Oil Well Plugging Material

Can Quick Clay/Leda Clay/Champlain Sea Clay replace cement?

So far, most exploration and production wells are plugged and abandoned using cement.

The challenge is that most of the oil and gas fields are, to a varying degree, subsiding. The pressure in abandoned oil and gas fields often builds up again over time due to lateral communication in the underlying aquifer. In addition, there are plans to inject C02 and Hydrogen into abandoned oil and gas fields which will rebuild the pressure.

The sequence of events:

The Quick Clay slide at Sørum, November 10th, 2016. Three men walking on the street after work died. I went to the site on January 29th, 2017 and took a sample of about 80 kg (40 L) of quick clay.

A patent to use Quick Clay to seal wells was filed by Homsø in June 2017. October 28th 2021 CaMa GeoScience was awarded the patent in the USA; US 11,156,058 B2. The patent is also approved in Australia

In January 2018 CaMa Geo applied for national funds and NFR approved a 500 000 NOK research project, joint between CaMa Geo, UiS, and Norce. It was completed in September 2018. The results were presented to Professor Rebecca Lynn at University of Strathclyde in Glasgow, August 2019. The research project was funded and began at University of Strathclyde May 2021.

What is Quick Clay?

Quick clay, also known as Leda clay and Champlain Sea clay in Canada, refers to several unique sensitive glaciomarine clays found in Canada, Norway, Russia, Sweden, Finland, the United States, and other locations around the world. The clay is so unstable that when a mass of quick clay is subjected to sufficient stress, the material behaviour may transition from that of a particulate material to that of a fluid.

Quick clay is typically originally deposited in a marine environment. In that environment, the positive charge of cations (e.g., sodium) was able to bind clay particles (negative surface charge) by balancing charge in the double layer. When the clay became uplifted above sea-level and was no longer subjected to saltwater conditions, rainwater infiltrated these clays and washed away the salts.

The original quick clay model proposed by Prof. Rosenkvist (1946), which is based on experience from Norwegian clays around the Oslo area that have experienced 213 meters of uplift since the ice melted 10000 years ago. He showed a connection between low salt content and high sensitivity. Later research by Talme (1968), Söderblom (1969), and Penner (1965), among others, has shown that a low salt content is a precondition for high sensitivity, but that this condition alone is not always sufficient. High water content is the second precondition.

Rainwater has during the last 10 000 years drained through many of these clay deposits. The leaching has reduced the salt concentration and, in some cases, also increased the water content. For any given composition of these post glacial clay deposits, Illite- Clorite- Sand-Silt at a given salt concentration and a given water content, the mix will transition into a liquid state if stressed.

Cement performs poorly as a well plugging material

The graph below shows the percentage of well barrier and integrity failures reported in 25 different studies around the world. Image from Davies et al., 2014

A classic example

Oil wells, at the Chevron operated Cymic field, in California have leaked since 2003. First it was GS-5. Then on Mai 10th, Y1 started leaking 3000 bbl/day, a mix of water and oil. As there is no known effective plugging material, they decided to build a collection facility. In theory OK as there is no rivers in the vicinity. So fare 800 000 bbl of water and oil have been collected.