DRILLING TECHNOLOGY Cuttings re-injection must keep pace with faster drilling

Jeff Reddoch Apollo Services Fast drilling is the standard for today's drilling industry. The drilling rig and the service companies are geared for a faster pace. When zero discharge operations are required, the drilling rates can be significantly impaired, if not adequate. A drilling contractor can only drill as fast as the service company can transfer, process, and inject zero discharge cuttings. The economics of slow or no hole drilling every 24 hours can add up.

Contractor injecting as much as 1,100 bbl of hole cuttings every 24 hours on Andrew

Jeff Reddoch
Apollo Services

Fast drilling is the standard for today's drilling industry. The drilling rig and the service companies are geared for a faster pace. When zero discharge operations are required, the drilling rates can be significantly impaired, if not adequate.

A drilling contractor can only drill as fast as the service company can transfer, process, and inject zero discharge cuttings. The economics of slow or no hole drilling every 24 hours can add up.

Contract award

Based upon the capacity to inject cuttings at an optimal drilling rate, Apollo Services was awarded the BP Andrew/Sante Fe Drilling service contract. The plan calls for drilling 17-1/2-in. hole at a minimum penetration rate of 40 meters per hour. This will be continued for four days straight with no trippings. The cuttings re-injection contractor had to maintain this pace with zero downtime and staffing of one operator per 12-hour tour.

High rate

This drilling rate equates to 1,100 bbl of hole drilled every 24-hour period.

Apollo's system has routinely handled this much on a 24-hour period with one man operating the cuttings transfer system, cuttings slurification, and the triplex injection equipment.

Hurtles

Among the hurtles to be overcome in achieving a handling rate comparable to the drilling rate are:

  1. The equipment had to fit in the substructure of a drilling unit, in less space than conventionally used.
  2. A dedicated variable speed injection triplex pump for Zone 1 explosion proof service had to be set up. Diesel engines could not be used. The system, with remote controls, had to be built to meet Lloyd's Register of Shipping requirements.
  3. The equipment had to be built according to ISO 9000 quality control standards, which had to be demonstrated prior to contract award.
  4. The 100% backup screw conveyor cuttings transfer had to fit in a space of 17-1/2-in. wide by 19-in. deep by 36 ft in length. This unit had to be capable of handling a rate of penetration of 40 meters/hour in 17-1/2-in. hole.
  5. The system had to be operated by one person at one point. Also, the system had to be completely automated with the operator performing maintenance and operations checks and adjustments.

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