Horizontal wells are becoming popular for primary and enhanced oil recovery operations because of unique advantages of horizontal wells in comparison to those for vertical wells. For example, horizontal wells are being used, at present, for the primary recovery of heavy oil worldwide. They allow a larger reservoir exposure, which increases productivity, accelerate recovery, and reduce coning tendencies. However, horizontal well testing is considerably more complex than vertical well testing.
This work addresses new solutions for well test analysis of horizontal wells. With the similar methods in Ref. [1,2,3], taking a horizontal well as a uniform line sink in three dimensional space, by developing necessary mathematical analysis, this paper presents horizontal wells pressure drawdown and buildup analyses in a single porosity reservoir with a circular cylinder drainage volume.
The solutions obtained here which are based on three dimensional models are more accurate than the two dimensional model based well testing equations in the literature. Simplified solutions for short and long times that exhibit straight-line sections when pressure is plotted vs. time are presented. Methods for analyzing pressure drawdown and build-up data are presented. The method allows reservoir characteristics, including permeability, skin to be determined.