b'ASEG newsCommitteesprovinces on the continental shelf ofdensity logs prove effective in identifyingResultsAustralia with numerous discoveriesunaltered igneous sections, while and significant production such as thegamma ray (GR) logs, commonly usedThis study examined drilling results giant Ichthys gas-condensate field,for estimating clay content, also serve asof 137 wells that were drilled in the the extensive occurrences of igneousindicators to distinguish felsic rocks richBrowse Basin and revealed that over rocks within Mesozoic strata presentin potassium feldspars from mafic rocks53% of them encountered igneous ongoing challenges for explorationpoor in alkaline components. The finalrocks in the Mesozoic interval, primarily and development (e.g. Zahedi andlithofacies logs are interpreted basedwithin Jurassic-aged strata. Results from MacDonald 2018). Their impact onon integration of wireline responses,Buffon-1/ST1, Kontiki-1, and Grace-1 petroleum exploration is demonstratedcuttings lithology, and availablewells illustrate that the fault-bounded by the number of wells whichthinsections. structure in the north-western part encountered unpredicted or thicker than expected igneous rock units both within and adjacent to target sections. This study therefore aims to document the reasons why igneous rocks are unexpectedly encountered so frequently, and to develop capability for more accurately predicting the occurrence of igneous rock units prior to drilling in the Browse Basin. Studies on uncommercial exploration wells were conducted by integrating petrophysical and seismic reflection data, focussing in particular along the outboard part of the basin where igneous rocks are most prevalent. Our study highlights the importance of understanding both petrophysical properties, and the spatial and chemical heterogeneities of igneous rocks in basins to explain their emplacement and distribution, and thereby predict their occurrence prior to exploration and development activities.Data and methodologyThis study uses publicly available well data from the National Offshore Petroleum Information Management System (NOPIMS) which includes wireline, borehole image, core and cuttings, along with completion reports and analytical studies such as X-ray diffraction analysis and quantitative evaluation of minerals by scanning electron microscopy. Publicly available 2D and 3D seismic reflection data are also compiled and examined to understand the basin framework and to investigate seismically resolvable igneous rock units. Cutting descriptions of mudlogs from 137 wells were reviewed to screen out the wells which encountered igneous rocks. We selected five exploration wells that penetrated thick igneous sequences (500 m) as key wells which are located along the outboard basin; Buffon-1/ST1, Maginnis-1A/ST2, Warrabkook-1, Kontiki-1 and Grace-1. Wireline logs were used to classify igneous rock faciesFigure 1. Well summary of Warrabkook-1. A-1) Seismic section through Warrabkook-1 (Browse 1998 based on combinations of log values and2DSpec line 26). A-2) Distribution of igneous rocks interpreted from seismic facies. B) Wireline logs and motifs. For instance, acoustic velocity andfaciesinterpretation of the Jurassic igneous rock interval.10 PREVIEWFEBRUARY 2024'