Automated determination of valve closure and inspection of a flowline

1. A method, comprising:

measuring a pressure profile using a sensor connected to a flowline;

generating a pressure pulse in the flowline by closing a valve connected to the flowline;

calculating a first derivative and a second derivative of the pressure profile from the valve closure;

determining a parameter of the pressure pulse based on the first derivative and the second derivative of the pressure profile, the parameter including at least a reference time of the valve closure;

measuring a change in the pressure profile with the sensor due to a pressure wave reflected back to the sensor from a flowline parameter characterizing the flowline;

determining the flowline parameter and the location of the flowline parameter along the flowline using the parameter of the pressure pulse and a time of flight of the reflected pressure wave from the reference time.

2. The method of claim 1 , wherein the parameter further comprises any one or combination of a start time of the valve closure, an end time of the valve closure, and a discard time associated with the pressure pulse.

3. The method of claim 2 , further comprising:

identifying the reference time by finding a peak value of the first derivative following a change in pressure that exceeds a threshold value;

identifying the start time by finding a time before the reference time where a change in the first derivative on a time scale meets a first threshold value and a change in the second derivative on the time scale meets a second threshold value;

identifying the end time by finding a peak of the second derivative occurring after the reference time; and

identifying the discard time by finding an additional separation of the first derivative and the second derivative that meets an additional threshold hold value occurring after the reference time.

4. The method of claim 1 , further comprising identifying a change in pressure, which exceeds a threshold value, of the pressure profile to determine whether the valve closure is generated by an inlet or an outlet.

5. The method of claim 2 , further comprising identifying a velocity of the valve closure using the start time and the end time to determine whether to analyze the pressure profile.

6. The method of claim 1 , wherein the flowline parameter includes any one or combination of an inflow into the flowline, a flowline collapse of the flowline, an effective diameter of the flowline, a deposit in the flowline, a leakage in the flowline, and a failure of the flowline.

7. The method of claim 1 , comprising

determining a leveled time, wherein the leveled time is determined as a return to an ambient pressure value identified before the start time;

determining an end time based on the leveled time and the first and second derivatives.

8. A system for inspecting a flowline for carrying a fluid, comprising:

a sensor connected to the flowline and operable to measure a pressure profile of a pressure wave generated in the flowline;

a valve connected to the flowline and operable to generate a pressure pulse in the flowline by closing the valve; and

a processor operable to analyze the pressure profile by calculating a first and second derivative of the pressure profile from the valve closure to determine a parameter of the pressure pulse based on the first derivative and the second derivative, the parameter including at least a reference time of the valve closure;

wherein the sensor is further operable to measure a change in the pressure profile due to a pressure wave reflected back to the sensor from a flowline parameter characterizing the flowline; and

wherein the processor is further operable to determine the flowline parameter and the location of the flowline parameter along the flowline using the parameter of the pressure pulse and a time of flight of the reflected pressure wave from the reference time.

9. The system of claim 8 , wherein the sensor comprises a pressure transducer.

10. The system of claim 8 , wherein the parameter further comprises any one or combination of a start time of the valve closure, an end time of the valve closure, and a discard time associated with the pressure pulse.

11. The system of claim 10 , wherein the processor is operable to:

identify the reference time by finding a peak value of the first derivative following a change in pressure that exceeds a threshold value;

identify the start time by finding a time before the reference time where a change in the first derivative on a time scale meets a first threshold value and a change in the second derivative on the time scale meets a second threshold value;

identify the end time by finding a peak of the second derivative occurring after the reference time; and

identify the discard time by finding an additional separation of the first derivative and the second derivative that meets an additional threshold hold value occurring after the reference time.

12. The system of claim 8 , wherein the sensor is positioned at an inlet or an outlet of the flowline.

13. The system of claim 8 , wherein the valve comprises a mechanically-closed valve, a valve closed by hand, or any combination thereof.

14. The system of claim 8 , wherein the flowline parameter includes any one or combination of an inflow into the flowline, a flowline collapse of the flowline, an effective diameter of the flowline, a deposit in the flowline, a leakage in the flowline, and a failure of the flowline.

15. The system of claim 8 , wherein the processor is operable to:

determine a leveled time, wherein the leveled time is determined as a return to an ambient pressure value identified before the start time; and

determine an end time based on the leveled time and the first and second derivatives.

16. The system of claim 8 , comprising an actuator mechanically coupled to the valve and configured to close the valve.