Wells – Vibrator
Patent
1999-02-01
2000-11-28
Neuder, William
Wells
Vibrator
166319, 175 56, 417225, E21B 2800
Patent
active
061522228
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulically operated device adapted to be connected in a pipe string, specifically coiled tubing. For example, the device can be used in order to facilitate pushing of the string into highly deviated or horizontal wells in connection with working, and in maintenance operations such as logging, assembling or disassembling parts, acid and sand washing etc.
It has previously been proposed to provide drill strings with hydraulically operated devices or vibrators to facilitate the advance of the string. Thus, U.S. Pat. No. 4,384,625 proposes subjecting the drill string to vibrations in the form of resonance oscillations to reduce the friction between the drill string and bore hole wall in deviated wells to extend the reach in rotary drilling. As an example of a vibrator the patent refers to a fluid operated eccentric weight, implying substantially transversal vibrations.
U.S. Pat. No. 3,235,014 describes a method and apparatus for generating axial vibrations through a drilling swivel to transmit a percussive effect to the drill bit. Furthermore, various types of hydraulic hammer or percussion tools are known, which are intended for loosening sticking drill strings. An example of this type of tool is disclosed in NO patent 171 379.
Coiled tubing has substantially lower mass and diameter than drill pipes, which means that a transversally acting resonance vibrator with accompanying hydraulic motor as proposed in the above U.S. Pat. No. 4,384,625 would be rather ineffective when used in connection with coiled tubing. The main object of the invention, therefore, is to provide a device that effectively reduces friction, both at the coiled tubing head (lowermost tool section) as well as upwardly along the coiled tubing itself.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved through a device as defined in the appendant claim 1. Advantageous embodiments of the invention are defined in the remaining appendant claims.
A device mounted to a coiled tubing through which pressurized fluid is flowing will continuously perform telescopic (axial) percussions or vibrations propagating along the entire lower part of the coiled tubing, including the coiled tubing head. The vibrations travel backwards along the coiled tubing. Due to the steady changes in the direction of transmission of the vibrations, the effective frictional resistance will be drastically reduced which will permit the coiled tubing to be pushed a substantial distance into a highly deviated and horizontal well bore before buckling and getting stuck. Calculations based on an 80.degree. deviated well bore indicate an enhanced reach of as much as 3000 m.
The device according to the invention differs from prior vibrators intended for use in petroleum wells, primarily by the fact that it generates a telescopic (axial) vibration at a relatively high amplitude. Existing vibrators as discussed above are primarily designed to provide short and violent percussive pulses during drilling, or for releasing stuck tools. These hammer tools operate at a much lower vibration amplitude, implying vibrations of a substantially shorter operational range. Thus, they are of little use in enhancing the reach of coiled tubing.
Of course, although the primary object of the invention, as discussed above, is to provide a vibrator suitable for reducing the push frictional resistance of coiled tubing, there is nothing to prevent it from being used with advantage also in ordinary rotary drill strings. Furthermore, the purpose of the use of the device need not necessarily be to reduce friction. Thus, in some cases it may be advantageously used as a percussion tool, preferably mounted in front of the pipe string.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic longitudinal cross sectional view of the device of the present invention in a first phase of operation.
FIG. 2 is a schematic longitudinal cross sectional view of the device of the present invention in a second phase of operation.
FIG
REFERENCES:
patent: 3235014 (1966-02-01), Brooks
patent: 4384625 (1983-05-01), Roper et al.
patent: 5411107 (1995-05-01), Hailey et al.
patent: 5632604 (1997-05-01), Poothodiyil
Kveilerorvibrator AS
Neuder William
Walker Zakiya
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