Example Drillpipe Tension

The weight indicator shows 230,000 lbs. The block and lines weight 30,000 lbs. A pump pressure gauge in line with the drillpipe shows 7,000 psi. The drillpipe is 5" by 4.276" by 19.5 ppf and the average weight per foot of the steel in the drillpipe is 21.4 lb/ft. What is the real tension in the drillpipe at the rotary table and at a depth of5,000 feet?

The inside end area of 5" drillpipe = 0c/4) 4.2762 = 14.360 sq. in.

Treal = 230,000 - 30,000 + 7,000 * 14.360 = 300,520 lb (rotary table)

Treal = 300,520 - 21.4 * 5,000 = 193,520 lb (at 5,000 ft)

DRAG LOADS

Drag loads may be measured with the weight indicator or estimated with equations.

MEASURED DRAG

The driller, as a standard practice, routinely measures three drillstring loads:

  1. Free rotating weight. It is the weight of the drill string with the string off bottom and while the string is being rotated. The rotary speed should be above 35 rpm.
  2. Pick-up weight. It is the weight of the drill string while raising the string at a normal working speed. Most drillers raise the string too slowly. Be careful not to add in the load of accelerating the drill string and breaking gel of the mud.
  3. Slack-off weight. It is the weight of the drillstring while lowering the string at a normal working speed. The above potentials for error must be once again avoided.

The differences in the pick-up and slack-off weights from the free rotating weight are the pick-up drag and the slack-off drag.

EXAMPLE DRAG

The free rotating weight of a drill string is 200,000 lbs, the pick-up weight is 250,000 lbs, and the slack-off weight is 170,000 lbs. What are the pick-up and slack-off drag loads?

Pick-up drag = 250,000 - 200,000 Slack-off drag = 200,000 - 170,000

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Responses

  • remo
    What is slack off weight oil drilling?
    8 years ago
  • lotta
    What is pickup weight in drilling?
    8 years ago
  • antonino
    How much does a 200000 lbs drilling block weight?
    4 years ago
  • LAILA NUORELA
    How to calculate drilling block weight?
    11 months ago
  • daniel
    Why pickup weight is less than slackoff?
    10 months ago
  • Heike Kuester
    What is pick down weight in drilling?
    10 months ago
  • LEOPOLDO DE LUCA
    Why is pick up weight and slck of weight important drilling?
    9 months ago
  • michael
    How to zero weight on bit when slacking off?
    7 months ago
  • SABRINA
    How does driller properly zero bit weight when drilling?
    1 month ago

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