Abstract: In productivity evaluation of infill horizontal well interference of oil or water wells are taken into account in a vertical and horizontal well mixed well pattern.With mirror-image method and source-sink theory,a semi-analytical model of productivity evaluation for infill horizontal well in random mixed pattern was built,in which interference of wells and pressure drop caused by wal friction and fluid acceleration were taken into account.It is suitable for infill horizontal well productivity calculation in arbitrary well pattern.

Key words: mixed well pattern, infill horizontal well, productivity calculation