A coating reservoir defining a chamber operable retain to a liquid coating. A retractable application assembly includes a nozzle fluidically coupled to the coating reservoir. The nozzle is configured to dispense the liquid coating onto a wall of a wellbore. A spreader is proximal to the nozzle. The spreader is configured to regulate a thickness of the liquid coating dispensed by the nozzle. A flexible coating housing is positioned between the coating reservoir and the nozzle. The coating housing is configured to seal against a wall of the wellbore and seal the nozzle, spreader, and dispensed liquid coating from contamination within the wellbore.

A wireline clean-out tool including a first opening and a second opening at or near a free-end portion. The first opening takes in debris from a wellbore, the second opening ejects fluid into the wellbore. A housing defines a first flow path from the first opening at the free-end portion to an opposite end portion of the housing and a second flow path from the opposite end portion to the second opening at the free-end portion. The flow paths couple with each other at the opposite end portion. A collection chamber is in the first flow path for collecting debris during operation. A progressive cavity pump with hollow rotors is placed inside the housing at a predefined distance from the free-end portion being configured for operating on the first flow path while the hollow rotor forms part of the second flow path.

A wellbore gauge cutter apparatus includes a sampling body defining a central recess extending from an inlet at a first end to an outlet at a second end. The apparatus further includes a gauge cutter connected to the sampling body configured to dislodge particles from an inner wall of a wellbore. The sampling body includes an inner wall defining the central recess, a hollow cylindrical divider having a central aperture, a first flow path defined in the central aperture of the hollow cylindrical divider, a second flow path defined between an outer wall of the hollow cylindrical divider and the inner wall of the sampling body, and a fluid permeable screen arranged in the first flow path or the second flow The fluid permeable screen is configured to collect a portion the particles dislodged by the gauge cutter.

A wellbore gauge cutter apparatus includes a sampling body defining a central recess extending from an inlet at a first end to an outlet at a second end. The apparatus further includes a gauge cutter connected to the sampling body configured to dislodge particles from an inner wall of a wellbore. The sampling body includes an inner wall defining the central recess, a hollow cylindrical divider having a central aperture, a first flow path defined in the central aperture of the hollow cylindrical divider, a second flow path defined between an outer wall of the hollow cylindrical divider and the inner wall of the sampling body, and a fluid permeable screen arranged in the first flow path or the second flow The fluid permeable screen is configured to collect a portion the particles dislodged by the gauge cutter.

A bell nipple includes a downhole end configured to sealingly couple to an uphole-end of a blow-out preventer. An uphole end of the bell nipple includes a first set of threads along an inner surface of the bell nipple. A thread saver is configured to be received by the uphole end. The thread saver is configured to protect the first set of threads from impact. An extension sub is configured to be received by the uphole end. The extension sub includes a downhole end with a second set of threads configured to engage with the first set of threads. An uphole end of the extension sub includes a third set of threads configured receive a well tool.

A frac sand separator system includes a sand separator having an inlet fluidly connected to a well for receiving a fracking return mixture from the well. The sand separator is configured to separate water of the fracking return mixture from particulate matter of the fracking return mixture. The sand separator includes an outlet. The frac sand separator system includes a collection container fluidly connected to the outlet of the sand separator for receiving the particulate matter from the sand separator. At least one outlet valve is fluidly connected between the outlet of the sand separator and the collection container. The frac sand separator system includes a computing device operatively connected to the at least one outlet valve. The computing device includes a processor configured to automatically open the at least one outlet valve such that the particulate matter is released from the sand separator into the collection container.

A frac sand separator system includes a sand separator having an inlet fluidly connected to a well for receiving a fracking return mixture from the well. The sand separator is configured to separate water of the fracking return mixture from particulate matter of the fracking return mixture. The sand separator includes an outlet. The frac sand separator system includes a collection container fluidly connected to the outlet of the sand separator for receiving the particulate matter from the sand separator. At least one outlet valve is fluidly connected between the outlet of the sand separator and the collection container. The frac sand separator system includes a computing device operatively connected to the at least one outlet valve. The computing device includes a processor configured to automatically open the at least one outlet valve such that the particulate matter is released from the sand separator into the collection container.

A well tool includes a perforating gun including multiple shaped charges, a sheath encapsulating the perforating gun and powdered acid in an internal chamber defined by the sheath. The perforating gun is lowered to a depth into a wellbore formed in a subterranean zone. The multiple shaped charges are fired to form multiple perforations in the wellbore at the depth. The multiple perforations provide access to the subterranean zone at the depth. The sheath, which covers at least some of the multiple shaped charges, breaks responsive to at least some of the multiple shaped charges being fired. The powdered acid in the internal chamber is applied to the subterranean zone responsive to the multiple shaped charges being fired. The powdered acid reacts with and weakens the subterranean zone at the depth to ease flow of hydraulic fracturing fluid into the subterranean zone at the depth.

A well tool includes a perforating gun including multiple shaped charges, a sheath encapsulating the perforating gun and powdered acid in an internal chamber defined by the sheath. The perforating gun is lowered to a depth into a wellbore formed in a subterranean zone. The multiple shaped charges are fired to form multiple perforations in the wellbore at the depth. The multiple perforations provide access to the subterranean zone at the depth. The sheath, which covers at least some of the multiple shaped charges, breaks responsive to at least some of the multiple shaped charges being fired. The powdered acid in the internal chamber is applied to the subterranean zone responsive to the multiple shaped charges being fired. The powdered acid reacts with and weakens the subterranean zone at the depth to ease flow of hydraulic fracturing fluid into the subterranean zone at the depth.

A sealing method for a drilled hole in three zones of overburden comprises: blocking the fissure zone and the caving zone with at least one filling bag; and transporting prepared cement slurry to the drilled hole through a hollow drill pipe, so as to block the curved subsidence zone. The three zones of overburden comprise a fissure zone, a caving zone and a curved subsidence zone.