非洲查德Doba盆地地化模擬與油氣潛能評估研究

本研究針對中非裂谷系統中的Doba盆地，以A-1及B-1井的原油、天然氣與岩樣進行地化油氣潛能分析，並根據二井之地層對比以及震測地層解釋來模擬Doba盆地及BI礦區的油氣生成移棲，評選最有利於油氣儲聚之可探構造，提供礦區未來經營策略之參考。生油岩評估地化分析顯示：A-1井之Kedeni層與Mangara層之黑色頁岩具有良好級至優良級之生油潛能，含產油和產氣型之有機混合物，熱成熟度介於近成熟至成熟中期，油氣潛能頗佳。油－油與油－岩對比之結果顯示：（1）查德A-1井DST#1與DST#2原油可能來自不同的生油岩層；（2）DST#2原油與Mangara層和部份Kedeni層之生物指標指紋對比良好，δ13C值也相近，推論Mangara層和Kedeni層是DST#2原油之生油岩；（3）B-1井FMT浮油之之生物指標指紋與A-1井DST#1之原油相似，推論其與A-1井DST#1之原油產自相同的生油岩層；（4）A-1井DST#1原油之雙環倍半萜烷指紋可與盆地南邊的MI油田的原油指紋對比良好，推論Doba盆地中心有一主要生油岩層，可能是Doba盆地之主要油廚，原油生成之後沿著深切盆地中心的斷層向上及向南北方向的高處移棲，分別儲聚於盆地周圍的斷層封閉構造中，A-1井鑽於邊界斷層上盤的斷層封閉上，儲油層與蓋層搭配完善，所以儲聚了相當豐沛的油氣。二維油氣生成移棲模擬結果顯示：盆地中心之下部白堊系地層仍在油窗範圍內，其成熟之生油岩生成的油氣往上移棲後被Mangara頁岩層阻隔再橫向往南北方向移棲。三維模擬之油氣飽和率顯示油氣已在A-1井之斷層封閉構造中儲聚；由油氣移棲方向模擬結果顯示：BI礦區中一系列西北-東南向雁形排列的邊界斷層之鼻狀構造均有儲聚油氣之潛能；在A-1井東南方之構造高區應可儲聚東西兩側油廚區運移而來的油氣，其油氣潛能甚高。

關鍵字

生油岩評估；油岩對比；生物指標分析；活化能分佈圖譜；油氣生成移棲模擬

並列摘要

The petroleum geochemistry and potential of the oil, gas and rock samples from two wells in Chad, Doba Basin, Central African Rift, have been evaluated. Based on the formation correlations between the two wells and seismic stratigraphy, simulated the generation and migration of oil and gas in the BI Block and the Doba Basin could be the possible structures of reservoirs have been evaluated and then provided a better policy for future exploration and development. The source rock geochemical analysis indicates that the black shales in the Kedeni and Mangara Formations have a very good potential for oil production. The maturity of the type I and type III kerogen mixtures ranges from moderately mature to mature (%Ro = 0.54~0.89) exhibits high production potential of oil and gas. The results of the oil-oil and oil-rock correlations showed that: (1) the crude oils of DST#1 and DST#2 in the A-1 well are likely from different source rock formations; (2) the biomarker fingerprints in the DST#2 oil samples are well consistent with those in the Mangara and part of the Kedeni formations, as well as the similar δ13C values, which is concluded that the DST#2 oil originated from the formations; (3) the biomarkers from the FMT oil in the B-1 well are similar to those in the DST#1 oil in the A-1 well, which indicates that the FMT and DST#1 oils originated from the same source rock formations; (4) the bicyclic sequiterpanes of the DST#1 oil correlates well with those of the crude oil from MI oil field, which is inferred that there is a main source rock formation in the central part of the basin which may be the main oil kitchen in the Doba Basin. After generation, the oil may have migrated upward and north-southward along the deep faults that cut through the central basin, then cumulated in the higher structures such as the traps sealed by faults around the basin. The A-1 well revealed the case that it was drilled down to the trap in the hanging wall of the boundary fault. The reservoir and cap were completed and matched up well with each other, therefore a plenty of oil and gas was cumulated. The results of 2D oil geochemical modeling showed that the Lower Cretaceous formations in the central basin are still within the oil window. The oil and gas generated from the mature source rock migrated upward and were blocked by the Magara Shale, and subsequently migrated horizontally to the north-south direction. The 3D geochemical modeling of the hydrocarbon saturation revealed that the oil and gas have been cumulated in the fault trap beneath the A-1 well. In addition, the results of hydrocarbon migration modeling showed that there is quite a potential for hydrocarbons in the nose area between a series of northwest-southeast echelon boundary faults in the BI region. The hydrocarbon potential is high in the southeast of the A-1 well as the oil and gas from the eastern and western oil kitchen area could be migrated and stored in the structural high.

並列關鍵字

Source Rock Evaluation ； Oil and Rock Correlation ； Biomarker Analysis ； Activation Energy Distribution ； Hydrocarbon Migration Modeling

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非洲查德Doba盆地地化模擬與油氣潛能評估研究

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