Transporting Sample To Surface By Fluid Patents (Class 175/60)
  • Patent number: 10443328
    Abstract: A method of controlling an influx in a petroleum well with a managed pressure drilling system can include directing mud into the well; regulating a pressure of the mud proximate to a surface of the well with a choke valve; detecting, with a computing device having one or more processors, an intrusion of the influx in the well; increasing, in response to the detecting, the pressure of the mud proximate to the surface to a first level of surface back pressure by controlling the choke valve; determining, with the computing device, a volume of the influx; ascertaining an intrusion depth substantially concurrent with the detecting; and evacuating the influx in response to a correlation between both of the first level of surface back pressure and the volume of the influx relative to the intrusion depth.
    Type: Grant
    Filed: September 8, 2016
    Date of Patent: October 15, 2019
    Inventor: Martin Culen
  • Patent number: 8869915
    Abstract: A system for removing desired subsurface materials. A drilling system has a sonic drill head assembly capable of rotating a drill string and transmitting oscillating forces to the drill string. A material removal system comprises an outer tube attachable to the drill string. An inner tube has an outer diameter sized so that that at least a portion of the inner tube is positionable in an inner volume of the outer tube with an annular void defined between the outer tube and the inner tube. A distal end of the inner tube defines at least one opening such that an interior conduit of the inner tube is in fluid communication with the annular void outside of the distal end of the inner tube. Pressurized fluid can be urged from the annular void through the opening to the interior conduit, entraining the desired subsurface materials therein for removal to a discharge tank.
    Type: Grant
    Filed: December 27, 2012
    Date of Patent: October 28, 2014
    Assignee: Longyear TM, Inc.
    Inventor: Mark Knolle
  • Patent number: 8813869
    Abstract: Methods and related systems are described for measuring and analyzing refracted acoustic energy. A plurality of receivers mounted are on a downhole tool, and are arranged and adapted to receive refracted acoustic energy from a downhole formation. Measurements of refracted acoustic energy is analyzed such that information relating to an azimuthal direction relative to the downhole tool of an interface within the downhole formation can be estimated. The receivers can be mounted on a drill collar as part of a LWD tool and steering of the drilling trajectory can be based in part on the estimated formation information.
    Type: Grant
    Filed: March 20, 2008
    Date of Patent: August 26, 2014
    Assignee: Schlumberger Technology Corporation
    Inventors: Nicholas Bennett, Jakob Brandt Utne Haldorsen, Hiroaki Yamamoto, Nobuyasu Hirabayasbi, Takeshi Endo, Richard Timothy Coates
  • Patent number: 8763696
    Abstract: Formation testing which may involve circulating mud in a pipe string from a mud pit through a port in the pipe string to a downhole diverter sub, wherein the pipe string is suspended in a wellbore extending into a subterranean formation, operating a downhole pump to pump formation fluid from the formation, wherein the formation fluid comprises gas, and mixing the pumped formation fluid with circulated mud such that a proportion of the pumped formation gas in the circulated mud is maintained below a threshold value.
    Type: Grant
    Filed: January 4, 2011
    Date of Patent: July 1, 2014
    Inventors: Sylvain Bedouet, Karre Otto Eriksen
  • Publication number: 20130240267
    Abstract: The present invention regards a method for performing core sampling during drilling of wells, comprising the steps of providing a dual bore drill pipe with drill bit in the end in the well bore, providing means to introduce a drill liquid into an annular space of the drill pipe and return it together with drill cuttings to the surface through centrally arranged return line in the dual bore drill pipe, removing larger cuttings at outlet of return pipe, and perform core testing on these cuttings, knowing where the cuttings come from in the well. The invention also regards a device for performing the invention.
    Type: Application
    Filed: November 15, 2011
    Publication date: September 19, 2013
    Applicant: REELWELL AS
    Inventors: Jostein Aleksandersen, Ove Hole
  • Patent number: 8025108
    Abstract: A subterranean method of processing a hydrocarbon fluid-containing deposit includes, from a subterranean room, providing a borehole into a deposit containing formation fluid comprising fluid hydrocarbon. The borehole has a first end at a wall of the subterranean room, and a second end remote from the subterranean room and received within the deposit. The first end is elevationally lower than the second end. A string of pipe is provided within the borehole from the subterranean room. A cuttings removal fluid is injected from the string of pipe into the borehole and against a wall of the borehole in underbalanced pressure conditions. One of drilling, reaming, or jetting is conducted within the borehole during said injecting of the cuttings removal fluid. Formation fluid comprising fluid hydrocarbon is flowed from the deposit into the borehole during said injecting of the cuttings removal fluid.
