Barium sulfate scale dissolution using chelatants: Laboratory analysis

A major North Sea Operator experienced severe scaling problem in a well with a production potential of 800 m3/day oil (>5000 BOPD). Barium and Strontium scales formed in the tubing, perforation and near well-bore area effectively "Killing" the well. The operator wanted the oil well service company to devise a treatment program that would remove the scale from the well. Scale milling was not considered to be the most cost effective option.; The main objective of this laboratory Study is to investigate the effectiveness of two commercially available chemicals on the removal of barium sulfate scales. The objective is implemented by simulating well conditions using an Aging Cell. An effort has been made to expedite the dissolution process by determining temperature dependence of the scale dissolver, since temperature has the largest effect on Barium Sulfate dissolution. Effects of organic acids, that works as catalyst for barium sulfate dissolver has also been investigated.