A side pocket mandrel, including defining a tubular body having opposing ends and a bore formed within the tubular body. The tubular body comprises an eccentric portion such that a first inner diameter (ID1) is formed at the opposing upper and lower ends, and a second larger inner diameter (ID2) is formed along an eccentric portion. The mandrel includes a movable curtain disposed along the eccentric portion, wherein in a first position the movable curtain covers a portion of the eccentric portion above the pocket to provide a reduced inner diameter that approximates (ID1), and in a second position the curtain is movable to a larger inner diameter (ID2) that enables access by a kick-over tool to install a gas lift valve in or to retrieve the gas lift from the pocket. A method of producing hydrocarbon fluids is also provided.