Abstract Small-angle neutron scattering (SANS) measurements were performed on 32 rock samples from the southern Georgina Basin, central Australia to assess nanopore anisotropy. Anisotropy can only be determined from oriented core material, hence the samples were cut perpendicular to bedding in cores selected from three wells that intersect the base of the hydrocarbon-bearing, organic-rich middle Cambrian Arthur Creek Formation; the latter is the source rock for both unconventional and conventional plays in the basin. The evolution of anisotropy of two-dimensional SANS intensity profiles with depth (for pore diameters ranging from 10 nm to 100 nm) was quantified and correlated with SANS intensity and total organic carbon (TOC) content. Our results confirm hydrocarbon generation at the base of the Arthur Creek Formation in the wells analysed. The nanopore anisotropy in the basal Arthur Creek Formation at the well locations CKAD0001 (oil generation window) and MacIntyre 1 (late oil generation window) varies roughly according to normal compaction. When the Arthur Creek Formation is in the gas window, as sampled at Baldwin 1, there is a strong (negative) correlation between the average vertical-to-horizontal pore shape anisotropy and SANS intensity. The results indicate that unconventional gas production from organic-rich regions of overmature shale may be adversely affected by abnormal pore compaction.

中文翻译：

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非常规烃源岩的孔隙各向异性：澳大利亚乔治娜盆地亚瑟溪组的小角度中子散射 (SANS) 研究

摘要 对来自澳大利亚中部乔治娜盆地南部的 32 个岩石样本进行了小角度中子散射 (SANS) 测量，以评估纳米孔各向异性。各向异性只能从定向的岩心材料中确定，因此在与含烃、富含有机物的中寒武统 Arthur Creek 地层底部相交的三口井中选择的岩心中垂直于层理切割样品；后者是盆地中非常规和常规油气藏的烃源岩。二维 SANS 强度分布随深度（孔径从 10 nm 到 100 nm）的各向异性演变被量化并与 SANS 强度和总有机碳 (TOC) 含量相关联。我们的结果证实了所分析的井中 Arthur Creek 组底部的碳氢化合物生成。CKAD0001（生油窗口）和MacIntyre 1（生油窗口）井位的亚瑟溪组基底纳米孔各向异性根据正常压实而变化。当 Arthur Creek 地层处于气体窗口时，如在鲍德温 1 号采样的那样，平均垂直到水平孔隙形状各向异性与 SANS 强度之间存在强（负）相关性。结果表明，过成熟页岩富含有机质区域的非常规天然气产量可能会受到异常孔隙压实的不利影响。平均垂直到水平孔隙形状各向异性与 SANS 强度之间存在强（负）相关性。结果表明，过成熟页岩富含有机质区域的非常规天然气产量可能会受到异常孔隙压实的不利影响。平均垂直到水平孔隙形状各向异性与 SANS 强度之间存在强（负）相关性。结果表明，过成熟页岩富含有机质区域的非常规天然气产量可能会受到异常孔隙压实的不利影响。