Biomarkers and Carbon Isotope of Monomer Hydrocarbon in Application for Oil-Source Correlation and Migration in the Moxizhuang-Yongjin Block, Junggar Basin, NW China.

Different opinions on the oil-source correlation and migration of the Moxizhuang-Yongjin block in the Junggar Basin, NW China, have seriously affected oil and gas exploration in this area. This research is based on the results of biomarker analysis and carbon isotope of monomer hydrocarbon on crude oil and source rock samples from different blocks. Two oil families (A1, A2, and B) are classified by cluster analysis on nine typical biomarker ratios. Typically, sub-family A1 oils are distributed in the Zhuang 102 well block of the Moxizhuang block, and their gammacerane index is the highest. The abundance of C24 tetracyclic terpanes is the lowest, the C27 regular steranes are dominant, and the organic matter is mainly input by lower aquatic organisms. Sub-family A2 oils are distributed in the Zheng 1-1 well block of the Moxizhuang block. The gammacerane index of oils is lower than the former, and the abundance of C24 tetracyclic terpanes is higher. In the dual input of lower aquatic organisms and terrestrial higher plants, the input of terrestrial higher plants accounted for a larger proportion. Family B oils are distributed in the Yong 2 well block of the Yongjin block, and their gammacerane index is the lowest. They have a high abundance of C24 tetracyclic terpanes, and C29 regular steranes are dominant, reflecting the characteristics of terrigenous organic matter contribution. Based on the biomarker compound composition, at least two oil charges are indicated: Sub-family A1 oils are likely sourced from the Wuerhe formation, sub-family A2 oils may be a mixture of Wuerhe formation and Badaowan formation, and family B oils are likely sourced from the Badaowan formation. The oil families with typical genetic affinities may indicate two major petroleum systems or multiple oil systems existing in the study area. In addition, the characteristics of hydrocarbon accumulation and migration are also discussed, the oil and gas in the West Sag of Well Pen 1 and Changji Sag are filled from deep to shallow in the vertical direction and migrated from south to north in the horizontal direction, at the same time, with the help of sand bodies and faults, and they migrated to the north and northeast. This work provides a scientific basis for oil and gas exploration in the hinterland of the Junggar Basin.

Carbazoles in Oils, and Their Application in Identifying Oil Filling Pathways in Eocene Syn-Rift Fault Blocks in the Dongpu Depression, Bohai Bay Basin, East China.

Carbazoles and dimethyl carbazoles (DMCs) are important nitrogen heterocyclic aromatic compounds in oils and sedimentary rock extracts. Based on both migration fractionation effects and differences in the thermal stability of their isomers, carbazoles can be used to trace oil migration orientations and filling pathways. Molecular biomarker compositions indicate that all oils and oil-bearing sand extracts in the Eocene fault-blocked reservoirs of the Huzhuangji area (Western Slope Belt) of the Dongpu Depression (Bohai Bay Basin, East China) belong to a single oil population. In this study, four geochemical indicators relating to carbazoles, namely (a) 1,8-/2,7-dimethyl carbazoles (1,8-/2,7-DMC); (b) 1,8-/2,5-dimethyl carbazoles (1,8-/2,5-DMC); (c) 1,8-/N-exposed dimethyl carbazoles (1,8-/N-exposed DMC); and (d) G1 N-shielded %, were applied to trace oil migration orientations and filling pathways. The results show that these parameter values gradually increase toward the Hu-5 fault block at the structural high. The measured values from the subsurface are consistent with the results calculated from the molecular adsorption modeling. Therefore, it is concluded that the relative parameters of dimethyl carbazoles are practical molecular indicators for tracing oil migration orientations and filling pathways in syn-rift fault-blocked reservoirs.

Impacts of root pruning intensity and direction on the phytoremediation of moderately Cd-polluted soil by Celosia argentea.

Root pruning can impact the physiological functions of various plants, which influence phytoremediation. A series of root pruning treatments with different combinations of direction (two-side pruning and four-side pruning) and intensity (10, 25, and 33% pruning) were performed on Celosia argentea L. All two-side pruning treatments, regardless of intensity, decreased the dry biomass of the C. argentea roots at the end of the experiment relative to that of the control. However, the two-side-10% and two-side-25% pruning treatments stimulated the growth rate of the plant leaves significantly by 58.6 and 41.4%, respectively, relative to that of the control, and even offset the weight loss of the plant roots. Contrastingly, the two-side-33% pruning treatment reduced the biomass yield of leaves by 24.1%. For the four-side pruning treatments, the low intensity increased the dry weight of both the plant roots and leaves, while both decreased under high-intensity root pruning. The dry weight, Cd content, pigment level, and photosynthetic efficiency in the four-side-10% treatment were higher than those in the other treatments during the experiment. This study indicates that root pruning with a suitable combination of direction and intensity can positively influence the Cd removal ability of C. argentea.

