Method and apparatus for logging inclined earth boreholes

• US 4,282,523 A
• Filed: 04/18/1979
• Issued: 08/04/1981
• Est. Priority Date: 11/02/1977
• Status: Expired due to Term

• Current Assignee: Western Atlas International Incorporated (Northrop Grumman Corporation)
• Original Assignee: Dresser Industries Incorporated (Halliburton Company)
• Inventors: Youmans, Arthur H.
• Primary Examiner(s): Moskowitz, Nelson
• Application Number:
  US06/031,245
• Time in Patent Office: 839 Days
• Field of Search: 340/860, 73/151, 73/151.5
• US Class Current: 340/854.1
• CPC Class Codes: E21B 19/22 Handling reeled pipe or rod units, e.g. flexible drilling pipes lifting or hauling appliances using two or more cooperating endless chains B66D3/003
• CPC Class Codes: E21B 23/14 for displacing a cable or a cable-operated tool, e.g. for logging or perforating operations in deviated wells
• CPC Class Codes: E21B 45/00 Measuring the drilling time or rate of penetration
• CPC Class Codes: E21B 47/00 Survey of boreholes or wells monitoring pressure or flow of drilling fluid E21B21/08
• CPC Class Codes: G01V 11/002 Details, e.g. power supply systems for logging instruments, transmitting or recording data, specially adapted for well logging, also if the prospecting method is irrelevant means for transmitting well survey signals E21B47/12; signal transmission systems in general G08C; transmission in general H04B

Abstract

An improved technique is provided for comparing the velocity of an elongated well logging instrument traversing an inclined earth borehole with the playout velocity of the well logging cable at the earth'"'"'s surface to control both the cable hoist drum rotation and the rate of movement of the subsurface instrument and thus insure cable playout is in equilibrium with the logging instrument movement. Method and apparatus are described for detecting any reduction in movement of the logging instrument through the borehole and for reducing the velocity of the logging cable playout in response thereto by reducing drum rotation. Further, when the velocity of cable playout slows to a preselected value, a monitoring circuit generates control signals which actuate a means of power attached to or integral with the logging instrument which, upon initiation, apply a force to move the logging instrument upward or downward within the borehole.

Claims

1. A method for logging the formations surrounding an earth borehole, comprising the steps of:

traversing an earth borehole with a well logging instrument connected to a well logging cable wound around a rotatable cable hoist drum at the earth'"'"'s surface;

generating a signal functionally related to the velocity of said cable at the earth'"'"'s surface;

generating a signal functionally related to the velocity of said well logging instrument;

comparing said cable velocity signal with said instrument velocity signal and generating a differential signal indicative of the comparison; and

controlling the rotation of said cable hoist drum in response to said differential signal for matching said cable velocity to said instrument velocity,

generating a signal functionally related to the tension on said well logging cable;

comparing said tension signal with said instrument velocity signal and generating a second differential signal indicative of the comparison,

comparing said second differential signal with a preselected threshold signal; and

generating a drive signal for initiating motive means contained in said well logging instrument upon the occurrence of said second differential signal exceeding said preselected threshold level in order to assist with displacing a well logging instrument through an earth borehole.

2. Apparatus for logging the formations surrounding an earth borehole, comprising:

a rotatable hoist drum at the earth'"'"'s surface;

a well logging cable wound around said hoist drum;

an elongated well logging instrument connected to the earth'"'"'s surface by said well logging cable and adapted to traverse an earth borehole, the pay out of said cable being controlled by the rotation of said hoist drum,

means in said instrument for providing an indication of the velocity thereof during traverse of the earth borehole;

means at the earth'"'"'s surface for providing an indication of the velocity of said well logging cable at the earth'"'"'s surface;

means for comparing the velocity of said instrument with the velocity of said well logging cable and for generating signals indicative of such comparison; and

means interconnected between said means for comparing and for generating and said hoist drum responsive to said generated signals for controlling the rotation of said hoist drum to match the velocities of said logging instrument in said well logging cable

means connected to the well logging cable at the earth'"'"'s surface for detecting the tension placed on said instrument during traversal of the borehole;

means for comparing said tension signal with the velocity of said instrument during traverse of the earth borehole and generating a drive signal indicative of said comparison; and

means for comparing said drive signal with an electrical signal having a preselected threshold level for energizing a motive means contained in said logging instrument upon the occurrence of said drive signal exceeding said preselected threshold level in order to assist in displacing said well logging instrument through the borehole.