EP0553908A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of and apparatus for making near-bit measurements while drilling
Assignee: Services Petroliers Schlumberger SA
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Filing: 1993-01-15
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Granted: —
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Expires: 2013-01-15
Abstract
Abstract In accordance with illustrative embodiments of the present invention, a measuring-while-drilling system includes a sensor sub (22) positioned at the lower end of a downhole motor assembly (14) so that the sub is located near the drill bit (13). The sub houses instrumentalities that measure various downhole parameters such as inclination of the borehole, the natural gamma ray emission of the formations, the electrical resistivity of the formations, and a number of mechanical drilling performance parameters. Sonic or electromagnetic telemetry signals representing these measurements are transmitted uphole to a receiver (T) associated with a conventional MWD tool located above the motor (14), and telemetered by this tool to the surface substantially in real time. The system has particular application to accurate control over the drilling of extended reach and horizontally drilled wells.
Inventors
- 👤 Jacques Orban
- 👤 Neil W. Richardson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 10:53
CPC Classifications
E; E21; E21B; E21B47/00; E21B47/12; E21B47/14; E21B47/16; E21B47/02; E21B47/022; E21B47/18; E21B7/00; E21B7/04; E21B7/06; E21B7/068
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
115 words
Apparatus for use in making downhole measurements during the drilling of a borehole using a bit at the bottom end of a drill string, said bit being rotated by a mud motor assembly having a power section, said apparatus comprising in combination: a measuring-while-drilling tool above said motor assembly and including first means for telemetering signals representative of downhole measurements to the surface; sensor means between said power section of said motor and said bit for making downhole measurements near said bit; and second means for telemetering signals representative of said downhole measurements from said sensor means to said first telemetering means to enable said first telemetering means to relay said signals to the surface.
Claim 2
Dependent Claim
53 words
The apparatus of claim 1 wherein said drill string has an internal bore and wherein said second telemetering means includes transmitter means for producing encoded signals which are representative of said measurements and for transmitting said encoded signals over a communication path that is external to said internal bore of said drill string.
Claim 3
Dependent Claim
30 words
The apparatus of claim 2 wherein said transmitter means includes means for producing sonic vibrations which are representative of said measurements and for coupling said vibrations to said drill string.
Claim 4
Dependent Claim
40 words
The apparatus of claim 2 wherein said transmitter means includes means for generating encoded electromagnetic signals that are representative of said measurements and pass through earth formations surrounding said borehole to an electromagnetic receiver associated with said first telemetering means.
Claim 5
Dependent Claim
36 words
The apparatus of claim 1 wherein said first telemetering means includes means for producing encoded pressure pulses in the mud stream inside the drill string which travel upward to the surface where said pulses are detected.
Claim 6
Dependent Claim
65 words
The apparatus of claim 1 further comprising: means included in said sensor means for making measurements of at least one of the following: gamma rays emanating naturally from the formations, electrical resistivity of the formations, inclination of the borehole, and motor performance characteristics; and means for focusing at least one of said gamma ray and said resistivity measurements to provide a generally azimuthal measurement thereof.
Claim 7
Dependent Claim
157 words
Apparatus for use in making downhole measurements during the drilling of a well bore with a drill string having a motor included therein that rotates a drill bit, said motor having a power section that drives an output shaft that is coupled to the bit and bearing means for stabilizing rotation of said bit and said shaft, said bearing means having a lower section adjacent the bit and an upper section spaced axially above said lower section, comprising: sensor means positioned between said upper and lower bearing sections, said sensor means including a tubular housing and a mandrel mounted inside said housing, said mandrel having a central bore through which a portion of said shaft extends; annular chamber means between said housing and said mandrel; means mounted in said chamber means for making said downhole measurements; and means for transmitting signals representative thereof upward along the drill string to a receiver that is located above said motor.
