1. What is Mud Pump?
| Mud pump is one of the most critical equipment on the rig. Powerful mud pumps pick up mud from the suction tank and circulate the mud down hole, out the bit and back to the surface. Although rigs usually have two mud pumps and sometimes three or four, normally they use only one at a time. The others are mainly used as backup just in case one fails. Sometimes however the rig crew may compound the pumps, that is, they may use three or four pumps at the same time to move large volumes of mud when required. |  |
2. What Type of Mud Pump is Used for The Drilling Rig?
Rigs use one of two types of mud pumps, Triplex pumps or Duplex pumps. Triplex pumps have three pistons that move back and forth in liners. Duplex pumps have two pistons that move back and forth in liners.
Triplex pumps have many advantages they weigh 30% less than a duplex of equal horsepower or kilowatts. The lighter-weight parts are easier to handle and therefore easier to maintain.
The other advantages include：
• They cost less to operate
• They are fluid end is more accessible and
• They discharge mud more smoothly. That is, the triplex's output does not surge as much as a duplex.
• One of the more important advantages of triplex over duplex pumps, is that they can move large volumes of mud at the higher pressure required for modern deep-hole drilling.
Triplex pumps are gradually phasing out duplex units. In a triplex pump, the pistons discharge mud only when they move forward in the liner. Then, when they moved back they drew in mud on the same side of the piston.
Because of this, they are also called "single acting." Single-acting triplex pumps, pump mud at relatively high speeds. Input horsepower ranges from 220 to 2200 or 164 to 1641 kW. Large pumps can pump over 1100 gallons per minute, over 4000 L per minute. Some big pumps have a maximum rated pressure of over 7000 psi over 50,000 kPa with 5-inch/127 mm liners.
3. What Are The Characteristics of Triplex Pump?
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Here is a schematic of a triplex pump. It has three pistons each moving in its own liner. It also has three intake valves and three discharge valves. It also has a pulsation dampener in the discharge line.
Look at the piston at left, it has just completed pushing mud out of the liner through the open discharge valve. The piston is at its maximum point of forward travel. The other two pistons are at other positions in their travel and are also pumping mud. But for now, concentrate on the left one to understand how the pump works. |
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The left piston has completed its backstroke drawing in mud through the open intake valve. As the piston moved back it instead of the intake valve off its seat and drew mud in.
A strong spring holds the discharge above closed. The left piston has moved forward pushing mud through the now open discharge valve.
A strong spring holds the intake valve closed. The left piston has completed its forward stroke they forms the length of the liner completely discharging the mud from it.
All three pistons work together to keep a continuous flow of mud coming into and out of the pump. |
4. How About Duplex Pump?
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In a duplex pump, pistons discharge mud on one side of the piston and at the same time, take in mud on the other side. Notice the top piston and the liner. As the piston moves forward, it discharges mud on one side as it draws in mud on the other then as it moves back, it discharges mud on the other side and draws in mud on the side it had earlier discharged it. Duplex pumps are therefore double acting.
Double-acting pumps move more mud on a single stroke than a triplex. However, because of they are double-acting, they have a seal around the piston rod. This seal keeps them from moving as fast as a triplex. Input horsepower ranges from 190 to 1790 hp or from 142 to 1335 kW. The largest pump's maximum rated working pressure is about 5000 psi, almost 35,000 kPa with 6-inch/152 mm linings. |
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5. How To Use Mud Pump?
The mud pump has a fluid end, an output end, as well as inlet and outlet valves. The fluid end of the pump contains a piston with a liner, used for suction or discharge of fluid or mud. The pump piston sucks in mud through the intake valve and pushes it out through the exhaust valve.
The power end accommodates a large crankshaft and gear assembly, which moves the piston assembly on the fluid end. The pump is driven by a pump motor. Large modern diesel/electric drilling rigs use powerful electric motors to drive pumps. Mechanical drilling rigs use a chain drive or power belt (belt) consisting of the drilling engine and compound to drive the pump.
The pulsation damper connected to the pump discharge pipeline can smooth out the surge generated when the piston discharges mud. This is a standard airbag shock absorber. The airbag and damper body separates the pressurized nitrogen gas above from the mud below. The airbag is made of synthetic rubber and has flexibility. When the mud discharge pressure is at the bottom of the airbag, the nitrogen pressure above the airbag will resist it. This resistance will make the mud leaving the pump fluctuate smoothly.
The latest pulsation dampers do not have airbags. It is a sphere with a diameter of approximately 4 feet or 1.2 meters. It is built into the discharge pipeline of the mud pump. This large room is made of mud. It has no moving parts, so it does not require maintenance. The mud in the large volume sphere absorbs the mud tide leaving the pump.
The suction damper ensures a smooth flow of mud entering the pump. The staff installed it on the suction pipeline of the three-cylinder mud pump. There is an inflatable rubber airbag or diaphragm inside the steel chamber. The crew inflated the airbag by approximately 10 to 15 pounds per square inch/50 to 100 kilopascals. The suction damper absorbs the fluctuations in the mud pump suction pipeline caused by the rapidly moving pump piston. The piston continuously starts and stops the flow of mud through the pump. At the other end of the filling pipeline, the suction pump smoothly delivers the mud to the inlet of the pump. When steady flow encounters surge flow, the impact is absorbed by the damper.
Workers always install a discharge pressure-reducing valve. They installed it on the discharge side of the pump, located inside or near the discharge pipeline. If for some reason, excessive pressure accumulates in the discharge pipeline, it may be due to a drill bit or annular blockage, and the safety valve will open. The lid opened above can protect the mud pump and system from damage caused by overpressure.
Some drilling platform owners have installed suction line safety valves. They installed it at the top of the suction pipe near the suction damper. They installed it on the top so that when the system is shut down, it will not be blocked by mud. The suction safety valve protects the charging pump and suction line shock absorber. Inhalation safety valves typically have a 2-inch or 50-mm seat opening. Installation personnel typically adjust it to a release pressure of 70 psi or 500 kPa. If both the suction valve and the discharge valve on the same side of the pump fail, high backflow or pressure surge may occur. High reflux may damage the fuel pump or suction line shock absorber. The discharge pipeline is a high-pressure pipeline through which the pump transports mud. Mud flows from the discharge pipeline through the riser and rotating hose to reach the drill string equipment.