Chemical squeeze treatment with scale inhibitor has been used extensively to combat downhole scale problems in the Murchison and Hutton fields in the North Sea. Considerable success has been achieved for several years. As the fields mature increasing amounts of water are being produced. These increasing volumes of water require ever larger volumes of chemical for control of scale. A review of the chemicals presently available for squeezing was carried out, with a view to obtaining more efficient squeezes, which would in turn reduce costs of scale control. The risk of an unsuitable chemical plugging a well justified considerable effort being expended in the evaluation.
This paper describes the background to the evaluation process which included two new approaches. The ability to monitor accurately chemical returns in the produced fluids is paramount to a successful and efficient squeeze programme. The accuracy of detection methods was evaluated prior to looking at the effectiveness of the inhibitors. The likelihood of formation impairment during the squeeze process was assessed from core studies. Squeeze life ultimately determines squeeze efficiency and simulation of mini-squeezes on cores was used to gauge minimum squeeze life as part of the commercial evaluation.