    Type: Grant
    Filed: September 4, 2008
    Date of Patent: September 27, 2011
    Assignee: New Era Petroleum, LLC.
    Inventors: Joseph McPhie, Clint Spence, Marty Fell, Greg Vandersnick, Brian Lunan, Albert Cerenzie
  • Patent number: 7972103
    Abstract: Apparatus for transferring settled or suspended solids from an open vessel into a closed vessel, the apparatus comprising a suction line which extends from the closed vessel to the open vessel via drive means, such as a pump or compressor, and a solids feed line which extends from a solids outlet in the open vessel to a solids inlet in the closed vessel, a fluidising apparatus being provided to fluidise the solids in the open vessel.
    Type: Grant
    Filed: November 3, 2003
    Date of Patent: July 5, 2011
    Assignee: Cameron International Corporation
    Inventors: James Edward Delves, David John Parkinson
  • Patent number: 7913774
    Abstract: A modular tool for use in subterranean formations includes a first module, a second module and one or more connectors for connecting the first and second modules. In particular, the first module includes a first collar that at least partially defines an exterior of the tool and that includes a first engagement mechanism at a first end of the collar and a second engagement mechanism at a second end of the collar. The first module also includes a fluid passageway for passing drilling fluid therethrough. The second module has a similar configuration as includes similar architecture. The one or more connectors facilitate the connection of at least one flowline fluidly connected to an exterior of the tool, and an electrical pathway for transmitting power and/or data between the modules.
    Type: Grant
    Filed: October 9, 2007
    Date of Patent: March 29, 2011
    Assignee: Schlumberger Technology Corporation
    Inventor: Ashers Partouche
  • Publication number: 20100319935
    Abstract: A method and device for drilling or cleaning in underground borehole including a drilling tool, a drill pipe with two pipe conduits extending up the surface and further including an arrangement for providing one drilling fluid for circulation with a drill string and a second arrangement for providing a second fluid in an annulus formed between the drill string and the wall of a wellbore.
    Type: Application
    Filed: August 5, 2010
    Publication date: December 23, 2010
    Applicant: REEL WELL AS
    Inventor: Ola Michael Vestavik
  • Patent number: 7775276
    Abstract: An embodiment includes an apparatus that includes a sample carrier adapted to receive a sample and return it to the surface. An embodiment includes a formation tester adapted to load the sample carrier. An embodiment includes a retriever to remove the carrier from the drilling mud. The retriever also includes a device for removing the sample from the carrier.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: August 17, 2010
    Assignee: Halliburton Energy Services, Inc.
    Inventors: Michael T. Pelletier, John C. Welch, Clive Menezes
  • Patent number: 7699124
    Abstract: A technique involves collecting formation fluids through a single packer having at least one drain located within the single packer. The single packer is designed with an outer layer that expands to create a seal with a surrounding wellbore wall. The drain is located in the outer layer between its axial ends for collecting formation fluid which is routed from the drain to an axial end of the outer layer via a fluid flow passage. Mechanical fittings are mounted at the axial ends of the outer layer, and at least one of the mechanical fittings comprises one or more flow members coupled to the flow passage to direct the collected fluid from the packer. The one or more flow members are designed to move in a manner that freely allows radial expansion and contraction of the outer layer.
    Type: Grant
    Filed: June 6, 2008
    Date of Patent: April 20, 2010
    Assignee: Schlumberger Technology Corporation
    Inventors: Pierre-Yves Corre, Stephane Metayer
  • Patent number: 7660672
    Abstract: A method and computer program product of either preventing or minimizing pore pressure increase near the wellbore wall within argillaceous formations through which a borehole has been drilled. By interpreting relevant drilling experience data, the type, extent and time-dependency of wellbore instability mechanisms are determined. The impact of drilling mud designs on the time-dependent wellbore instability and hole enlargement is determined by back-analyzing observed drilling events. At least one field-based criterion relationship between net mud weight reduction percentage ratio and hole enlargement is determined. A maximum allowable percentage ratio(s) of net mud weight reduction and either breakout mud weight or mud weight used for the adopted maximum hole enlargement that the wellbore may experience during drilling is determined. Drilling mud salinity value and salt type to satisfy maximum allowable percentage ratio(s) is then determined.
