Inspection of Drilling rigs and equipment; types and purposes of rig inspections and how to do them, AMOCo
IADC/SPE 23900 Surface BOP inspections, Chevron
MODU rig inspection. Rig inspection Leo Nagtegaal
WestHOU. Michael Montgomery [Michael@WestEngineer.com]
· Veritas Associates. Drilling unit inspection & management audit services. Paul D Baumgardner
The hole size will give you the drill bit size then the required hydraulic horse power is obtained and finally the mud pump equipment can be selected.
Rule of thumb: Hydraulic horse power = 3-5 hhp/sq. in of bit diameter
Assume 65% of the available surface horsepower when bit horsepower is being maximized
Bigger the size of the DP the less circulation loses which then has to be balanced against cost and weight.
Potential Hole Problems:
a. Shale sloughing will require more bottom hole cleaning therefore the calculated available surface horsepower must be corrected accordingly (increased)
b. Pipe stuck will require a higher derrick loads therefore the safety factor for derrick loads must be increased
Derrick maximum hook load capacity – under what conditions the ratings are made when comparing them.
If in doubt an API certified inspector should verify all ratings:
- Check if the rating is made for a certain type of crown/travelling-block line configuration or not)
- Check for leg loading, substructure rating, maximum wind loading with drill pipe in the derrick.
Drawworks horse power rating applicability rests primarily on the necessary time to hoist a load rather then actual ability to hoist the load.
The power required to stop a load in free fall can be far greater than the drawworks capacity
Triplex Mud Pumps
- Are much lighter than duplex for the same horsepower rating (e.g. 70 lbs vs. 400 lbs)
- Can operate at higher pressure with fewer fluctuations
Horse power rating is based on input horsepower but when make the selection it is the output horsepower that is relevant (it will give the maximum values for pressure and flowrate).
Also, the contractor must provide the maximum sustained levels at which the pump has run which allows an adequate pump selection and planning the hydraulics program.
Discuss with the firm that performed the last inspection and if in doubt require an inspection to be run.
Tank capacity needed in the active system
The rule of thumb is the total pipe displacement at the projected total depth multiplied by 2.5
Centrifugal pump is the most preferred option for a good mud mixing and stirring.
Select the solid control equipment needed based on the performed analyze.
Auxiliary equipment (e.g. degasser, mixing tanks, chemical barrel, charging pumps, pit level indicator) hast to be inventoried and ask for the absence of equipment, if applicable.
- Check the ratings not only for the BOP but for lines connections, and valves
- Check the availability for the annular and rotating preventers, choke manifold, accumulator, remote and direct controls, choke and kill lines.
- Make a sketch of BOP system to ensure the adequacy of the system
If the required horsepower is greater than 1,000 a diesel electric generator is selected.
Power allocation between rig components is more efficient.
I hope this will help you out.