US 4,542,488 AGranted

Method and system for producing a PPI display

AssigneeMobil Oil Corporation

InventorsJames A. Clishem, Charles L. Dennis, Joseph Zemanek, Jr.

Life of this patent

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Abstract

A borehole logging tool employs an energy transmitter and receiver for scanning a borehole with energy pulses. An orientation pulse is produced each time the tool rotates past a predetermined orientation position. The time period between orientation pulses is measured and divided into a plurality of discrete intervals. Sine and cosine functions are generated for the measured time period having a sine and cosine value corresponding to each of the discrete intervals. The sine and cosine functions are used to produce sweep functions for controlling the outward sweep of the electron beam of a PPI display device so as to produce a circular rotating pattern in which each revolution corresponds in time to a measured time between orientation pulses. The output of the receiver modulates the electron beam sweep to generate a visual display of the azimuthal scan of the borehole.

Claims10

Dependent claims

A method for recording data obtained from azimuthal scanning operations within a borehole, comprising:

(a) cyclically rotating energy transmitting and receiving means in a borehole,
(b) operating said transmitting means during each cycle to transmit energy pulses,
(c) operating said receiving means to detect said energy pulses as they are reflected back to said receiving means,
(d) producing orienting pulses each time said transmitting and receiving means pass a known geographic orientation,
(e) measuring the time variable periods between said orienting pulses,
(f) producing sine and cosine functions in response to each of said orienting pulses, said sine and cosine functions having variable time periods corresponding to said measured time variable periods,
(g) producing first and second time variable sweep functions corresponding to said time variable sine and cosine functions respectively,
(h) applying one of said time variable sweep functions to the horizontal deflection means of a PPI display system and the other of said time variable sweep functions to the vertical deflection means of the PPI display system to rotate the sweep of the electron beam of the PPI display system in a reference circle corresponding in time to the time period between the pairs of time variable orientation pulses, whereby a uniform reference circle is continuously generated on the face of the PPI display medium, regardless of variability in the occurrences of said orienting pulses, and
(i) applying said detected energy pulses to the electron beam modulating means of said PPI display to produce an azimuthal display of said scanning operations.

6 more elements

A borehole logging system for producing an azimuthal scan of a borehole comprising:

(a) an energy transmitter and receiver assembly adapted to be moved through the borehole and rotated about the borehole axis,
(b) means for generating an orientation pulse each time said assembly passes a known geographical orientation,
(c) means for measuring the time variable periods between successive orientation pulses,
(d) means for dividing said measured time variable periods into a plurality of discrete intervals,
(e) means for producing sine functions and cosine functions in response to each of said orientation pulses and having time periods corresponding to said measured time variable periods, said sine and cosine functions having a plurality of sine and cosine values corresponding in number to said plurality of discrete intervals, and
(f) means for producing first and second time variable sweep functions having a plurality of sweep cycles corresponding to said plurality of sine and cosine values respetively,
(g) a PPI display device,
(h) means for applying said plurality of sweep cycles of said first and second time variable sweep functions to the electron beam deflection means of said PPI display device to produce a circular rotating beam sweep in which each revolution corresponds in time to one of said measured time variable periods, and
(i) means for applying the output of said energy transmitter and receiver assembly to the electron beam modulation input of said PPI display device so as to produce a visual display of the azimuthal scan of the borehole.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 06/400,842Filed 22 Jul 1982
Granted: 17 Sep 1985
Term ends: Not estimatedThe source records don’t support an estimate.

Classification8 codes

G01V 11/002
Prospecting or detecting by methods combining techniques covered by two or more of main groups G01V1/00 - G01V9/00: details, e.g. power supply…
E21B 47/0025
By visual inspection: generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric
E21B 47/024
Determining slope or direction: of devices in the borehole
E21B 47/085
Measuring diameters or related dimensions at the borehole: using radiant means, e.g. acoustic, radioactive or electromagnetic