    Type: Grant
    Filed: February 5, 2008
    Date of Patent: February 9, 2010
    Assignee: Schlumberger Technology Corporation
    Inventors: Chee Phuat Tan, Magdalena Povstyanova
  • Publication number: 20090049889
    Abstract: A method for determining a property of formations surrounding an earth borehole being drilled with a drill bit at the end of a drill string, using drilling fluid that flows downward through the drill string, exits through the drill bit, and returns toward the earth's surface in the annulus between the drill string and the periphery of the borehole, including the following steps: obtaining, downhole near the drill bit, a pre-bit sample of the mud in the drill string as it approaches the drill bit; obtaining, downhole near the drill bit, a post-bit sample of the mud in the annulus, entrained with drilled earth formation, after its egression from the drill bit; implementing pre-bit measurements on the pre-bit sample; implementing post-bit measurements on the post-bit sample; and determining a property of the formations from the post-bit measurements and the pre-bit measurements.
    Type: Application
    Filed: October 29, 2008
    Publication date: February 26, 2009
    Inventors: JULIAN J. POP, Reza Taherian, Martin E. Poitzsch, Jacques R. Tabanou
  • Publication number: 20080245570
    Abstract: A modular tool for use in subterranean formations includes a first module, a second module and one or more connectors for connecting the first and second modules. In particular, the first module includes a first collar that at least partially defines an exterior of the tool and that includes a first engagement mechanism at a first end of the collar and a second engagement mechanism at a second end of the collar. The first module also includes a fluid passageway for passing drilling fluid therethrough. The second module has a similar configuration as includes similar architecture. The one or more connectors facilitate the connection of at least one flowline fluidly connected to an exterior of the tool, and an electrical pathway for transmitting power and/or data between the modules.
    Type: Application
    Filed: October 9, 2007
    Publication date: October 9, 2008
    Applicant: SCHLUMBERGER TECHNOLOGY CORPORATION
    Inventor: ASHERS PARTOUCHE
  • Publication number: 20080196942
    Abstract: A system for determining produced drill solids volume including a receiving vessel for receiving drill solids and a pressure vessel coupled to the receiving vessel. The receiving vessel has an isolation valve system to control the flow of drill solids between the receiving vessel and the pressure vessel, and the pressure vessel is adapted to allow a compressed gas to convey drill solids from the pressure vessel to a discharge line. The system also includes a skid having a plurality of weight sensors for weighing the drill solids in the pressure vessel, wherein the pressure vessel is disposed on the plurality of weight sensors and a programmable logic controller operatively couples to at least the plurality of weight sensors for calculating the weight of the drill solids in the pressure vessel.
    Type: Application
    Filed: February 15, 2008
    Publication date: August 21, 2008
    Applicant: M-I LLC
    Inventors: Richard Bingham, Gordon M. Logan, Jan Thore Eia
  • Patent number: 7027968
    Abstract: A method of simulating subsea mudlift drilling well control operations using a computer system. The method includes simulating a drilling circulation system. The simulation includes simulating drilling the wellbore at a selected rate of penetration, and the simulating drilling a wellbore includes simulating drilling selected earth formations. A kick is simulated at a selected depth in the wellbore, and the kick is simulated as a two-phase mixture including drilling fluid and a formation fluid. Controlling the kick is then simulated, and wellbore parameters are displayed via a graphical user interface connected to the computer system. The simulating drilling the wellbore is then repeated after the kick has been controlled.
    Type: Grant
    Filed: January 18, 2002
    Date of Patent: April 11, 2006
    Assignee: ConocoPhillips Company
    Inventors: Jonggeun Choe, Hans C. Juvkam-Wold
  • Patent number: 6941804
    Abstract: A method of determining an in situ PVT property of a hydrocarbon reservoir fluid that is present in a hydrocarbon-bearing formation layer traversed by a borehole, which method involves the steps of: a) calculating along the hydrocarbon-bearing formation layer the pressure gradient; and b) determining the in situ PVT property from the pressure gradient using an empirical relation that had been obtained by fitting a curve (11) through previously obtained data points (12, 13, 14) having the measured PVT property as a function of the pressure gradient.
