Earth boring – well treating – and oil field chemistry – Earth boring – Contains organic component
Reexamination Certificate
2001-05-08
2003-05-13
Tucker, Philip (Department: 1712)
Earth boring, well treating, and oil field chemistry
Earth boring
Contains organic component
C507S100000, C507S904000, C366S302000, C366S306000, C366S316000, C175S066000
Reexamination Certificate
active
06562763
ABSTRACT:
TECHNICAL FIELD
The present invention relates to methods and apparatuses for processing drilling fluids used in oilfield well drilling and, more particularly, to a method and an apparatus for homogenizing drilling fluid in an open-loop process. In general, the method and apparatus for homogenizing drilling fluid dissolve polymers and other additives to homogenize drilling fluid in an effort to eliminate clogging within the closed-loop designed drilling fluid system while simultaneously increasing the throughput of the homogenized drilling fluid for use in the closed-loop designed drilling fluid system.
BACKGROUND OF THE INVENTION
In the oilfield industry, when drilling a well, a lubricant termed “drilling fluid” or “drilling mud” (hereinafter referred to as “drilling fluid”) is used. The major functions of the drilling fluid are to: (1) remove the drilled cuttings from the wellbore hole; (2) control the subsurface pressures; (3) cool and lubricate the bit and drill pipe; (4) prevent the walls of the wellbore hole from caving; (5) release the drilled cuttings and sands at the wall's surface; (6) prevent damaging effects to the formation (subterranean earth) penetrated; (7) allow maximum information from the formation penetrated; (8) suspend the cuttings and weight material when circulation of the drill is stopped; and (9) help suspend the weight of the drill string and casing, all of which are described in “FUNCTIONS OF DRILLING FLUIDS AND TESTING PROCEDURES,” in
Applied Mud Technology
, Chapter 1, pages 3-4, by IMCO SERVICES (A Division of HALLIBURTON Company). Moreover, drilling fluid, as described in the Fourth Edition of “A Primer of Oilwell Drilling,” by Ron Baker, copyright 1979, page 47, “provides the first line of defense against blowouts.”
There are numerous formulas for the formulation of the drilling fluid some of which are water-based and others of which are oil-based or synthetic drill fluids. Depending on the subterranean geology of the earth, such as when deep sea drilling, a water-based drilling fluid is used for part of the drilling operation and thereafter, an oil-based drilling fluid is used. Moreover, depending on the subterranean geology of the earth, the water-based drilling fluid may be altered during the drilling operations. For example, when drilling a wellbore hole, a 2400 ft. subterranean section may require a drilling fluid with a 10% salt content while, just below, another subterranean section of 2000 ft. may require a drilling fluid with a much higher salt content.
A water-based drilling fluid may include, without limitation: (1) water (such as, salt water or fresh water), the drilling fluid base, (2) a viscosifier polymer, such as, XCD Polymer (a biopolymer), available from a Business Unit of M-I L.L.C., for assisting in suspending cuttings; (3) a fluid loss polymer, such as, DRISPAC Polymer (a cellulosic polymer), available from a Business Unit of M-I L.L.C., for forming a filter cake around the welbore hole wall surface; (4) a stabilization polymer, such as, Poly-Plus RD (an acrylic polymer), available from a Business Unit of, M-I L.L.C.; and, (5) other additives. Examples of other additives in the drilling fluid are (1) for the control of the salt content, sodium chloride, available from by a Business Unit of M-I L.L.C.; and, (2) for water treatment, soda ash (sodium carbonate), available from a Business Unit of M-I L.L.C. to treat out calcium which may be present in water. Nevertheless, there are numerous alternatives which can be substituted for the above identified polymers and additives, as well as, other polymers and/or additives which may be need to create the drilling fluid for the specific subterranean geology of the earth. For example, the MAYCO MAPP™ polymer, as described in “MAYCO MAPP™ MAYCO All Purpose Polymer,” from the web site (www.maycowellchem.com), can be used in the same manner as DRISPAC. Other formate brines are described in “HYDRO CHEMICALS (UK) LTD-DRILLING AND COMPLETION FLUIDS,” from the web site (www.offshore-techonogy.com).
