Wells – Processes – Operating valve – closure – or changeable restrictor in a well
Reexamination Certificate
1999-11-17
2001-10-16
Tsay, Frank S. (Department: 3672)
Wells
Processes
Operating valve, closure, or changeable restrictor in a well
C166S187000, C166S285000
Reexamination Certificate
active
06302214
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention is in the field of oil and gas drilling and has a common, although not exclusive, application in off shore drilling where horizontal wells are involved.
It is recognised in the art of oil and gas drilling that it is, at times, desirable to provide annular isolation in a well liner using formation packers in lieu of conventional annular cementing. This allows for improved well management, and more specifically, the creation of zones to enable:
the separation of phases of oil, gas or water, in a well;
the injection of chemicals, cement or the like at a particular predetermined location in the well; and or
the monitoring or analysis of flow or other conditions at a particular location in the well.
Typically, packers used for the creation of such annular isolation or zones are of the inflatable type, adapted to be filled with cement or some other settable composition such as resin. Occasionally, the packers may be inflated with drilling mud, particularly if their use is only needed for a short time. The present invention results from a desire to provide improved and more reliable means of inflating these packers.
Inflatable packers may also be used in certain situations on the outside of the liner. The present invention also encompasses the inflation of packers in such location. Indeed, the invention may be applied to any situation or location where down hole packers require to be inflated.
Where cement or other settable fluid has been used in the past, the task of inflating a packer required pumping a relatively small amount of the settable fluid from the surface to a remote location where a packer is to be set, potentially tens of thousands of feet from the surface. The cement or other composition has been required to be pumped to the precise location of the packer or each packer to be inflated. This involved several procedural steps, with the success of the entire procedure being dependent on each step being performed successfully
In many cases, it is important also for the cement or other settable composition to be delivered to the packer without having been contaminated by other fluids, such as mud or the like. Again this has proved difficult to achieve in the past, leading to eventual packer failure as a result of it being inflated with cement or other composition of low integrity.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved method of setting and inflating packers in oil or gas wells. A further and related object of the present invention is to improve the reliability of delivering the cement or other setting fluid to the packers. A yet further object of the present invention is to improve the quality of the settable fluid (or reduce the level of contaminants therein) that is delivered to the inflatable packers. The invention also provides apparatus and method for improving the efficiency of setting several packers, and indeed doing so simultaneously.
According to a first aspect of the present invention there is provided a method for inflating a packer in a well bore or down hole environment, the method comprising the steps of:
a) filling a compartment in or associated with a work string or liner string with cement or other settable fluid at or near the surface of the well;
b) thereafter transporting the cement or settable fluid down the well bore in conjunction with the work string or liner string; and
c) injecting the cement or other settable fluid into an inflatable packer.
As it might otherwise be difficult to inject the cement or other settable fluid into the inflatable packer without first injecting at least some mud or other fluid, the method may also include the step of injecting an associated secondary packer substantially with mud or drilling fluid until the cement or settable fluid is presented for injection prior to step c) above, the additional packer typically being positioned adjacent to the first inflatable packer.
The method may be used for providing an annular seal or barrier in a liner. Alternatively, the method may be used in the task of hanging a liner or for packing the outside of a liner.
It may be necessary to pick up the string to align a port in the string with a port or the like in a said packer to allow Step c) above to be performed. This, together with Step c) above may be repeated for additional inflatable packers.
Where there are a plurality of inflatable packers, the packers may be adapted for setting at different pressures. More particularly, the method may include inflating a first packer at a first setting pressure, picking up or relocating the string to align a port in the string with an inlet in a second packer and then inflating said second packer at a second setting pressure, the second setting pressure being higher than the first setting pressure. Additional packers may be successively inflated each having successively higher setting pressures. This has the advantage that in the event of any one inflatable packer failing, it may be bled off back to a negligible pressure without affecting the ability to inflate subsequent packers.
The work string may be an inner string that supports the cement or other fluid between a plug located at the lower end of the inner string and a barrier further up the inner string. The work string may also be one of dual strings, the other of the dual strings enabling circulation.
The method may further include the step of performing a pressure test to test the integrity of the inner string.
According to a second aspect of the invention, there is provided a method of setting a plurality of inflatable packers comprising the steps of:
locating dedicated inflation tools on a string prior to running the string, the tools being separated by a distance corresponding to the distance separating the packers to be set;
subsequently running the string, thereby transporting the inflation tools to the vicinity of the packers;
aligning the inflation tools with the packers; and
thereafter injecting fluid into the packers simultaneously.
The fluid may be cement, a settable resin, drilling mud or any other fluid known in the art. Preferably the fluid is cement that has been prior prepared under controlled conditions on-shore, the cement having been mixed with an additive or catalyst prior to use and typically off-shore, wherein the additive or catalyst is adapted to cause the setting of the cement at a known or predetermined rate.
The string may be a work string, drill string or liner string. The string may also be one of dual strings, the other of the dual strings enabling circulation.
According to a third aspect of the present invention there is provided a work string or liner for use in a well bore, the work string or liner comprising means for supporting cement or other fluid while being run in the well bore, the cement or other settable resin being suitable for inflating one or more inflatable packers in the well bore.
The work string may be associated with locating means such as collets adapted to locate the string at an appropriate position for the inflation of a respective packer.
The work string may be an inner string and may include a plug located at its lower end. A barrier may also be provided in the work string above the cement or other fluid to prevent or mitigate the influx of mud or other contaminants into the cement phase. The barrier may be a foam ball.
The work string may include a bypass means to enable circulation of fluid through the work string, the fluid being able to bypass the cement or other settable fluid and plug. Alternatively, the work string may be one of dual strings running parallel in the well, wherein the other of the dual strings is a circulation string. The circulation string may be associated with means for opening and closing a circulation path therein. For example, the circulation string may have a seat for landing a ball or dart.
According to a fourth aspect of the present invention, there is provided a work string supporting a plurality of inflation tools for inflating packers on a liner or the like,
Carmichael Mark
Howlett Paul
Fleshner & Kim LLP
Specialised Petroleum Services Limited
Tsay Frank S.
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