One of the main components of this safe artificial rock is norite. Norite is a waste material from the mining industry in Norway so this new material also has great potential for saving the environment.
When Mahmoud Khalifeh started his PhD at University of Stavanger in September 2012, the scope of the project was to identify a material for plug and abandonment that had three characteristics:
- Shall be pumpable like cement slurry
- No shrinkage or less shrinkage than cement
- Impermeable as cap rock
Eight research papers
After a lot of research, including four journal papers, four conference papers and a comprehensive series of testing and failing, Dr. Khalifeh has now produced a prototype of artificial rock that is pumpable like cement. And it shrinks only 0.5 percent, compared to neat cement which shrinks approximately 3-4 percent.
Moreover, it has one thousand times less permeability than oilwell cement which means that it offers lower risk of leakage across the artificial rock.
70 percent less CO2 emission
Using the low pH waste norite from the mining industry is not the only environmental advantage. When manufacturing ordinary cement the heating process in the rotary kiln generates some 650 kg of CO2 when producing one ton of cement. Worst case up to 900 kg of CO2.
“The production of the artificial rock emits approximately 70 percent less CO2 compared to ordinary cement which is quite remarkable”, Dr. Khalifeh says.
“The norite-based rock can be described as safe”, Dr. Khalifeh continues. It has been heat tested at 1,000 °C and after that cooled down with water at 8-9 °C without developing any cracks, staying in shape, unaffected by the high temperature and the sudden temperature change.
Mahmoud Khalifeh defended and finished his PhD dissertation four months ahead of schedule on May 20th 2016. After that he has been working as Postdoctoral fellow and Assistant Professor at University of Stavanger (UiS) and now has two patents.
One for aplite-based cementitious, geopolymeric material and one for norite-based cementitious geopolymeric material.
“I am very thankful for the three years at DrillWell that provided me a fantastic environment, acknowledgeable and motivated supervisors (Prof. Helge Hodne, Prof. Arild Saasen and dr. Torbjørn Vrålstad) and industrial contacts throughout my research career. It was a very interesting project between UiS and DrillWell centre with preset goals”, Dr. Khalifeh says.
Dr. Khalifeh is of course eager to see the potential of this new artificial rock unleashed within plug and abandonment but at the same time he says that there is a great potential for using it within normal construction work on buildings and other constructions where safety is a big issue such as tunnels, banks etc.
These findings are described in Dr. Khalifeh’s latest research article published August 23rd 2017 (download link in new window): Development and Characterization of Norite-Based Cementious Binder from an Ilmenite Mine Waste Stream.
Text & photo: Søren Arentsen/IRIS