The Evolution of Fracture Surface Parameters in Heterogeneous Carbonate Reservoirs Employing Chelating Agents as Acid Fracturing Fluids

Acid fracturing is one technique for increasing carbonate formation productivity. The injection of acid causes dissolution along the fracture, which results in conductivity. The success of the acid fracturing process is influenced by several factors, including acid type, acid concentration, formation type, and contact time. Many fluids have been examined for their ability to maintain conductivity, beginning with strong acids such as hydrochloric acid (HCl) and progressing to weak acids such as organic acids. The main issues with HCl are its rapid and strong reactions, as well as its ability to corrode wellbore tubular. This research investigated the impact of chelating agents such as GLDA and DTPA on acid fracturing stimulation to maintain fracture conductivity in heterogeneous carbonate formations formed of calcite and dolomite. At reservoir temperature, chelating agents are less reactive than HCl and do not require a corrosion inhibitor. the image illustrations were observed using a laser profilometer prior to and after acid treatment. The fracture conductivity was measured before and after acid etching with a core-flooding system at various flow rates and closure stresses. The results show that chelating agents improved fracture conductivity sufficiently when compared to HCl for layered carbonate formation. Remarkably, DTPA softened the rock and made change in surface roughness more than GLDA, while GLDA improved fracture conductivity more than the other one. the reason behind this is that DTPA smashed the fracture surface uniformly in some areas instead of generating channels like HCl and GLDA, resulting in a non-significant improvement in fracture conductivity when compared to the other two acids. For the first time, chelating agents were investigated and tested as acid fracturing fluids on heterogeneous carbonate reservoirs to generate sustainable conductivity.