A method of stabilizing a core sample is described, and an agent for use in the stabilising method. The method involves injecting a foam around a core sample in a cylindrical liner. The foam comprises mixture of a first pressurized polymerisable-based fluid and a second pressurized fluid, which are simultaneously injected as a foam into an annulus between the core sample and liner. The foam preserves the sample and cushions it for transportation. The foam can include a dye or colorant to distinguish the foam from other materials in the core sample.

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 core 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.

An elongate sample core (14) is prepared for non-destructive analysis, eg. computed tomography, by locating it in a container (10) and filling gaps between the sample and the container with a flowable solid stabilizing material (22).

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.

An elongate sample core (14) is prepared for non-destructive analysis, eg. computed tomography, by locating it in a container (10) and filling gaps between the sample and the container with a flowable solid stabilizing material (22).

A device for extracting an undisturbed sample (S) of soil to be tested from a subsurface location uses a cutter (28) to remove unwanted soil from above the undisturbed sample. The device is particularly intended for extraction of soil from contaminated areas without loss of contaminants which are volatile at ambient temperatures. Means (80) are therefore also disclosed for chilling or freezing the sample in situ before extraction and testing. A method of using the device to take samples whenever volatile contaminants are sensed is also disclosed.

A device for extracting an undisturbed sample (S) of soil to be tested from a subsurface location uses a cutter (28) to remove unwanted soil from above the undisturbed sample. The device is particularly intended for extraction of soil from contaminated areas without loss of contaminants which are volatile at ambient temperatures. Means (80) are therefore also disclosed for chilling or freezing the sample in situ before extraction and testing. A method of using the device to take samples whenever volatile contaminants are sensed is also disclosed.

A well coring apparatus (10) includes an outer barrel (12) and an inner barrel (18). The inner barrel (18) is sealed atone end with a sealing member (80) and has a reciprocating piston (70) disposed in the other end thereof. On 0-ring (68) is disposed at the receiving end of the inner barrel (18) to provide a seal therefor. Spring members (76) provide a restrictive force to the piston (70). A sponge (50) is disposed around the inner walls of the inner barrel (18) for contacting the core (82). A fluid is disposed in the inner space (78) of the inner barrel (18) and pressurized. Reciprocation upward of the piston (70) causes the fluid to flow therefrom out the receiving end of the inner barrel (18). This flow of fluid washes the sides of the core (82) to prevent drilling mud from caking about the surface thereof and preventing proper transfer of fluids contained within the core (82) to the sponge (50). The fluid in the inner space (70) has a density that is lower than that for fluids external to the inner barrel (18) such that contamination of the sponge (50) is prevented.

A method of and apparatus for obtaining a core at in situ pressure of sedimentary deposits at the bottom of a well bore or body of water. The core barrel has a pressure chamber (28) that is closed and opened by a ball valve (30) actuated from the surface. When in position above the sedimentary deposits to be cored, a sample tube (16) is extended from the pressure chamber (28) into the sedimentary deposits to obtain a core. The sample tube is retracted into the pressure chamber and the valve closed to trap ambient pressure in the chamber. The sample tube and valve are operated from the surface.

Also a transfer tube (114) is described, which serves to store cores on the surface at in situ pressure.