Abstract Pyrolysis and bulk kinetic studies were used to investigate the hydrocarbon generation potential and source rock organofacies variability of marine organic-rich rocks from the Middle Ordovician (Darriwilian) Goldwyer Formation in the Canning Basin, Western Australia. Rock-Eval pyrolysis results for the analysed immature to mid-mature calcareous mudstones imply that the upper Goldwyer Sequence I contains oil-prone type I kerogen, while the lower Goldwyer Sequence III contains type II/III oil- and gas-prone kerogen. This is supported by pyrolysis gas chromatography (Py-GC) results that show the presence of homogenous organofacies in the Goldwyer Sequence I having aliphatic molecular signatures, possibly due to selective preservation of lipids derived from Gloeocapsomorpha prisca (G. prisca). The heterogeneous organofacies of the Goldwyer Sequence III contain aromatic moieties in similar abundance to the aliphatic compounds. The calcareous claystones of the Goldwyer Sequence I have the capacity to generate low wax paraffinic oil, whereas the Goldwyer Sequence III has potential for paraffinic-naphthenic-aromatic (P-N-A) low wax oils, gas, and condensate. The temperature for hydrocarbon generation for the type I kerogen, assuming a constant geological heating rate of 3 °C/my, is estimated to occur over a narrow interval between 145 °C and 170 °C for the Goldwyer Sequence I samples. Generation from the type II/III kerogen occurs from 100 °C to 160 °C in the Goldwyer Sequence III samples which are significantly less thermally stable than the Goldwyer Sequence I samples. The kinetic results for both sequences were used in standard thermal and burial history plots to evaluate their transformation ratio and hydrocarbon generative potential. This provided basin-specific kinetic inputs for burial history modelling and better constraint on kerogen transformation and hydrocarbon generation on the Broome Platform.

中文翻译：

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西澳大利亚坎宁盆地海相奥陶系 Goldwyer 组生烃动力学

摘要 利用热解和体动力学研究，研究了西澳大利亚坎宁盆地中奥陶统 (Darriwilian) Goldwyer 组海相富含有机质岩石的生烃潜力和烃源岩有机相变异性。分析的未成熟至中成熟钙质泥岩的 Rock-Eval 热解结果表明，上部 Goldwyer 层序 I 含有易油 I 型干酪根，而下部 Goldwyer 层序 III 含有 II/III 型易油气干酪根。这得到了热解气相色谱 (Py-GC) 结果的支持，该结果表明 Goldwyer 序列 I 中存在具有脂肪族分子特征的同质有机相，这可能是由于选择性保存了来自 Gloeocapsomorpha prisca (G. prisca) 的脂质。Goldwyer 层序 III 的异质有机相含有与脂肪族化合物相似丰度的芳香族部分。Goldwyer 层序 I 的钙质粘土岩具有生成低蜡石蜡油的能力，而 Goldwyer 层序 III 具有生成石蜡-环烷-芳烃 (PNA) 低蜡油、天然气和凝析油的潜力。对于 Goldwyer 序列 I 样品，假设 3 °C/my 的恒定地质加热速率，I 型干酪根的碳氢化合物生成温度估计发生在 145 °C 和 170 °C 之间的狭窄区间内。在 Goldwyer Sequence III 样品中，II/III 型干酪根发生在 100 °C 到 160 °C 之间，其热稳定性明显低于 Goldwyer Sequence I 样品。两个序列的动力学结果都用于标准的热和埋藏历史图，以评估它们的转化率和生烃潜力。这为埋藏历史建模提供了盆地特定的动力学输入，并更好地约束了布鲁姆平台上的干酪根转化和油气生成。