Program Manager: Dr Nick Lemon
Reservoir rocks in the immediate vicinity of an oil/gas well can be subjected to damage during the process of drilling the well. Such damage may restrict or prevent the flow of hydrocarbons from the reservoir when the well is brought into production. Damage occurs at the level of individual pores and must be studied at that level. Clay distribution and mineralogy is the fundamental control on formation damage, thereby providing a link between these studies and those of reservoir characterisation and seals.
Aims and Benefits of the Program:
- Identification of the clay types and distribution pattems which influence formation damage
- Remote detection of likely trouble spots using downhole logging tools (Nuclear Magnetic Resonance imaging)
- Prediction of areas of damage
- Provide choices for remedial action to clean up wellbores
- Production of an atlas of formations subject to damage
Project: Swelling behaviour in greensands
Project leader: Dr Nick Lemon
Research personnel: Dr Ghazi Kraishan, Dr Nick Lemon
The range of glauconitic clays in greensands display a range of swelling characteristics. The change from a smectite structure to an illitic structure is the main reason for the observed differences in swelling but not all the controls on this mechanism are known. The availability of potassium can determine the rate of change but it appears that oxidation of glaucony to a goethitic clay can also alter the swelling behaviour. Influx of meteoric water and proximity to
exposure surfaces are therefore controlling factors. Prediction of likely zones of formation damage may then follow from detailed sequence stratigraphic studies.
MSc Project: Inter relationship between reservoir properties and nuclear magnetic
resonance (NMR) measurements in the Cooper Basin
MSc student: Nita Musu (commenced 1998)
Supervisors: Dr Nick Lemon, Dr John Kaldi
Funding support: Santos Ltd and APCRC
Scholarship support: AusAid
The project investigated the possibility of downhole recognition of low permeability rocks likely to be susceptible to water block. A suite of samples from the Cooper Basin were analysed by traditional petrographic techniques including thin section petrography, image analysis, x-ray diffraction, scanning electron microscopy, cathodoluminescence and mercury injection capillary pressure. The clay, pore size and pore throat size distribution were determined.
The same samples were then subjected to bench-top nuclear magnetic resonance analysis. The pore size and distribution from NMR analysis compared favourably with the traditional measurements. A series of published equations to convert NMR results to permeability were also compared with the known values. Some equations were better at estimating permeability then others.
The research has been completed and the thesis was submitted for examination on the 1st of December.