Halite Scale Formation Mechanisms, Removal and Control: A Global Overview of Mechanical, Process and Chemical Strategies

摘要

Halite scale has long been a challenge in the oil and gas industry. In recent years there has been a marked increase in the occurrence of this scale type due to the increased development of hotter and deeper gas and gas condensate fields. As the formation of this scale is commonly in the downhole production tubing, it is a challenge to identify and mitigate, so a non- conventional approach has to be taken for removal and control. Furthermore, it is very difficult to replicate the formation of this scale in the laboratory with complex and specific equipment being utilized to replicate field observations. This paper provides a review of several examples of halite scale formation in the field, detailing the mechanism of deposition and the strategies employed to remove and subsequently prevent reoccurrence. Details are also provided for two different types of laboratory test methods; the first being a simple static test method designed to quickly screen the extent of halite challenge and the suitability of a range of inhibitors. The second laboratory method concerns a novel, dynamic method whose primary aim is to accurately measure and predict the severity of scaling in the field, and then go on to determine the minimum effective dose of inhibitor required to prevent build-up. The different types of halite inhibitor chemistries are evaluated, including the use of wash water and where this is used in combination with organo-ferrous compounds, as well as more novel polymeric compounds. The paper concludes by providing an insight into the economics of the different types of treatment, namely the use of wash water versus the use of chemical inhibitors and combinations of these two techniques.