Wednesday, 26 August 2020


Your Guide To Rig Commissioning | Prime Movers (Diesel Engines and Generators)

Rig Commissioning | Prime Movers (Diesel Engines and Generators)

What Is The Drilling Rig Prime Mover:


The Rig Prime Mover is considered the  source of power for any drilling rig . On recent rigs, the prime mover contains one to four or more diesel engines. These  diesel engines produce many thousand HP. Typically, the diesel engines are connected directly to electric generators. The electrical power is then distributed by something called (SCR) silicon controlled rectifier system around the drilling rig site. Drilling rigs that are able to alter the diesel power to electricity are called electric diesel rigs.

Older drilling rigs designs transmit the power from the diesel engines to specific drilling rig components (drawworks, mud pumps and rotary table) through a system which consist of mechanical belts, clutches & chains. On these drilling rigs, a much smaller electrical generator provide power for lighting and any small electrical needs. These older rigs are referred to as mechanical rigs or more commonly, simply power rigs.

The Purpose of Testing & Inspecting Drilling Rig Prime Movers During Rig Acceptance / Commissioning

  • Verify the proper working of all the instrumentation connected to the above equipment (pressure gauges, flow indicator, counters, etc.).
  • Load test all the SCR’s (silicon controlled rectifier system) driving the drilling mud pumps. Verify the maximum power delivered by the generator. 
  • Verify that all the diesel engine/generator groups work properly. 
  • Verify the proper working of choke manifold power chokes and remote control panel.
  • Pressure test the mud pumps and discharging lines, rig floor mud manifold, stand pipe manifold, top drive wash pipe. 

Guidelines For Drilling Rig Prime Mover Inspection Tests

  1. Connect two mud pump through the choke manifold and get them ready for circulation at  high flow rate and high pressure
  2. Connect the swivel head (or Top drive) with choke manifold to circulate at high pressure through the power choke.
  3. Record the mud pump liners. It is preferable to have 6 inch liners or less installed, in order  to reach a pressure as high as possible, set the mud pump relief valve accordingly and check the pulsation dampener pre-charge pressure. 
  4. Connect on the main bus the minimum generators that can deliver enough power to drive the two mud pumps running at 3000-3500 lpm (or maximum flow rate allowed for acceptance test).  
  5. Start pumping slowly with one mud pump  with power choke fully open and verify the followings: 
    1. Any leak along the mud pump discharging lines.
    2. Check if all parameters recorded are working properly.
    3. Check if all pressure gauges, stroke counters on different consoles show the same values.
  6. If there are no evident anomalies, increase the pump rate slowly up to the maximum rated speed allowed by the mud pump manufacturer. 
  7. Close the power choke gradually to obtain one of the following conditions:
    1. maximum power delivered from the diesel/generator.
    2. maximum allowed pressure for the size of the liners installed on the mud pumps. 
  8. Circulate enough at the above conditions in order to record reliable parameters as requested on next Table n°1. 
  9. Repeat the same test for all the other power groups using alternate equipment not used in the previous test (other mud pump, discharge line, stand pipe, rotary hose, SCR, etc.). 
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