Effects of both wellbore and reservoir properties on pressure and pressure derivative distribution of a horizontal well subject to complete external fluid drive

Abstract

The task of clean oil production from a horizontal well under complete external fluid drive is a huge challenge to the operator who intends to exclude unwanted fluid production. In order to determine guidelines for drilling or modifying a horizontal well to achieve economic production therefore, dimensionless pressures and their derivative for such a well were studied theoretically, to investigate the effects of all wellbore and reservoir properties on overall well performance, assuming unsteady flow. For all sets of parameters considered, the dimensionless time of attainment of steady state, t_Dss, was calculated. This is the minimum dimensionless time beyond which clean oil production can no longer be guaranteed for a particular well completion. Results obtained show that the dimensionless time of arrival of external fluid at the wellbore increases with shorter dimensionless well lengths, unaffected by dimensionless well radius, and decreases with shorter reservoir size. Furthermore, well completion and re-completion practices can delay external fluids breakthrough. However, well eccentricity and perforation locations do not affect arrival times as well as well productivities. Finally, results also show that well productivities are affected inversely by dimensionless wellbore radius and directly by reservoir thickness and reservoir geometry.

Journal of the Nigerian Association of Mathematical Physics, Volume 15 (November, 2009), pp 189 - 196