Dissolution Kinetics of Iron Containing Materials in Sour Wells

Abstract

Crude oil and natural gas can carry various high-impurity products which are inherently corrosive such as carbon dioxide (CO₂) and hydrogen sulfide (H2S). These impurities increase operations safety risk and can be detrimental to production both in terms of equipment damage and permeability impairment by scale build up. Problems with FeS containing scale build occur when H2S comes in contact with spent acid solutions containing dissolved iron ions. While dissolution of pipeline and iron bearing core materials in H2S solutions is known to result in FeS scale build up, reactivity of iron containing proppant material under sour conditions is poorly understood and documented. Here presented study evaluates and compares dissolution kinetics of pipeline material, iron bearing formation and iron containing proppants in H2S acid solution in order to evaluate their relative contribution to FeS containing scale build up. Study uses X-ray diffraction (XRD), X-ray fluorescence (XRF) analysis and inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis to qualify present Fe containing crystallite forms and quantify dissolution and scale build up reaction kinetic. Scanning electron Microscopy (SEM) evaluates surface morphology changes associated with iron dissolution and FeS scale build up. Finally reactivity of all tested materials is compared based on their initial iron concentration and relative dissolution affinity. Effects of FeS scale build up on EUR and proppant cost related ROI is also discussed.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015