Baker Hughes Corporation

Pierre E Collee

Dorothy P Enright

Steven R Radford

William A Mallow

Michael H Johnson

John W Harrell

Luc Van Puymbroeck

Barry W Struthers

A method for protecting integrity of a core sample during transport from a subterranean formation to the surface comprising: cutting a core sample from the subterranean formation using a drilling fluid; encapsulating the core sample with an encapsulating material that is separate from the drilling fluid and comprises a property which renders the encapsulating material capable of protecting the chemical integrity of the core sample during transport from the subterranean formation to the surface, wherein the property is other than a property selected from the group consisting of a viscosity which increases in response to a decrease in temperature and an ability to solidify in response to a decrease in temperature; and, transporting the encapsulated core sample from the subterranean formation to the surface.

Method for preserving core sample integrity

A core barrel having an inner tube for coring and, alternately, a center plug assembly for closing the throat of the core bit at the bottom of the assembly for drilling in lieu of coring. The inner tube assembly and plug assembly are disposable and retrievable through the drill string on a wireline using an overshot. The core bit is of a stabilized, preferably anti-whirl, design and may be a low-invasion core bit used in cooperation with a low-invasion coring shoe. A logging tool and data transmission assembly may be incorporated in the plug assembly for logging while drilling. Alternatively, sensors for logging borehole parameters and a data transmission assembly may be incorporated in the inner tube assembly, in the wall of the core barrel, above the core barrel, or in a combination of such locations. A significant feature of the apparatus and its operation is the ability to concurrently sense one or more characteristics of the formation surrounding the core barrel in combination with the sensing of one or more such parameters of the core being cut as it proceeds into the inner tube assembly.

Method and apparatus for simultaneous coring and formation evaluation

The present invention provides a method for protecting the integrity of a core sample during transport from a subterranean formation to the surface comprising: cutting a core sample from the subterranean formation using a drilling fluid; encapsulating the core sample with an encapsulating material separate from the drilling fluid, the encapsulating material being capable in the absence of a chemical reaction of protecting core sample integrity during transport from said subterranean formation to said surface; and, transporting the encapsulated core sample from the subterranean formation to the surface.

A core barrel having an inner tube for coring and, alternately, a center plug assembly or closing the throat of the core bit at the bottom of the assembly for drilling in lieu of coring. The inner tube assembly and plug assembly are disposable and retrievable through the drill string on a wireline using an overshot. The core bit is of a stabilized, preferably anti-whirl, design and may be a low-invasion core bit used in cooperation with a low-invasion coring shoe. A logging tool and data transmission assembly may be incorporated in the plug assembly for logging while drilling.

Bit-stabilized combination coring and drilling system

The present invention provides a method for maximizing the chemical integrity and, if desired, maintaining the mechanical integrity of a core sample during transport from a subterranean formation to the surface. The method involves cutting and encapsulating the core sample as it enters the core barrel with an encapsulating material that either (a) inherently is capable of protecting the chemical integrity of the core sample, or (b) is capable of increasing in viscosity and/or solidifying in response to natural decreases in temperature to maintain the mechanical integrity and maximize the chemical integrity of the core sample during transport.

Method and composition for preserving core sample integrity using an

The present invention provides a method and composition for encapsulating a core sample as it enters a core barrel with a water-based encapsulating material that preferably comprises an expandable lattice type clay. The water-base causes the expandable lattice type clay to swell, forming a plastic mass which can be pumped into a core barrel to encapsulate the core sample and maintain the chemical and mechanical integrity of the sample during transport to the surface. Filtration control agents preferably are added to the encapsulating material to prevent water from penetrating into or interacting with the core. These control agents prevent the loss and/or invasion of water or other gaseous or fluid components. The control agents are (a) a water soluble thickening agent, and, (b) a particulate sealing agent capable of (i) sealing the pores of the core sample, or (ii) bridging the pores of the core sample and permitting the thickening agent to adsorb to the bridge to seal the pores. The integrity of the core sample will be maximized if a pressure core barrel is used to transport the encapsulated core sample to the surface.

Method and composition for preserving core sample integrity using a

A pressure core barrel including an inner tube containing a non-invasive gel for encapsulating a core sample. An anti-whirl core bit is employed, and the core bit and inner tube pilot shoe are configured and arranged to prevent damage to the core from drilling fluid. A special high viscosity, low spurt loss coring fluid is employed in the coring operation. When the encapsulated, pressurized care sample is brought to the surface, pressure is bled off and the core sample's chemical and mechanical integrity are substantially preserved by the gel.

Method and apparatus for pressure coring with non-invading gel

The present invention provides a method for maintaining the mechanical integrity and for maximizing the chemical integrity of a core sample during transport from a subterranean formation to the surface. The method involves cutting and encapsulating a core sample with an encapsulating material that increases in viscosity or even solidifies, at temperatures slightly lower than those expected downhole, or relatively early in the transport process. A preferred encapsulating material contains at least one polyglycol or chemically modified polyglycol from the oxyalkylene polymer family. The specific formulation of the encapsulating material differs depending upon the expected downhole conditions. For example, the encapsulating material can include a thickener, a nucleating agent, and a water swellable material or another inert material that is capable of sealing the core sample against water. A preferred nucleating agent would serve both as a heat transfer agent and a crystallization trigger, and therefore would speed up the rate at which the encapsulating material would solidify or increase in viscosity, particularly downhole. The encapsulating material should either solidify or increase in viscosity enough to protect the mechanical integrity and maximize the chemical integrity of the core sample for analysis at the surface. The chemical integrity of the core sample can be further maximized by using the present invention in conjunction with a pressure core barrel.

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Kingwood, TX, United States of America

Pierre E Collee