Abstract: In some embodiments, a method for reducing magnetic debris accumulation on a downhole sensor within a tubular conveyed in a borehole comprises supplying a voltage to temporarily neutralize a magnetic field of a permanent electromagnet proximate to the downhole sensor and removing magnetic debris on the downhole sensor via a flow of a first fluid in the tubular while the magnetic field is neutralized.

Abstract: Disclosed herein are embodiments of a sensor assembly apparatus, system, and method. In one embodiment, an apparatus comprises a sensor assembly adapted to be integrated into a casing to be positioned in a wellbore, the sensor assembly comprising a housing; a magnet located within the housing; a magnetic sensor located within the housing to measure a magnetic measurement change resulting from a force between the magnet and magnetic particles flowing with a cement slurry inside the casing from a reverse cementing; and a sensor plug having a side with a non-flat shape that is to be in contact with the slurry flowing in the casing of the wellbore; a processor communicatively coupled to the magnetic sensor and configured to determine whether the magnetic measurement change exceeds a magnetic threshold; and determine that the slurry is flowing back up internal to the casing at or beyond a location in the wellbore.

Abstract: A sensor device can be used to detect the presence of a cement composition in a reverse cementing operation. The sensor device can include a resistivity sensor, an acquisition and measurement apparatus, and an actuator. The actual derivative of resistivity of the drilling mud, spacer fluid, and cement composition to be used can be pre-determined. The acquisition and measurement apparatus can be pre-programmed with a slope change derivative of resistivity profile for the fluids. The resistivity sensor can measure the resistivity of the fluids as they flow past the resistivity sensor in the wellbore. When the acquisition and measurement apparatus receives a desired slope change reading within the slope change derivative of resistivity profile, instructions can be sent to the actuator to close a valve and block fluid flow through the casing or tubing string.

Abstract: Disclosed herein are embodiments of a sensor assembly apparatus, system, and method. In one embodiment, an apparatus comprises a sensor assembly adapted to be integrated into a casing to be positioned in a wellbore, the sensor assembly comprising a housing; a magnet located within the housing; a magnetic sensor located within the housing to measure a magnetic measurement change resulting from a force between the magnet and magnetic particles flowing with a cement slurry inside the casing from a reverse cementing; and a sensor plug having a side with a non-flat shape that is to be in contact with the slurry flowing in the casing of the wellbore; a processor communicatively coupled to the magnetic sensor and configured to determine whether the magnetic measurement change exceeds a magnetic threshold; and determine that the slurry is flowing back up internal to the casing at or beyond a location in the wellbore.

Abstract: A sensor device can be used to detect the presence of a cement composition in a reverse cementing operation. The sensor device can include a resistivity sensor, an acquisition and measurement apparatus, and an actuator. The actual resistivity of the drilling mud, spacer fluid, and cement composition to be used can be pre-determined. The acquisition and measurement apparatus can be pre-programmed with a resistivity profile for the fluids. The resistivity sensor can measure the resistivity of the fluids as they flow past the resistivity sensor in the wellbore. When the acquisition and measurement apparatus receives a desired reading within the resistivity profile, instructions can be sent to the actuator to close a valve and block fluid flow through the casing or tubing string.