Automated well pressure control and gas handling system and method

A method, comprising:

• pumping fluid of a drilling unit into a drill string extending through a riser into a well;
• detecting a fluid influx into the well or a fluid loss into a formation;
• abating the fluid influx by closing an annular blowout preventer disposed in the riser and diverting the fluid flowing through a flow spool below the annular blowout preventer from the riser to a distribution manifold and then to a choke manifold;
• abating the fluid loss by closing the annular blowout preventer and pumping a sacrificial fluid into the drill string using a pump that is located adjacent to the well by lifting fluid from a base of the riser, wherein the pump is in fluid communication with the riser at the base of the riser;
• maintaining a predetermined fluid pressure in the well when neither the fluid influx nor the fluid loss is detected by directing the fluid from the well to a manifold and then to a choke;
• coupling the flow spool to the annular blowout preventer such that the annular blowout preventer is disposed above the flow spool;
• and
• connecting a blowout preventer assembly stack to a wellhead of the well such that the blowout preventer assembly stack is disposed below the flow spool.

An apparatus, comprising:

• a drilling unit comprising a derrick and hoisting equipment, the drilling unit comprising drilling mud pumps having a discharge in fluid communication with an interior of a drill string suspended in a well by the hoisting equipment;
• a riser extending from a subsea blowout preventer assembly stack to the drilling unit, wherein the subsea blowout preventer assembly stack is coupled to a top of the well;
• a pump in fluid communication with the riser at a base of the riser adjacent the top of the well, wherein an inlet pressure to the pump is selected by the drilling unit;
• an annular blowout preventer disposed between the subsea blowout preventer assembly stack and the riser, the annular blowout preventer having a controllable flow bypass;
• a flow spool separating the subsea blowout preventer assembly stack and the annular blowout preventer such that the annular blowout preventer is disposed above the flow spool, and the subsea blowout preventer assembly stack is disposed below the flow spool;
• a managed pressure drilling system disposed proximate the drilling unit and comprising a controllable orifice choke in a fluid discharge path from the well, wherein the pump is in fluid communication with the managed pressure drilling system via the fluid discharge path;
• a first manifold in fluid communication with the well and the controllable orifice choke;
• a second manifold in fluid communication with the annular blowout preventer;
• a choke manifold in fluid communication with the second manifold;
• and
• a flow meter in fluid communication with the choke manifold and configured to determine an amount of fluid influx from a formation, an amount of fluid lost into the formation, or both;
• wherein, when the flow meter determines that the amount of fluid influx is less than a first predetermined threshold and the amount of fluid lost is less than a second predetermined threshold, then the fluid from the well is directed to the first manifold and then to the controllable orifice choke to maintain a predetermined fluid pressure in the well;
• wherein, when the flow meter determines that the amount of fluid influx is greater than the first predetermined threshold, then the annular blowout preventer is closed, the fluid flowing through the flow spool below the annular blowout preventer is diverted from the riser to the second manifold and then to the choke manifold;
• and
• wherein, when the flow meter determines that the amount of fluid lost is greater than the second predetermined threshold, then the annular blowout preventer is closed, and a sacrificial fluid is pumped into the drill string, wherein the sacrificial fluid comprises additives that seal cracks in the formation.