Abstract: Pulsed-electric drilling systems can be augmented with multi-component electromagnetic field sensors on the drillstring, at the earth's surface, or in existing boreholes in the vicinity of the planned drilling path. The sensors detect electrical fields and/or magnetic fields caused by the electrical pulses and derive therefrom information of interest including, e.g., spark size and orientation, bit position, at-bit resistivity and permittivity, and tomographically mapped formation strictures. The at-bit resistivity measurements can be for anisotropic or isotropic formations, and in the former case, can include vertical and horizontal resistivities and an orientation of the anisotropy axis. The sensors can illustratively include toroids, electrode arrays, tilted coil antennas, magnetic dipole antennas aligned with the tool axes, and magnetometers.

Abstract: A formation monitoring well system accurately measures formation electrical properties behind the casing to determine water-oil contact positions and/or to assess the integrity of the cement seal over the life of the well. The well system includes a casing string having one or more formation monitoring modules embedded therein, each having a toroid sensor. During operation, current is provided to the casing string, and the toroid measures the current flowing into the formation. Also, the voltage drop between the sensor and an electrode positioned between the cement layer and formation may be measured. This data may then be processed to determine the resistivities of the formation and/or cement layer, whereby the cement seal quality, water-oil contact surface position, etc. may be extracted from the results.

Abstract: A well system and associated method, in which a kill weight fluid can be flowed into a wellbore via a flow passage extending from the surface to a downhole location, and prior to the flowing, the flow passage is installed with a casing string into the wellbore. A well system and associated method, in which a flow passage is positioned external to a casing, and wherein a downhole well parameter is measured via the flow passage. Another method can include flowing a kill weight fluid into a wellbore via a flow passage extending along a casing string, the flowing being performed while a formation fluid flows into the wellbore.

Abstract: A formation monitoring well system accurately measures formation electrical properties behind the casing to determine water-oil contact positions and/or to assess the integrity of the cement seal over the life of the well. The well system includes a casing string having one or more formation monitoring modules embedded therein, each having a toroid sensor. During operation, current is provided to the casing string, and the toroid measures the current flowing into the formation. Also, the voltage drop between the sensor and an electrode positioned between the cement layer and formation may be measured. This data may then be processed to determine the resistivities of the formation and/or cement layer, whereby the cement seal quality, water-oil contact surface position, etc. may be extracted from the results.

Abstract: A well system and associated method, in which a kill weight fluid can be flowed into a wellbore via a flow passage extending from the surface to a downhole location, and prior to the flowing, the flow passage is installed with a casing string into the wellbore. A well system and associated method, in which a flow passage is positioned external to a casing, and wherein a downhole well parameter is measured via the flow passage. Another method can include flowing a kill weight fluid into a wellbore via a flow passage extending along a casing string, the flowing being performed while a formation fluid flows into the wellbore.

Abstract: A well system and associated method, in which a kill weight fluid can be flowed into a wellbore via a flow passage extending from the surface to a downhole location, and prior to the flowing, the flow passage is installed with a casing string into the wellbore. A well system and associated method, in which a flow passage is positioned external to a casing, and wherein a downhole well parameter is measured via the flow passage. Another method can include flowing a kill weight fluid into a wellbore via a flow passage extending along a casing string, the flowing being performed while a formation fluid flows into the wellbore.

Abstract: A well control method can include removing from a wellbore an undesired influx from a formation into the wellbore, determining a desired pressure profile in real time with a hydraulics model, and automatically operating a flow choking device while removing the undesired influx from the wellbore, thereby influencing an actual pressure profile toward the desired pressure profile. Another well control method can include removing out of a wellbore an undesired influx from a formation into the wellbore, determining a desired wellbore pressure with a hydraulics model, the desired wellbore pressure preventing further influx into the wellbore while removing the undesired influx from the wellbore, and automatically operating a flow choking device while removing the undesired influx from the wellbore, thereby influencing an actual wellbore pressure toward the desired wellbore pressure.

Abstract: A pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current from one or more electrodes, and a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole. The system modulates the fluid flow across the one or more electrodes.

Abstract: Pulsed-electric drilling systems can be augmented with multi-component electromagnetic field sensors on the drillstring, at the earth's surface, or in existing boreholes in the vicinity of the planned drilling path. The sensors detect electrical fields and/or magnetic fields caused by the electrical pulses and derive therefrom information of interest including, e.g., spark size and orientation, bit position, at-bit resistivity and permittivity, and tomographically mapped formation strictures. The at-bit resistivity measurements can be for anisotropic or isotropic formations, and in the former case, can include vertical and horizontal resistivities and an orientation of the anisotropy axis. The sensors can illustratively include toroids, electrode arrays, tilted coil antennas, magnetic dipole antennas aligned with the tool axes, and magnetometers.

