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The Nanpu sag is a typical petroliferous area in the Bohai Bay Basin. Crude oil density and viscosity, natural gas components and biomarker chemistry of crude oil, and shale sample extracts were analyzed to determine the characteristics and the origin of oil and gas and the effects of source rock on oil and gas distribution. The discovered heavy oil present in the shallow layers of the Liuzan, Gaoshangpu, and Laoyemiao regions are a product of biodegradation and oxidation. The crude oil samples from the offshore locations are low density and viscosity, indicating good preservation conditions. Biomarker compositions indicate that the crude oils can be divided into four types: A, B, C, and D. Both type A and D oils were sourced from the third member of the Shahejie Formation. Type A oil is primarily distributed in the Liuzan and Gaoshangpu regions, whereas type D oil is chiefly distributed in the nos. 1, 2, 5, and Beipu structural belts (SBs). Type B oil, derived from the third member of the Dongying Formation, is primarily distributed in the Laoyemiao, Gaonan, and Liunan SBs. The type C oil is primarily derived from the first member of the Shahejie Formation and is distributed in the Beipu and nos. 1–4 SBs. The hydrocarbons are primarily distributed in the regions where the thick source rocks interact with faults. The discovered natural gas in the Nanpu sag is primarily observed as dissolved gas in oil and free gas.

This paper focuses on active compliance control of hydraulic quadruped robot, especially the analysis of the inner-loop of the coupled system. Current researches on active compliance control regard the bandwidth of the inner loop of the system as infinite, while ignoring that the extra-load will cause the inner-loop response characteristics to deteriorate when the leg is in the stance phase. In this work, we first briefly introduced the structure of the robot, and its kinematics and dynamics are analyzed. Next, the robot’s active compliance control framework is established, and the inner-loop two-cylinder coupling system is analyzed in depth. It can be concluded that the existence of low frequency poles in the system is the main reason for the poor response characteristics. Then through the analysis of the state equation and transfer function matrix of the multi-input multi-output system, we show that the equivalent hydraulic spring stiffness (EHSS) is the main factor affecting the zero-pole distribution. Furthermore, we optimize the structure to increase the EHSS to improve the response characteristics of the system. Finally, the co-simulation platform and single-leg experiment bench are introduced. The simulation and experimental results show that the response speed of the inner-loop control is significantly improved after optimization, and the robot with active compliance control strategies can significantly reduce the impact of the foot.

Described here is the chromium-catalyzed cleavage of C(aryl)-SMe bonds leading to coupling with organomagnesium to give functionalized benzaldehydes under mild conditions. This reaction was promoted specifically by a low-cost and simple CrCl

We report here the first example of cross-coupling between two different and unactivated C(aryl)–O bonds with chromium catalysis. The combination of low-cost Cr(II) salt, 4,4-di-tert-butyl-2,2-dipy...

This research reveals the depositional environment can affect the organic matter enrichment. The major elements and trace elements are important indexes to reconstruct the depositional environment of Ordovician subsalt marine formations in the central-east Ordos Basin, combining organic parameters with inorganic parameters. Based on the microfacies, the study area is divided into gypsum-bearing dolomite flat, dolomite flat, gypsum-salt depression and limy dolomite flat. The higher Ti/Al ratios and the characteristics of trace elements show that there were detrital inputs in the sedimentation process. When the amounts of detrital inputs are large enough, they can obviously adsorb the elements and dilute the organic matter. Therefore, gypsum-bearing dolomite flat and dolomite flat have lower organic matter accumulation with higher detrital input. Lower P/Ti and Baexcess indicate the deficiency of paleoproductivity. Sr/Ba is higher than 0.6, indicating marine-continental transitional and marine environment. Even the paleosalinity is higher, previous researches have demonstrated the descending sea levels and strong hydrodynamic conditions are unfavorable for organic matter preservation. Lower paleoclimate index “C” and higher Sr/Cu illustrate arid and hot conditions. The value of V/(V + Ni) suggests that the limy dolomite flat is under the oxidizing conditions, and the three other environments are reductive to a certain extent. The Mo-U covariation shows that the water body is under strongly restricted conditions. These conditions are not conducive to biological growth and the accumulation of organic matter, causing low ancient productivity. The partial correlation analysis shows: the organic matter enrichment is affected by multiple factors; paleoproductivity, paleosalinity and paleoclimate have greater influence on the results of organic matter enrichment, and detrital input and oxidation conditions can decrease the paleoproductivity, indicating multiple factors are interrelated and interact with each other.

