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الحفر

العزم والسحب — نموذج السلسلة المرنة

Pick-up, slack-off and rotating hookload and surface torque from a survey, a string tally and a friction factor.

كل الأدوات

المدخلات

Survey stations
صفMDInclination°Azimuth°
1
2
3
4
5
6
7
8
9
String tally, from the bit upwards

First row is the component at the bit. Weight is in air.

صفLengthWeight in airOD
1
2
3

Zero for an off-bottom trip calculation.

النتائج

يجري تحميل الحساب…

جرى هذا الحساب داخل متصفحك. لم يُرسل أي رقم أدخلته إلى أي جهة، ولم يُحفظ شيء.

كيف تُحسب

  • Johancsik soft-string: normal force Fn = √[(Ft·Δα·sinĪ)² + (Ft·Δθ + W·sinĪ)²] on each 30 ft element.
  • Axial force integrates from the bit upwards: ΔFt = W·cosĪ ± μ·Fn, with the sign set by direction of travel.
  • Torque accumulates as μ·Fn·r with r the pipe radius. Rotating off bottom carries no axial friction, which is why it sits between pick-up and slack-off.
  • Buoyancy factor = 1 − MW/65.5, applied to every element weight.

المعايير التي تتحدثها

أين تتوقف عن الصحة

Soft string means the pipe is treated as a cable: it carries no bending stiffness and touches the wall everywhere. That is a good approximation for drill pipe in a smooth hole and a poor one for stiff BHA components through a dogleg, for anything in compression, and for a well with a tortuous, wiggly survey. Once slack-off goes into compression the model is outside its range and the answer it gives is optimistic. A single friction factor per hole section is also a fiction that absorbs cuttings beds, key seats and differential sticking into one number.

القدرة التي تؤتمت هذا العمل

أدوات ذات صلة