| 摘要: | 本研究乃從應用有機地球化學的角度，探討有機材料特性及熱成熟度與油氣潛能的關係，研究方法以煤素質成分分析、元素分析、鏡煤素反射率量測、Rock-Eval 熱裂分析、與多變量統計分析等建構確實有效之生油潛能評估參數。有機材料生烴潛能與油母質的類型、沉積環境及成熟度密切相關，其可能涉及的參數與有機質豐度有關的如TOC、S1、S2 等，與品質有關的如Atomic H/C、HI、BI、QI等，及與成熟度有關的如Ro%、Tmax、PI 等。這些參數彼此間必存在著某些相關性，可以數學及統計分析的方法進行更深入探討。 結果顯示 (1)Ro自0.60%上升至1.00%，或Tmax 430oC至450 oC呈現漸增之生油潛能(HI值)；Ro超越1.0%或Tmax超越450 oC時，HI值漸減；至Ro~2.00%或Tmax~510 oC時至無生油潛能。(2)依HI與Ro關係圖可將生油潛能劃分四區，以Ro 0.75%至1.05%，Tmax 440 oC-455 oC及Ro 1.25%~1.95%，Tmax 465 oC-500 oC為生油區與生氣區；(3)HI、QI值與Ro%之線性迴歸顯示成熟度超越Ro 1.00%後，生烴潛能迅速下降。 隨著熱成熟度指標鏡煤素反射率(Ro%)值增大，HI、S1、S2、H/C值將減小。H/C原子比值在Ｒo％＝0.55?0.85 (H/C=1.1~0.7)時下降有趨緩情形。以H/C原子比值對下列各項參數HI、S1、S2、S1+S2、S1/(S1+S2)、S1/TOC、(S1+S2)/TOC、Tmax與TOC等作圖後，顯示當H/C原子比值在0.7~1.1的範圍時，各項參數值在該氫碳原子比值範圍內呈現大範圍的變化。整體而言，當H/C原子比值增加時，氫指數HI値有升高的趨勢，因此氫指數HI與H/C原子比值也呈現一定的相關性。再以(S1+S2)/TOC値作為主要指標，對不同有機材料的生油潛能進行評估發現本研究之有機材料單位有機碳生油潛量(S1+S2/TOC)値約在100~380間，與一般產氣、產油及優質生油型腐殖煤相當。此外對本研究所有樣品而言，當反射率(Ro%)值在0.55以下時，其HI值呈現不規律的大幅度變化(Ro%=0.55~0.35→HI=80~520mg/g)；而Atomic H/C值在0.7~1.1時，其HI值則呈現穩定漸增的變化(Atomic H/C=0.7~1.1→ HI = 120~520 mg/g)，由此可知，有機材料在開始進入油窗Ro%=0.55、Atomic H/C=1.1時，具有一定的成熟度與生油潛能。 This research discussed the relationship of organic material characteristics and thermal maturity versus hydrocarbon potential from the viewpoint of applied organic geochemistry. The purpose is to establish the reliable indices of synthetic assessment of organic matter in the evaluation of petroleum potential. Therefore, the scope is focused on maceral composition analysis, vitrinite reflectance measurement, Rock-Eval pyrolysis, elements analysis, and multivariate statistical analysis. In addition, it is to present new guidelines for improved assessment of the kerogen type, generative potential and thermal maturity using Rock-Eval parameters. The analytic results indicate that petroleum generation potential is completely exhausted at a vitrinite reflectance of 2.00-2.20% or a Tmax of 510-520°C. A decline in BI signifies the start of the oil expulsion window and occurs within the vitrinite reflectance range 0.75-1.05% or a Tmax of 440-455 oC. The petroleum potential can be divided into four different parts based on the cross-plot of HI vs. %Ro. The area with the highest petroleum potential is located in section B with %Ro=0.60-1.00%, and HI>100. The start of the oil expulsion window occurs within the %Ro range of ~ 0.75–1.05%Ro or the Tmax range ~ 440-455°C and the total oil window extends to %Ro = ~ 1.25-1.95 or Tmax = ~ 465-525°C. The H/C ratio, as well as the HI, S1, and S2, generally decreases with the maturity increasing. The H/C ratio decreases slightly from 1.1 to 0.7 with the maturity increasing from Ro 0.55% to 0.85%. Samples with H/C ratio in this range show significant change in certain other geochemical parameters (eg. HI, S1, S2, S1+S2, S1/(S1+S2), S1/TOC, (S1+S2)/TOC, Tmax). The (S1+S2)/TOC ratio (defined as QI) was used as an indicator of the hydrocarbon potential. The QI, HI and H/C ratio show a certain correlation, all increasing accordingly. The QI of the samples analyzed in this study is approximately 100 to 380 (mgHC/gTOC), similar to that of most humic coals for oil and gas generation. Samples with Ro value lower than 0.55% always show significant variation in their HI, ranging from 80mgHC/gTOC to 520mgHC/gTOC. It is inferred that hydrocarbon potential started from Ro 0.55% and atomic H/C ratio 1.1 in this study. |
