Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.