Dual tank structure integrally supported on a portable base frame

A method of preparing a well at an oilfield site for producing hydrocarbons from the well, the method comprising:

• (i) providing a dual tank structure comprising:
• a base frame which is elongate in a longitudinal direction and which includes at least two beams extending in the longitudinal direction along a bottom side of the base frame so as to be arranged to facilitate handling and transport of the dual tank structure;
• a common containment structure integrally supported on the base frame comprising a floor panel joined to the at least two beams so as to span in the longitudinal direction and a plurality of side walls extending upwardly from the floor panel about a full perimeter of the floor panel;
• a first tank integrally supported on the floor panel on the base frame within a perimeter boundary of the floor panel of the common containment structure and which includes a side wall extending in the longitudinal direction of the base frame between an inner end wall defining an inner end of the first tank and an outer end wall defining an outer end of the first tank;
• the first tank being adapted to receive the produced hydrocarbon fluids from the oilfield site therein;
• a second tank integrally supported on the floor panel on the base frame within the perimeter boundary of the floor panel of the common containment structure with the first tank and which includes a side wall extending in the longitudinal direction of the base frame between an inner end wall defining an inner end of the second tank and an outer end wall defining an outer end of the second tank;
• the side wall of the first tank and the side wall of the second tank being joined in fixed relation to one another such that the inner ends of first and second tanks are longitudinally in series with one another and such that an interior of the first tank and an interior of the second tank are separated from one another by a space between the inner end walls;
• the common containment structure having a containment volume which is greater than a storage volume of a largest one of the first tank and the second tank and which is less than a combined storage volume of both the first tank and the second tank;
• a passageway which extends between a first end communicating with the first tank adjacent a top end of the first tank and a second end communicating with the second tank, the passageway only communicating with the first tank adjacent the top end of the first tank so as to be adapted to transfer separated lighter portions of the produced hydrocarbon fluids from the first tank to the second tank;
• the passageway extending through the side wall of the first tank and through the side wall of the second tank so as to include an external portion which is external of the first tank and the second tank and which is contained within the perimeter boundary of the floor panel of the common containment structure;
• and
• a shut-off valve connected in series with the external portion of the passageway so as to be located externally of the first tank and the second tank and so as to be contained within the perimeter boundary of the floor panel of the common containment structure and so as to be accessible externally of the common containment structure;
• the shut-off valve being operable between an open position and a closed position so as to maintain separation between the first tank and the second tank;
• and
• (ii) transporting dual tank structure as an integral structure including the common containment structure, the first tank, and the second tank, and the passageway joined in fixed relation, using a single truck.