Abstract:

Wellbore pressure is an important parameter in gas well performance analysis. However, reports on the method of wellbore pressure calculation for tubing-casing production system (TCPS) of gas wells are rare. Applying the hydrodynamics fun-damentals, the TCPS is treated as a parallel connection of tubing and casing production. Based on the wellbore pressure calculation method for the cases of tubing production system and the system of production from the annul space between the casing and the tubing, we obtained an equation describing the allocated production from the casing and the tubing. By analyzing the weighted importance of each item in the equation, a simplified production distribution equation is obtained, which translate the wellbore pressure calculation for the TCPS into one for tubing and (or) casing production system. An example is given which shows that the relative error between the result obtained by using the proposed equation and that by using the accurate production distribution equation is very small, indicating that proposed method is reliable and applicable.

Key words: gas well, tubing, casing, commingled production, bottom hole pressure