    Type: Grant
    Filed: January 17, 2002
    Date of Patent: September 13, 2005
    Assignee: Shell Oil Company
    Inventors: Mohamed Naguib Hasem, Gustavo Antonio Ugueto
  • Patent number: 6938503
    Abstract: A suction lysimeter for sampling subsurface liquids includes a lysimeter casing having a drive portion, a reservoir portion, and a tip portion, the tip portion including a membrane through which subsurface liquids may be sampled; a fluid conduit coupled in fluid flowing relation relative to the membrane, and which in operation facilitates the delivery of the sampled subsurface liquids from the membrane to the reservoir portion; and a plurality of tubes coupled in fluid flowing relation relative to the reservoir portion, the tubes in operation facilitating delivery of the sampled subsurface liquids from the reservoir portion for testing. A method of sampling subsurface liquids comprises using this lysimeter.
    Type: Grant
    Filed: October 25, 2004
    Date of Patent: September 6, 2005
    Assignee: Battelle Energy Alliance, LLC
    Inventors: Don T. Clark, Eugene E. Erickson, William L. Casper, David M. Everett, Joel M. Hubbell, James B. Sisson
  • Publication number: 20030042021
    Abstract: A downhole sampling tool and related method are provided. The tool is provided with a main flowline for communicating fluid from the formation through the tool. A main valve is positioned in the main flowline and defines a first portion and a second portion of the main flowline. At least one sample chamber with a slidable piston therein defining a sample cavity and a buffer cavity is also provided. The sample cavity is in selective fluid communication with the first portion of the main flowline via a first flowline and with the second portion of the main flowline via a second flowline. Fluid communication is selectively established between the sample cavity and the first and/or second portions of the main flowline for selectively flushing fluid through the sample cavity and/or collecting samples of the fluid therein. Fluid may also be discharged from the buffer cavity via a third flowline.
    Type: Application
    Filed: November 1, 2002
    Publication date: March 6, 2003
    Inventors: Victor M. Bolze, Jonathan W. Brown
  • Patent number: 6401840
    Abstract: A coring apparatus permitting the taking of a non-rotating core sample and testing of same, as by NMR, prior to breakage and ejection from the apparatus. A core barrel is suspended from a rotating outer sleeve by one or more bearing assemblies which permit the core barrel to remain stationary during rotation of the sleeve with attached core bit for cutting the core. A core test device is fixed with respect to the core barrel on the outside thereof to test the core as it proceeds through the barrel. The apparatus optionally includes a directional detecting device such as an inclinometer and a compact set of circumferentially-spaced steering arms for changing the direction of the apparatus during coring.
    Type: Grant
    Filed: September 12, 2000
    Date of Patent: June 11, 2002
    Assignee: Baker Hughes Incorporated
    Inventors: Arthur D. Hay, Mike H. Johnson, Volker Krueger
  • Patent number: 5785131
    Abstract: A borehole drilling apparatus has a jacket attachable to a well head and through which a drill rod passes and which carries pressurized drilling fluid to a working end of the drill rod and out into an annulus of the borehole. The jacket has a drill rod seal and an outlet port leading from the interior of the jacket to a pressure regulator. The pressure regulator comprises an annular space through which fluid can flow from an inlet to an outlet. The annular space is defined between an inner rod and a surrounding elastomer pipe. In use, the elastomer pipe is squeezed radially inwards toward the inner rod by fluid pressure maintained between the outside of the elastomer pipe and a surrounding housing. A sampling system is in communication with the outlet port at a location upstream of the regulator.
    Type: Grant
    Filed: March 18, 1996
    Date of Patent: July 28, 1998
    Inventor: Ian Gray
  • Patent number: 5469917
    Abstract: A method for monitoring oil-drilling mud. A supported capillary membrane (SCMS) device having a support member, a capillary membrane permeable to hydrocarbons, and flights on the surface of the support member within which the capillary member is supported is disposed in a stream returning mud from a drill hole to the surface of an oil well. A stream of inert gas is passed through the SCMS device, thereby entraining hydrocarbon vapors in the gas stream and providing a sample of the hydrocarbons associated with the oil-drilling mud. The hydrocarbon-laden gas stream is input to an analytical instrument such as a gas chromatograph capable of identifying and quantitatively determining the concentrations of the hydrocarbons.
