Accumulation chambers are recommended for wells with low bottom-hole pressure and high productivity index. An insert chamber is one type of accumulation chamber used when casing conditions do not allow installation of dual-packer chambers or when lowering the point of gas injection below the top of the perforations. For insert-chamber installations, formation gas must travel downward through the annular space between the casing and chamber. A complicated two-phase-flow process takes place in this annulus, with formation gas trying to move upward and accumulate at the top while the Liquid is moving downward carrying some formation gas with it. To avoid accumulation of formation gas in this annular space, it is important to vent free gas to the surface. An installation with a port to vent formation gas increased production by 70%.