Boring or penetrating the earth – Processes – Boring with specific fluid
Reexamination Certificate
1999-03-01
2001-09-04
Bagnell, David (Department: 3672)
Boring or penetrating the earth
Processes
Boring with specific fluid
C175S324000, C175S424000
Reexamination Certificate
active
06283230
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to methods and apparatus for penetrating a side of a well casing and drilling into earth strata surrounding the well casing, and more particularly, to an improved method and apparatus for drilling into the surrounding earth strata utilizing a rotating fluid discharge nozzle and reduction of static head pressure in the well casing in conjunction with the drilling operation.
BACKGROUND ART
A large number of wells have been drilled into earth strata for the extraction of oil, gas, and other material therefrom. In many cases, such wells are found to be initially unproductive, or decrease in productivity over time, even though it is believed that the surrounding strata still contains extractable oil, gas or other material. Such wells are typically vertically extending holes including a casing usually of mild steel pipe having an inner diameter of from just a few inches to about eight (8) inches in diameter for the transportation of the oil, gas or other material upwardly to the earth's surface.
In an attempt to obtain production from unproductive wells and increase production in under producing wells, methods and apparatus for cutting a hole in the well casing and forming a lateral passage therefrom into the surrounding earth strata are known. Reference for instance, Landers U.S. Pat. No. 5,413,184 issued May 9, 1995; and Schellsteed U.S. Pat. No. 4,640,362 issued Feb. 3, 1987, which disclose exemplary methods and apparatus for producing lateral holes in the earth's strata surrounding a well casing. However, such known methods and apparatus have not yet been known to provide satisfactory results. In particular, the known apparatus of Landers utilizes a non-rotating blasting type fluid nozzle wherein fluid under pressure is directed at the earth's strata has been found to be unable to produce a hole in the strata of more than a few inches in depth. This shortcoming is believed to be due largely to the inability of the non-rotating blaster type nozzles to form a passage in the strata sufficiently unobstructed to allow advancement of the nozzle into the strata, particularly in strata having suitable porosity and permeability characteristics for oil, gas and/or other commercial products. Also, it has been found that any formation that a well is located in will produce a given hydrostatic head in the well which is equal to the formation pressure. This is problematic because the formation has a capability of absorbing fluid around the nozzle, including immediately ahead of and shortly behind the nozzle, when the hydrostatic head becomes greater than the formation pressure, resulting in at least partial and in many cases total stoppage of movement of cuttings away from the nozzle.
Accordingly, the present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
According to one aspect of the present invention, a method for penetrating a well casing and surrounding earth strata at a desired elevation within a well is disclosed, the method including the steps of:
a) forming a hole through said well casing at the desired elevation;
b) inserting a flexible tube having a nozzle on an end thereof into said hole; and
c) pumping a fluid into the flexible tube and out through the nozzle while rotating said nozzle for drilling an extension of said hole into said earth strata.
According to another aspect of the present invention, apparatus adapted for drilling into strata surrounding a well casing through an existing hole in a side of the well casing is disclosed. The apparatus includes:
a flexible tube adapted for passage through the hole having a first end, an opposite second end, and an internal cavity extending therethrough between the first end and the second end;
a nozzle adapted for passage through the hole in the side of the well casing mounted to the first end of the flexible tube, the nozzle having at least one aperture therethrough in communication with the internal cavity of the flexible tube;
structure attached to the second end of the tube for supporting the tube in the well casing;
structure for rotating at least the nozzle; and
structure for communicating fluid under pressure to the second end of the flexible tube for passage through the tube and discharge through the nozzle during the rotation thereof.
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Bagnell David
Haverstock, Garrett & Roberts LLP
Walker Zakiya
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