A well casing is cemented in a well bore in a subterranean formation by pumping cement slurry down into the well casing so that the cement slurry flows up into an annulus surrounding the well casing. While pumping the cement slurry, the position of the top of the cement slurry in the annulus is sensed, and the rise of the sensed position of the top of the cement slurry in the annulus is recorded as a function of time. The recording is analyzed to evaluate the cement job. For example, the analysis may indicate a problem addressed by adjusting a cement plan for a future cement job, and the analysis may indicate a need to repair a location of the set cement by perforating the well casing at the location to be repaired, and pumping cement slurry down the well casing to fill the location to be repaired.

A communication unit is situated in or on a casing collar. The casing collar has two threaded ends for joining casing joints to construct a well casing, and a communication unit is disposed in or on a central region of the tube between the two threaded ends. In an example, the communication unit has a transmitter for transmitting sensor data uphole from a sensor sensing a well bore condition. For example, the communication unit has a receiver for receiving sensor data from Micro-Electro-Mechanical Systems (MEMS) sensors, a transceiver for interrogating RFID tags, an acoustic transceiver for sensing wellbore conditions, a pressure sensor, a temperature sensor, and batteries for powering the communication unit.

A running tool coupled to a running string and for operational use in a well casing. The running tool having a collapsed and expanded state, a tubular positioned around the centralizer to hold the centralizer in the collapsed state, a release assembly maneuverable to release the tubular causing the centralizer to enter into an expanded state, and a cleaning device for cleaning walls of the well casing. The cleaning device includes at least one of a scraper, magnet, brush, and a high flow rate circulation valve for channeling fluid from the running string into the well casing. The centralizer functions as a stabilizer in the expanded state protecting the running tool during operation.

A computer-implemented method includes receiving a plurality of sensor signals, each signal of the plurality of sensor signals being tagged with an associated time and depth. The method also includes selecting a baseline signal. The method further includes comparing a selected sensor signal, of the plurality of sensor signals, to the baseline signal. The method also includes determining a difference between the baseline signal and the selected sensor signal exceeds a threshold. The method includes identifying, based at least in part on the difference, a feature of interest associated with the selected sensor signal.

A computer-implemented method includes receiving a plurality of sensor signals, each signal of the plurality of sensor signals being tagged with an associated time and depth. The method also includes selecting a baseline signal. The method further includes comparing a selected sensor signal, of the plurality of sensor signals, to the baseline signal. The method also includes determining a difference between the baseline signal and the selected sensor signal exceeds a threshold. The method includes identifying, based at least in part on the difference, a feature of interest associated with the selected sensor signal.

A method for lifting a tubular string from a wellbore includes cutting the tubular string at a selected depth in the wellbore. A check valve is disposed in the tubular string above the selected depth. An interior of the tubular string is pressurized with gas to displace liquid in the tubing through the check valve. The tubular string is lifted, and a portion of the tubular string extending out of the wellbore is cut.

A method for lifting a tubular string from a wellbore includes cutting the tubular string at a selected depth in the wellbore. A check valve is disposed in the tubular string above the selected depth. An interior of the tubular string is pressurized with gas to displace liquid in the tubing through the check valve. The tubular string is lifted, and a portion of the tubular string extending out of the wellbore is cut.

A method and apparatus for evaluating light-weight cement (LWC) bond conditions in production well in presence or absence of the tubing. The apparatus includes a tool string that can be lowered into the casing or the tubing. The tool string includes a segmented transducer ring matrix to excite the surrounding medium resulting in vibrations. The tool string further includes an impedance measurement circuit that can determine natural resonance frequencies of the structural components. The impedance measurement circuit can determine certain non-harmonic resonance mode shapes for mechanical impedance measurements that are sensitive to the LWC bond conditions. A machine learning model can be used for segmented impedance measurements to correct effects from the tubing eccentricity inside the casing. Lab calibration generates bond index mapping table and the field logging impedance measurement data can be processed into the bond indexes to further evaluate LWC bond conditions.

A method and apparatus for evaluating light-weight cement (LWC) bond conditions in production well in presence or absence of the tubing. The apparatus includes a tool string that can be lowered into the casing or the tubing. The tool string includes a segmented transducer ring matrix to excite the surrounding medium resulting in vibrations. The tool string further includes an impedance measurement circuit that can determine natural resonance frequencies of the structural components. The impedance measurement circuit can determine certain non-harmonic resonance mode shapes for mechanical impedance measurements that are sensitive to the LWC bond conditions. A machine learning model can be used for segmented impedance measurements to correct effects from the tubing eccentricity inside the casing. Lab calibration generates bond index mapping table and the field logging impedance measurement data can be processed into the bond indexes to further evaluate LWC bond conditions.

A method for identifying zones in an annulus with poor cementing that may include deploying a fiber optic cable within the wellbore, creating a temperature gradient in the wellbore, and collecting temperature data over a period of time as the wellbore returns to a thermal equilibrium. The method may also include comparing the temperature data collected by the fiber optic cable at one or more locations to predicted temperature data over the period of time at the one or more locations to identify locations where the measured temperature data deviates from the predicted temperature data for identifying locations or zones of the annulus that have poor cementing.