Boring or penetrating the earth – Bit or bit element – Cutting edge self-renewable during operation
Reexamination Certificate
1998-11-16
2003-04-15
Tsay, Frank S. (Department: 3672)
Boring or penetrating the earth
Bit or bit element
Cutting edge self-renewable during operation
C175S393000
Reexamination Certificate
active
06547017
ABSTRACT:
Portions of this application have been disclosed in U.S. Disclosure Document No. 445,686 filed with the United States Patent and Trademark Office on Oct. 11, 1998, an entire copy of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The field of the invention relates to an article of manufacture that is a long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has at least one self-actuating compensation mechanism triggered by bit wear that is responsive to the hardness of the geological formation to minimize the time necessary to drill a borehole using rotary drilling techniques typically used in the oil and gas drilling industries. The field of the invention also relates to a long lasting rotary drill bit for drilling a hole into variable hardness geological formations that has a compensating mechanism controllable from the surface of the earth to change the mechanical configuration of the bit in the well to minimize the time necessary to drill a borehole. The field of invention further relates to an article of manufacture that is a drill bit possessing hard abrasive rods cast into steel, such as tungsten carbide rods cast into steel, that is used to drill holes into geological formations. The field of invention also relates to a composition of matter comprised of tungsten carbide rods cast into relatively softer bit matrix materials, such an alloy steel, to make a self-sharpening drill bit as the bit wears during drilling. The field of invention further relates to the method using the drill bit having tungsten carbide rods cast in steel to drill holes into geological formations that relies upon the progressive exposure of the tungsten carbide rods during the natural wear and erosion of the softer steel alloy matrix material in the drilling bit which results in the self-sharpening of the drill bit. The field of invention further relates to the method of making a long-lasting drill bit comprised of hard abrasive rods cast into steel that is self-sharpening upon the wear of the drill bit during drilling operations. The field of invention further relates to the method of making a long-lasting drill bit by pre-stressing mechanical elements comprising the drill bit that results in the expansion of the drill bit at its bottom during wear of the drill bit thereby producing a constant diameter hole as the bit wears. The field of invention also relates to a method of making the self-sharpening drill bit that relies upon using hardened metal scrapers that become exposed as the bit undergoes lateral wear which tend to produce a constant diameter hole as the bit wears. And finally, the field of invention relates to a method of making the self-sharpening drill bit that relies upon the lateral drill bit wear to uncover and expose new mud channels that results in lateral mud flow which in turn tends to produce a constant diameter hole as the bit undergoes lateral wear.
2. Description of Prior Art
Other than the applications of the inventor previously cited above, at the time of the filing of the application herein, the applicant is unaware of any art in the field that is relevant to the invention.
SUMMARY OF THE INVENTION
The rotary drilling industry presently uses the following types of drill bits that are listed in sequence of their relative importance: roller cone bits; diamond bits; and drag bits (please refer to page 1 of the book entitled “The Bit”, Unit 1, Lesson 2, of the “Rotary Drilling Series”, Third Edition, published by the Petroleum Extension Service, Division of Continuing Education, The University of Texas at Austin, Austin, Tex., hereinafter defined as “Ref. 1”, and an entire copy of “Ref. 1” is included herein by reference, and furthermore, entire copies of all of the lessons, or volumes, in the entire “Rotary Drilling Series” are also included herein by reference).
The early types of roller cone bits were steel-toothed (milled) bits that are still in general use today (Ref. 1, FIG.
7
). The longest lasting generally available variety of roller cone bits are presently the tungsten carbide insert roller cone bits that have sealed, pressure compensated, bearings. Small tungsten carbide inserts are embedded in the rollers that are used to scrape and fracture the formation while the bit rotates under load. However, there are a large number of rapidly moving parts in a tungsten carbide insert roller cone bit, including the bearings, which make it relatively expensive and prone to eventual failure. Further, the small tungsten carbide inserts in such bits eventually tend to fall out of the cones into the well that results in the failure of the bits (Ref. 1, page 21).
Under ideal operational conditions, the diamond bits can last the longest downhole (Ref 1, page 27). Even though the diamond bits can wear, they have no rapidly moving parts such as bearings, ie., they are “monolithic”. For the purposes of this application the definition of “monolithic” shall be defined to be a one piece item that has no rapidly moving parts. (For the purposes herein, the very slow deformation of mechanical parts due to interior stresses or due to mechanical wear shall not classify the part as a “moving part”.) Monolithic structure is a considerable design advantage over the tungsten carbide insert roller cone type bits which have many rapidly moving parts. However, a diamond bit costs 3 to 4 times as much as an equivalent tungsten carbide insert roller cone bit (Ref. 1, page 27). The expense of the diamond bits are a major disadvantage to their routine use.
The earliest drill bits were a form of drag bit (Ref. 1, page 35). Some modern drag bits have replaceable blades. These bits have no moving parts and are relatively inexpensive. These bits are still used today to drill relatively soft geological formations.
All of the above drill bit designs provide for circulation of the mud from the drill string through the drill bit and into the well. Roller cone bits have drilled watercourses in a “regular bit” and fluid passageways in a “jet bit” (Ref. 1, pages 3-4). Diamond bits have typically “cross-pad” or “radial flow” watercourses (Ref. 1, pages 27-29). Drag bits can have a modified “jet bit” type watercourse (Ref. 1, page 36).
When any of the present drill bits are brand new and unused, many of the above drill bit designs provide various methods to minimize “undergauging” wherein a smaller hole is drilled than is desired (Ref. 1, page 19). Sending a fresh bit into an undergauged hole can result in “jamming” or other significant problems (Ref. 1, page 1). When the bits are new, many of the various designs provide a relatively controlled inside diameter of the well and also prevent the tool from being stuck or “jammed” in the well. The outer teeth on the cones of a roller cone drill bit (“gauge teeth” or “gauge cutters”) determine the inside diameter of the hole and prevent sticking or jamming of the bit (Ref. 1, pages 8 and 19). The oversize lower portion of the diamond bit determines the inside diameter of the hole and prevents sticking or jamming of the bit. The lower flared taper on the drag bits determine the inside diameter of the hole and prevents sticking or jamming of the bit.
However, as any well is drilled, the roller cone bits, the diamond bits, and the drag bits undergo wear towards the ends of the bit. In this application, the definition of “longitudinal” shall mean along the axis of the bit—i.e., in the direction of hole being drilled at any instant. Therefore, the roller cone bits, the diamond bits, and the drag bits all undergo longitudinal wear during drilling operations. As the bit undergoes progressive longitudinal wear, the drill bit becomes dull, and the drilling rate of penetration (feet per hour) slows. The bit can undergo wear to the point that it ultimately fails. Put simply, the roller cone bits, the diamond bits, and the drag bits become progressively duller and wear-out during drilling. The drilling industry instead desires long-lasting, self-sharpening drill bits. In this application
Smart Drilling and Completion, Inc.
Tsay Frank S.
LandOfFree
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