The two-stage cultivation strategy was optimized in this study to simultaneously promote the growth and lipid accumulation of Tetradesmus obliquus. Results showed that the optimal dual-stress conditions were nitrogen concentration at 25 mg N·L

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 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

Tables S1-S3

The Beidagang buried-hill structural belt (BBHSB), located in the central part of the Qikou Sag, Bohai Bay Basin, hosts a multi-source and structurally complex petroleum system, in which the interpretation of oil-source relationships and the definition of hydrocarbon accumulation features are challenging due to the highly variable composition of oils and complex oil migration pathways. In this study, we use biomarkers, fluid inclusions, and geologic data to address the complexities of petroleum system analysis in BBHSB. Based on hierarchical cluster analysis, four genetic groups of oils (A, B, C and D) with distinct molecular compositions were identified. Group A, B, and C oils are originated from the source rocks in the third member (Es3) of the Eocene Shahejie Formation (Es), the lower (Es1x) section of the first member (Es1) of Es, and the middle (Es1z) section of Es1, respectively. Group D oils are mixed oils contributed by the source rocks of Es1x and the second member (Es2) of Es. Bounded by geological settings, the charging histories of the four groups of oils were different. Fluid inclusion analysis suggests that Group A oils have two charging stages, i.e., the late Oligocene and the Pliocene-present. During the first stage, Group A oils mainly accumulated in Es3 with relatively low maturity. During the second stage, the Group A oils vertically migrated along the fault in a large scale, resulting in its accumulation in the middle-shallow formations near the fault. Due to the late maturity of source rocks, Group B, C, and D oils have one accumulation stage that occurred during the Pliocene-present. Due to the blocking effect of the reverse drag anticline on the migration of oils to the fault, the accumulation of Group B and C oils were limited to inner source-layers and the distribution of Group D oils in the northeastern BBHSB was limited in Es1x.

The Tu-Ha Basin is a typical Jurassic coal-derived petroliferous basin in western China. Seventeen natural gas samples were collected from the Jurassic Sanjianfang and Qiketai Formations, the Cretaceous Tugulu Formation, and the Paleogene Shanshan Formation to analyze the source and secondary alteration of natural gas. The natural gas samples were characterized by molecular and stable carbon (δ 13 C) and hydrogen (δD) isotope compositions. The results indicate that the natural gases are wet gases, in which methane is the main alkane component. Nitrogen (N 2 ) and carbon dioxide (CO 2 ) are the two non-hydrocarbons. The N 2 values (>12%) are relatively higher, which increase rapidly at the burial depth of 1500–2000 m. Some natural gases have suffered secondary alteration at this depth. The natural gases are thermal genetic coal-derived gases (humic gas), coming from the Jurassic coal measure source rocks, which are chiefly in the low mature to early mature stage. Nitrogen in the shallow is chiefly derived from the atmosphere, while nitrogen at the deeper burial depth is mainly derived from the thermal decomposition of organic matter (OM). The shallow natural gas samples have the heaviest carbon isotope composition of ethane (δ 13 C 2 ) and a carbon isotope sequence of (δ 13 C 1 13 C 2 > δ 13 C 3 > δ 13 n -C 4 13 i -C 4 ), which is mainly caused by the biodegradation. The higher nitrogen content illustrates that a large amount of surface water is running into the reservoirs. Water washing occurs in the reservoirs, which decreases the molecular methane content and increases the amount of heavier hydrocarbons at 1500–2000 m depth.

