REVERSE CIRCULATION DRILLING SYSTEM, APPARATUS AND METHOD
First Claim
1. A reverse circulation drilling apparatus comprising:
- a concentric dual wall drill pipe, having a first end, a second end, an outer pipe and an inner pipe positionable within the outer pipe and defining an annulus therebetween, said inner pipe defining a central inside passage, wherein said inside passage is not in fluid communication with the annulus;
a first drill sub attached to the first end and having an internal through passage and at least one annular passage, wherein said internal through passage is not in fluid communication with said annular passage;
a second drill sub attached to the second end and having an internal through passage and at least one annular passage, wherein said internal through passage is not in fluid communication with said annular passage;
wherein the annular passages of the first and second drill subs are in fluid communication with said annulus; and
wherein the internal through passages of the first and second drill subs are in fluid communication with said central inside passage.
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Abstract
In one embodiment, the present invention provides a reverse circulation drilling apparatus which comprises a concentric dual wall drill pipe, having a first threaded end, a second threaded end, an outer pipe and an inner pipe captured in a concentric arrangement within the outer pipe and defining an annulus therebetween. The inner pipe defines an inside passage, which is not in fluid communication with the annulus. A first means for directing an outer flow of fluid through the annulus is provide. A second means for directing an inner flow of fluid through the inside passage is also provided. The first means and the second means prevent fluid communication between the outer flow and the inner flow. The first threaded end and the second threaded end are each suitable to connect the reverse circulation drilling apparatus to another reverse circulation drilling apparatus.
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Citations
16 Claims
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1. A reverse circulation drilling apparatus comprising:
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a concentric dual wall drill pipe, having a first end, a second end, an outer pipe and an inner pipe positionable within the outer pipe and defining an annulus therebetween, said inner pipe defining a central inside passage, wherein said inside passage is not in fluid communication with the annulus; a first drill sub attached to the first end and having an internal through passage and at least one annular passage, wherein said internal through passage is not in fluid communication with said annular passage; a second drill sub attached to the second end and having an internal through passage and at least one annular passage, wherein said internal through passage is not in fluid communication with said annular passage; wherein the annular passages of the first and second drill subs are in fluid communication with said annulus; and wherein the internal through passages of the first and second drill subs are in fluid communication with said central inside passage. - View Dependent Claims (2, 3, 4, 5, 6, 10)
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7. A reverse circulation drilling apparatus comprising:
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a concentric dual wall drill pipe, having a first threaded end, a second threaded end, an outer pipe and an inner pipe captured in a concentric arrangement within the outer pipe and defining an annulus therebetween, said inner pipe defining an inside passage, wherein said inside passage is not in fluid communication with the annulus; a first means for directing an outer flow of fluid through said annulus; a second means for directing an inner flow of fluid through said inside passage; wherein said first means and said second means prevent fluid communication between the outer flow and the inner flow; and wherein the first threaded end and the second threaded end are each suitable to connect the reverse circulation drilling apparatus to another reverse circulation drilling apparatus. - View Dependent Claims (8, 9, 11)
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12. A method of assembling a reverse circulation drilling apparatus having an inner pipe, a slightly shorter outer pipe and first and second drill subs, the method comprising the steps of:
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placing the inner pipe within outer pipe; adjusting the inner pipe so that its ends project a predetermined distance out of the ends of the outer pipe; sealably connecting first and second drill subs to the outer pipe and over said inner pipe ends; and wherein the inner pipe is captured in a concentric arrangement within the outer pipe and defines an annulus therebetween.
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13. A drill sub for use in reverse circulation drilling operations and having a pipe end and a connection end, the drill sub comprising:
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an internal through passage through the drill sub spanning from pipe end to connection end; and at least one annular passage; wherein said internal through passage is not in fluid communication with said annular passage. - View Dependent Claims (14, 15, 16)
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Specification