Kick detection systems and methods

1. An apparatus comprising:

a drill string positioned in a well;

a mud circulation system coupled to supply drilling mud to the drill string; and

a mud analyzer including a sensor that is positioned along a drilling mud return path closer to a wellhead assembly installed at the well than to a mud tank of the mud circulation system, wherein the mud analyzer enables identification of a potential formation kick based on data acquired by the sensor, the mud analyzer is an ultrasonic mud analyzer configured to monitor a parameter of an ultrasonic signal in the drilling mud and to infer the potential formation kick from a step change in the monitored parameter of the ultrasonic signal, and the parameter of the ultrasonic signal which the ultrasonic mud analyzer is configured to monitor is at least one of frequency or velocity of sound.

2. The apparatus of claim 1 , wherein the sensor of the mud analyzer is positioned at the wellhead assembly.

3. The apparatus of claim 1 , wherein the sensor is an ultrasonic sensor positioned at a subsea wellhead assembly and enables earlier detection of potential formation kicks compared to detecting the potential formation kicks through monitoring of drilling mud at a drilling rig.

4. The apparatus of claim 1 , wherein the well is a subsea well.

5. An apparatus comprising:

a drilling mud analyzer including:

an ultrasonic sensor; and

a controller configured to monitor a parameter of an ultrasonic signal in drilling mud and to infer a potential formation kick of a well from a step change in the monitored parameter of the ultrasonic signal, wherein the parameter of the ultrasonic signal which the controller is configured to monitor is at least one of frequency or velocity of sound.

6. The apparatus of claim 5 , wherein the ultrasonic sensor is positioned to enable receipt of ultrasonic waves transmitted through the drilling mud within a drilling mud return path from the well to a mud tank.

7. The apparatus of claim 5 , wherein the ultrasonic sensor is positioned at a subsea wellhead assembly.

8. The apparatus of claim 5 , wherein the ultrasonic sensor includes at least one pair of ultrasonic transducers arranged to cooperate with one another to transmit and receive ultrasonic waves.

9. A method comprising:

circulating drilling fluid through a well, wherein circulating the drilling fluid includes routing the drilling fluid through a supply path to a drill string, through the drill string, and then out of the well via a return path;

monitoring the drilling fluid at the well as the drilling fluid flows through the return path; and

detecting a kick based on the monitoring of the drilling fluid at the well;

wherein monitoring the drilling fluid at the well as the drilling fluid flows through the return path includes monitoring, at a location along the return path, a parameter that varies based on the density of the drilling fluid, and wherein detecting the kick based on the monitoring of the drilling fluid at the well includes determining a deviation of the parameter measured at the location along the return path from a prior measurement of the parameter at the location along the return path and comparing a magnitude of the deviation to a deviation threshold;

wherein the monitored parameter is at least one of frequency or velocity of sound.

10. The method of claim 9 , wherein monitoring the drilling fluid at the well as the drilling fluid flows through the return path includes monitoring the drilling fluid with a sensor at a wellhead assembly.

11. The method of claim 10 , wherein monitoring the drilling fluid with the sensor at the wellhead assembly includes monitoring the drilling fluid using an ultrasonic transducer.

12. The method of claim 9 , wherein monitoring the parameter that varies based on the density of the drilling fluid includes monitoring an acoustic signal transmitted through the drilling fluid.

13. The method of claim 9 , wherein circulating the drilling fluid includes routing the drilling fluid out of the well via the return path to a tank.

14. The method of claim 9 , comprising triggering an alert to an operator in response to the detected kick.

15. The method of claim 9 , comprising automatically actuating a blowout preventer in response to the detected kick.