Pinar Karpuz-Pickell and Levins Thompson
LUFKIN Industries
Surface coatings are often needed for sucker rod pump components to protect them from the harsh downhole environments of corrosives, formation solids, and even treatment chemicals. Most coatings have both positive and negative characteristics in protecting from each of the downhole aggressors, therefore further precautions must be taken to ensure the survival rate of components, given the economics of wellbore interventions.
A common dilemma when using chrome plating on barrels is although the high hardness is capable to protect against solids abrasion, the very method to effectively stimulate a well is proved to be detrimental to chrome. Hydrochloric Acid (HCl), a commonly used ingredient in stimulate solutions, will dissolve away the chrome when in contact. Once the chrome is compromised the life expectancy of the pump is greatly reduced.
Therefore, better understanding the deteriorating effects that acidizing has on chrome will better inform users on how to protect downhole equipment. Is the acid concentration and soak times being implemented too risky? Are they too conservative and sacrificing possible extra wellbore stimulation?
This study focuses on discovering the degradation rates of chrome coatings when placed in various concentrations of HCl solutions to observe the survivability of one of the industry’s most useful coatings.