Abstract: Horizontal well is an important tool for enhancing productivity of oil wells. At present, the formulae that are frequently used to calculate horizontal well production rate include Borisov's formula, Joshi's formula, Giger et al formula and Renard-Dupuy's formula. Based on the studies on horizontal well given by Joshi and Giger, this paper makes use of the physical conceptions of areal equivalent pseudo-circular drainage radius and production rate equivalent pseudo-circular production channel. The former transforms the elliptic drainage boundary into pseudo-circular drainage boundary; the latter transforms the length of horizontal well interval into pseudo-circular production channel. Moreover, using equivalent flow resistance method of water electric analogy principle, a new formula for calculating horizontal well production rate is obtained in this paper. The actual application and correlation of these five formulae indicate that the new formula proposed here is practical and effective.

Key words: horizontal well, production rate formula, derivation, correlation, comparison, application