Well logging device

Claim 2

A well logging method for locating and defining wall defects along a section of a well casing, comprising: repeatedly transmitting a sequence of pulses of acoustic energy from a movable interior acoustic probe through a transmission medium to a wall surface of the well casing at selected locations along the section of the well casing: measuring a time interval between transmission of each pulse to the surface and reception of each echo pulse at the acoustic probe of the pulse from the wall surface of the well casing; measuring variations of transmissibility of the acoustic energy through the transmission medium at each selected acoustic probe location due to variations of temperature and composition of the transmission medium changes; and calculating the distance of the wall surface from the acoustic probe at each selected position as a function of the measured time interval and the measured variation of transmissibility to accurately determine whether the well casing has a defect at each selected location.

Claim 3

A well logging method, as defined in claim 1, wherein the calculation step further comprises: determining the distance of the wall surface from the acoustic probe for each pulse by application of the formula: D = VT/2 where: D = the distance between the wall surface and the probe; V = the transmissibility of the pulse through the transmission medium as determined at the selected acoustic probe location; and T = the interval between transmission of each pulse and reception at the acoustic probe of a corresponding echo of the pulse from the wall surface of the well casing.

Claim 4

A well logging method, as defined in claim 1, wherein the measuring of the variation of the transmissibility step comprises: transmitting a reference pulse of acoustic energy from the movable acoustic probe through the transmission medium at a selected location; receiving an echo of the reference pulse at the acoustic probe from a reference reflecting surface located a fixed distance from the acoustic probe; measuring a time interval between transmission of the reference pulse and reception of the echo of the pulse; calculating the transmissibility of the pulse through the transmission medium as a function of the fixed distance between the acoustic probe and the reflecting surface and the measured time interval between the transmission of the reference pulse and reception of the echo pulse from the reference reflecting surface.

Claim 5

A well logging device for locating and defining wall defects along a section of a well casing, comprising: an acoustic probe movable along the section of the well casing for transmitting a sequence of pulses of acoustic energy through a transmission medium to a wall surface of the well casing at selected locations along the section of the well casing and for receiving corresponding echo pulses from the wall surface of the well casing; means for measuring a time interval between transmission of each pulse and reception of a corresponding echo pulse from the wall surface of the well casing; means for measuring variations in the transmissibility of acoustic energy through the transmission medium at various selected acoustic probe locations due to temperature changes and variations in the composition of the transmission medium; means for calculating a distance between the acoustic probe and the wall surface of the well casing at each location as a function of the measured time interval between transmission of each pulse and the reception of a corresponding echo pulse from the wall surface of the well casing and the measured variations of the transmissibility of the acoustic energy through the transmission medium at each selected location to accurately detect defects in the well casing.

Claim 6

A well logging device for locating and defining wall defects along a section of a well casing, comprising: an acoustic probe movable along the section of the well casing for transmitting a sequence of pulses of acoustic energy through a transmission medium to a wall surface of the well casing at selected locations along the section of the well casing and for receiving corresponding echo pulses from the wall surface of the well casing; means for measuring a time interval between transmission of each pulse and reception of a corresponding echo pulse from the wall surface of the well casing; means for measuring variations in the transmissibility of acoustic energy through the transmission medium at various selected acoustic probe locations due to temperature changes and variations in the composition of the transmission medium; means for calculating a distance between the acoustic probe and the wall surface of the well casing at each location as a function of the measured time interval between transmission of each pulse and the reception of a corresponding echo pulse from the wall surface of the well casing and the measured variations of the transmissibility of the acoustic energy through the transmission medium at each selected location to accurately detect defects in the well casing.

Claim 7

A well logging device, as defined in claim 4, wherein the movable acoustic probe further comprises: a plurality of ultrasonic transducers for transmitting and receiving the pulses of acoustic energy; the ultrasonic transducers being angularly located about a center axis of the acoustic probe; and means for sequentially operating the ultrasonic transducers.

Claim 8

A well logging device, as defined in claim 4, wherein the means for measuring variations of the transmissibility comprises: a first reference ultrasonic transducer for transmitting a reference pulse of acoustic energy through the transmission medium at a selected location; a second reference ultrasonic transducer for receiving the reference pulse located at a fixed distance from the first ultrasonic transducer such that a sample of the transmission medium at a selected location is interposed between the first and second ultrasonic transducers; the ultrasonic transducers being located on the movable acoustic probe; means for measuring a time interval between transmission of the reference pulse and reception of the reference pulse; means for calculating the transmissibility of the reference pulse through the transmission medium as a function of the fixed distance between the two ultrasonic transducers and the time interval between transmission of the reference pulse and reception of the reference pulse to determine any variations in the transmissibility due to temperature changes and/or variations in the composition of the transmission medium.

