Scale deposition in oil and gas wells is still a major issue in the oil and gas industry as it reduces hydrocarbon production, restricts well access to production logging tools and, in addition, causes safety issues due to blocking and ineffective operation of chokes and valves. Scale is predominantly controlled with chemical scale inhibitors and the most common methods to control scale deposition are through continuous injection and scale squeeze treatments although solid inhibitors can be deployed in ratholes, hydraulic fractures and gravel packs. Non-chemical methods can also be applied and are becoming more common over the last few years especially for calcium carbonate control.

Scale management is clearly still a very important factor for the good health of existing oil and gas wells and the trend towards net zero will only increase this reliance as the need for maximum production from existing assets becomes more pertinent compared to the alternative of developing new fields which will be more carbon intensive.

Existing scale management strategies will also have a CO2 footprint and scale control methods will be reviewed to become more aware of this and to highlight how certain areas of scale management can become more effective and adapt to the changing needs of the energy industry such as the increasing use of enhanced oil recovery (EOR) in both conventional and unconventional fields.

The review will include several areas of scale management including scale prediction risk, chemical and non-chemical treatments, scale inhibitor chemistry from renewable sources, monitoring techniques coupled with improved data processing techniques and automation.

The drive towards net zero has also instigated the development of alternative energy sources to fossil fuels which have resulted in a major focus on projects in geothermal energy and increased the potential for carbon capture, utilisation and storage (CCUS) projects where CO2 captured from heavy industry is transported to site and injected into geological reservoirs for storage and/or enhanced oil recovery.

Scale control will be important to both geothermal and CCUS projects and this paper will highlight examples including scale control in geothermal wells with options for treatment and desirable chemical properties and carbonate scale control in CO2Water Alternating Gas (WAG) injection whilst also demonstrating CO2 storage and enhanced oil recovery (CCUS). In addition, the potential for halite deposition and carbonate mineral dissolution and its impact on rock mechanical integrity during CO2 injection into hyper saline aquifers and depleted oil and gas reservoirs will be discussed.

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