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Taking the Member 1 oil reservoir of Dongying Formation in Nanpu Sag as an example, this article puts forward an integrated study method for oil reservoir description and evaluation. First, with the correlation of seismic, log, and geological data, the isochronous stratigraphic framework of the oil reservoir is built up, sequence boundaries are interpreted, the sequence constrained prestack seismic inversion is processed, and a geological conceptual model of reservoir is established. Second, with the results of prestack seismic inversion and the Petrel software, the structure model of the isochronous stratigraphic framework and the quantitative geological database are built up. Third, through contrasting and selecting the most reasonable method of stochastic modeling, the reservoir facies modeling and the petrophysical modeling with the constraint of facies models are processed, the oil geological reserves are computed and evaluated, and some oil reservoirs are described finely. The study shows that the Member 1 oil reservoir is a layered, structure-controlled, edge water drive reservoir. It has thick sands, good properties, and complicated oil–water systems. The geological reserves estimated by the nine designed implementation models are the realization of Monte Carlo methods and conform to a certain probability distribution. The models are favorable for the reasonable evaluation of reserves. Key words: Nanpu No. 1 structure, Dongying Member 1 oil reservoir, integrated oil-reservoir description and evaluation, stochastic modeling under determinable constraints

The Bohai Bay Basin, located on the eastern Asian margin, is the second largest oil-production basin in China. It contains numerous depressions and sags, among which Nanpu Sag has become particularly important because of significant oil discoveries in recent years. Geologically and tectonically, however, the rifting mechanism and geodynamic evolution of the basin remain uncertain. This paper uses detailed volcanic and stratigraphic records obtained through extensive drilling and sampling in Nanpu Sag to interpret tectono-stratigraphic sequences and discuss basin dynamic evolution and crust-mantle interactions of the Bohai Bay Basin. Nanpu Sag contains voluminous volcanic rocks of dominantly alkaline basalts. Drill core samples, well logs, and seismic profiles reveal three volcanic cycles between the Eocene and Miocene Epochs. These basalts were created during a transition from garnet- to spinel-peridotite. Five tectono-stratigraphic sequences produced by episodic continental rifting have been identified, each composed of a basal coarse clastic sequence, a lower volcanic sequence, a middle deep-water clastic sequence, and an upper infilling sequence. Tectonically, Nanpu Sag experienced four evolutionary phases. The first three corresponded to three rifting events revealed by cyclic volcanism and sedimentary depositional features. The fourth phase was marked by extreme thermal subsidence and prograding fluvial deposition fallowed by tectonic inversion. A diapiric upper-mantle upwelling model is proposed to explain the dynamics that controlled the multiple rifting processes, the cyclic volcanism, and the periodic tectonic evolution of Nanpu Sag and the greater Bohai Bay Basin. doi: 10.1130/B30041.1

Paleogene sediments, especially the third member of the Dongying Formation (Ed3) and the first and third members of the Shahejie Formation (Es1 and Es3), have been regarded as the most important source rocks in the Nanpu Sag. Organic and inorganic analyses, including Rock-Eval pyrolysis, gas chromatography-mass spectrometry, and element geochemistry, in 91 mudstone samples, were used to reconstruct the palaeoenvironmental conditions, such as palaeoclimate, palaeo-salinity and palaeo-redox conditions, and to recognize the origin of organic matter. The results show that Es3 has a higher TOC content than Es1 and Ed3. Hydrocarbon genetic potential (S1 + S2) of the samples indicate fair to good hydrocarbon potential. The kerogen type of Ed3 and Es1 source rocks are Type II1–II2, while Es3 source rocks are dominated by Type II2–III kerogens. Biomarkers and inorganic geochemical indicatives of source rocks, such as Pr/Ph, V/(V + Ni) and Cu/Zn, indicate a lacustrine environment with fresh to brackish water under suboxic to anoxic conditions during deposition. Ed3 source rocks are characterized by low G/C30H (gamacerane/C30hopane) (<0.1), TT/C30H (tricyclic terpane/C30hopane) and S/H (serane/hopane), high Pr/Ph (pristane/phytane) and C24TeT/C23TT (C24tetracyclic terpane/C23tricyclic terpane), indicating mixed input of both algae and terrestrial higher plants, dominated by terrestrial higher plants. Es1 source rocks display medium G/C30H, TT/C30H, S/H, Pr/Ph and C24TeT/C23TT, indicative of a mixed input of both algae and terrestrial higher plants. Es3 source rocks are characterized by high G/C30H (>0.1), TT/C30H and S/H, low Pr/Ph and C24TeT/C23TT, typical of a mixed input of algae and terrestrial higher plants, with algal dominance. Ed3, Es1 and Es3 source rocks were mostly deposited in semi-arid to humid-warm climate conditions, with an average temperature higher than 15°C. This study suggests that suitable temperatures, a fresh to brackish lacustrine environment and suboxic to anoxic conditions could result in a high organic matter concentration and preservation, thus providing prerequisites for the formation of high-quality source rocks. Supplementary material: Tables S1–S3 are available at https://doi.org/10.6084/m9.figshare.c.5227684 [ABSTRACT FROM AUTHOR]

