Meeting the Challenges in Downhole Scale Control for High-Water-Production Horizontal Wells in an Environmentally Sensitive Part of the Norwegian North Sea

Abstract

Summary As a result of the seawater injections in one of the Norwegian North Sea oil fields, sulfate-scale depositions have been identified in the near-wellbore region and inside the production well. Scale-inhibitor squeeze treatments are carried out regularly. Most of the production wells are horizontal producing, with a fairly high water cut, and increasing the squeeze treatment life is one of the major issues for the selection of scale inhibitors and placement technologies. In addition, the inhibitor selected has to be environmentally acceptable and meet regulations from environmental authorities. Both challenges from the high-water-production wells and environmental requirements limited the choice of the inhibitor candidate selections. Through extensive laboratory qualification testing, a newly developed polymer inhibitor was qualified for the field and satisfactory results were achieved from several field trials. This paper presents the inhibitor chemistry, as well as laboratory tests such as inhibitor efficiency and compatibility and inhibitor coreflood. The environmental properties of the chemistry will be outlined. A comparison was made between the field treatments using this polymer inhibitor and widely applied polymer chemistries. The treatment optimization using a software package will also be highlighted. The field used a gelled scale-inhibitor package, and the technology improved the inhibitor placement in the horizontal well. The updated treatment data will be reviewed in this paper.