Wells – Packers or plugs – Expanded by confined fluid from central chamber – pump or...
Reexamination Certificate
2000-01-28
2001-10-16
Tsay, Frank (Department: 3672)
Wells
Packers or plugs
Expanded by confined fluid from central chamber, pump or...
C166S373000
Reexamination Certificate
active
06302202
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to plug assemblies and more particularly, to inflatable plug assemblies for boreholes.
2. Description of Related Art
Boreholes are drilled for the purpose of delivering an explosive charge to a selected location in, for example, an underground earth structure. The setting of the explosive charge often requires the borehole to be blocked so that the charge can be set at a desired level. Boreholes often tend to at least partially fill with water and the presence of the water can prevent successful detonation of the explosive. In attempts to overcome this problem, water proof explosives have been used. However such explosives are expensive in comparison to other explosives.
Furthermore, it is often the case that more than one explosive charge needs to be used with the explosives being positioned at spaced intervals along the borehole. This requires that the borehole plugs or other decking be placed at the selected depths along the borehole. The types of decking which have been used in the past include the application of a column of concrete or the like to a section of the borehole to space the explosive charges. Another system employs wooden, concrete or other types of discs with similar cross-sectional dimensions to the borehole which are lowered into the borehole so that they float on the surface of water within the borehole. It has also been proposed to use flexible polyester resins which float on the water and subsequently solidify. A further device which has been used comprises an inflatable plug with a time delay mechanism to allow inflation of the plug at a selected depth to thereby plug the borehole. More recently, a gel or slurry explosive has been used to replace the typical decking. Each of the above techniques suffers from certain disadvantages. Timber or concrete decking are cumbersome and generally not sufficiently reliable. Polyester resins are difficult to handle and slow to place. Internally inflated borehole plugs of the type described in U.S. Pat. No. 5,346,005, wherein a time delay mechanism permits the inflating plug to be lowered before inflation occurs may experience freezing of the time delay liquid and do not offer a ready delay time option.
SUMMARY OF THE INVENTION
It is an objective of this invention to provide inflatable plug assemblies having a simple, reliable and inexpensive means to select a quick or a slow inflation time by choice of plug orientation by the operator at the time of plug assembly insertion into a borehole.
In a particular embodiment of the invention, the pressurized container within an inflatable main body of the plug assembly may release working fluid slowly as a gas when triggered in an orientation wherein the working fluid liquid phase is away from the discharge outlet resulting is slow inflation of the plug assembly. Alternately, in this embodiment, working fluid mass is released quickly as a liquid when the pressurized container is triggered in an orientation wherein the working fluid liquid phase is adjacent to the discharge outlet resulting in quick inflation of the plug assembly. Inflation time of the plug assembly may be controlled, for example, from one to five minutes by choice of plug assembly orientation at the time of actuation and passage into a borehole for placement. The mechanism being reliable and inexpensive due to simplicity.
In a preferred embodiment, an elongate pressure container is fixedly mounted to the interior of the main body, the working fluid being discharged at a controlled rate, whether as gas phase or liquid phase, through a restriction orifice. In a more preferred embodiment, the working fluid is a gas at atmospheric pressure and ambient temperatures but existing at least partially as a liquid in the untriggered pressurized container. In a most preferred embodiment, the working fluid consists of tetrafluoroethane, propane, butane, or a mixture of these gases.
In a preferred embodiment, the main body has an internal chamber lined with a flexible bag composed of one or more gas impermeable layers. In a most preferred embodiment, the selection of plug assembly orientation, and thus inflation time, is by choice of alternate line attachment eyelets for lowering the plug assembly into a borehole; the attachment eyelets being mounted to opposing ends of the main body in fixed relation to the pressurized container.
The method of using the plug assembly being the steps of selecting a time delay working mode for the plug assembly, orienting the pressure container appropriately for the selected mode, operating the actuator to cause discharge of pressurized working fluid from the pressure container to the internal chamber, passing the plug assembly along the borehole to a location where inflation of the main body fixes the plug assembly within the interior of the borehole.
REFERENCES:
patent: 3918520 (1975-11-01), Hutchison
patent: 3995694 (1976-12-01), Freiburger
patent: 4609042 (1986-09-01), Broadus et al.
patent: 4846278 (1989-07-01), Robbins
patent: 5392853 (1995-02-01), Toon
patent: 5441302 (1995-08-01), Johnson et al.
patent: 6073592 (2000-06-01), Wood et al.
patent: B-30436/92 (1992-12-01), None
patent: 1159524 (1967-07-01), None
patent: 2262757 (1993-06-01), None
Senior Inspector of Coal Mines—Jadefoil ‘Wombat’ Gasbags 1 page Mar. 20, 1998 Department of Mineral Resources.
Jadefoil—Hazchem Sheet 1 page Mar. 1998 Published Mar. 1998.
Jadefoil—Splash Bags for Wet Blastholes, Brochure 2 pages produced Nov. 1999 Published Feb. 2000.
Jadefoil—Your Answer to Improved Blasting, Brochure 2 pages produced Jul. 1999 Published Nov. 1999.
Mintech Gasbags, Brochure 2 pages ?? Available to Jadefoil.
Baker, Esq. Gary
Tsay Frank
LandOfFree
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