Oil–source correlation for the paleo-reservoir in the Majiang area and remnant reservoir in the Kaili area, South China

The origin of solid bitumen in the Honghuayuan Formation (O1h) of the Majiang paleo-reservoir—Evidence from catalytic hydropyrolysates

“…In some of the previous literature (Wu, 1989;Tian et al, 2006;Hu et al, 2007;Zhang et al, 2007;Tenger et al, 2008;Fang et al, 2011), the O 1 h solid bitumens in the Majiang paleo-reservoir were deemed to be mainly generated from the Lower Cambrian marine mudstones. Other researchers pointed out that the O 1 h solid bitumens in the Majiang paleo-reservoir may be generated from both Lower Cambrian marine mudstones and Lower Silurian shales in the Xuefeng thrust nappe (Qiu et al, 1994), which is located to the east of the Majiang paleo-reservoir.…”

“…Only solid bitumens are left in the Majiang paleo-reservoir because the reservoir had been breached by continuous tectonic orogenies since the Caledonian. The solid bitumens of the Majiang paleo-reservoir are stored mainly in the pores and structural fissures of carbonates in the Lower Ordovician Honghuayuan Formation (O 1 h) (Wu, 1989;Fang et al, 2011). Some of the solid bitumens in the Honghuayuan Formation are of high maturity (%Ro > 2%) owing to severe thermal maturation resulting from deep burial.…”

“…Some of the solid bitumens in the Honghuayuan Formation are of high maturity (%Ro > 2%) owing to severe thermal maturation resulting from deep burial. Additionally, Xue et al (2007) and Fang et al (2011) pointed out that some O 1 h paleo-reservoirs in the Majiang area had experienced severe evaporation, oxidation and biodegradation when the reservoirs were uplifted and the caprock was eroded. Previous studies (Ma et al, 2004;Chen et al, 2006;Tian et al, 2006;Ding et al, 2007;Tenger et al, 2008) have provided much information on the geological structure and oil-source correlation in the study area.…”

“…of Type IIa kerogen The Lower Permian Qixia Formation (P 1 q) contains rocks with lower concentrations (TOC 2% max) of Type II kerogen at moderate maturity. Many Permian oil seepages and solid bitumens in the study area have been correlated to P 1 q source rock (Zhang et al, 2007;Fang et al, 2011).…”

“…The amounts of extractable organic matter (EOM) from both solid bitumens and source rocks in the study area were too low for instrumental analysis. Meanwhile, biodegradation and subsequent thermal alteration may influence the characteristics of routine biomarkers in crude oils such as steranes and terpanes (Fang et al, 2011). Unfortunately, most previous research failed to eliminate the influence of such secondary alterations when making bitumen-bitumen correlation studies based on biomarkers in EOM (Ma et al, 2004;Chen et al, 2006;Tian et al, 2006;Ding et al, 2007;Zhang et al, 2007).…”