Removal of water-based filter cake and stimulation of the formation in one-step using an environmentally friendly chelating agent

Chelate solutions, GLDA (pH of 3.3 to 13) and HEDTA (pH of 4 and 7) were incompatible with a-amylase over a wide range of temperatures. GLDA (pH 3.3) and HEDTA (pH 4) can be used to remove the filter cake in one step. GLDA (20 wt% in a 200 g solution and pH of 3.3) and HEDTA (20 wt% in a 200 g solution and pH 4) had 100% removal efficiency of the filter cake. The retained permeability was 110% and 106% for Berea sandstone and Indiana limestone cores, respectively when using GLDA (13.3 wt% in 300 g solution and pH of 3.3). The retained permeability was 115% and 100% for Berea sandstone and Indiana limestone cores, respectively when using HEDTA (20 wt% in 200 g solution and pH of 3.3). No core damage was observed when using GLDA and HEDTA solutions as a breaker to remove water-based filter cake.