Most oil and gas production facilities use a device known as a choke to control the flow of fluids produced from wells. Typically, equipment such as the line heaters and wellsite separators contain a choke. It has a small opening called a choke bean, which helps to reduce the pressure as the liquids flow through it. The choke is designed to handle an erosive service in the form of sand particles in the fluids. Read on to learn more about the choke, its parts, and types.
What is a Choke Valve?
(Caption: Positive Choke)
The choke valve in an oilfield heater, wellsite separator, and other oil and gas equipment is similar to the positive choke. It replaces the bonnet assembly and comes with a plug assembly and adjustable rising stem that seats into the bean. This allows the operator to adjust the pressure and flow according to the requirements of the process. Adjustable choke valves typically come with a manual or automatic valve stem operator and are more common due to their flexibility.
Bean Size in a Choke Valve
(Caption: Choke Bean)
Made using steel or other durable materials, a choke bean is a replaceable bean or insert, crafted with a precise diameter. It comes in a variety of sizes and forms the choke through which the fluids pass.
Types of Choke Valve
Needle and Seat Choke
(Caption: Needle and Seat Choke)
This is the most simplistic variation of the positive choke, consisting of a cone-shaped plug that seats into the bean. It comes with a rising stem and handwheel.
Plug and Cage Choke
(Caption: Plug & Cage Choke)
This typically uses the plug as the controlling component to throttle the flow of fluids in the ported cage’s internal diameter. The ports in the cage are arranged in a way that results in the most appropriate combination of flow and control capacity for different purposes.
Types of Port Cages
- 4-Port Cage – is standard for the valves used in wellsite separators and line heaters. The smaller, lower ports typically provide the control range for the initial 15% of the valve, while the larger ones are responsible for the remaining 85%. This results in an equal percentage flow, allowing maximum control in the device.
- Multi-Ported Cage – is mostly used for critical applications, including high-pressure drops. It also allows custom configurations suitable for specific applications.
- Plug and Cage Design – is perfect for high-capacity applications because it helps to incorporate the largest-possible flow area in the equipment.
Multiple Orifice Valves (MOVs)
(Caption: Multiple Orifice Valve)
Multiple orifices refer to the adjacent discs that have a pair of circular orifices or openings. The rotation of one disk with respect to the other helps to control the flow or pressure reduction. The mating surfaces of both the discs are made with precision, allowing complete shutoff. MOVs are ideal for production choke applications, including line heater inter-coil pressure control and wellhead control, because of their near-linear flow characteristics.
Line Heater Choke Valve
A line heater package typically consists of a choke valve placed between the pre-heat and reheat coils coil. It helps reduce the pressure from wellhead to pipeline. The choke valve and pre-heat coil are designed to contain the maximum well shut-in pressure when the valve closes. Also, selecting the correct choke bean ensures that the flow in the equipment is not restricted.
Choose the Right Choke Valve for Your Device
Selecting the right choke valve to use in a line heater package or wellsite separator is essential to ensure overall equipment efficiency and safety. At Aspire Energy Resources Inc., we have the knowledge, resources, and expertise to help you choose an appropriate choke valve for your application. To know which choke valve is the best for your next line heater project, call us at 403-314-5422 or toll-free 1-800-993-9958 to discuss with our designers.