HyLogging unconventional petroleum core from the Cooper Basin, South Australia

The Cooper Basin is currently Australia's premier onshore hydrocarbon-producing province and hosts a range of unconventional gas play types, including the very extensive basin-centred and tight gas accumulations in the Gidgealpa Group, both shallow and deep dry coal seam gas associated with the Patchawarra and Toolachee formations, as well as the shale gas plays in the Murteree and Roseneath shales. Characterisation of mineralogical properties of shales is critical to hydraulic fracture design and development of unconventional hydrocarbon resources. Properties are sensitive to variations in mineralogy, especially clays, and historically, acquisition of a suite of rock mechanics analyses has been on a point-source basis rather than on a continuous sampling approach, which is uncommon. In this paper, a near-continuous 382 m cored section, comprising the lower Permian Daralingie Formation, Roseneath and Murteree shales, the Epsilon Formation and the top portion of the Patchawarra Formation from Holdfast-1 well (DH261958) in the southern Cooper Basin, was measured using robotic core scanning spectroscopy with automated mineral identification. HyLogger 3 incorporates visible, near infrared, shortwave infrared and thermal infrared hyperspectral measurements recorded every 0.8 cm along the core at the rate of approximately 1 m per minute. These data are co-registered with a high-resolution image and a laser profile of the core. X-ray diffraction and thin-section petrology from the Holdfast-1 well-completion report (Beach Energy, 2011) provided relative proportions of minerals including quartz, kaolinite, dickite, muscovite, illite, chlorite and siderite that enabled the modelled vs actual mineralogies to be constrained in the thermal infrared with a correlation coefficient of 0.85 for quartz, 0.79 for muscovite and 0.68 for kaolin; illite and siderite were more poorly correlated. HyLogger logging, when integrated with other petrophysical and analytical core data, provides a useful tool to better understand unconventional reservoirs and may assist in identification of zones that are conducive to fracture stimulation.

库珀盆地（Cooper Basin）是澳大利亚目前最主要的陆上油气生产盆地，发育多种非常规油气藏类型，包括吉德加帕群（Gidgealpa Group）中分布极广的盆地中心型气藏与致密气藏，与帕奇沃拉组（Patchawarra Formation）和图拉奇组（Toolachee Formation）伴生的浅、深干性煤层气，以及穆特里页岩（Murteree Shale）与罗斯尼思页岩（Roseneath Shale）中的页岩气藏。页岩矿物学特征表征对于水力压裂设计与非常规油气资源开发至关重要。矿物组成尤其是黏土矿物的变化会显著影响储层物性；历史上，岩石力学分析多采用单点采样方式获取数据，而非连续采样手段，而连续采样在业内并不常见。本文以库珀盆地南部霍尔德法斯特-1井（Holdfast-1 Well，井号DH261958）中的一段近连续382米岩心段为研究对象，该岩心段覆盖下二叠统达林吉组（Daralingie Formation）、罗斯尼思页岩、穆特里页岩、埃普西隆组（Epsilon Formation）以及帕奇沃拉组顶部地层，采用搭载自动化矿物识别功能的岩心扫描光谱机器人开展测试分析。HyLogger 3系统可沿岩心每0.8厘米采集一次数据，采集速率约为每分钟1米，涵盖可见光、近红外、短波红外与热红外高光谱测量。上述数据会与岩心的高分辨率图像及激光轮廓数据进行配准。基于霍尔德法斯特-1井完井报告（Beach Energy，2011年）中的X射线衍射（X-ray diffraction）与薄片岩石学数据，可获得石英、高岭石、地开石、白云母、伊利石、绿泥石与菱铁矿等矿物的相对含量；以此为约束，可对热红外光谱反演的矿物组分进行校准，其中石英的相关系数达0.85，白云母为0.79，高岭土为0.68，伊利石与菱铁矿的相关性相对较弱。将HyLogger测井数据与其他岩石物理及岩心分析数据相结合，可为非常规储层的精细表征提供有效工具，同时有助于识别适合压裂改造的储层段。