ConocoPhillips
Decomplexation of chelated hardness at high pH

Abstract:

A process for removing metals and chelators from SAGD liner flowback that can be implemented at the wellhead using temporary tankage and equipment. In the first step, caustic is added to the flowback until the concentration of hydroxyl ion is high enough for the metals (Fe, Ca, Mg) to dissociate from the metal-chelate complexes and precipitate as hydroxides. In the second step, hydrogen peroxide is added and allowed to react until all of the chelator molecules are oxidized and decomposed. Once treated, the flowback can proceed to the CPF.