    Type: Grant
    Filed: December 14, 1994
    Date of Patent: November 28, 1995
    Inventor: Duane K. Wolcott
  • Patent number: 4825963
    Abstract: A simple low-cost and highly passive bitless nonrotational nondeviating jam-proof thin-kerf Newtonian hydraulics retrievable core-sampling method and apparatus that advances its circular core kerf through the rock by a combination of high-pressure droplet-impact and abrasive particle-jet effects, and which is independent of the weight of any drillpipe, drill collars, or any other heavy cylindrical conduit or tubular conduit associated with the coring operation. The Newtonian hydraulics features high-pressure solids-free fresh water or solution-weighted brine as the drilling fluid, which excavates rock along the inner periphery of the circular core kerf by droplet-impact effects of the high-pressure and high-velocity circular sheet of drilling fluid and by the abrasive particle-jet effects of the deflected drilling fluid and excavated rock particles along the outer periphery of the circular core kerf.
    Type: Grant
    Filed: July 11, 1988
    Date of Patent: May 2, 1989
    Inventor: James L. Ruhle
  • Patent number: 4659257
    Abstract: A method and a hollow body for forming a hole in the ground are disclosed. After the hollow body has been brought to the desired depth in the ground high pressure fluid is jetted through spray nozzles into the hollow body near the lower end thereof. The fluid jets effect a cutting of the ground core in the hollow body whereafter the pressurized fluid displaces the overhead ground core upwardly. The spray nozzles are spaced circumferentially and lie in the same transverse plane so that a very flat horizontal cut in the ground is accomplished by the fluid jets.
    Type: Grant
    Filed: October 18, 1985
    Date of Patent: April 21, 1987
    Assignee: Funderingstechnieken Verstraeten B.V.
    Inventor: Alexander J. Verstraeten
  • Patent number: 4168755
    Abstract: A nutating earth drilling bit which is adapted for use in drilling systems in which the drilling fluid and cuttings are transported from bit to surface through the interior of the drill string. The nutating bit is provided with a toroidal cutting member and a longitudinally extending annular shank, both of which have longitudinally extending passageways aligned with one another and in flow communication with the central return conduit of the drill string. The cutting member of one embodiment has a segmented cutting web at its lower end which divides the central passageway into three separate fluid return channels. Another embodiment drills an annular hole face around an uncut earth core, the core being permitted to rise into the shank member where it is broken into short segments by a core breaker.
    Type: Grant
    Filed: August 8, 1977
    Date of Patent: September 25, 1979
    Assignee: Walker-Neer Manufacturing Co.
    Inventor: Clyde A. Willis
  • Patent number: 4100981
    Abstract: Apparatus for concentric multi-string drilling with reverse air vacuum for the entrainment of chips and dust, selectively controlled through a plurality of annuli defined by the multiplicity of drill strings adapted to individually and/or cooperatively operate drill bits and reamers and the like to bore geological formations as required.
    Type: Grant
    Filed: February 4, 1977
    Date of Patent: July 18, 1978
    Inventor: John D. Chaffin
  • Patent number: 4098698
    Abstract: The present invention relates to a system for automatically recovering the entirety of the excavated materials in the order in which they are raised to the surface.The excavated materials being delivered through the central passage of a double pipe system pass into a strainer pipe 6 discharging into a perforated recovery sheath 5 which is closed at its base. A decompression sleeve 3 encloses the strainer pipe. Air and water are evacuated through the strainer slots 6 and all the excavated materials are deposited at 5 in the order in which they are brought up.The invention is applicable to any reverse circulation drilling system.
    Type: Grant
    Filed: September 20, 1976
    Date of Patent: July 4, 1978
    Assignee: Foraco Forage Rationnel Construction
    Inventor: Andre Lamothe
  • Patent number: 4098361
    Abstract: The invention relates to a drilling head connection specifically designed for reverse circulation operation and the connection can be screwed on a double pipe system in such a way that the drilling fluid injected into the annular space passes through the annular channel and thereafter through the channel of the drilling head so as to lubricate the leading surfaces of the bit and the plug moves up through the inner space with the excavation material passing through the lateral channels and also the connection can be used with any drilling head.
