Abstract: A production tank has at least one fluid outlet having a first flow area, an access port having a second flow area, and a fluid-containment space defined by a sidewall and a roof, the second flow area being larger than the first flow area. The fluid-containment space stories production liquids from a wellbore. A plurality of individual insulating elements are distributed across a horizontal section of the production tank, the insulating elements having a density that is less than the production fluids and having a size and shape that prevents passage through the first flow area and that permits passage through the second flow area.

Abstract: A production tank has at least one fluid outlet having a first flow area, an access port having a second flow area, and a fluid-containment space defined by a sidewall and a roof, the second flow area being larger than the first flow area. The fluid-containment space stories production liquids from a wellbore. A plurality of individual insulating elements are distributed across a horizontal section of the production tank, the insulating elements having a density that is less than the production fluids and having a size and shape that prevents passage through the first flow area and that permits passage through the second flow area.