Determination and Fate of Formic Acid in High Temperature Acid Stimulation Fluids

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractFormic acid is present in some corrosion inhibitors and is used as an intensifier in the acid treatment of oil and gas wells. This organic acid is important for the protection of low-carbon steels from acid corrosion at high temperatures and pressure. In this paper, the fate of formic acid used during acid treatments at temperatures up to 250ºF in deep gas wells is investigated in detail. To the best of the authors' knowledge, this is the first study of this type.The following conclusions were made from this work:• Most of the commercial organic additives for corrosion inhibitors contain formic acid while one inhibitor intensifier contains both formic and acetic acids. • Formic acid concentration in flow back samples from high temperature gas wells was higher than 85% of the injected value in most of the treatments. • In concentrated HCl at 250ºF, the amount of formic acid present in corrosion inhibitors and intensifiers decreased with time. After 8 hours corrosion inhibitors and intensifiers contained approximately 60% of the initial formic acid concentration. Acetic acid concentration did not significantly change with time in these tests. This work shows the fate of formic acid during acidizing of high temperature wells. Formic acid concentration in acid treatment flowback samples was near the injected value, showing that it remains available to act as a corrosion inhibitor intensifier. However, since it degrades with time, long shut-in times should be avoided. High formic acid concentrations in flow back samples may promote corrosion since the corrosion inhibitor concentration in these samples is significantly reduced.

A censorious appraisal of the oil well acidizing corrosion inhibitors

“…Acetic acid, in the other hand was found to follow the same path, but at a higher temperature of 504 • F (Benziger and Madix, 1980). Al-Katheeri et al (2002) observed that in 28 wt% HCl at 250 • F, after 8 h of contact time, the corrosion inhibitors and intensifiers contained approximately 60% of the initial formic acid concentration but the concentration of acetic acid remained almost the unchanged.…”

“…Formic acid has a long history of being used in the oil and gas industry to aid the inhibition performance of corrosion inhibitors (Cassidy et al, 2007;Al-Katheeri et al, 2002). Al-Katheeri et al (2002), for instance noted that at Saudi Aramco, the use of formic and acetic acids is of major importance in well stimulation.…”

“…Formic acid has a long history of being used in the oil and gas industry to aid the inhibition performance of corrosion inhibitors (Cassidy et al, 2007;Al-Katheeri et al, 2002). Al-Katheeri et al (2002), for instance noted that at Saudi Aramco, the use of formic and acetic acids is of major importance in well stimulation. Formic acid is thought to function as intensifier by undergoing a dehydration reaction that produces water and carbon monoxide (CO), a known corrosion inhibitor according to Eq.…”

“…Formic acid is thought to function as intensifier by undergoing a dehydration reaction that produces water and carbon monoxide (CO), a known corrosion inhibitor according to Eq. ( 16) (Cassidy et al, 2007;Al-Katheeri et al, 2002). Formic acid could therefore be accurately described as a precursor to CO, the inhibiting molecule.…”

Effect of Intensifier Additives on the Performance of Butanolic Extract of Date Palm Leaves against the Corrosion of API 5L X60 Carbon Steel in 15 wt.% HCl Solution

“…Normally, an intensifier also known as inhibitor aid [22] or synergist [23] is added to an inhibitor to upgrade its performance [23][24][25]. Common synergists include formic acid [26,27] (used at a concentration range of 0.5 to 10 wt.% [22]), potassium iodide [10,22,28] (used at a concentration range of 0.5 to 10 wt.% [22]), copper halides [22], and metals ions (e.g., Zn(NO 3 ) 2 , Sb 2 O 3 , SbCl 3 , Sb 2 O 5 , etc.) [22,29,30], which are used at the concentration range of 1-1.5 wt.% [22].…”