Method for verifying the correct operation of a safety valve of an oil well

• US 5,365,769 A
• Filed: 12/14/1992
• Issued: 11/22/1994
• Est. Priority Date: 03/08/1991
• Status: Expired due to Fees

• Current Assignee: ELF Aquitaine Production
• Original Assignee: ELF Aquitaine Production
• Inventors: Ferry, Jean-Claude
• Primary Examiner(s): Williams, Hezron E.
• Assistant Examiner(s): FAYYAZ, NASHMIYA SAQIB
• Application Number:
  US07/946,344
• Time in Patent Office: 708 Days
• Field of Search: 73/4 R, 73/168, 166/321, 166/322
• US Class Current: 73/1.71
• CPC Class Codes: E21B 34/10 operated by control fluid supplied from outside the borehole
• CPC Class Codes: E21B 47/00 Survey of boreholes or wells monitoring pressure or flow of drilling fluid E21B21/08
• CPC Class Codes: E21B 47/117 Detecting leaks, e.g. from tubing, by pressure testing
• CPC Class Codes: F16K 37/0091 by measuring fluid parameters
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00

Abstract

A method of verifying that a safety valve, normally biased to a closed position and opened by hydraulic pressure applied thereto by a fluid supplied at a constant flow rate, is operating correctly within an oil well involves comparing reference and operating curves associated with the valve. The reference curve represents the hydraulic pressure over time applied to the safety valve to open the valve when the valve is operating correctly. The operating curve is prepared with the safety valve installed within an oil well and also represents the hydraulic pressure over time applied to the safety valve to open the valve. Any deviation between the reference and operating curves indicates a potential malfunction and, possible, a precise type of malfunction associated with the safety valve.

Claims

1. A method of verifying that an oil well safety valve, normally biased to a closed position and opened by hydraulic pressure applied thereto by a fluid supplied at a constant flow rate, is operating correctly when installed within the oil well comprising:

preparing a reference curve of applied hydraulic pressure versus elapsed time prior to installation of the safety valve in the well and when the safety valve is known to be operating correctly, said curve being prepared by applying hydraulic pressure to the safety valve by supplying fluid at a constant flow rate causing the safety valve to open;

preparing an operating curve of applied hydraulic pressure versus elapsed time when the valve is installed within the oil well, said operating curve also being prepared by applying hydraulic pressure to the safety valve by supplying fluid at a constant flow rate causing the safety valve to open; and

comparing the reference and operating curves in order to determine if the safety valve is operating correctly.

2. The method according to claim 1, wherein a deviation between said reference and operating curves indicates a potential malfunction associated with the safety valve.

3. The method according to claim 2, wherein the deviation indicates a precise type of malfunction associated with the safety valve.