Boring or penetrating the earth – Processes – Boring with specific fluid
Reexamination Certificate
2002-01-23
2004-01-27
Dang, Hoang (Department: 3672)
Boring or penetrating the earth
Processes
Boring with specific fluid
C175S206000, C175S207000, C210S784000, C210S808000
Reexamination Certificate
active
06681874
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
NONE
STATEMENTS AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
NONE
INVENTORS
OWEN THOMAS RISHER
NOLAN JOSEPH FITCH
RONALD CHARLES LANDRY
MICHAEL DAVID BILLEAUD
DAVID JON TILLEY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the treatment of drill cuttings generated during oil and gas well drilling operations. More particularly, the present invention relates to a method and apparatus for the removal of fluids, such as drilling mud, mud additives and contaminants, from drill cuttings. More particularly still, the present invention relates to a method and apparatus for the separation of entrained and/or adherent fluids from drill cuttings, thereby permitting recovery of such fluids as well as efficient disposal of the solid components of said drill cuttings.
2. Description of the Related Art
Drilling rigs used for the drilling of oil and gas wells typically include a supportive rig floor positioned over a well, a derrick extending vertically above said rig floor, and a traveling block which can be raised and lowered within said derrick. During drilling operations, a drill bit is generally conveyed into a well and manipulated within said well via tubular drill pipe. The drill pipe is raised and lowered within the well utilizing the drilling rig derrick.
When installing drill pipe or other tubular pipe into a well, such pipe is typically installed in a number of sections of roughly equal length called “joints”. As such pipe penetrates farther and farther into a well, additional joints of pipe must be added to the ever lengthening “string” or “drill string” in the rig derrick. Thus, a typical drill string comprises a plurality of sections or joints of pipe, each of which has an internal, longitudinally extending bore. During drilling operations, a drill bit or other desired equipment is typically attached to the lower or distal end of said drill string.
During drilling operations, a fluid known as drilling mud or drilling fluid is normally pumped down the longitudinally extending bore of the tubular drill pipe, and circulated up the annular space which is formed between the external surface of said drill pipe and the internal surface of the wellbore. The basic functions of drilling mud are: (1) to cool and lubricate the drill bit and downhole equipment during drilling operations; (2) to transport pieces of drilled-up rock and other debris from the bottom of the hole to the surface; (3) to suspend such rock and debris during periods when circulation is stopped; (4) to provide hydrostatic pressure to control encountered subsurface pressures; and (5) to seal the porous rock in the well with an impermeable filter cake.
As circulated drilling mud returns to the earth's surface and is pumped out of a well, the mud often contains pieces of broken, drilled-up rock and other solid debris known as “cuttings” or “drill cuttings”. In most cases, an effluent mud stream flowing out of a well, together with associated drill cuttings, is directed to one or more devices which are specifically designed to separate such drill cuttings from the mud. Such devices include, but are not limited to, “shale shakers,” desanders, desilters, hydrocyclones and centrifuges.
Shale shakers, which are well known in the art, are essentially screens that are used to separate drill cuttings from the drilling mud. In many cases, shale shakers utilize a series of screens arranged in tiered or flat disposition relative to each other. Further, such screens are often made to vibrate in order to increase the quality of such separation. The bulk drilling mud falls through the screens by gravity, while the predominantly solid cuttings pass over the end of the screens. Certain shale shakers are designed to filter coarse material from the drilling mud, while other shale shakers are designed to remove finer particles from the well drilling mud.
Shale shakers and other cuttings-removal equipment perform a valuable function in the overall drilling process. If drill cuttings are not removed from the effluent mud stream as such mud is circulated out of a well, said cuttings would remain in the active mud system. These drill cuttings and other debris would then be recirculated into the well. This often leads to problems, because such drilled solids can dramatically alter the characteristics and performance of the drilling mud. Further, recirculation of drill cuttings can also increase wear in mud pumps and other mechanical equipment used in the drilling process. As such, shale shakers and other similar devices are frequently necessary to efficiently separate drill cuttings from drilling mud as it is circulated out of a well.
Once drill cuttings and other debris have been separated from the bulk mud stream flowing out of a well, it is necessary to dispose of such cuttings. Unfortunately, in most instances the disposal of drill cuttings can present a number of different problems. Often, the most economical way to dispose of drill cuttings would simply be to discharge said cuttings directly into the surrounding environment. However, even though drill cuttings leaving a shale shaker have been separated from a well's effluent mud stream, such cuttings nonetheless typically include entrained and/or adherent mud and other fluids which could be damaging to the environment.
In order for drilling mud to accomplish its intended objectives, it is often necessary to adjust or control certain characteristics of such drilling mud. Thus, chemicals and/or other additives are often mixed into such drilling muds. Common drilling mud additives include gelling agents (e.g., colloidal solids and/or emulsified liquids), weighting materials, and other chemicals which are used to maintain mud properties within desired parameters. Further, although drilling mud has historically been water-based, improved results have been obtained using oil-based or synthetic-based muds, especially in severe drilling environments. Many of these additives, oil-based muds and synthetic-based muds can be environmentally harmful. Thus, it is often undesirable and a violation of environmental regulations to release such fluid-laden cuttings directly into the surrounding environment.
In order to avoid environmental contamination and comply with applicable governmental regulations, drill cuttings are frequently transported from a drilling rig to an off-site facility for disposal. In order to accomplish such off-site disposal, drill cuttings are generally loaded into boxes or other storage containers for transportation away from the rig. While this solution can be generally functional, it is not without significant problems.
One major problem associated with the off-site disposal of drill cuttings is increased cost. In most cases, special equipment is needed to move fluid-laden drill cuttings from a rig's shale shakers to another location on the rig where storage boxes are loaded. Such equipment is often in the form of complicated and elaborate conveyors, augers and/or vacuum units. Moreover, large numbers of storage boxes must be rented or purchased in order to accommodate such cuttings. All of this added equipment and labor increases the costs associated with the drilling process.
Another major problem associated with off-site disposal of fluids-laden drill cuttings is the use of valuable rig space. Space is at a premium on most drilling rigs, and particularly those that work in a marine environment. In most instances, cuttings disposal equipment takes up a great deal of a rig's available work area. For example, large storage boxes, which must be loaded on and off a rig, take up a significant amount of space. Similarly, equipment used to move such cuttings from a rig's shale shaker to cuttings boxes can also take up a great deal of space. This additional equipment can present logistical and/or safety problems on many rigs.
Another problem associated with off-site disposal of drill cuttings is environmental impact. Such off-site dis
Billeaud Michael David
Fitch Nolan Joseph
Landry Ronald Charles
Risher Owen Thomas
Tilley David Jon
Anthony Ted M.
Dang Hoang
Drill Cuttings Technology, L.L.C.
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