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Run In Hole

In this document we describe the load case "Run in hole" available Oliasoft WellDesign.#



Run in hole is an installation load case, similar to Overpull.

NOTE!
In this documentation we denote any tubular as casing or tubing. All calculations however encompass any tubular, such as tubings, casings, liners, tie-backs etc.


Summary#


Run in hole is an installation load case, similar to Overpull, and the unknowns are the axial load with and without bending from dogleg when running the casing / tubing in the hole. Contrary to the usual axial loads calculations, which give the axial load on a tubing at a given pressure and temperature, this load case calculates the maximum load a given point on the tubing experience while running the tubing in the hole, with and without bending. Effects included are the weight of the tubing, buoyancy forces from piston effects, bending forces from dogleg, and finally, a shock load describing a possible sudden stop.


Printable Version#


Oliasoft Technical Documentation - Load Cases - Run in hole


Inputs#

  1. A complete description of the wellbore, including measured depths, true vertical depths, and dogleg severities.
  2. A complete description of the tubing dimensions, including density and weight, inner- and outer- diameters, internal- and external- crossovers.
  3. The mud weight/density, ฯmud\rho_{mud}
  4. A running speed, vrv_r, used in the shock load calculation.

Calculation#


The run in hole axial load on the tubing is calculated as follows

  1. Calculate the hydrostatic pressure in the wellbore from mud.

  2. Calculate the bending force due to dogleg severity.

  3. Calculate the shock load

    Fshock=32vrAxEฯsteelโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šโ€…โ€Šย (1)F_\text{shock} = \frac32 v_r A_x \sqrt{E\rho_\text{steel}} \;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\ (1)

    where AxA_x is the cross section of the tubing, EE is Young's modulus of steel, and ฯsteel\rho_{steel} is the density of steel.

  4. Calculate the axial load sequentially as the tubing is run in the hole, from weight and piston forces, and add the shock load. For axial load with bending, add the bending force from dogleg severity as well. Then, at every measured depth, referenced to the tubing, report the maximum load experienced.