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The beaches of Palliser Bay, exposed to oceanic waves from the south, are composed of mixed sand and gravel derived from mountain ranges of greywacke and argillite that rise above both sides of the bay. Beach gravel tracer experiments, each using up to 75 tonnes of limestone pebbles, were conducted at three sites. Increase in the roundness of these tracer pebbles at each site during the year of observation was compared with the increase in roundness and rate of weight loss of limestone and greywacke pebbles in a laboratory tumbler. The comparison enabled estimation of the rate of attrition of the natural beach pebbles. A weight loss of 41% per year was found for pebbles at the most exposed site and 15 and 7% at the other two sites.

The Waitsia Field represents a new commercial play for the onshore north Perth Basin with potential to deliver substantial reserves and production to the domestic gas market. The discovery was made in 2014 by deepening of the Senecio–3 appraisal well to evaluate secondary reservoir targets. The well successfully delineated the extent of the primary target in the Upper Permian Dongara and Wagina sandstones of the Senecio gas field but also encountered a combination of good-quality and tight gas pay in the underlying Lower Permian Kingia and High Cliff sandstones. The drilling of the Waitsia–1 and Waitsia–2 wells in 2015, and testing of Senecio-3 and Waitsia-1, confirmed the discovery of a large gas field with excellent flow characteristics. Wireline log and pressure data define a gross gas column in excess of 350 m trapped within a low-side fault closure that extends across 50 km2. The occurrence of good-quality reservoir in the depth interval 3,000–3,800 m is diagenetically controlled with clay rims inhibiting quartz cementation and preserving excellent primary porosity. Development planning for Waitsia has commenced with the likelihood of an early production start-up utilising existing wells and gas processing facilities before ramp-up to full-field development. The dry gas will require minimal processing, and access to market is facilitated by the Dampier–Bunbury and Parmelia gas pipelines that pass directly above the field. The Waitsia Field is believed to be the largest conventional Australian onshore discovery for more than 30 years and provides impetus and incentive for continued exploration in mature and frontier basins. The presence of good-quality reservoir and effective fault seal was unexpected and emphasise the need to consider multiple geological scenarios and to test unorthodox ideas with the drill bit.

The Ngatoro Field in Taranaki, New Zealand has been producing for (9) nine years. Currently the field is producing 1000 bopd from 7 wells at 3 surface locations down from a peak of over 1500 bopd. The field has been analysed using new techniques in 3D seismic imaging to locate by-passed oil, and identify undrained pools. Three questions define the objectives of the study:Can we image reservoir pools in a complex stratigraphic and structural environment where conventional grid-based interpretation is not applicable due to lack of lateral continuity in reservoir properties?Can we distinguish fluids within each reservoir pools?Can extrapolate reservoir parameters observed at drilled locations to the entire field using 3D seismic data to build a 3D reservoir model? This case study illustrates how 3D generalised inversion of seismic facies for reservoir parameters can be successfully applied to image and laterally predict reservoir parameters in laterally discontinuous turbidite depositional environment where hydrocarbon pools are located in complex combined stratigraphic-structural traps. Such conditions mean that structural mapping is inadequate to define traps and to estimate reserves in place. Conventional seismic amplitude analysis has been used to aid definition but is not sufficient to guarantee presence of economic hydrocarbons in potential reservoir pools. Using new 3D seismic attributes such as bright spot indicators, attenuation and edge enhancing volumes coupled with 6 AVO (Amplitude Versus Offset) volumes integrated into a single class cube of reservoir properties, made the mapping of reservoir pools possible over the entire data set. In addition, 4 fluid types, as observed in more than 20 reservoir pools were validated by final inverted results to allow lateral prediction of fluid contents in un-drilled reservoir targets. Well production data and 3D seismic inverted volume were later integrated to build a 3D reservoir model to support updated volumetrics reserves computation and to define additional targets for exploration drilling. Introduction The Ngatoro oil field is located approximately 20 km southeast of New Plymouth within PML 38148 (Figure 1). The licence is operated by New Zealand Oil and Gas Limited (operator) on behalf of its co-venturers, Fletcher Challenge Energy Taranaki Limited and Ngatoro Energy Limited. The history of the Ngatoro oil field demonstrates the complexity that can be expected in Mt Messenger Formation oil reservoirs. Such complexity creates both risk and opportunity for oil explorers. The risk is predominantly associated with reservoir continuity and quality, while the intersected reservoirs have provided opportunities for significant oil and gas recovery through long-term low-cost production, efficient artificial lift, and detailed technical reviews leading to production optimisation projects. Before this study, the Ngatoro oil field was considered largely fully developed, in that sufficient wells had been drilled to drain the known and intersected oil and gas reservoirs. This report presents how 3D AVO classification has the potential to refine the understanding of the geological depositional model, confirm existing reserves and possibly locate additional hydrocarbon pools. Additional drilling locations and a revised water injection program are two of the outputs of this study. The results presented here will be validated as one additional well is planned for the beginning of 2001. In addition and for the first time in the region, a deterministic 3D reservoir model has been built by directly using the results of the 3D seismic classification to populate the lithology and fluid classes, leading to an easier computation of the estimated additional reserves in place.

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