Abstract: In the past 20 years, major development has been made in horizontal drilling and production technologies applied to domestic onshore and offshore areas. How to reliably calculate the production rate by horizontal drilling process is becoming an important task to reservoir engineers. There are four methods widely applied at home and abroad at present: Joshi's method, Borisov's method, Giger's method and Renard-Dupuy's method. This paper presents a new method for it proposed by Prof. Yuanqian Chen. Under homogeneous conditions, satisfactory results can be all given by these methods. In anisotropic conditions, Joshi had given two modified methods which were widely used, but this study indicates that such modified methods have no basis from theoretic derivation, so the results are not correct. Adding theoretic analysis and derivation, this paper presents Joshi's production rate formula for horizontal well in anisotropic reservoir. Meanwhile, anisotropic corrections for other methods are made correspondingly, including calculations of different factors influencing individual productivity. Case study shows that the method proposed in this paper is proper and effective.

Key words: horizontal well, anisotropy, production rate, formula, correction, comparison