a limited depth, depending on the resistivity of the earth.
Acoustic telemetry through the drill pipe itself has been studied extensively but not used commercially, so far. In theory, data rates in the 10's of bits/second should be possible using acoustic waves in the steel.
The idea of putting a wire in the drill pipe has been proposed numerous times over the past 25 years. Shell and Exxon each reportedly built an experimental wired drill string in the late 1970's. Prior art relating to these efforts is disclosed in U.S. Pat. No. 4,126,848 to Denison, “Drill String Telemeter System”; U.S. Pat. No. 3,957,118 to Barry et al., “Cable System for use in a Pipe String and Method for Installing and Using the same”; and U.S. Pat. No. 3,807,502 to Heilhecker et al., “Method for Installing an Electric Conductor in a Drill String”; and the publication “Four Different Systems Used for MWD”, W. J. McDonald, The Oil and Gas Journal, pages 115-124, Apr. 3, 1978. Such systems are believed to have suffered from poor reliability and high cost because of the large number of electrical connectors.
IFP developed a system known as “Simphor” which used wireline cables and large, robust wet connectors. It has never been commercialized for measurement while drilling applications. This system is believed to have suffered from interference with the drilling process.
The use of current-coupled inductive couplers in drill pipe is known. U.S. Pat. No. 4,605,268, to Meador, “Transformer cable connector” describes the use and basic operation of current-coupled inductive couplers mounted at the sealing faces of drill pipes. Russian Federation published patent application 2140527, “A method for drilling oblique and horizontal boreholes”, filed Dec. 18, 1997, and an earlier Russian Federation published patent application 2040691, “A system for transmitting electrical energy and data within a column of adjoining tubes”, filed Feb. 14, 1992, both describe a drill pipe telemetry system that uses current-coupled inductive couplers mounted proximate to the sealing faces of drill pipes. WO Publication 90/14497A2, by Eastman Christensen GMBH, “Process and device for transmitting data signals and/or control signals in a pipe train” describes an inductive coupler mounted at the ID of the drill pipe joint for data transfer.
Other US patents are as follows: U.S. Pat. No. 5,052,941 to Hernandez-Marti et al., “Inductive coupling connector for a well head equipment”; U.S. Pat. No. 4,806,928 to Veneruso, “Apparatus for electro-magnetically coupling power and data signals between well bore apparatus and the surface”; U.S. Pat. No. 4,901,069 to Veneruso, “Apparatus for electro-magnetically coupling power and data signals between a first unit and a second unit and in particular between well bore apparatus and the surface”; U.S. Pat. No. 5,531,592 to Veneruso; “Method and apparatus for transmitting information relating to the operation of a downhole electrical device”; U.S. Pat. No. 5,278,550 to Rhein-Knudsen, et al., “Apparatus and method for retrieving and/or communicating with downhole equipment”; and U.S. Pat. No. 5,971,072 to Huber et al., “Inductive coupler activated completion system”.
None of these references has provided a telemetry system for reliably transmitting measurement data at high data rates from locations near the drill bit to a surface station. Therefore, there exists a need for a telemetry system for reliably transmitting measurement data at high data rates to a surface station from locations in a borehole.
SUMMARY OF THE INVENTION
The present invention provides a robust, low-loss wired pipe joint for service as a component of a wired pipe string for transmitting measurement data to a surface station from locations in a borehole in oil well drilling and oil well operations. Conductive layers reduce signal energy losses over the length of the drill string by reducing resistive losses and flux losses at each inductive coupler. The wired pipe joint is robust in that it remains operational in the presence of gaps in the conductive layer.
A wired pipe joint in accordance with the present invention includes an elongate tubular shank having an axial bore, a threaded box-end, and a threaded pin end. A first annular coil, fixedly mounted to the box-end is partially surrounded by a first high-conductivity, low-permeability layer, and a second annular coil fixedly mounted to the pin-end is partially surrounded by a second high-conductivity, low-permeability layer, such that when the box-end of a first wired pipe joint is coupled for operation with the pin-end of a second wired pipe joint, the first and second high-conductivity, low-permeability layers form at least a portion of a toroidal path enclosing the first annular coil of the first wired pipe joint and the second annular coil of the second wired pipe joint. Coil windings of the first and second coils of the wired pipe joint are electrically coupled.
An inductive coupler in accordance with the present invention includes a threaded box-end with a first annular coil fixedly mounted thereto and a first high-conductivity, low-permeability layer partially surrounding the first annular coil. It further includes a threaded pin-end with a second annular coil fixedly mounted thereto and a second high-conductivity, low-permeability layer partially surrounding the second annular coil. A first electrical terminal is coupled to a first coil winding of the first annular coil, and a second electrical terminal is coupled to a second coil winding of the second annular coil. The threaded box-end, the threaded pin-end, and the two layers are structured such that when the threaded box-end is coupled for operation with the threaded pin-end, the first and second layers form at least a portion of a toroidal path enclosing the first and second annular coils.
A first preferred embodiment is shown in FIG.
1
.
FIG. 1
shows wired pipe joint including an elongate tubular shank having an axial bore, a first inductive coupler element at a box-end, and a second inductive coupler element at a pin-end. An inductive coupler is shown as constituted by a first inductive coupler element and a second induc
Boyle Bruce W.
Jundt Jacques
Madhavan Raghu
Jeffery Brigitte L.
Patel Tulsidas
Ryberg John J.
Salazar Jennie (JL)
Schlumberger Technology Corporation
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