Wells – Processes – Cleaning or unloading well
Reexamination Certificate
1998-02-06
2001-01-09
Dang, Hoang (Department: 3672)
Wells
Processes
Cleaning or unloading well
C166S222000, C134S022120
Reexamination Certificate
active
06170577
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to the field of apparatus and methods used for removing material from inside a conduit. More particularly, the present invention relates to a system capable of loosening and removing material built-up on the inside surface of, or disposed within, a metal conduit.
Undesirable materials that build-up on the inside walls of conduits, such as well tubing, injection lines, pipelines, flowlines, boiler tubes, heat exchangers and water lines, or that otherwise collect inside the conduits, are known to restrict or interfere with the desired movement of fluids, materials and devices, tools, liquids and gases through the conduits. As a result, in many cases, the conduit becomes useless, or inoperable for its intended purpose. For example, thousands of petroleum wells in this country have been shut down or abandoned due to the crippling effect on operations of obstructions in the well tubing. Examples of such undesirable, or obstructive, materials include barium sulfate, strontium sulfate, calcium sulfate, calcium carbonate, iron sulfide, other scale precipitates (such as silicates, sulfates, sulfides, fluorides, carbonates), cement, corrosion products, deteriorated conduit lining, and dehydrated material (such as drilling fluid).
Existing methods of removing obstructive materials from conduits have numerous disadvantages. Various techniques involve the use of a mill or bit to remove obstructive material from conduits. In many applications, the mills or bits have a short useful life due to damage from contact between the mills and bits and commonly occurring hard, dense obstructive materials. The mills or bits must therefore be frequently removed from the conduit and replaced, consuming time and expense. Further, rotation of the mill or bit requires additional component parts, such as a motor, bearings and rotary seals, which are complex and costly to manufacture and operate and subject to failure. Rotary seals typically limit the use or effectiveness of the system due to their vulnerability to wear or damage from high temperatures.
These techniques are also largely ineffective at loosening and removing substantially all obstructive material without damaging the conduit. For example, the inside walls of conduits cleaned with mills or bits are highly subject to damage from contact by the mill or bit. Such contact commonly occurs when the obstructions in the conduit are unevenly dispersed, causing the mill or bit to jam or rub against, or drill into, the side of the conduit. Further, reactive torque due to the rotation of the drill or mill can also cause it to contact the inside surface of the conduit and cause damage thereto. Such reactive torque also accelerates deterioration to the tubing, such as coiled tubing, that carries the mill or bit.
Other conventional cleaning methods utilize jet nozzles that eject only liquid or angular-shaped solid particles in a foam or liquid transport medium. Typical liquid-only systems insertable in a conduit of significant length, such as petroleum tubing and pipelines, operate in low to moderate pressure ranges. These systems have proven ineffective at loosening or removing commonly encountered hard, tightly bonded obstructive materials, such as barium sulfate. The jet systems using angular-shaped solids typically damage the inside surface of metal conduits as a result of the angular solids cutting, scarring and eroding the metal. These systems lack the ability to minimize or control the amount of damage that occurs to the metal conduit; therefore, their use is not entirely satisfactory for many applications. Further, the angular solids provide an erratic erosion pattern, limiting their effectiveness in loosening and removing obstructions.
Thus, there remains a need for a system for loosening and removing undesirable materials built-up on the inside surface of metal conduits, or that otherwise collect inside the conduits, that does not cause substantial or undesirable damage to the conduit. Preferably, the system will be simple, and cost effective and easy to manufacture and operate. Ideally, the system could utilize existing equipment. Especially well received would be a system that can quickly remove all, or substantially all, of the undesirable materials. Ideally, the system would not need to be rotated and would have static seals unaffected by high temperatures. Further, it would be beneficial for the system to be capable of recirculating or reusing its cleaning mixture or the constituents of the cleaning mixture.
BRIEF SUMMARY OF THE INVENTION
In accordance with the present invention, there is provided a system for removing obstructive material from inside a conduit that includes a mixture including a plurality of substantially spherically shaped solid abrasive particles and fluid, a mixture delivery tubing insertable into the conduit and a nozzle assembly attached to the mixture delivery tubing. The nozzle assembly includes a plurality of nozzle jets capable of ejecting the mixture to loosen obstructive material inside the conduit.
The substantially spherically shaped solid abrasive particles may be constructed at least partially of glass, metal, plastic, ceramic, epoxy, other suitable material, or a combination thereof, and may have any suitable size, such as between about 20 mesh and about 100 mesh. Further, the particulate density of the substantially spherically shaped solid abrasive particles may be greater or less than the density of the fluid.
In preferred embodiments, the nozzle assembly is capable of ejecting the mixture to loosen obstructive material inside the conduit without substantially damaging the conduit, and ejecting the mixture around the inner circumference of the conduit without rotating the nozzle assembly.
The system may include a filter capable of preventing clogging of the nozzle jets by particles carried in the mixture. The system may include a mixer capable of mixing the substantially spherically shaped solid abrasive particles and the fluid to form the mixture, and a pump capable of pumping the mixture under pressure into the mixture delivery tubing.
In another aspect of the invention, there is provided a nozzle assembly for ejecting a mixture that includes substantially spherically shaped solid abrasive particles and fluid, the nozzle assembly having a central axis and being associated with a mixture delivery tubing. The nozzle assembly includes a connector member connectable with the mixture delivery tubing, a nozzle head member having a plurality of nozzle jets, at least two of the nozzle jets disposed at angles of between approximately 80 degrees and approximately 100 degrees relative to the central axis of the nozzle assembly, and a gauge ring member disposed between the connector member and the nozzle head member.
In alternate embodiments, the nozzle assembly includes a plurality of nozzle jet inserts matable with a plurality of recesses in the nozzle head member. In alternate embodiments, at least one of the nozzle jets is disposed in the nozzle assembly at an angle of approximately 0 degrees relative to the central axis of the nozzle assembly. At least one of the nozzle jets may be disposed in the nozzle assembly at an angle of between approximately 0 degrees and approximately 90 degrees relative to the central axis of the nozzle assembly, or at least two of the nozzle jets may be disposed in the nozzle assembly at angles of between approximately 10 degrees and approximately 20 degrees relative to the central axis of the nozzle assembly. The nozzle assembly may include a plurality of nozzle assembly sections, each nozzle assembly section having a diameter different than the diameter of adjacent nozzle assembly sections and wherein at least one nozzle jet is disposed in each nozzle assembly section.
The gauge ring may include at least one wide portion and at least one external fluid flow passageway, the wide portion(s) and external fluid flow passageway(s) disposed between the nozzle jets and the mixture delivery tubing. The gauge ring may include a plu
Kuhlman Larry George
Noles, Jr. Jerry W.
Skinner Leslie Dale
Advanced Coiled Tubing, Inc.
Dang Hoang
Smith E. Randall
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