Our study suggests that a suitable root pruning pattern can significantly increase the phytoremediation effect of Celosia argentea L. Compared with chemical and biological regulation including plant hormone application, chemical reagent spraying, and endophytes inoculation which might introduce unpredictable risks into the ecological system, root pruning can be considered as an environmentally friendly physical trigger to modulate physiological features and to induce advantages in plants. This finding can be extrapolated into the real-world easily since root pruning is an established, convenient, and feasible method. We believe readers would be interested in this method.

Effects of magnetically treated Sedum alfredii seeds on the dissolved organic matter characteristics of Cd-contaminated soil during phytoextraction.

The effects of magnetic field treatments on the two determining factors of phytoremediation, growth status and element uptake capacity, of Sedum alfredii Hance. have been thoroughly studied; however, minimal studies have been performed to determine the influence of the Cd hyperaccumulator S. alfredii, grown from magnetically treated seeds, on the dissolved organic matter (DOM) characteristics in its rhizosphere. A series of pot experiments were conducted to evaluate the variations in the DOM concentration and fractionations in the rhizosphere of S. alfredii treated with external magnetic fields. Compared with the untreated seeds, S. alfredii grown from magnetically treated seeds excreted more DOM in its rhizosphere. Additionally, the hydrophilic DOM fractionation proportion, which presented a greater capacity to mobilize Cd in the soil, increased from 42.7 % in the control sample to 47.2 % in the 150 mT magnetically treated S. alfredii sample. The water-soluble and exchangeable forms of Cd in the rhizosphere of the magnetically treated S. alfredii were significantly lower than those of the control sample. Furthermore, the Cd extraction capacity of DOM from the rhizosphere of the magnetically treated S. alfredii was greater than that of the control sample, thereby increasing the Cd uptake ability of the magnetically treated species. This study proves that a suitable magnetic field treatment can enhance the phytoremediation effect of S. alfredii, and reveals the mechanism of the phenomenon from the perspective of changes in soil DOM.

Methyltrimethyltridecylchromans in Mature Oils from Saline Lacustrine Settings in the Dongpu Depression, Bohai Bay Basin, East China.

The measured composition and distribution of methyltrimethyltridecylchroman (MTTC) compounds in the crude oils from Wenliu (salt-rich zone) and Machang (salt-free zone) areas of the Dongpu Depression were correlated with redox conditions and paleosalinity. The oil samples derived from the mesosaline environment were found with all alkylated MTTC series present. In addition, the dimethyl MTTCs developed more favorably in the oils derived from a relatively reducing and hypersaline environment (Wenliu) compared to those from the fresh lacustrine settings (Machang), while the trimethyl MTTCs developed more favorably in the fresh water environment (Machang). Determination of the oil maturity in the "oil window" by a series of aromatic maturity indicators suggests that MTTC compounds are not only present in immature or low-mature oils but also distributed in mature oils. Therefore, the "low-mature" oil found with abundant MTTC compounds, especially derived from the saline lacustrine settings, should be assessed with caution.

Distribution and Geochemical Significance of Rearranged Hopanes in Jurassic Source Rocks and Related Oils in the Center of the Sichuan Basin, China.

Gas chromatography-mass spectrometry (GC-MS) analysis has revealed extremely high abundances of rearranged hopanes in Jurassic source rocks and related crude oils in the center of the Sichuan Basin. The detected rearranged hopanes include 17α(H)-diahopanes (C27D and C29-35D), early-eluting rearranged hopanes (C27E and C29-33E), and 18α(H)-neohopanes (C29Ts and Ts). Both the 17α(H)-diahopanes and the early-eluting rearranged hopanes exhibit a distribution pattern similar to that of the 17α(H)-hopane series, with a predominance of the C30 member and the presence of 22S and 22R epimers of hopanes in the extended series (>C30). The results of this study show that the relatively high abundance of rearranged hopanes in Jurassic source rocks in the study area is associated with their depositional environments and with clay-mediated acidic catalysis rather than, as was previously thought, thermal maturity. Shallow lacustrine facies with brackish water and a suboxic to weak reducing sedimentary environment have contributed to the enrichment of rearranged hopanes, and clay-mediated acidic catalysis may also have had a positive influence on their abundance. The distribution patterns of the diahopane series indicate that the oils from Jurassic reservoirs in the Gongshanmiao Oilfield are sourced from Jurassic source rocks. Rearranged hopanes are therefore considered to be effective biomarkers for oil-source correlation in the center of the Sichuan Basin.