System and method for intelligent flow control system for production cementing returns

1. A system of controlling and monitoring a casing cementing process injecting a cement slurry down a well that causes a return of a drilling fluid at a wellhead, comprising:

a first pressure sensor configured to measure a first fluid pressure of the cement slurry prior to injection down the casing;

a second pressure sensor configured to measure a second fluid pressure of the returned drilling fluid in a primary return conduit;

at least one flowmeter disposed downstream from the second pressure sensor configured to measure a flow rate of the returned drilling fluid;

a third pressure sensor downstream from the at least one flowmeter configured to measure a third fluid pressure of the returned drilling fluid;

a first control valve downstream from the third pressure sensor configured to regulate conducting the returned drilling fluid to a reservoir;

a choke valve downstream from the third pressure sensor configured to regulate diverting the returned drilling fluid in the primary return conduit;

a mud-gas separator disposed in the primary return conduit downstream from the choke valve configured to receive the diverted drilling fluid and separate into a mud component for return to the reservoir and a gas component for controlled burn off; and

a microprocessor configured to receive and analyze the fluid pressure and flow rate measurements, and generate control signals to close the first control valve and open the choke valve in response to detecting presence of gas in the returned drilling fluid.

2. The system of claim 1 , further comprising a second control valve configured to regulate conducting the separated mud component from the mud-gas separator to the reservoir.

3. The system of claim 2 , wherein the microprocessor is configured to generate a control signal to regulate the second control valve in response to a sensed level of the separated mud component within the mud-gas separator dropping below a threshold.

4. The system of claim 3 , wherein the mud-gas separator further measures the fluid levels of the separated mud component within the mud-gas separator, and the microprocessor is configured to control a second control valve configured to regulate conducting the separated mud component from the mud-gas separator to the reservoir.

5. The system of claim 1 , further comprising a vent gas analyzer configured to analyze a composition of the separated gas component and determine a flow rate thereof for analysis by the microprocessor.

6. The system of claim 1 , wherein the at least one flowmeter comprises first and second flowmeters of different types, where the microprocessor is configured to detect the presence of gas in the returned drilling fluid by analyzing the flow rate measurements from the first and second flowmeters.

7. A system of controlling and monitoring a cementing process injecting a cement slurry down a well casing that causes a return of a drilling fluid in a primary return conduit, comprising:

a first flowmeter disposed in the primary return conduit configured to generate a first flow rate of the returned drilling fluid;

a second flowmeter disposed in the primary return conduit configured to generate a second flow rate of the returned drilling fluid from the well casing;

a first control valve downstream from the first and second flowmeters configured to regulate conducting the returned drilling fluid to a reservoir;

a choke valve disposed downstream from the first and second flowmeters configured to regulate diverting the returned drilling fluid in the primary return conduit;

a mud-gas separator disposed in the primary return conduit downstream from the choke valve configured to receive the diverted drilling fluid and separate the diverted drilling fluid into a mud component for return to the reservoir and a gas component for controlled burn off; and

a microprocessor configured to receive the first and second flow rates, determine a presence of gas in the returned drilling fluid in response to a comparison of the first and second flow rates, and regulate the actuation of the first control valve and choke valve to conduct the drilling fluid to the fluid reservoir in the absence of gas in the drilling fluid, and conduct the drilling fluid to the mud-gas separator in the presence of gas in the drilling fluid.

8. The system of claim 7 , further comprising:

a first pressure sensor configured to measure a first fluid pressure of the cement slurry prior to injection down the well;

a second pressure sensor configured to measure a second fluid pressure of the returned drilling fluid in the primary return conduit; and

a third pressure sensor downstream from the first and second flowmeters configured to measure a third fluid pressure of the returned drilling fluid.

9. The system of claim 7 , further comprising a vent gas analyzer configured to analyze a composition of the separated gas component and determine a flow rate thereof.

10. The system of claim 7 , wherein the first and second flowmeters are of different types, where the microprocessor is configured to detect the presence of gas in the returned drilling fluid by analyzing the flow rate measurements from the first and second flowmeters.

11. A method of controlling and monitoring a cementing process injecting a cement slurry down a well casing that causes a return of a drilling fluid at a wellhead, comprising:

measuring at least two flow rates of the returned drilling fluid;

determining one of absence and presence of gas in the returned drilling fluid by analyzing the at least two flow rates;

controllably conducting the returned drilling fluid to a reservoir in response to a determination of an absence of gas in the returned drilling fluid; and

controllably diverting the returned drilling fluid to a mud-gas separator configured to separate the returned drilling fluid into a mud component for return to the reservoir and a gas component in response to a determination of a presence of gas in the returned drilling fluid.

12. The method of claim 11 , further comprising sensing a level of the separated mud component in the mud-gas separator, and regulating the flow of the separated mud component to the reservoir in response to the level dropping below a threshold.

13. The method of claim 11 , further comprising analyzing a composition of the separated gas component and determine a flow rate thereof.

14. The method of claim 11 , wherein measuring at two flow rates comprises measuring a density of the returned drilling mud to determine absence and presence of gas.

15. The method of claim 11 , further comprising:

measuring a first fluid pressure of the cement slurry prior to injection down the well; and

measuring at least one second fluid pressure of the returned drilling fluid.