Measurements of TOC, Rock-Eval pyrolysis, carbon isotope composition, solvent extract, extract fractionation, and the gas chromatography-mass spectrum (GC-MS) of the saturated fraction were conducted on the Lower Permian Fengcheng Formation carbonate-bearing shales and argillaceous dolomites of Well FN7 in the northwestern Junggar Basin to understand the geochemistry and depositional environmental evolution of the carbonate-bearing lacustrine source rocks. The results indicate that the Fengcheng Formation carbonate-bearing shales are fair to good source rocks with Type II kerogen for generating oil and minor gas, and the argillaceous dolomites are poor source rocks. The thermal mature shales contain more residually generated hydrocarbon, whereas the argillaceous dolomites contain more migrated hydrocarbon. This property is favorable for shale oil or tight oil accumulation in the Fengcheng Formation. Biomarker analyses indicate that the Fengcheng Formation source rocks were formed in the anoxic reducing lacustrine depositional environment with a stratified water column and high salinity. The source rock organic matter has major aquatic phytoplankton and algae input and less terrestrial organic matter input. During the Fengcheng Formation period, oxidation had a weak increasing tendency and salinity had a weak decreasing tendency from the early to late periods under the background of a reducing environment. Except for poor source rocks in upper and lower parts, the good source rocks are primarily in the middle part of the Fengcheng Formation.

The shale from the Cretaceous Taizhou Formation is an important source rock in the Gaoyou Sag, Northern Jiangsu Basin. Fifty-three shale core samples analyzed for total organic carbon (TOC) and Rock-Eval pyrolysis analyses were used to evaluate the geochemistry of this shale. Twenty-one samples of them were analyzed using solvent extraction, extract fractionation, Gas Chromatography-Mass Spectrometer (GC-MS) of the saturated fraction, and organic petrology analyses. Based on the test results, the shale of the Taizhou Formation contains mainly Type II-III organic matter and is chiefly oil-prone and oil-gas-prone, as a fair to good oil-source rock with a small quantity of gas-source rock. Vitrinite reflectance, Rock-Eval pyrolysis, and biomarker suggest that in this sag, the shale of the Taizhou Formation is mainly in the early mature stage and within the oil window, so the shale generates chiefly liquid oil. The Gaoyou Sag is an oil-generating sag. The saturated fraction and biomarker composition of the shale provide evidence that the Taizhou Formation shale was formed mainly in a reductive sedimentary environment with anoxic fresh to low salinity water. The organic matter came chiefly from plankton and partly from land plants and bacterial organisms.

Solid bitumen was identified in the pore spaces of the Triassic Baikouquan Formation glutenite reservoir in the Mahu Sag of the Junggar Basin, northwestern China. Optical microscopy, scanning electron microscopy, and organic geochemical techniques were used to characterize solid bitumen and determine its source and origin. Rock core observations as well as optical microscopy, scanning electron microscopy, and energy spectrum analyses show that the reservoir pores are filled with isotropic solid bitumen. Biomarker geochemistry indicates that the solid bitumen is early mature to mature and formed in a reductive lacustrine environment with saline water. Oil–source correlation suggests that the solid bitumen was sourced from the low-early mature Fengcheng Formation shale. Bulk composition, alkane composition, and terpane analyses indicate that the solid bitumen did not experience oxidation or biodegradation. Geothermal evolution of the Baikouquan Formation confirms that thermal alteration is not effective for...

The shales in the Baijiantan Formation are considered to be an important potential source rock in the Junggar Basin. To evaluate this basin’s source-rock characteristics, 61 core samples from 14 boreholes were analyzed using total organic carbon and total sulfur analyses and Rock-Eval pyrolysis. Thirty-two core samples were analyzed using solvent extraction, column fractionation, biomarker analysis and the organic petrology of kerogen. The results suggest that the shales in the Baijiantan Formation have fair to excellent hydrocarbon generation potential, and the organic matter types include both Type II and Type III. The shales in the Baijiantan Formation are mainly oil-generating rocks, and better source rocks are mainly distributed in the middle–lower section of the Baijiantan Formation. The total organic carbon and total sulfur analyses, Rock-Eval pyrolysis, and biomarkers indicate that the shales in the Baijiantan Formation formed in a low-salinity to freshwater lacustrine sedimentary environment under reducing conditions. Biomarkers indicate that the organic matter input of the shales exhibits varying contributions from plankton, algae and terrestrial organisms. The biomarker molecular composition of the source rock is related to the organic matter source, salinity, redox conditions and maturation.

