Injection Down Casing

In this document we describe the load case "Injection down casing"

Injection down casing is a burst load case, where the unknown is the internal pressure profile of the casing / tubing

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

This is a load case that models an applied surface pressure to a static fluid column.

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Inputs

The following inputs define the injection down casing 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 casing / tubing, $\text{TVD}_{\text{hanger}}$.

   2. The shoe of the tubing, $\text{TVD}_{\text{shoe}}$.

3. The applied injection pressure, $p_\text{inj}$.

4. The density of the injection fluid, $\rho_\text{inj}$.

Calculation

The internal pressure profile of the tubing is simply calculated as

$$\begin{equation} p_i = p_\text{inj} + \rho_\text{inj}\, g\, h, \qquad\quad \text{TVD}_{\text{hanger}} \leq h \leq \text{TVD}_{\text{shoe}} \end{equation}$$