Objective Of The Pressure Testing Of Choke Manifold:
- Explain the procedures for the rig-accepting & pressure testing process for the choke manifold.
- Explain the components, design & application of the choke manifold.
- Explain the purpose of the rig accepting for choke manifold
Choke Manifold
Before going into the rig accepting for rig choke manifold, we have to identify the choke manifold.
The choke manifold consists of a group of valves, lines, and chokes, which are lined in a way to control any flow of drilling mud and Kick fluids from the annulus during any Well Control issue. Some of the conditions that the manifold may be required to work under are a variety of fluids such as Water Based Mud, Oil Based Mud, water, or gas, high pressures, downstream velocities, upstream flow rates, and obstructions in the produced fluids such as sand, pipe protector rubbers or shale.
The choke manifold should control pressures by utilizing one of many chokes. It should direct flow to one of many areas, including a burning boom, the reserve pit, the drilling fluids pit, or overboard a drilling vessel when applicable. The choke manifold must have pressure ratings at least equal to the BOP stack and should have the exact pressure testing specifications performed on the BOPs. It should be well-fixed to prevent movement during any Killing operation. Also, The choke manifold should have easy access to every manifold component, with all lines fixed as straight as possible. All lines and valves must have an equivalent consistent inner diameter to decrease turbulent erosion at any diameter changes.
Choke Manifold Design.
The principle used for BOP stack design will also be used for designing the choke manifold. The proper procedure is to make sure that there is a backup system in case of tool failure. Also, it is a good practice to utilize the manifold necessary to reach the total depth to avoid fixing a different manifold with each casing run in the hole. The below figure shows a choke manifold utilized in many drilling wells. Note that such a design meets all of the needs for choke manifolds.
- Buffer chambers are used at the downstream connections as hydraulic cushions and to reduce erosion.
- Two hand-adjustable chokes may be used due to their high stem and seat erosion rates and tendency to cause drilling pack off with cuttings.
- A direct line from the BOP stack to the burning pit for gas is provided should it become necessary to divert the well temporarily.
- A current and more appropriate practice is to utilize two remote hydraulic adjustable chokes and a single manual choke.
- A tap may allow manifold pressurization to decrease pressure surges to zero when opening the valves near the stack.
- Note that this design does not constitute an accurate diverter system.
The video below describes well what is the choke manifold and its application.
Choke Manifold Application
- A choke manifold is used to control the pressures encountered during a Kick. (check also significant Kick warning Signs).
- In well testing, a choke manifold attached to the wellhead allows flow and pressure control for test components downstream.
Purpose Of Rig Accepting For Choke Manifold Pressure Test
- Verify the hydraulic integrity of all the components of the choke manifold at their rated working pressure.
What is The Procedure For Rig Accepting The Choke Manifold Pressure Test
- Connect the testing pump or cement unit with the pressure recorder to the choke manifold inlet.
- Pump water through the choke manifold for some minutes to flush all lines and purge it from the air.
- Close the first valve after the inlet pump to reach the working pressure. Hold the pressure for 10 minutes.
- If the test is satisfactory, continue the test of all the other components in the cascade, from the inlet(s) to the low-pressure buffer.
- Pressure test the flare lines, installing a plug at the end of each line.
- Fill in the following table and attach the choke manifold drawing to the test report with references to all components.
Checklist To be In Mind While Rig Accepting Choke Manifold
- Manifold sizes and working pressure as per specifications
- Manifolds and valves are easily accessible and free of obstruction.
- Valves wheels turn easily.
- Pressure gauges are installed, and calibration is documented.
- Manifolds provided with connections for transducers.
- Casing and drill pipe pressure gauges installed and calibration documented
- Casing and drill pipe pressure gauges are easily visible from the manual choke operator’s position.
- MAASP posted at manual choke.
- Safety chains/whip checks are used for pressure hoses, lines with hammer unions, or chickens in temporary or permanent use.
- Lines from BOP to choke manifold of the approved type
- Manual and power chokes at choke manifold as per approved number
- Lines and valves are free from mud or solid wastes and flushed with water.