In recent years, researchers at home and abroad have accumulated a lot of experience in the research of data visualization technology, and they have played animportant role in scientific discovery, medical diagnosis, business decision-making, and engineering applications. As a library developed using Python language, Matplotlib has a concise language, high drawing accuracy, and simple and easy-to-understand code. This article first introduces data visualization and related technologies used and then uses Python’s Matplotlib library and pyecharts library to realize data visualization. Through representative examples, combined with the use of correct charts, visual processing of data in different fields, so as to further analyze the effect of visualization.

The Lower Cretaceous Xiagou Formation in Qingxi Sag consists of more than 1000 m of lacustrine sediments, including dolomitic mudstone/argillaceous dolomite and sandstone/mudstone, which is considered to be the most important source rock in the Jiuquan Basin. Power spectra, evolutionary fast Fourier transform (FFT), and correlation coefficient analyses of the gamma-ray (GR) series from four wells, including Liu 8 well, Long 14 well, Q2-36 well and Liu 9 well, through the Xiagou Formation reveal strong astronomical signals of long eccentricity (405 kyr), short eccentricity (100 kyr), obliquity (37 kyr) and precession (22 kyr). These provide an excellent opportunity to establish a floating astronomical time scales (ATS) then to determine variations in the sediment accumulation rate (SAR). Based on the floating ATS of the Xiagou Formation, the Xiagou Formation covers a 10.3 myr period depositional duration, and depositional duration of three members in the Xiagou Formation are 3.5 ± 0.1 myr, 3.1 ± 0.1 myr and 3.65 ± 0.15 myr, respectively. The high-resolution SARs of the Xiagou Formation vary from 8.5 cm/kyr to 19.8 cm/kyr. The different lithologies in the Xiagou Formation exhibit the same variation tendency in SARs, but the mechanisms of astronomical forcing that affect the SARs are different. In addition, the correlation between total organic carbon (TOC) and SARs can be used to investigate the impact of the SAR on organic matter abundance and conclude that relatively high SAR can protect organic matter and prevent oxidation, but rapid SAR can also dilute organic matter abundance of source rock.

In order to study the organic matter source in stylolite and its effect on hydrocarbon migration, carbonate rock core samples containing stylolites in the eastern Sichuan Basin were collected. The stylolite and matrix in the cores were analyzed by total organic carbon (TOC), Rock-Eval pyrolysis and gas chromatography-mass spectrometer (GC–MS) for the saturated fractions. The organic matter is more enriched in the stylolite than the matrix, and the stylolite have higher hydrocarbon expulsion efficiency than the matrix, which can be used as a supplement to the later generation of the source rock. The hydrocarbons formed by the matrix aggregated near the stylolites and cause the Hydrocarbon Index of the matrix which adjacent to the stylolites to become higher, this indicates that the stylolite is an important channel for hydrocarbon discharge of carbonate rocks. The ratios of close molecular biomarker in stylolite indicate that the deposition environment, biological origin and maturity of organic matter in the stylolites are consistent with the matrix, therefore, the organic matter in the stylolite should be inherited from the matrix, but the light to heavy molecular biomarker ratios of the stylolite indicate that component fractionation occurred when the hydrocarbons generated in the matrix migrated to the stylolite. Especially, a series of light to heavy molecule ratios of C19 to C23 tricyclic terpanes and C14 to C19 normal alkane of stylolite are lower than that of matrix, this indicates that the hydrocarbon fractionation in the course of hydrocarbon migration along the stylolite is more obvious than that in the matrix.