Evaluation of latest techniques for remedial treatment of scale depositions in petroleum wells

A major phenomenon altering well productivity is increasing water production. In addition to raising energy consumption, higher water production leads to phenomena such as mineral and organic scaling, which may temporarily or even permanently alter the whole flow assurance chain. The build-up of scale inside well bore can smother a productive well within 24 hours, causing millions of dollars in damage every year. A project was carried out to review and evaluate new techniques and tools developed for scale treatments in order to find an appropriate tool, at least deployed with wireline rather than with coiled tubing to overcome the adverse scale problems encountered in most of the fields. This paper presents results of this evaluation and shows the advantages and disadvantages of different tools for scale removal process. Solid blasters, deployed with CT, have proved to be efficient in removing most of the scales but it is costly as well as inapplicable to wellbore and near-wellbore. Tools using fluidic oscillator technology is not that expensive however they are not strong enough to treat very hard scales like barium sulphate. In addition, these tools have great standoff distances and are deployed with CT. String shots, wireline-deployed, are good for short intervals, thin layers of scales. Recent techniques, which use acoustic waves to clean the near wellbore damage are not good tools to be applied for tubing and casing scale depositions since they have only proved to have the ability to remove fines and soft materials like mud cakes from near wellbore region.