Distribution and geochemical significance of dibenzofurans, phenyldibenzofurans and benzo[b]naphthofurans in source rock extracts from Niger Delta basin, Nigeria

Occurrence and geochemical significance of fluorene and alkylfluorenes in crude oils and source rock extracts from Niger Delta basin, Nigeria

“…Therefore, the Ro values obtained in the rock samples indicate immature to early mature stage. This finding is in agreement with the recent report on the source rocks from the same fields using rock-eval pyrolysis [ 40 ]. The equivalent vitrinite reflectance (0.018∗T max – 7.16) calculated for the rock samples are in the range of -0.27 to 0.81 % ( Table 1 ), supporting immature to early maturity range already inferred from the measured vitrinite reflectance (Ro %) in the source rocks [ 33 ].…”

“…The values of maceral compositions recorded in OKN rock samples indicate type II kerogen ( Table 1 ) which are consistent with the Type II kerogen source rocks and this agreed with the recent study on the same set of rock samples using rock-eval pyrolysis [ 40 ]. Figure 2 shows that the dominant component of the samples in OKN field is vitrinite (48–61%).…”

Applying biomarkers as paleoenvironmental indicators to reveal the organic matter enrichment of shale during deep energy exploration: a review

“…This means that Z1/(Z1 + C 24 TT), Y1/(Y1 + C 24 TT), and Pr/Ph are all constrained by the same depositional conditions, implying that these newly discovered tetracyclic terpanes were formed in both oxidative and reducing environments. 169,170 The Z1/(Z1 + C 24 TT), Y1/(Y1 + C 24 TT), and (C 19 + C 20 ) TT/C 23 TT ratios are related to the Pr/Ph and (C 19 + C 20 )TT/C 23 TT ratios, as shown in Fig. 11a-d.…”

“…154 The Eocene Shahejie (Es) formation, particularly the third (Es 3 ) and fourth (Es 4 ) members, is the principal source rock for both conventional and "shale oil-producing" formations in the Dongying depression, as several studies have shown. [155][156][157] The levels of -carotane in the oils vary greatly between the Es 169,170 linked to a higher contribution of marine algae. 162 The relationship between high tricyclic terpane concentrations and "tasmanite" oil shale suggests that it may have originated from Tasmanites algae.…”

“…The ratio of C 24 TeT over C 26 TT is a source parameter due to differences in likely precursors of tetracyclic and tricyclic terpanes. [168][169][170] Most marine oils formed from mudstones to carbonate source rocks contained abundant C 24 TeT. 171 C 24 -C 27 tetracyclic terpanes are oen referred to as de-E-hopanes, or 17,21-secohopanes and are suggested to be more resistant against biodegradation and maturity effects than hopanes.…”