Claim 8
Dependent Claim
40 words
The apparatus of claim 7 further including means for sealing the upper and lower ends of said annular chamber means so that a power supply and electrical circuit means associated with said measuring means are located in an atmospheric environment.
Claim 9
Dependent Claim
32 words
The apparatus of claim 7 further including upper and lower means mounted externally on said housing for measuring the electrical resistivity of earth formations surrounding said well bore adjacent said sensor means.
Claim 10
Dependent Claim
91 words
The apparatus of claim 9 wherein said upper measuring means includes a first electromagnetic coil assembly for generating electrical currents which flow through walls of said housing and out into said formations below said lower measuring means and then return to said wall of said housing above said upper measuring means, and wherein said lower measuring means includes a second electromagnetic coil assembly for producing an electrical output that is related to a characteristic of the electrical current returning to the said walls of said housing above said upper measuring means.
Claim 11
Dependent Claim
25 words
The apparatus of claim 9 wherein one of said measuring means is mounted radially on said housing to provide a substantially laterally focused, azimuthal response.
Claim 12
Dependent Claim
60 words
The apparatus of claim 7 wherein said means for making said downhole measurements includes detector means for producing an output in the presence of gamma rays which emanate naturally from said formation; and further including means for substantially focusing the response of said detector means so that it responds primarily to gamma rays emanating from a selected outward radial direction.
Claim 13
Dependent Claim
103 words
The apparatus of claim 7 wherein said means for making said downhole measurements includes detector means for measuring the number of revolutions per minute of said drive shaft, said detector means comprising: a tubular housing having said shaft extending axially therethrough; means fixed to said shaft and carrying at least one magnet that rotates with said shaft; magnetically operable sensing means mounted on said housing adjacent the path of rotation of said magnet; and means associated with said sensing means for measuring the change in flux density opposite said sensing means as a function of time due to rotation of said magnet therepast.
Claim 14
Independent Claim
105 words
A method for directionally drilling a borehole into a targeted earth formation with a tool string that includes a drilling motor that drives a bit on the lower end of a drill string, comprising the steps of: curving said borehole until its lower end is within said targeted formation; drilling ahead while substantially within said targeted formation; measuring one or more characteristic properties of the earth formations adjacent the borehole which provide an indication if the borehole is approaching the top or the bottom of said targeted formation; and if said indication is given, deviating the wellbore such that it remains within said targeted formation.
Claim 15
Dependent Claim
33 words
The method of claim 14 wherein said measuring step includes azimuthally sensing naturally occurring gamma radiations from the formation by measuring primarily those radiations coming into the borehole from a selected radial direction.
Claim 16
Dependent Claim
24 words
The method of claim 14 wherein said measuring step includes generally azimuthally determining the electrical resistivity of the formation in a selected radial direction.
Claim 17
Dependent Claim
61 words
The method of claim 14 including the further steps of making said measurements in the lowermost section of the borehole below said drilling motor; telemetering first signals representative of said measurements to detector means in the drill string above said motor; detecting said first signals; and then telemetering second signals representative of the detected signals to the top of the borehole.
Claim 18
Dependent Claim
23 words
The method of claim 17 wherein said first signals are in the form of sonic vibrations that travel upward through said drill string.
Claim 19
Dependent Claim
28 words
The method of claim 17 wherein said second signals are in the form of encoded pressure pulses that travel upward through the mud stream inside the drill string.
Claim 20
Dependent Claim
80 words
The method of claim 16 wherein said electrical resistivity is determined by operating a first electromagnetic means that induces axial flow of current in the walls of a portion of said tool string which passes out into the earth formations and then returns to the walls of said tool string above said first electromagnetic means; and using a second electromagnetic means spaced below said first electromagnetic means to sense the magnitude of the current flow that returns to said walls.