Claim 9

A well logging device as defined in claim 6, where- - in the means for measuring variations in transmissibility further comprises: means for applying the formula: V = 2D/T to determine the transmissibility of the reference pulse through the transmission medium, where: V = the transmissbility of the reference pulse through a sample of the transmission medium as determined at the selected location; D = the fixed distance between the ultrasonic transducers; T = the time interval between transmission of the reference pulse from the first ultrasonic transducer and reception of the reference pulse at the second ultrasonic transducer.

Claim 10

A well logging device, as defined in claim 4, wherein the means for measuring the variations in transmissibility comprises: a reference ultrasonic transducer for transmitting a reference pulse of acoustic energy through the transmission medium at a selected location and for receiving an echo of the pulse; the ultrasonic transducer being located on the movable acoustic probe; a reflecting surface located a fixed distance from the ultrasonic transducer for reflecting the reference pulse; the reflector surface being located on the movable acoustic probe such that a sample of the transmission medium at a selected location is interposed between the ultrasonic transducer and a reflecting surface; means for measuring a time interval between transmission of the reference pulse and reception of the echo of the pulse; means for calculating the transmissibility of the reference pulse through the transmission medium as a function of the fixed distance between the ultrasonic transducer and the reflecting surface and the time interval between transmission of the reference pulse and reception of the echo pulse from the reflecting surface to determine any variations in the transmissibility due to temperature changes and/or variations in the composition of the transmission medium.

Claim 11

A well logging device, as defined in claim 8, wherein the reference transmissibility calculating means further comprises: means for applying the formula: V = 2D/T to determine the transmissibility of the reference pulse through the transmission medium, where: V = the transmissibility of the reference pulse through a sample of the transmission medium as determined at the selected location; D = the fixed distance between the ultrasonic transducer and the reflecting surface; T = the time interval between transmission of the reference pulse and reception of the echo of the reference pulse at the ultrasonic transducer.

Claim 12

The well logging method as defined in claim 1 wherein the sequence of pulses of acoustic energy is repeatedly transmitted through the transmission medium to an inner wall surface of the well casing and wherein the distance from the acoustic probe to the inner surface is calculated at each selected position to determine whether the well casing is deformed at any of the selected locations and obtain a profile of the well casing along the section of the well casing.

Claim 13

The well logging method as defined in claim 1 wherein the sequence of pulses of acoustic energy is repeatedly transmitted through the transmission medium to an inner wall surface and to an outer wall surface and wherein the time intervals between transmission of pulses to and from the inner and outer wall surfaces are measured and wherein the thickness of the well casing is calculated at each selected position to determine whether the well casing is defective at any of the selected locations.

Claim 14

The well logging method as defined in claim 1 wherein the sequence of pulses of acoustic energy is repeatedly transmitted through the transmission medium to an inner wall surface and to an outer wall surface and wherein time intervals between transmission of pulses to and from the inner and outer surfaces are measured and wherein the distance from the acoustical probe to the inner surface and the thickness of the casing are measured at each selected position to determine whether the well casing is deformed and whether the casing wall is defective at any of the selected locations and to obtain a profile of the well casing along the section of the well casing. of the microprocessor 21 determines the transmissibility of acoustic energy through the transmission medium.

Claim 15

(c) the transmissibility value becomes the basis (along with that of data from the other transducers 22) for calculation of the distance from the acoustic probe 10 to the inner surface 13 and to the outer surface 14 of the well casing 12.,

Claim 16

(c) the transmissibility value becomes the basis (along with that of data from the other transducers 22) for calculation of the distance from the acoustic probe 10 to the inner surface 13 and to the outer surface 14 of the well casing 12.,

Claim 17

Once the real time value for transmissibility of acoustic energy is determined, the distance of the inner surface 13 and the outer surfaces of the well casing 12 from the acoustic probe 10 are determined.

Claim 18

Once the real time value for transmissibility of acoustic energy is determined, the distance of the inner surface 13 and the outer surfaces of the well casing 12 from the acoustic probe 10 are determined.

Claim 19

In operation, pulses are transmitted from each ultrasonic transducer 22 to the inner surface 13 and to the outer surface 14 of the well casing 12. Reflections of the pulses from the inner surface 13 and the outer surface 14 are received at the transducer 22. The time-of-flight of the pulses (the time interval between transmission of the pulses and reception of the echo pulses of the pulse) is determined by timing means 16. The time value thus determined and the transmissibility value for that particular probe 10 location are used by a distance calculating component 20 of microprocessor 21 to determine the distances of the probe 10 from the inner surface 13 and outer surface 14 of the well casing 12. The distance and wall thickness information is then digitized by the digital to analog converter 23, amplified by line driver 25, and sent to the surface over the wire line 27 for display and recordation (Fig. 5).

