Characterisation of Geomechanical Properties of Bentonite Clay Used for Plug and Abandonment Operations of Coal Seam Gas Wells
- Resource Type
- Authors
- Heinz-Gerd Holl; Alexander Scheuermann
- Source
- Journal of Minerals and Materials Characterization and Engineering. :218-234
- Subject
- Materials science
business.industry
Coal mining
Pellets
020101 civil engineering
02 engineering and technology
021001 nanoscience & nanotechnology
0201 civil engineering
law.invention
Shear (sheet metal)
law
Bentonite
Abandonment (emotional)
medicine
Shear strength
Geotechnical engineering
Swelling
medicine.symptom
0210 nano-technology
business
Spark plug
- Language
- ISSN
- 2327-4085
2327-4077
Compressed bentonite in the form of pellets or plugs is used for the abandonment of production wells for the oil and gas industry. The design of the abandonment systems is based on the hydro-mechanical behaviour of the compressed bentonite defined by mechanical parameters that are used from published data rather than quantified for the used material by laboratory investigations. This paper presents an experimental study on characterising the swelling and shear strength behaviour of raw and polymer (polyvinylpyrrolidone, PVP) treated bentonite. Dislodgement tests consist of three hydrated bentonite plugs inserted in steel casings with the failure mechanism characterised. The bentonite used comes from a local mine (in Queensland, Australia) and is comparable to other bentonites usually used for the abandonment of wells or for other problems where mineral sealing is required (e.g. basal clay barriers of landfills). The experiments have shown that polymer treated bentonite shows significantly larger shear strengths than raw bentonite with simultaneously less swelling. More compressed samples also showed higher shear strengths and less swelling. The dislodgement tests have characterised for the first time the cascaded failure mechanism of a series of plugs forming an abandonment system. This investigation is the first step towards the development of an improved design for abandonment systems for wells using bentonite plugs.