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.

We establish a 2D diffusion mathematic model considering transverse diffusion and feature of channeling reservoir.With Laplace transform an analytical model is solved.A solution with small slug is found.With general-purpose finite element software in a geometrical model numerical solution is solved.2D concentration profile is ploted.It is shown that larger Peclet number leads to higher peak concentration and later break through time.With combination of analytic solution and numerical solution,it is helpful in understanding the essential of mass transfer diffusion.