Successful Mechanical Removal of Barium Sulfate Tubular Scale by Coiled Tubing: A Gulf of Mexico Case History of an Engineered Approach for Offshore Rigless Interventions

Sopngwi, Jean-Jose S. (Marathon Oil ) | Gauthreaux, Alex (Marathon Oil ) | Kiburz, Daniel E. (Marathon Oil) | Sonnier, Baine (Halliburton) | Moghalu, David (Halliburton) | Smith, Steve K. (Halliburton )

OnePetro 

Abstract

Discovered in 1991 and located approximately 130 miles south of New Orleans, the Ewing Bank 873 (EW 873) field is an offshore mature field in the Gulf of Mexico that produces hydrocarbon from unconsolidated sandstone reservoirs of Middle-Upper Pliocene age. Most wells within the field were completed using cased-hole gravel packed completions, and field production began in 1994.

Throughout the production cycle of the EW 873 field, wells such as Well A-04 had experienced severe production impairment from near-wellbore (NWB) formation damage, as well as tubular buildups from barium sulfate (BaSO4) scale caused by incompatible mixing between formation water and biocide inhibited seawater that broke through from an offset injection well. While mechanical techniques such as coiled tubing-conveyed hydroblasting have been commonly used to remove BaSO4 tubular scale, the success of these techniques largely depends on the nature and magnitude of the BaSO4, as well as effective operational planning.

This paper presents the five-step engineered approach of the coiled tubing hydroblasting intervention that mechanically removed as much as 3,150 ft. measured depth (MD) of BaSO4 tubular scale from Well A-04. Additionally, the paper presents the tools that were utilized throughout the intervention and the laboratory and field methods that were applied to characterize the BaSO4. With NWB formation damage and production impairment already established to be a problem on Well A-04, the successful coiled tubing-conveyed hydroblasting intervention created an opportunity to effectively conduct a chelant-based hydrofluoric (HF) acid treatment that increased oil production by as much as 305% on the well (Sopngwi et al. 2014).