Acidization of sandstone reservoirs relies on fast reacting hydrofluoric acid (HF) to remove damage associated with aluminosilicate minerals and restore original formation permeability. Titanium alloy (Ti) is currently used in deep water (DW) platforms in the Gulf of Mexico (GOM) because of its higher strength-to-weight ratio compared to steel, and corrosion resistance to the most common acids employed in oilfield stimulation, except hydrofluoric (HF) acid. Corrosion-resistant Ti alloys are conventionally not rated for use with HF acid, hence there is the need to establish testing standards to help guide the acid fluid selection process for existing operations requiring HF acid. Here we present a testing protocol delineating discriminatory criteria to assess the corrosion inhibition of Ti alloys using fluoride-containing fluids. The following challenges are addressed: solubility and stability of inhibitor composition, compatibility of inhibitor composition with stimulation fluids, as well as the temperature and pressure effects. The inhibitor composition prevents corrosion of Ti for up to 24 hours (120 or 140°F), maintaining a corrosion mass loss below detectable levels (&lt;0.000 mpy or 0.0005 lbm/ft<sup>2</sup>). The optimum inhibitory effect is observed above a pH of 2 using an inhibitor concentration (w/v) of 3 to 10%. The identification of crucial factors impacting corrosion inhibition of Ti alloy supports the feasibility of protecting the surface of sensitive components, such as a Ti stress joint, against spent HF acid fluid corrosion and increases the use of HF for formation damage remediation in the GOM.

Expanding the compatibility of hydrofluoric acid-containing fluids for formation damage remediation and titanium alloy: Deep water challenges

254th National Meeting (2017)

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