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.

A high pressure core chamber for use in collecting pressurized core samples from a reservoir is equipped with at least two high pressure access valves, allowing the core chamber to also function as a vessel for various high pressure experiments. In some embodiments, the core chamber is also equipped with a heater, allowing high pressure, high temperature experiments, and thus duplicating reservoir conditions. Various assays using the core chamber are also described.

Disclosed is a method for determining three-dimensional in-situ stress based on displacement measurement of borehole wall, including the following steps: selecting a testing borehole section for in-situ stress testing; arranging 6-9 measurement points in the testing borehole section; using a coring drill to perform a radial cut around the displacement measurement device to relieve the stress at the measurement point; cutting off the drilled core by the coring drill; recovering the sidewall coring device and removing the cores, and then measuring the elastic deformation parameters of each core; The beneficial effect of the technical scheme proposed in this disclosure is: the method provided by this disclosure overcomes the disadvantage that the measurement can only be performed at the bottom of a borehole and thus it has a wider application range.

Disclosed is a method for determining three-dimensional in-situ stress based on displacement measurement of borehole wall, including the following steps: selecting a testing borehole section for in-situ stress testing; arranging 6-9 measurement points in the testing borehole section; using a coring drill to perform a radial cut around the displacement measurement device to relieve the stress at the measurement point; cutting off the drilled core by the coring drill; recovering the sidewall coring device and removing the cores, and then measuring the elastic deformation parameters of each core; The beneficial effect of the technical scheme proposed in this disclosure is: the method provided by this disclosure overcomes the disadvantage that the measurement can only be performed at the bottom of a borehole and thus it has a wider application range.

A system includes a bottom hole assembly and a core sampling tool. The bottom hole assembly includes a housing and a drill bit coupled to the housing. The core sampling tool includes a first compartment positioned within the housing, the first compartment including a motor; a second compartment positioned within the housing and radially spaced apart from the first compartment, the second compartment including a coring bit; and a flexible drilling shaft extending between and coupled to the motor and the coring bit.

A system includes a bottom hole assembly and a core sampling tool. The bottom hole assembly includes a housing and a drill bit coupled to the housing. The core sampling tool includes a first compartment positioned within the housing, the first compartment including a motor; a second compartment positioned within the housing and radially spaced apart from the first compartment, the second compartment including a coring bit; and a flexible drilling shaft extending between and coupled to the motor and the coring bit.

A subterranean formation is drilled using a drill bit of a bottomhole assembly to form a wellbore in the subterranean formation. The bottomhole assembly includes a storage chamber and sidewall coring bits. While the bottomhole assembly is disposed within the wellbore, a sidewall of the wellbore is cut into using the sidewall coring bits to obtain sidewall core samples. While cutting into the sidewall of the wellbore using the sidewall coring bits, fluid is circulated through the wellbore. The sidewall core samples are received within the storage chamber.

A subterranean formation is drilled using a drill bit of a bottomhole assembly to form a wellbore in the subterranean formation. The bottomhole assembly includes a storage chamber and sidewall coring bits. While the bottomhole assembly is disposed within the wellbore, a sidewall of the wellbore is cut into using the sidewall coring bits to obtain sidewall core samples. While cutting into the sidewall of the wellbore using the sidewall coring bits, fluid is circulated through the wellbore. The sidewall core samples are received within the storage chamber.

A method of determining the depth of a sidewall core sample taken from a borehole relative to a reference log of the borehole. The method includes obtaining a reference log recorded on a reference log depth scale and a borehole image log recorded on a borehole image log depth scale of a portion of the borehole from which the sidewall core sample has been taken. The method further includes generating a calibrated borehole image log from the borehole image log and the reference log and identifying a candidate sidewall core image artifact in the calibrated borehole image log. The method also includes assigning a confidence value for the candidate sidewall core image artifact based on a characteristic of the candidate sidewall core image artifact, and determining, using the confidence value, a probability that the sidewall core sample was collected at a certain depth on the reference log depth scale.

Downhole core sampling apparatus including first and second sealing elements and at least one pump configured to pump wellbore fluid from the annular space defined by the sealing elements. The downhole core sampling apparatus is capable of obtaining formation fluid saturated core samples for laboratory testing and reservoir evaluation. Method and system for obtaining formation fluid saturated core samples from the sidewall of subterranean wellbores is provided.