The application temperature for oilfield chemicals often exceeds 120°C (248°F). This temperature is important because it is the threshold for the thermal breakdown of many oilfield chemicals. The breakdown of oilfield chemicals used to treat problems such as corrosion, scale, oil-water separation, bacterial corrosion, etc. can create additional problems if they are applied at temperatures greater than their breakdown temperatures. The breakdown products can cause gunking and in some cases the breakdown products can be corrosive to mild steel. This paper explores the high temperature thermal stability of several common families of molecules including amines, quaternary amines, phosphate esters, alkylthiols, imidazolines, and polymers at temperatures above and below this key temperature and provides data which describes why this temperature is a hard limit for many oilfield chemicals. Guidance is provided for personnel incorporating chemical treatment in their oilfield systems. This guidance will help identify system components or locations where thermal breakdown should be studied before implementing a chemical program.
As oilfield technologies have advanced, they have made high temperature (HT) reservoirs more accessible. HTs make the application of chemical more difficult because chemical instability at HT restricts what intermediates will work in these environments and the safety and complexity of HT testing further adds to the challenge.
HTs in oilfield applications are often found at bottomhole conditions. Operators often apply chemical at the bottom of the well to protect the tubing or casing from corrosion or scaling, but bottomhole temperatures can exceed 230°C in some cases. Electric submersible pump applications exacerbate this problem because they can add 10 to 20°C locally to the local temperature. HTs can also be found in geothermal applications and solvent regeneration systems like glycol and glycerin regeneration loops, as well as heat exchangers common to HT gas operations. Flowline applications can exceed 120°C in fields with extremely high bottomhole temperatures or in gas systems where compression is employed. Other HT industries are discussed in the literature.1
