Variations and Controls of Reservoir Quality in Permian Reservoir Sands, Baryulah Area, Southwest Queensland, Australia
Patterson, Brett M.
Geoscience Honours Degree, 2010
University of Adelaide
Gas exploitation of the Baryulah Area (Cooper Basin, Southwest Queensland) by SANTOS is focused upon identifying zones of elevated permeability. This was accomplished by the application of Permeability Estimation from Reservoir Cuttings (PERC) to the reservoir sandstone intervals of interest. These intervals were located within the Patchawarra, Epsilon, Roseneath, Daralingie and Toolachee Formations. There are approximately fifty wells within the study area but not all of which contain all the intervals of interest. A subset of eight wells was selected with containing as many intervals of interest present as possible and are located throughout the study area. A total of 160 cuttings samples were examined by the PERC method over the intervals from the eight wells.
Once the PERC analysis was completed, twelve different samples from two different wells (six from each well) were selected for examination by Scanning Electron Microscopy (SEM). Five samples from two different wells, three from one well and two from another were selected for Thin Section (TS) examination. These two different types of analysis were completed on a subset of samples to check the validity of the results of the PERC method.
Intervals were also examined using gamma and resistivity logs; to identify both sand content and permeability zones. This in conjunction with PERC, TS and SEM was used to identify both the controls on reservoir quality and the reservoir quality itself of the different intervals from the Permian reservoir sands in the Baryulah Area.
These methods identified a variety of parameters which control the reservoir quality of the Permian sandstones of the Baryulah Area. These parameters include; quartz overgrowths as they have a more damaging effect on the reservoir quality of finer grained sandstones, a preference for larger kaolin clays to form in larger pores and favour platelets to become larger towards the centre of these pores. It was found that within the Baryulah Area the sandstones within the Daralingie and Roseneath Formations were finer and poorer reservoir quality than those located within the Patchawarra, Epsilon and Toolachee Formations.