A method of estimating properties of wellbore cement by penetrating the cement, and monitoring the amount of energy or power required for penetrating the cement. Penetrators include a drill bit that bores into the cement, and probes or pins that are forced into the cement. The energy or power monitored can be current and/or voltage supplied to a motor that drives the drill bit or probe. Comparing the monitored energy or power with that required to penetrate a reference cement sample of known properties can yield information about the cement being sampled. When the wellbore is lined with multiple coaxially disposed strings of casing with cement between adjacent strings and on the outer surface of the outer string; the method further includes obtaining core samples from portions of each string, each layer of cement, and formation adjacent the wellbore.

Methods of procuring a core sample may involve engaging an earth formation with a cutting structure of a coring bit. A core sample may be received within a receptacle connected to the coring bit, the receptacle being lined with a sponge material. A space of about 1 mm or less may be maintained between the core sample and the sponge material. Coring tools may include a coring bit comprising an inner gage and an outer gage and a sponge material positioned to at least partially surround a core sample cut by the coring bit. A radial distance between an inner surface of the sponge material and the inner gage of the coring bit may be about 1 mm or less. A distance between a center of curvature of the inner gage and a center of curvature of the outer gage may be about 0.3 mm or less.

A method of coring to preserve subterranean soluble salt cements gives careful consideration to the selection and use of drilling fluids, specific logging of the zone of interest, displacing the near wellbore with an agent that when cured has either bound all subterranean water or cemented up all the available pore space, coring of the target formation zone containing the cured agent and retrieval of pressurized core material that allows CT scanning.

Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

Pressure coring where the core apparatus drills the core sample and seals the core sample at its native downhole pressure (e.g., several thousand psi) may be expanded to include nuclear magnetic resonance (NMR) imaging components to produce a pressurized NMR core holder that allows for NMR imaging of the core samples having been maintained in a downhole fluid saturation state. NMR imaging performed may include 1H and also 19F imaging depending on the chamber fluid used in the pressurized NMR core holder.

An excavation apparatus includes a supporting linkage mountable to a vehicle, and a rotary spindle operable to drive a coring element about a cutting axis. The supporting linkage supports the rotary spindle and is operable to displace the rotary spindle relative to a ground surface. The supporting linkage can lower the rotary spindle to a deployed position and raise the rotary spindle to a stored position. The cutting axis can be maintained in a vertical direction in the deployed and stored positions. The rotary spindle can move relative to the supporting linkage about a hinge axis. The hinge axis can be generally parallel to the vertical direction.

An excavation apparatus includes a supporting linkage mountable to a vehicle, and a rotary spindle operable to drive a coring element about a cutting axis. The supporting linkage supports the rotary spindle and is operable to displace the rotary spindle relative to a ground surface. The supporting linkage can lower the rotary spindle to a deployed position and raise the rotary spindle to a stored position. The cutting axis can be maintained in a vertical direction in the deployed and stored positions. The rotary spindle can move relative to the supporting linkage about a hinge axis. The hinge axis can be generally parallel to the vertical direction.

A fidelity retaining type coring device for a rock sample, comprising a rock core drilling tool, a rock core sample storage barrel, and a rock core sample fidelity retaining cabin. The rock core drilling tool comprises a coring drilling tool, a core catcher (11), and an inner core pipe (12); the coring drilling tool comprises an outer core pipe (13) and a hollow drill bit (14), and the drill bit (14) is connected to the lower end of the outer core pipe (13); the lower end of the inner core pipe (12) extends to the bottom of the outer core pipe (13), and the inner core pipe (12) is in clearance fit with the outer core pipe (13); the rock core sample fidelity retaining cabin comprises an inner coring barrel (28), an outer coring barrel (26), and an energy accumulator (229); the outer coring barrel (26) is sleeved on the inner coring barrel (28); the upper end of the inner coring barrel (28) is communicated with a liquid nitrogen storage tank (225), and the liquid nitrogen storage tank (225) is located in the outer coring barrel (26); the energy accumulator (229) is communicated with the outer coring barrel (26); the outer coring barrel (26) is provided with a flap valve (23). According to the device, a rock core can maintain its state in an in-situ environment; in addition, the drilling speed can be increased, and the coring efficiency can be improved.

A fidelity retaining type coring device for a rock sample, comprising a rock core drilling tool, a rock core sample storage barrel, and a rock core sample fidelity retaining cabin. The rock core drilling tool comprises a coring drilling tool, a core catcher (11), and an inner core pipe (12); the coring drilling tool comprises an outer core pipe (13) and a hollow drill bit (14), and the drill bit (14) is connected to the lower end of the outer core pipe (13); the lower end of the inner core pipe (12) extends to the bottom of the outer core pipe (13), and the inner core pipe (12) is in clearance fit with the outer core pipe (13); the rock core sample fidelity retaining cabin comprises an inner coring barrel (28), an outer coring barrel (26), and an energy accumulator (229); the outer coring barrel (26) is sleeved on the inner coring barrel (28); the upper end of the inner coring barrel (28) is communicated with a liquid nitrogen storage tank (225), and the liquid nitrogen storage tank (225) is located in the outer coring barrel (26); the energy accumulator (229) is communicated with the outer coring barrel (26); the outer coring barrel (26) is provided with a flap valve (23). According to the device, a rock core can maintain its state in an in-situ environment; in addition, the drilling speed can be increased, and the coring efficiency can be improved.

A core sampling and preservation system comprises the following sequentially connected modules: a drive module (300), a preservation module (200) and a core sampling module (100). The core sampling module (100) comprises a core drilling tool and a core sample storage compartment. The preservation module (200) comprises a core sample preservation container. The drive module comprises a core drill having a liquid channel. The core sample preservation container comprises an inner core barrel (28), an outer core barrel (26) and an energy storage device (229). The outer core barrel (26) is sleeved onto the inner core barrel (28). An upper end of the inner core barrel (28) is in communication with a liquid nitrogen storage tank (225). The liquid nitrogen storage tank (225) is positioned inside the outer core barrel (26). The energy storage device (229) is in communication with the outer core barrel (26). The outer core barrel (26) is provided with a butterfly valve (23). The system facilitates preserving a core at in-situ conditions, and has an increased drilling speed, thereby enhancing core sampling efficiency.