Successful Application of a Differentiated Chelant-Based Hydrofluoric Acid for the Removal of Aluminosilicates, Fines, and Scale in Offshore Reservoirs of the Gulf of Mexico

Sopngwi, Jean-Jose S. (Marathon Oil ) | Gauthreaux, Alex (Marathon Oil ) | Kiburz, Daniel E. (Marathon Oil ) | Kashib, Tarun (Marathon Oil) | Reyes, Enrique Antonio (Halliburton) | Beuterbaugh, Aaron (Halliburton) | Smith, Alyssa L. (Halliburton) | Smith, Steve K. (Halliburton )


The Ewing Bank 873 (EW 873) field is an offshore mature field in the Gulf of Mexico that produces hydrocarbon from Pliocene stacked turbidite sands. Wells on EW 873 have experienced production impairment from formation damage caused by aluminosilicates, fines, and scale including calcium carbonate (CaCO3) and barium sulfate (BaSO4).
This paper discusses the results of the successful application of a new chelant-based Hydrofluoric (HF) acid to remove formation damage and optimize production on EW 873. Additionally, the paper also presents the chemical analyses of acid flow backs, as well as the methods that were used to characterize the formation damage. More importantly, the paper also focuses on the multidisciplinary research efforts that led to the development and successful application of the new chelant-based HF acid.
Throughout the research, analytical experiments and corefloods were performed with three different HF acid formulations on cores that contained acid sensitive clays, CaCO3 and BaSO4. Two formulations contained hydroxypolycarboxylic acids such as citric acid, and the third formulation was based on the new chelant HF acid which contained an aminopolycarboxylic acid. The new chelant-based HF acid proved to be the most effective formulation as it achieved the highest permeability increase and dissolved ions while mitigating precipitation. Furthermore, compatibility and corrosion testing indicated that the new chelant-based HF acid was compatible with both the reservoir fluids and metallurgy of EW 873 wells.
The development of this novel chelant-based HF acid highlights the potential of performing successful acid treatments where heterogeneous mineralogy including CaCO3 and BaSO4 are present.