Abstract: Disclosed embodiments include systems and methods for improving the accuracy of bottom hole pressure control. One example embodiment includes a torque and drag model that calculates the elasticity of the drill string, which is included in a managed pressure drilling control system. The addition of the torque and drag calculations provide more accurate surge/swab effect calculations based on pipe movement corrected for elasticity effects. The results of these calculations will be used in a real-time hydraulics model to determine a setpoint pressure which will be utilized by a MPD choke system. Further, the real-time torque and drag models are calibrated to actual hole conditions in real-time using survey, temperature, pressure and downhole tool data to calculate friction factors in a wellbore.

Abstract: A method of freeing a pipe stuck in a subterranean well can include determining a location of a portion of the pipe stuck in the well, and penetrating and/or heating a sidewall of the pipe portion with a beam of light. A system for freeing a pipe stuck in a subterranean well can include a tool deployed into a portion of the pipe stuck in the well by a differential pressure from a wellbore to a formation penetrated by the wellbore. A beam of light emitted from the tool penetrates the pipe portion. Another method of freeing a pipe stuck in a subterranean well can include determining a location of a portion of the pipe which is biased against a wall of a wellbore by differential pressure, and directing a beam of light to the pipe portion.

Abstract: A method of maintaining a desired temperature at a location in a well can include adjusting fluid circulation parameters, thereby reducing a difference between an actual temperature at the location and the desired temperature. A well system can include at least one sensor, an output of the sensor being used for determining a temperature at a location in a well, and a hydraulics model which determines a desired change in fluid circulation through the well, in response to the temperature at the location being different from a desired temperature at the location. Another method of maintaining a desired temperature at a location in a well can include adjusting a density, solids content and/or flow rate of a fluid circulated through the well, thereby urging a temperature at the location toward the desired temperature.

Abstract: A drilling method includes assigning values to behaviors of drilling parameters during a drilling operation; forming multiple parameter signatures, each of the parameter signatures comprising a respective combination of the values; comparing the parameter signatures to multiple event signatures, each of the event signatures being indicative of a respective drilling event; and controlling the drilling operation in response to at least a partial match resulting from comparing the parameter signatures to the event signatures.

Abstract: Disclosed embodiments include systems and methods for improving the accuracy of bottom hole pressure control. One example embodiment includes a torque and drag model that calculates the elasticity of the drill string, which is included in a managed pressure drilling control system. The addition of the torque and drag calculations provide more accurate surge/swab effect calculations based on pipe movement corrected for elasticity effects. The results of these calculations will be used in a real-time hydraulics model to determine a setpoint pressure which will be utilized by a MPD choke system. Further, the real-time torque and drag models are calibrated to actual hole conditions in real-time using survey, temperature, pressure and downhole tool data to calculate friction factors in a wellbore.

Abstract: A well drilling method can include detecting a drilling event by comparing a parameter signature generated during drilling to an event signature indicative of the drilling event, and automatically controlling a drilling operation in response to at least a partial match resulting from comparing the parameter signature to the event signature. A well drilling system can include a control system which compares a parameter signature for a drilling operation to an event signature indicative of a drilling event, and a controller which controls the drilling operation automatically in response to the drilling event being indicated by at least a partial match between the parameter signature and the event signature.

Abstract: A method of freeing a pipe stuck in a subterranean well can include determining a location of a portion of the pipe stuck in the well, and penetrating and/or heating a sidewall of the pipe portion with a beam of light. A system for freeing a pipe stuck in a subterranean well can include a tool deployed into a portion of the pipe stuck in the well by a differential pressure from a wellbore to a formation penetrated by the wellbore. A beam of light emitted from the tool penetrates the pipe portion. Another method of freeing a pipe stuck in a subterranean well can include determining a location of a portion of the pipe which is biased against a wall of a wellbore by differential pressure, and directing a beam of light to the pipe portion.

Abstract: A method of maintaining a desired temperature at a location in a well can include adjusting fluid circulation parameters, thereby reducing a difference between an actual temperature at the location and the desired temperature. A well system can include at least one sensor, an output of the sensor being used for determining a temperature at a location in a well, and a hydraulics model which determines a desired change in fluid circulation through the well, in response to the temperature at the location being different from a desired temperature at the location. Another method of maintaining a desired temperature at a location in a well can include adjusting a density, solids content and/or flow rate of a fluid circulated through the well, thereby urging a temperature at the location toward the desired temperature.

Abstract: A method of controlling pressure in a wellbore can include placing a barrier substance in the wellbore while a fluid is present in the wellbore, and flowing another fluid into the wellbore while the first fluid and the barrier substance are in the wellbore. The first and second fluids may have different densities. Another method can include circulating a fluid through a tubular string and an annulus formed between the tubular string and the wellbore, then partially withdrawing the tubular string from the wellbore, then placing a barrier substance in the wellbore, then partially withdrawing the tubular string from the wellbore and then flowing another fluid into the wellbore. A well system can include at least two fluids in a wellbore, the fluids having different densities, and a barrier substance separating the fluids.

Abstract: A method of controlling pressure in a wellbore can include placing a barrier substance in the wellbore while a fluid is present in the wellbore, and flowing another fluid into the wellbore while the first fluid and the barrier substance are in the wellbore. The first and second fluids may have different densities. Another method can include circulating a fluid through a tubular string and an annulus formed between the tubular string and the wellbore, then partially withdrawing the tubular string from the wellbore, then placing a barrier substance in the wellbore, then partially withdrawing the tubular string from the wellbore and then flowing another fluid into the wellbore. A well system can include at least two fluids in a wellbore, the fluids having different densities, and a barrier substance separating the fluids.

Abstract: A method of controlling pressure in a wellbore can include placing a barrier substance in the wellbore while a fluid is present in the wellbore, and flowing another fluid into the wellbore while the first fluid and the barrier substance are in the wellbore. The first and second fluids may have different densities. Another method can include circulating a fluid through a tubular string and an annulus formed between the tubular string and the wellbore, then partially withdrawing the tubular string from the wellbore, then placing a barrier substance in the wellbore, then partially withdrawing the tubular string from the wellbore and then flowing another fluid into the wellbore. A well system can include at least two fluids in a wellbore, the fluids having different densities, and a barrier substance separating the fluids.

Abstract: A method of controlling pressure in a wellbore can include placing a barrier substance in the wellbore while a fluid is present in the wellbore, and flowing another fluid into the wellbore while the first fluid and the barrier substance are in the wellbore. The first and second fluids may have different densities. Another method can include circulating a fluid through a tubular string and an annulus formed between the tubular string and the wellbore, then partially withdrawing the tubular string from the wellbore, then placing a barrier substance in the wellbore, then partially withdrawing the tubular string from the wellbore and then flowing another fluid into the wellbore. A well system can include at least two fluids in a wellbore, the fluids having different densities, and a barrier substance separating the fluids.

Abstract: A drilling method includes assigning values to behaviors of drilling parameters during a drilling operation; forming multiple parameter signatures, each of the parameter signatures comprising a respective combination of the values; comparing the parameter signatures to multiple event signatures, each of the event signatures being indicative of a respective drilling event; and controlling the drilling operation in response to at least a partial match resulting from comparing the parameter signatures to the event signatures.