Abstract: Several fluid mechanics problems involving reservoir engineering and production engineering where horizontal wells are used to produce oil are discussed in the present paper, such as,the calculation of production of a horizontal well, the unsteady well test and flow field analysis ofa horizontal well, the effect of pressure drop along wellbore on production of a horizontal well, andthe fluid flow couple both in wellbore and the reservoir near well, and so on. It is suggested that themechanism of horizontal ...