Wells – Processes – Cleaning or unloading well
Reexamination Certificate
1999-07-26
2001-04-03
Schoeppel, Roger (Department: 3672)
Wells
Processes
Cleaning or unloading well
C166S173000, C015S104200
Reexamination Certificate
active
06209647
ABSTRACT:
BACKGROUND OF THE INVENTION
In the development of oil and gas fields, operators will drill a well to a hydrocarbon reservoir, and thereafter, run a casing string through the production formation. The casing string will then be cemented into place. In turn, the well will then be completed as is well appreciated by those of ordinary skill in the art.
The optimization of production is an important criteria of any completion. Studies have shown that residue on the internal diameter of the casing string (such as cement, pipe dope, scale, burrs, etcetera) have a negative impact on productivity. Specialized completion fluids devoid of fines, solids and other debris are used to complete the well. Therefore, a major emphasis has been made to clean the inner diameter of the casing string.
Thus, when the operators have finished the pumping of a cement composition through the well casing, a work string is lowered on which a mechanical scraping device is used to scrap the walls of the casing. In the prior art, various types of casing scrapers are in use prior to displacement of a clean completion fluid. That is why it is so important to clean the casing wall as much as possible since it takes less time to ultimately filter the displaced completion fluids. Also, cleaning will eliminate foreign matter such as cement sheaths, scale, burrs and barite which in turn allows the tools used in the completion process to properly perform.
The scraping action of traditional scrapers with blades also have been known to leave a fine film of oil base or synthetic fluid residue on the casing wall. Prior art devices also cause problems because of the hardness of their blades cannot get into the casing connections as brushes can. Also, casing scrapers in high deviated holes collapse to the low side of the casing causing a great deal of wear on one side and the top side of the hole is not properly cleaning the high side due to ineffective engagement with the high side.
Therefore, there is a need for a down hole assembly that will be effective in cleaning a well bore that contains an oil base and/or synthetic fluid. There is also a need for a cleaning apparatus that will be effective in highly deviated wells. There is also a need for a down hole assembly that will have brush pads that are of sturdy construction and allow for ease of replacement.
SUMMARY OF THE INVENTION
A down hole cleaning assembly is disclosed. Generally, the down hole assembly is connected to a work string concentrically located within a casing string. In one embodiment, the down hole assembly comprises a mandrel operatively connected to the work string, with the mandrel having an opening therein. A pad member is received within the opening, with the pad member having a groove formed therein. Also provided is a wire brush means, operatively positioned within the groove of the pad member, for cleaning the internal diameter of the casing string.
The down hole assembly further comprises a biasing member, operatively positioned between the mandrel and the pad member, adopted for biasing the wire brush means against the inner diameter of the well bore. In the preferred embodiment, the wire brush means comprises a wire bundle having a first end and a second end, a brace disposed about the second end of the wire bundle, and wherein the brace is disposed within the groove of the pad member.
The brace herein disclosed includes an open end and a closed end, with the closed end having disposed therein the second end of the wire bundle, and wherein the open end and the closed end cooperate to form a triangular shaped profile. The groove will also contain a triangular shaped profile adapted to slidably receive the triangular brace.
In the preferred embodiment, the mandrel contains a second of slot, and wherein the down hole assembly further comprises a second pad member adapted to be received within the second slot, the second pad containing a second groove formed therein. A second wire brush means, operatively positioned within the second groove of the pad member, is also provided for cleaning the internal diameter of the casing string.
The down hole assembly may also contain a centralizer means, operatively adopted to the work string, for centralizing the mandrel within the casing string. A dove tail means, operatively associated with the mandrel, is also included for selectively adapting the wire brush means onto the work string.
In the preferred embodiment, the first and second wire brush means are arcuate, and wherein said first wire brush means is disposed about the periphery of the mandrel to cover a first 180 degree phase and wherein the second wire brush means is disposed about the periphery of the mandrel to cover a second 180 degree phase so that the first wire brush means and the second wire brush means cover a 360 degree phase about the mandrel. In another embodiment, a plurality of wire brush means may be placed about the periphery of the mandrel, with the wire brush means being staggered circumferentially in relation to each other so that the wire brushes have an effective coverage area of 360 degrees.
Also disclosed herein is a method of cleaning a casing string. The method comprises lowering a work string within the casing string. The work string will have provided therewith a down hole cleaning apparatus operatively associated with the work string. The wire bundle of the cleaning apparatus will be urged against the inner diameter of the casing string via the spring to allow for constant pressure of the brushes against the casing wall at all times. The method provides for cleaning the inner diameter of the casing string as the work string is lowered.
The method further comprising rotating the work string, and thereafter, lowering the work string. The operator may then circulate a drilling fluid through the inner diameter of the work string. The work string may be stationary or rotating during circulation.
In one embodiment, the well casing has a horizontal section so that a low side of the well casing and a high side of the well casing is created. In this embodiment, the apparatus includes a centralizer operatively associated with the work string. Also included will be a second cleaning apparatus, with the first cleaning apparatus covering a 180 degree phase and the second cleaning apparatus covering a complimentary 180 degree phase so that the entire 360 degree periphery is covered.
The method would further comprise lifting the apparatus from the low side of the inner diameter of the well casing with the centralizer. Also, the wire bundle of the first cleaning apparatus is urged against the low side of the inner diameter of the well casing with the spring at a constant force. Simultaneously therewith, the wire bundle of the second cleaning apparatus is urged against the high side of the inner diameter of the well casing with its spring at a constant force so that both the low side of the casing and the high side of the casing will be cleaned.
In a second embodiment, which in this application is the preferred embodiment, an apparatus for cleaning an inner diameter of a casing string is disclosed. In this embodiment, the down hole assembly comprises a mandrel having a first end and a second end, with the first end of said mandrel being configured to be connected to an opened end of a first tubular member and the second end of the mandrel being configured to be connected to an opened end of a second tubular member. The mandrel contains a first helical opening.
The apparatus further contains a first helical pad configured to be positioned within the first helical opening, with the helical pad having a groove therein. A wire brush member is inserted within the groove and a first spring is inserted between the first helical pad and the mandrel, with the spring biasing the helical pad radially outward.
The apparatus further contains a dove tail means, operatively associated with the mandrel, for selectively adapting the first second helical pad member with the mandrel. The dove tail means comprises the first tubular member having an opened
Dominigue & Waddell, PLC
Schoeppel Roger
LandOfFree
Down hole casing string cleaning device and method does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Down hole casing string cleaning device and method, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Down hole casing string cleaning device and method will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2448092