Formatted Title
Steam Injection in Unconventional Environments to Improve Thermal Remediation Sustainability
Background/Objectives
Background/Objectives. This paper outlines ERM’s recent successful experience in application of steam enhanced extraction (SEE) in unconventional settings. Two case studies will be presented, both of which are operational manufacturing facilities located in Europe, impacted by solvents (Site 1) and petroleum hydrocarbons (Site 2). Site 1 is underlain predominantly by clays and silts, while Site 2 is situated upon fractured chalk bedrock.
Approach/Activities
Approach/Activities. At Site 1, field data suggested the lithology to comprise predominantly low permeability silty clays; therefore, electrical resistance heating (ERH) was initially expected to be the selected heating method; however, following detailed high resolution investigation the material was shown to be more silt rich. Given this, the possibility to use SEE was further evaluated by steam injection into a single well, which confirmed relatively high flow rates of steam could be injected to achieve the required treatment temperature.
It was also expected that heating at Site 2 would be undertaken using ERH. However, this would have meant electrode installation at a spacing of 4.5 m, which was not acceptable to site management from an operational perspective. Therefore, a field-scale steam trial, similar to that undertaken at Site 1, was carried out to evaluate SEE using more widely spaced heating locations. As expected, fractures influenced the steam flow, but the area containing the greatest contaminant mass was heated in a controlled way.
Results/Lessons Learned
Results/Lessons Learned. At both sites, the change in heating methodology resulted in significant cost savings and at Site 2 allowed the thermal remediation approach to be accepted by site management.
Multiple lines of evidence were evaluated at both sites to support possible use of SEE, and subsequent field-scale steam injection trials confirmed successful application within geology where use of this heating methodology would not have traditionally been considered.
The advantages of increasing the SEE operational window are reduction in drilling and equipment costs compared to using ERH, where heating locations need to be significantly more closely spaced and where more power intensive equipment would otherwise be required. This is particularly relevant given pilot-scale steam generators are now more routinely in use and steam is often available at a broad range of industrial sites, enabling further cost savings and reduced energy consumption.