Claim 20

In operation, pulses are transmitted from each ultrasonic transducer 22 to the inner surface 13 and to the outer surface 14 of the well casing 12. Reflections of the pulses from the inner surface 13 and the outer surface 14 are received at the transducer 22. The time-of-flight of the pulses (the time interval between transmission of the pulses and reception of the echo pulses of the pulse) is determined by timing means 16. The time value thus determined and the transmissibility value for that particular probe 10 location are used by a distance calculating component 20 of microprocessor 21 to determine the distances of the probe 10 from the inner surface 13 and outer surface 14 of the well casing 12. The distance and wall thickness information is then digitized by the digital to analog converter 23, amplified by line driver 25, and sent to the surface over the wire line 27 for display and recordation (Fig. 5).

Claim 21

Control information from the surface is received over the wire line 27 and amplified by receiver 29 before being routed to the microprocessor 21. Operating power is supplied over the wire line 27 and converted for use by the downhole electronics by the DC/DC converter 31.

Claim 22

Control information from the surface is received over the wire line 27 and amplified by receiver 29 before being routed to the microprocessor 21. Operating power is supplied over the wire line 27 and converted for use by the downhole electronics by the DC/DC converter 31.

Claim 23

Transducer 22 pulsing rates are controlled from uphole and can be selected to inspect in increments as small as 0.006 inches (from 0.006 inches to 0.036 inches) or at a preset rate up to approximately forty inspections per second for the full set of transducers. At the maximum inspection speed of 10 feet per minute, the arrangement provides inspection at approximately every 0.050 inches of the well casing 12. All eight well casing radius values and eight wall thickness values, for each inspection or scan cycle, are recorded uphole on magnetic disks for later playback if desired. Uphole, the eight well casing radius values are converted to four diameter values that are displayed on an updating TV display. The operator can choose the number of feet displayed on the TV screen, which is divided into approximately 200 pixels. Under normal operation, several feet of the last inspection may be displayed.

Claim 24

Transducer 22 pulsing rates are controlled from uphole and can be selected to inspect in increments as small as 0.006 inches (from 0.006 inches to 0.036 inches) or at a preset rate up to approximately forty inspections per second for the full set of transducers. At the maximum inspection speed of 10 feet per minute, the arrangement provides inspection at approximately every 0.050 inches of the well casing 12. All eight well casing radius values and eight wall thickness values, for each inspection or scan cycle, are recorded uphole on magnetic disks for later playback if desired. Uphole, the eight well casing radius values are converted to four diameter values that are displayed on an updating TV display. The operator can choose the number of feet displayed on the TV screen, which is divided into approximately 200 pixels. Under normal operation, several feet of the last inspection may be displayed.

Claim 25

Surface equipment (not shown) includes control and display consoles, cable metering equipment, and interconnecting cables. The control and display consoles at the surface have data storage and display capabilities. Surface equipment can also include a video display to "roll through" to show data, a dual pen script chart recorder to display minimum casing diameter and nominal wall thickness and various data recording devices, such as a disk drive.

Claim 26

Surface equipment (not shown) includes control and display consoles, cable metering equipment, and interconnecting cables. The control and display consoles at the surface have data storage and display capabilities. Surface equipment can also include a video display to "roll through" to show data, a dual pen script chart recorder to display minimum casing diameter and nominal wall thickness and various data recording devices, such as a disk drive.

Claim 27

The data collected are shown as a deviation from a nominal well casing diameter value and as a deviation from a nominal casing wall thickness. An advantage of the present system is that data can be recorded on a magnetic disk for replay at any later time. Transmission from a well casing probe 10 to the surface through a wire line 27 is digital to minimize ground loop effects. Control data functions and transmission rates for surface and downhole equipment are microprocessor controlled. Header information, such as time, date, well number, and any other pertinent information, is recorded on the magnetic disk through a keyboard entry on the surface consoles.

Claim 28

The data collected are shown as a deviation from a nominal well casing diameter value and as a deviation from a nominal casing wall thickness. An advantage of the present system is that data can be recorded on a magnetic disk for replay at any later time. Transmission from a well casing probe 10 to the surface through a wire line 27 is digital to minimize ground loop effects. Control data functions and transmission rates for surface and downhole equipment are microprocessor controlled. Header information, such as time, date, well number, and any other pertinent information, is recorded on the magnetic disk through a keyboard entry on the surface consoles.

Claim 29

The movable acoustic probe 10 is connected to surface equipment (not shown) via a wire line logging winch (not shown) and armored cable (not shown) . A cable meter (not shown) is placed at the well head to measure the probe depth and logging speed. The cable meter is included to synchronize a surface display to the acoustic probe 10 positions.

Claim 30

The movable acoustic probe 10 is connected to surface equipment (not shown) via a wire line logging winch (not shown) and armored cable (not shown) . A cable meter (not shown) is placed at the well head to measure the probe depth and logging speed. The cable meter is included to synchronize a surface display to the acoustic probe 10 positions.

Claim 31

As noted above, this description was given merely by way of example. Only the following claims are to be taken as definitions of this invention.