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Drill Ahead Burst

In this document we describe the load case "Drill ahead Burst" available in Oliasoft WellDesign™.​


Drill ahead is a burst/collapse load case, where the unknown is the internal pressure profile of the tubing.

NOTE!
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. //: # (end - note)

Summary​

This load case is calculated using the hydrostatic pressure from mud and Equivalent Circulating Density (ECD) for drilling a new section from RKB to the casing shoe.



Illustrating Pressure Profile Graph​

Printable Version​

Oliasoft Technical Documentation - Drill Ahead


Inputs​

The following inputs define the drill ahead load case:

  1. The true vertical depth (TVD) along the wellbore as a function of measured depth. Alternatively, the wellbore described by a set of survey stations, with complete information about measured depth, inclination, and azimuth.
  2. The true vertical depth / TVD of
    1. The hanger of the tubing, TVDhanger_{hanger}
    2. The shoe of the tubing, TVDshoe_{shoe}
  3. The mud weight/density, ρm\rho_m, for drilling the next section.
  4. Equivalent Circulating Density, ρECD\rho_{ECD} //: # (end - inputs)

Calculation​

The internal pressure profile from hanger to shoe, parametrized by TVD, of the tubing is then given by

pi=(ρm+ρECD)gTVD,                                         (1)p_{i}=\left(\rho_{m}+\rho_{\mathrm{ECD}}\right) g \mathrm{TVD},\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\ (1)

where gg is the gravitational constant. //: # (end - calculation)