Institute of Petroleum Engineering

FAST 3 logo, 6K

Scale background



One of the major problems experienced in the oil production industry is the formation of mineral scale. Scale is deposited downhole within an oil reservoir and topside, throughout the water production of a producer well. This creates formation damage (restriction / blockage within the rock matrix) and blockage of the production tubing, causing a detrimental effect to the productivity of the well.

Various forms of inorganic scales can be found in the North Sea and elsewhere such as insoluble barium/strontium/calcium sulphates and calcium/magnesium carbonates. The most predominantly formed precipitates are of barium sulphate (BaSO4) and calcium carbonate (CaCO3). These are normally prevented using a process known as a "squeeze" treatment, where scale inhibitor chemicals are applied to the rock formation to stop scale deposition in the pipelines and to protect the wellbore area, or by continual chemical injection, which treats the topside precipitated calcium carbonate and barium sulphate scale.

Scaling problems arise in high pressure, high temperature (HP/HT) fields in the North Sea and around the World, but also in systems where low temperatures are prevalent e.g. in long line tie-backs. In order to treat the scale that is formed under such severe conditions as these, the chemicals applied in the squeeze treatment must be thermally stable at the high or low temperatures or the breakdown products must prevent scale formation.

Project background



Scale formation and prevention has been an active area of research within the Institute of Petroleum Engineering since the mid 1970's. In the late 1980's, the Oilfield Scale Research Group (OSRG) formed. It ran as a joint industry funded project (JIP) to carry out research into the nature, effect and prevention of scale. This first project grew rapidly due to the severe and detrimental scaling problems observed in the field, specifically under the conditions the OSRG Sponsors operate.

In 2001, OSRG relaunched itself in order to meet the new challenges facing the oil industry in the 21st Century. The research title became "Flow Assurance and Scale Control" and represented quite a radical departure from previous research, introducing several major new topics, but it also continued the further development of the existing expertise and knowledge base within the former OSRG.

The Flow Assurance and Scale Control project combines fundamental studies and field applied research in order to solve remaining and future challenges associated with the build up of scale and related flow restricting precipitates downhole, in the near wellbore area and in the production system. Extensive laboratory based experimental studies are conducted and the data obtained can be modelled, as can field specific data, to ensure fields are effectively managed. An improved understanding of the fundamental mechanisms involved in all aspects of scale control will enable future challenges to be addressed more readily.

In addition to the work conducted on scale inhibitor research, FAST (Flow Assurance and Scale Team) has also carried out over 100 field or product specific technical studies in order to solve real production / reservoir scaling problems. In such instances, staff are in regular communication with Sponsors regarding field specific scale control issues, and discuss outcomes on a regular basis.

This also makes staff aware of "real" current issues in the field, and ensures that the research conducted within the project maintains an applied focus.


Consultancy



In addition to the research activity FAST also undertakes contract consultancy (FASTrac) on scale related issues and coreflooding.

We also collaborate with other flow assurance consultants who specialise in the areas of corrosion (CoSERG) and organic deposits/hydrates (HYDRAFACT) to provide a Comprehensive Flow Assurance Service.