One of the major challenges encountered in the sour wells is iron sulfide scale deposition. It causes issues of well deliverability, well intervention, and production loss. Mechanical descaling is currently applied, but it is time-consuming and costly. Dissolvers based on concentrated hydrochloric (HCl) acid have high dissolving power, but they also have limited applicability due to overwhelming drawbacks such as corrosion and H2S generation.

A non-acidic chemical dissolver was developed to remove iron sulfide deposited at downhole tubular and near wellbore region. The chemical is non-corrosive and no H2S generation during dissolution. The standalone chemical treatment for iron sulfide removing in the downhole tubing in a sour oil well was successfully executed. Jetting, repeated treatment and longer soaking time were applied to overcome the limitation of this scale dissolver. The results demonstrated the chemical process provided desirable scale removal with significantly reduced cost compared to the conventional mechanical descaling. The multi-fingered caliper log runs pre-chemical and post-chemical treatment showed up to 90% of the scale can be removed by the chemical treatment. The dissolution efficiency is higher in the deeper section of the production tubing due to higher temperature at the bottom part of the tubular.

Subject
X-ray diffraction, Iron sulfides, Calipers, Dissolution, Soaking, Descaling, Scale deposition, Sour oil, Tubing, Scale dissolvers, Dissolvers, Scale, Samples
Keywords:
iron sulfide, scale, dissolver
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2021
Association for Materials Protection and Performance (AMPP)
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