    Type: Grant
    Filed: September 20, 1976
    Date of Patent: July 4, 1978
    Assignee: Foraco Forage Rational Construction
    Inventor: Andre Lamothe
  • Patent number: 4066138
    Abstract: Earth boring apparatus is mounted above ground and directs an annulus of high powered laser energy downwardly for boring a cylindrical hole by fusing successive annular regions of the stratum to be penetrated at a power level that shatters and self-ejects successive cores from the hole. A first fluid blast above the hole deflects the ejected core as it exits from the hole. A second fluid blast above the hole ejects fluid to provide adequate fluid at the strata to be penetrated prior to actuation of the laser for promoting a thermal shock capable of shattering and ejecting the core.Optical sensing separately detects the core shattering and the core ejection to control timed actuation of the system components.
    Type: Grant
    Filed: December 15, 1976
    Date of Patent: January 3, 1978
    Inventors: Winfield W. Salisbury, Walter J. Stiles
  • Patent number: 4031973
    Abstract: This invention relates to placer mining and more particularly to a novel bit adapted for use in stream beds, dependably to break up and deliver to and through a sluice box a quantity of divided, water-borne gravel, sand, clay and ore for the conventional analysis and segregation of the precious metal or metals contained therein. There have been prior proposals of a generally similar nature but the material dislodging bits employed have been so poorly designed that they have been severely limited in capacity or have quickly become clogged by gravel, clay, etc. so that the ore digging operation has had to be frequently interrupted for the elimination of obstructing material. The present invention substantially eliminates this shortcoming.
    Type: Grant
    Filed: November 10, 1975
    Date of Patent: June 28, 1977
    Inventors: Robert G. Claye, David S. Wilson
  • Patent number: 3991838
    Abstract: A self-centralizing sealed diverter for aiding the surface collection of underground samples including a rigid casing driven into the ground to line a partially drilled hole, a rigid chamber mounted above and firmly but removably attached to the casing to receive drill samples, a sleeve fastened to the top of the chamber and including a stuffing box having a self-lubricating stuffing gland which lines the box, a journal removably mounted on the top of the sleeve for journalling a drill rod and for axially locating initially the stuffing gland, a casing including a bearing for aligning the rod with respect to a drill head, a protective top-plate attached to the bearing casing, and a pressed-in bush interposed between the rod and the bearing.
    Type: Grant
    Filed: June 2, 1975
    Date of Patent: November 16, 1976
    Inventor: Barry Frederick Clark
  • Patent number: 3981371
    Abstract: A core sampling drill comprising a drill bit having a series of cutting surfaces arranged around a central core hole, the upper end of the drill bit being threaded so that it can be fitted to the lower end of a tubular drill stem, a core tube positioned within the lower end of the drill stem substantially concentric therewith and spaced apart therefrom to provide an outer annular passage, the inner portion of the outer wall of the drill bit being provided with an annular recess which is arcuate in cross section so that air flowing downwardly through the outer annular passage is turned through approximately 180.degree. and directed upwardly into the core tube so that the material cut by the drill bit is entrained therein and carried into the core tube.
    Type: Grant
    Filed: June 6, 1975
    Date of Patent: September 21, 1976
    Inventor: Jamie Malcolm Wallis
  • Patent number: 3968845
    Abstract: Apparatus and method for complete reverse air vacuum drilling by entrainment of chips and dust in a high velocity air stream created by applying a vacuum to the drill stem or the annulus of a drilled hole, removing the drilled particles by entrainment in the flow of air created by the vacuum and collection of the drilled particles for visual or other analysis.
    Type: Grant
    Filed: March 6, 1975
    Date of Patent: July 13, 1976
    Inventor: John D. Chaffin
  • Patent number: 3941196
    Abstract: An airhammer and core bit apparatus including a housing and a hammer piston reciprocable in the housing for delivering repeated impact blows to an anvil secured to or forming part of a core bit which produces a core in a bore hole being drilled. A central core receiving tube extends through the housing and hammer piston, through which the core formed by the bit is conducted upwardly and through the hammer piston to the top of the bore hole, part of the compressed air supplied to the airhammer being diverted to the central tube for elevating the core therewithin toward the top of the bore hole.
    Type: Grant
    Filed: October 24, 1974
    Date of Patent: March 2, 1976
    Assignee: Bakerdrill, Inc.
    Inventors: Alfred R. Curington, Theodore J. Roscoe, Jr.