U.S. Pat. No. 4,867,256, issued to Snead, entitled “INJECTION OF POLYMER CHEMICALS INTO DRILLING MUD” discloses various functions and characteristics of drilling muds and is incorporated herein by reference as if set forth in full below. However, the invention of the Snead patent is primarily focused on introducing a liquid water loss controlling polymer into the suction of a main circulating mud pump rather than by pouring the liquid chemical into the open collar of a drill pipe joint.
U.S. Pat. No. 4,462,470, issued to Alexander, entitled “EXTRUSION OF BENTONITE CLAY FOR FLUID LOSS REDUCTION IN DRILLING FLUIDS,” discloses general principles of drilling fluid. However, the Alexander invention is related to extruding bentonite clay into clay pellets having a majority of oriented clay platelets. The output of the mill used for extruding the bentonite clay includes a rotating wiper blade, scraping blade or cutter positioned on the interior side of apertured surface of a die plate to extrude bentonite clay into clay pellets having a majority of oriented clay platelets. The mill is used to create bentonite pellets which are dried and ground. Alexander does not teach using the mill in the processing of drilling fluids.
Referring now to
FIG. 1
, a general diagram of a conventional closed-loop designed drilling fluid system
1
is shown and described, in brief, in the Fourth Edition of “A Primer of Oilwell Drilling,” by Ron Baker, copyright 1979, pages 42-46. It should be noted that the closed-loop designed drilling fluid system
1
is designed to be closed-loop in that the drilling fluid flowing therein is adapted to be recovered and recycled through the closed-loop designed drilling fluid system
1
. However, during drilling operations, drilling fluid is inherently lost from the closed-loop designed drilling fluid system
1
and, thus, may need to be replenished.
The closed-loop designed drilling fluid system
1
includes at least one holding tank T
1
, an active tank T
2
, and at least one reclamation tank T
3
which stores the initial mixture of the drilling fluid, the processed drilling fluid, and the recycled drilling fluid, respectively. As can be appreciated, the closed-loop designed drilling fluid system
1
begins with hopper H
1
having the poured contents flowing to the holding tank T
1
and ends with the at least one reclamation tank T
3
. The closed-loop designed drilling fluid system
1
includes further includes suction line SL, pumping station PS, discharge line DL, stand pipe SP, rotary hose RH, wellbore hole WH, drilling fluid return line RL, and shale shaker SS. Finally, the kelly K, coupled to the rotary hose RH, the drill pipe DP and drill bit DB (collectively, the “drilling unit”) are coupled in series with the closed-loop designed drilling fluid system
1
to complete the closed-loop.
During drilling operations, the drilling fluid is pumped from the active tank T
2
via suction line SL, through the pumping station PS via filter/screen FS to the discharge line DL, up through the stand pipe SP, through the rotary hose RH, down the kelly K and drill pipe DP and out though drill bit DB. As the drilling fluid exists through the drill bit DB, the drilling fluid moves upward in the wellbore hole WH to the drilling fluid return line RL and continues to flow over shale shaker SS. The shale shaker SS includes a mesh M positioned over the at least one reclamation tank T
3
which allows the drilling fluid to be poured into the at least one reclamation tank T
3
. Thereby, the drilling fluid is recycled for re-circulation through the closed-loop designed drilling fluid system
1
. The above description of the closed-loop designed drilling fluid system
1
is of course rather simplistic. While not shown, further included in the closed-loop designed drilling fluid system
1
are desilters, desander and/or degasser for filtering fine silt, sand and gas from the drill fluid before re-circulation.
In a holding (mixing) tank T
1
of the drilling rig, having a storage capacity of, for example,
Adams Ben A.
Cooper Chris G.
Areaux Raymond G.
Diamond Tank Rentals, Inc.
Tucker Philip
Velez Lisa
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