Claim 21
Dependent Claim
198 words
Apparatus for use in measuring the electrical resistivity of earth formations surrounding a borehole adjacent a drill bit that is rotated by a mud motor assembly, comprising: sensor means including a tubular housing located adjacent the lower end of said motor assembly; upper electromagnetic means on said housing including a first insulated ring member having a first coil of insulated conductor wire wound thereon; lower electromagnetic means on said housing and being closely spaced to said upper electromagnetic means, said lower means including a second insulated ring member having a second coil of insulated conductor wires wound thereon; sleeve means providing a protection for each of said upper and lower electromagnetic means; and insulation means between said sleeve means and housing arranged in a manner such that some of the electric currents produced through operation of said upper electromagnetic means flow downward through the walls of said housing and to pass out into the earth formations at locations below said lower electromagnetic means, and other of said electric currents are permitted to flow out of the walls of said housing through said sleeve means and into the well annulus at locations between said upper and lower electromagnetic means.
Claim 22
Independent Claim
188 words
A method of transmitting signals representing downhole measurements from a measurement sub positioned near the bit in a drill string that includes a mud motor assembly and a measuring and telemetry tool in the drill string above the mud motor assembly, comprising the steps of: making measurements with said measurement sub and producing a telemetry frame of encoded signals that represents each of said measurements; using said encoded signals to drive a transmitter that produces sonic vibrations and couples said vibrations into the walls of the drill string; transmitting said vibrations up through the walls of the drill string to a receiver that is associated with said measuring and telemetry tool; sensing said vibrations with said receiver and producing output signals representative thereof; processing said output signals to convert them into digital signals; feeding said digital signals to said measuring and telemetry tool; and using said measuring and telemetry tool to transmit to the surface pressure pulses in the drilling mud that represent said digital signals, so that said pressure pulses can be detected and decoded at the surface to reproduce the said measurements for display and analysis.
Claim 23
Dependent Claim
36 words
The method of claim 22 including the steps of exciting said transmitter in a manner such that it produces sequences of individual bursts of sonic vibrations; and timing said bursts such that they provide digital data.
Claim 24
Dependent Claim
33 words
The method of claim 22 wherein said sensing step includes recognizing patterns of said digital output signals; and converting said patterns to digital signals which are fed to said measuring and telemetry tool.
Claim 25
Dependent Claim
32 words
The method of claim 22 further including the steps of filtering said output signals; storing the filtered signals in a register; and sensing the content of said register at selected time intervals.
Claim 26
Dependent Claim
35 words
The method of claim 22 including the step of operating said receiver in a manner such that it resonates at the carrier frequency to thereby act as a band-pass filter to provide improved noise rejection.
Claim 27
Independent Claim
111 words
A method of making near-bit measurements with a sensor sub located adjacent the low end of a drilling motor assembly, said sensor sub having a power supply for providing electrical power to associated measuring means on said sub, comprising the steps of: providing said measurement means with electrical power from said power supply during operation of said drilling motor; switching off said power supply when said motor is not operating to conserve energy furnished by said power supply; and switching said power supply back on when said drilling motor starts operating, said switching being accomplished in response to a measurement of the rpm of the drive shaft of said drilling motor.
Claim 28
Independent Claim
191 words
A method of telemetering signals representing downhole measurements from a measurement sub positioned near the bit in a drill string that includes a mud motor assembly and a measuring and telemetry tool in the drill string above said motor assembly, comprising the steps of: making measurements with said sub and providing a telemetry frame of encoded signals that represents each of said measurements; energizing a transmitter coil on said sub with said signals which induces electrical currents to flow downward through the walls of said sub, out into the earth formations surrounding the lower portion of said drill string, upward through said formations, and then back into the walls of said drill string adjacent said measuring' and telemetry tool, said telemetry frame of signals being encoded by causing periodic shifts in the phase of said induced electrical currents; sensing the returning currents adjacent said measuring and telemetry tool with a receiver coil that produces output signals in response to said returning currents; decoding said output signals; and using said decoded signals to cause said measuring and telemetry tool to transmit other signals to the surface which represent each of said measurements.
References Cited (Backward Citations)
No citation records indexed.
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