Recently, great breakthroughs in natural gas exploration have been achieved in the Nanpu Sag, Bohai Bay Basin, eastern China; however, the genetic type and formation mechanisms of the gas are still unclear, impeding further exploration. Chemical and isotopic compositions were investigated to determine the origins for the gas. Three groupings of the natural gases are recognized: oil-type gas, coal-type gas, and mixed-source gas. The oil-type gases are relatively depleted in 13 C (δ 13 C 1 < −43‰); δ 13 C 2 < −29‰ and low wetness (0.60–0.89). The coal-type gases are enriched in 13 C (δ 13 C 1 > −40‰; δ 13 C 2 > −28‰) with higher wetness (0.80–0.95). The third grouping of gases exhibits intermediate molecular and isotopic values. Most of the gases in the shallow layers of the No. 1 and 4 structural belts have δ 13 C values similar to those of underlying gases and display evidence for microbial alteration. Primary cracking of kerogen is responsible for the generation of most of this gas. Pyrolysis of the source rocks combined with maturity estimations revealed that the relatively shallow oil-type gas was derived primarily from Oligocene and Eocene (Ed 3 –Es 1 ) source rocks bearing Type I–II 1 kerogen, whereas the coal-type gas was generated from the Eocene (Es 2+3 ) source rocks containing II 2 –III kerogen. We concluded that the kerogen type and maturity of the source rocks and the activity of source-connecting faults primarily controlled the distribution of the different gases. We suggest that there is significant deep gas potential in the Nanpu Sag, perhaps even over the whole Bohai Bay Basin, that would be prospective for further deep gas exploration in the area. [ABSTRACT FROM AUTHOR]

Highlights: [•] Input parameters and boundary conditions were customized and simulated. [•] Hydrocarbon generation and migration was modeled on wells, cross-section, and maps. [•] Fluid potential and flow line modeling reveals that structural highs are directions of hydrocarbon migration. [Copyright &y& Elsevier]

Terrestrial oils and rock extracts from the Nanpu Sag (Huanghua Depression, Bohai Bay Basin, China) were characterized by negative-ion electrospray ionization (ESI) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and gas chromatography mass spectrometry (GC-MS). Molecular composition of neutral nitrogen and acidic oxygen compounds, mainly by N 1 , O 1 , and O 2 species were investigated in the samples. Increases in relative abundance and molecular condensation degree of oxygen-containing compounds and a decrease in the carbon number range of N 1 species were observed with the changes of kerogen from Type I to III for both the source rock extracts and the relevant oils, which indicates the influence of source input and discrimination potential. We also observed an apparent increase in the condensation degree and a decrease in the carbon number of the N 1 , O 1 and N 1 O 1 species with increasing maturity. The carbon numbers and double bond equivalent (DBE) values of the N 1 and N 1 O 1 species in the extracts showed a positive relationship (an approximately linear distribution) during thermal evolution. These results indicate that thermal maturity has a crucial influence on the composition. The relative abundance ratios of N 1 and O 1 species with specific DBE values and carbon number ranges, C 16–20 /C 21–50 -DBE 12 -N 1 , C 20–24 /C 25–50 -DBE 15 -N 1 , C 11–15 /C 16–27 -DBE 4 -O 1 , DBE 12 /DBE 9 -N 1 , and DBE 8–9 /DBE 4 -O 1 are proposed as thermal maturity indicators for the evaluation of mature and post-mature source materials. A strong primary migration fractionation effect on the heteroatom compounds was also observed, implying that these compounds can be used as migration auxiliary proxies. [ABSTRACT FROM AUTHOR]

4-(1 H -Isochromen-1-yl)isoquinoline derivatives were synthesized in high yields via the AgBF 4 -catalyzed self-reaction of ortho -alkynylarylaldehydes to give isochromene intermediates, followed by the dehydration of the 1,5-dicarbonyl motif with NH 3 . Compared with electron-rich aromatic substituents, this strategy can provide the desired isochromene products with an electron-deficient isoquinoline unit. The reactions feature simple experimental operations, mild reaction conditions and high product yields., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)