Abstract: Downhole apparatus for converting conventional petroleum wells to gas lift or chemical injection operation by perforating the well tubing at the desired depth and thereafter installing a packoff anchor within the well tubing, without disturbing the setting thereof, to bridge the perforation, the packoff anchor having an elongate tubular body with a lateral flow port in its wall, seals above and below the flow port for sealing with the well tubing above and below the perforation, and a receptacle for receiving a flow control device, such as a gas lift valve or injection valve for controlling flow through the lateral port. Fluids, such as lift gas or treating fluids injected into the annulus at the surface enter the flow stream inside the well tubing through the perforation and lateral flow port but under control of the flow control device. Preferably this elongate tubular body is a side pocket mandrel, and that preferably of the orienting type.