Abstract: In a pulsed-electric drilling system, a nonrotating bit is given a noncircular shape to drill a correspondingly-shaped borehole, e.g., triangular, rectangular, polygonal, oval, or a more complex shape. Some embodiments employ a reconfigurable bit that deploys extensions as needed to dynamically vary the cross-section of the borehole at selected locations. In this fashion, a driller is able to create borehole with a preferred cross-sectional shape to, e.g., drill the smallest possible hole while simultaneously providing additional clearance for equipment or instrumentation, additional surface area for well inflow, channels for improved borehole cleaning, teeth for improved cementing, reduced contact area to reduce drag on the drillstring, or any other benefits achievable by customizing the borehole cross-section.

Abstract: Pulsed-electric drilling systems can be augmented with multi-component electromagnetic field sensors on the drillstring, at the earth's surface, or in existing boreholes in the vicinity of the planned drilling path. The sensors detect electrical fields and/or magnetic fields caused by the electrical pulses and derive therefrom information of interest including, e.g., spark size and orientation, bit position, at-bit resistivity and permittivity, and tomographically mapped formation structures. The at-bit resistivity measurements can be for anisotropic or isotropic formations, and in the former case, can include vertical and horizontal resistivities and an orientation of the anisotropy axis. The sensors can illustratively include toroids, electrode arrays, tilted coil antennas, magnetic dipole antennas aligned with the tool axes, and magnetometers.

Abstract: An assembly to recover hydrocarbon gas from a seabed comprises one or more self-propelled drilling devices that include hydrocarbon sensors and a sublimation mechanism to induce sublimation of crystallized hydrates into hydrocarbon gases. As the drilling device moves through the wellbore, hydrocarbon deposits are detected and the sublimation mechanism induces sublimation of the deposits to release hydrocarbon gases up through the formation to the seabed. A bladder is positioned atop the wellbore to capture the release hydrocarbon gas and transfer it to a surface vessel for collection.

Abstract: In at least some embodiments, a pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current, and a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole. A feed pipe transports at least a part of said fluid flow to said path, and the feed pipe is equipped with a cooling mechanism to cool the fluid flow. The use of a cooled fluid flow may enhance the performance of the pulsed-electric drilling process.

Abstract: A well system and associated method, in which a kill weight fluid can be flowed into a wellbore via a flow passage extending from the surface to a downhole location, and prior to the flowing, the flow passage is installed with a casing string into the wellbore. A well system and associated method, in which a flow passage is positioned external to a casing, and wherein a downhole well parameter is measured via the flow passage. Another method can include flowing a kill weight fluid into a wellbore via a flow passage extending along a casing string, the flowing being performed while a formation fluid flows into the wellbore.

Abstract: Pulsed-electric drilling systems can be augmented with multi-component electromagnetic field sensors on the drillstring, at the earth's surface, or in existing boreholes in the vicinity of the planned drilling path. The sensors detect electrical fields and/or magnetic fields caused by the electrical pulses and derive therefrom information of interest including, e.g., spark size and orientation, bit position, at-bit resistivity and permittivity, and tomographically mapped formation structures. The at-bit resistivity measurements can be for anisotropic or isotropic formations, and in the former case, can include vertical and horizontal resistivities and an orientation of the anisotropy axis. The sensors can illustratively include toroids, electrode arrays, tilted coil antennas, magnetic dipole antennas aligned with the tool axes, and magnetometers.

Abstract: In at least some embodiments, a pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current, and a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole. A feed pipe transports at least a part of said fluid flow to said path, and the feed pipe is equipped with a cooling mechanism to cool the fluid flow. The use of a cooled fluid flow may enhance the performance of the pulsed-electric drilling process.

Abstract: In at least some embodiments, a pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current from one or more electrodes, and a drillstring that defines at least one path for a fluid flow to the bit to flush detached formation material from the borehole. The system modulates the fluid flow across the one or more electrodes. This modulation may enhance the performance of the pulsed-electric drilling process.

Abstract: In at least some embodiments, a pulsed-electric drilling system includes a bit that extends a borehole by detaching formation material with pulses of electric current, and a drillstring that transports a fluid flow from the bit to convey detached formation material out of the borehole. The use of reverse circulation may enhance the performance of the pulsed-electric drilling system.

Abstract: In a pulsed-electric drilling system, a nonrotating bit is given a noncircular shape to drill a correspondingly-shaped borehole, e.g., triangular, rectangular, polygonal, oval, or a more complex shape. Some embodiments employ a reconfigurable bit that deploys extensions as needed to dynamically vary the cross-section of the borehole at selected locations. In this fashion, a driller is able to create borehole with a preferred cross-sectional shape to, e.g., drill the smallest possible hole while simultaneously providing additional clearance for equipment or instrumentation, additional surface area for well inflow, channels for improved borehole cleaning, teeth for improved cementing, reduced contact area to reduce drag on the drillstring, or any other benefits achievable by customizing the borehole cross-section.

Abstract: Pulsed-electric drilling systems can be augmented with a steering mechanism that shifts at least a portion of a bit relative to a borehole centerline. Illustrative mechanisms include ball-and-socket joints, pivot-and-hinge joints, rotary steerable systems, and bent subs. As the bit detaches formation material using electric pulses, the detached material being flushed away by a flow of drilling fluid, the shifting of the bit from the centerline causes the borehole to turn in the direction of the bit.