Downhole instruments for well operations

• US 5,512,889 A
• Filed: 05/24/1994
• Issued: 04/30/1996
• Est. Priority Date: 05/24/1994
• Status: Expired due to Term

• Current Assignee: Atlantic Richfield Company Incorporated (BP PLC)
• Original Assignee: Atlantic Richfield Company Incorporated (BP PLC)
• Inventors: Fletcher, Paul A.
• Primary Examiner(s): Eldred, J. Woodrow
• Application Number:
  US08/248,295
• Time in Patent Office: 707 Days
• Field of Search: 340/854.5, 340/854.6, 340/854.4, 340/854.8, 175/40
• US Class Current: 340/854.6
• CPC Class Codes: E21B 47/13 by electromagnetic energy, e.g. radio frequency

Abstract

Pressure and temperature signals are transmitted between a predetermined point in a wellbore and the earth'"'"'s surface by an electromagnetic wave transmitter disposed in the well and connected to a bow-spring centralizer forming one contactor of a dipole and a mandrel or hanger connected to a landing nipple of a tubing string in the well whereby the other conductive path forming the other end of the dipole may be formed by a packer or similar mechanism in conductive engagement with the tubing string and the well casing. The hanger may be a lock mandrel or a suitable conventional downhole tool hanger. The electromagnetic wave transmitter may be deployed in the well and engaged with the casing by spaced-apart magnets to establish the conductive path and the dipole distance. The transmitter may also be deployed on and connected to coilable tubing which has an insulative coating on the exterior surface for a predetermined length to prevent short-circuiting the conductive path by engagement of the coilable tubing with the casing wall, for example.

Claims

1. In an arrangement for a downhole instrument for transmitting data to the surface from a well, said well having a casing extending through an earth formation, said well having perforating means in said casing in communication with a predetermined zone of said earth formation, a signal transmitting device interposed in said well, comprising at least one sensor for sensing a condition in a portion of the wellbore of said well and a signal transmitter for transmitting information related to said condition to the earth'"'"'s surface, a contactor connected to said device and engaged with said casing at one point, a tubing extending within said well for positioning said devices and a mandrel engaged with a landing nipple connected to said tubing for locking said device in a predetermined position in said well and for providing an electrically conductive path between said device and said casing at a predetermined distance from said contactor for establishing a dipole for the generation of electromagnetic waves in the earth by said device.

2. The invention set forth in claim 1 wherein:

said contactor comprises a centralizer connected to said device and engageable with said casing.

6. The invention set forth in claim 1 wherein:

said contactor comprises a centralizer connected to said device and engageable with said casing.

7. The invention set forth in claim 1 wherein:

a predetermined part of said tubing includes an electrically insulative covering on the exterior thereof.

3. In an operation for substantially real-time monitoring of at least one of pressure and temperature in a predetermined portion of a wellbore of a well extending within the earth, the improvement characterized by:

providing an electromagnetic wave transmitting device including a first contactor connected thereto and engageable with a first wall portion of said wellbore and a second contactor connected thereto and engageable with a tubing string extending from a hanger for hanging said device within said wellbore;

connecting said device in assembly with said contactors and said hanger to a running tool and lowering said device in assembly with said contactor and said hanger into said well by a deployment line;

engaging said hanger with a landing nipple connected to said tubing string;

engaging said landing nipple with a mandrel connected to a second wall portion of said wellbore;

retrieving said deployment line from said well; and

transmitting information by electromagnetic wave propagation between said device and a receiver disposed on the earth'"'"'s surface.

4. In an arrangement for a downhole instrument for transmitting data from a well, said well having a casing extending through an earth formation and perforation means in said casing in communication with a predetermined zone of said earth formation,

a signal transmitting device interposed in said well, comprising at least one sensor for sensing a condition in a portion of the wellbore of said well and a signal transmitter for transmitting information related to said condition to the earth'"'"'s surface, and

a pair of magnets connected to said device and adapted to be magnetically connected to said casing at spaced apart points, said pair of magnets supporting said device and establishing a dipole for the generation of electromagnetic waves in the earth by said device.

5. In an operation for substantially real-time monitoring of at least one of pressure and temperature in a predetermined portion of a wellbore of a well extending within the earth, the improvement characterized by:

providing an electromagnetic wave transmitting device including spaced apart magnets operably connected to said device and engageable with a wall of a casing disposed in said wellbore to support said device in said casing and provide two points of electrical contact with said casing;

connecting said device to a running tool and lowering said device in assembly with said magnets into said well by a deployment line;

engaging said magnets with said casing;

retrieving said deployment line from said well; and

transmitting information by electromagnetic wave propagation between said device and a receiver disposed on the earth'"'"'s surface.

8. In an arrangement for a downhole instrument for transmitting data to the surface from a well, said well having a casing extending through an earth formation and perforation means in said casing in communication with a predetermined zone of said earth formation, a signal transmitting device interposed in said well comprising:

at least one sensor for sensing a condition in a portion of the wellbore of said well and a signal transmitter for transmitting information related to said condition to the earth'"'"'s surface,

a centralizer connected to said device and engaged with said casing at one point, and

a hanger connected to said device and to a tubing extending within said well for positioning said device in said well and for providing an electrically conductive path between said device and said casing at a predetermined distance from said contactor for establishing a dipole for the generation of electromagnetic waves in the earth by said device, said hanger comprising means engageable with a receptacle formed in a landing nipple connected to said tubing and forming an electrically conductive path between said device and said tubing through said hanger.