TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract'Oil Soluble' scale inhibitor delivery systems are believed to have been first applied to an onshore well in Colombia in 1997. Products of a similar type have since been used in a number of applications including wells in the UK and Norwegian Sectors of the North Sea and in North America.In addition to oil soluble products, other technologies designed to avoid the problems sometimes observed with aqueous treatments have also been developed and deployed in similar, challenging, environments. The different technologies are now commonly referred to as non-aqueous systems to distinguish them from more traditional, aqueous methods. This paper will review each of the non-aqueous technologies currently available followed by a detailed description of field experiences, both good and bad, found by BP, ChevronTexaco, Statoil and other operators using oil soluble systems. Where problems were encountered, the laboratory work to investigate these difficulties will be described and the main findings presented. Recent advances using the knowledge gained from the investigation of earlier challenges will also be presented.