Casing annulus remediation system

Details Casing annulus remediation system Casing annulus remediation system

1999-07-20

2001-02-13

Dang, Hoang (Department: 3672)

Wells

Processes

Placing or shifting well part

C166S077100, C166S090100, C166S097100, C166S242200, C166S242500, C166S325000, C166S379000

Reexamination Certificate

active

06186239

ABSTRACT:

TECHNICAL FIELD
This invention relates in general to well remediation systems and in particular to the process and components used for filling an annulus in a well with heavy liquid sealant, or other media, to control or eliminate sustained casing pressure in outer casing string.
BACKGROUND OF THE INVENTION
In wells drilled for petroleum production, a plurality of well casings of different sizes are suspended from a wellhead. A problem encountered in such wells is that of annular pressure control. In the annulus between different casing sizes, pressure may develop due to leaks between strings of casing, tubing leaks, packer leaks, wellhead packoff leaks and a poor or failed primary cement job. Currently, to control the annular pressure, a relatively heavy liquid is pumped into the annulus at the upper end of the well. The heavy liquid migrates slowly downward, displacing lighter liquid. This technique is expensive, time consuming and has yielded limited results.
BRIEF SUMMARY OF THE INVENTION
A system is needed that inserts a fluid delivery system through an existing wellhead or tubing head assembly into a constricted and pressurized annulus and transports the fluid delivery system far enough downhole to achieve the needed hydrostatic column for pressure control. The fluid delivery system delivers a suitable fluid or other media to establish permanent hydraulic control and to provide a simple method of renewal if necessary.
In this system, a flexible hose is lowered into an annulus between strings of casing to depths of 1200 feet or more. The flexible hose is preferably elastomeric, but may be made of metallic, composite or other suitable materials. A nozzle is affixed to the lower end of the hose. The hose must be pressurized and rigid to keep the hose from winding about the well during insertion. To keep the hose rigid, internal pressure is maintained in the hose. The nozzle is provided with a closure member such as a pressure relief valve, burst disk, or other suitable device that holds the pressure within the hose. Once the hose is lowered to a desired depth, the operator increases the pressure sufficiently in the hose to open the closure member, e.g., break the disk or open the valve, thereby allowing heavy liquid to flow out. The heavy liquid displaces the lighter well production fluids. An injection sealer at the surface seals around the hose. A gate valve is employed to shear the hose in the event of an emergency.


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