Source rock samples can be “contaminated” by expelled oils from nearby mature source rocks or from the organic-rich laminae within the same source rock units. The “contaminations” on the Rock-Eval ...samples could produce a false high S1 peak, a high Production Index (PI), a suppressed Tmax and other anomalies. Identifying the samples affected by expelled oils, assessing and correcting the impacts are crucial in source rock study for shale oil/shale gas resource evaluation. This study analyzes the Rock-Eval 6 results of 43 core samples from two recent shale oil exploration wells of the Eocene Qianjiang Formation, a confined source rock unit embedded with salt intervals formed in a hypersaline lacustrine setting in central China. The geochemical anomalies of the affected samples are shown through the available samples in this study. Criteria for identifying the affected samples are discussed, and impacts on the conventional Rock-Eval parameters and subsequent estimation of kinetic parameters presented. This study provides insights into Rock-Eval data interpretation, particularly in source rock evaluation for estimating shale oil resources.
•Source rock samples can be contaminated by oils expelled from adjacent organic-rich rocks•Exogenous hydrocarbons in confined source rocks may affect Rock-Eval data interpretation•Identifying the affected samples will help improve Rock-Eval data interpretation
Carbonate-rich fine-grained rocks in saline lakes have become potential targets for shale oil and gas exploration. However, few studies have investigated the processes of carbonate formation and ...organic matter enrichment in hypersaline environments. The Qianjiang Depression is a hypersaline rift lake basin that contains carbonate-rich fine-grained rocks in the inter-salt strata of the Qianjiang Formation. In this study, sedimentological observations and multiple geochemical analyses were conducted on the inter-salt strata in the sixth and eighteenth rhythmites of the Qianjiang 4 Member. The results showed that the middle inter-salt stratum in the sixth rhythmite is rich in dolomite, calcite, and organic matter, whereas the inter-salt stratum in the eighteenth rhythmite is rich in dolomite and sulfate minerals and low in organic matter. Comparisons among multiple redox parameters revealed that the middle inter-salt stratum in the sixth rhythmite was formed in a deep saline lake, while the inter-salt stratum in the eighteenth rhythmite was formed in a shallow saline lake. Further, sedimentary observations and analyses of δ34S and trace and rare-earth elements revealed that the inter-salt stratum in the sixth rhythmite contained a significant amount of volcanic ash, whereas that in the eighteenth rhythmite was influenced by hot brine derived from older strata. Therefore, the differing environments and material inputs notably affected the carbonate crystallization and organic matter enrichment in these strata. This study suggests that the input of volcanic materials is conducive to improving biological productivity in saline lakes, and anoxic conditions with moderate salinity are conducive to the preservation of organic matter. These findings provide theoretical guidance for future self-sourced inter-salt shale oil reservoir explorations.
•The multiple source materials participated in the formation of the inter-salt strata.•Volcanic activity affected organic matter enrichment in saline lakes.•Hydrothermal fluids affected the nucleation of inter-salt carbonate.
Because the profit from the development of unconventional resources can be small, success usually depends on the quick identification of favorable areas. It is therefore very important to identify a ...rapid and robust resource potential evaluation method. However, it is challenging to evaluate shale oil content, especially the recoverable oil part. We explore a new evaluation index (SE) by using Rock-Eval data and mass balance. When SE ˃ 0, the shale interval has already expelled a certain amount of hydrocarbons, so it has poor shale oil potential. When SE is near 0, almost all the generated hydrocarbons are trapped in the shale itself, and simultaneously, no externally migrated hydrocarbons enter the shale. In the case of an SE near 0, the shale oil potential may depend on whether it is organic-rich; however, this type of shale tends to be compact and does not develop fractures. When SE ˂ 0, externally migrated hydrocarbons entered the shale interval, which usually indicates good shale oil potential. The more negative the SE is, the greater the shale oil potential. One of the advantages of this index is that it takes into account not only the residual oil content but also the conditions of hydrocarbon expulsion and migration. Moreover, this method is economical and convenient and is based on commonly available Rock-Eval data.
•Three types of shale intervals can be divided according to the proposed new index.•The method uses only routine Rock-Eval data to evaluate shale oil potential.•The new index considers the conditions of hydrocarbon expulsion and migration.•The combination of SE and OSI improves the shale oil potential prediction accuracy.
This article presents a novel numerical decomposition method based on generation kinetics for studying oil composition characteristics from S1 peak of single heating rate pyrolysis of source rock ...samples. Furthermore, phase behavior and PVT analysis were introduced in the calculation to make a full correction for evaporative loss of gaseous and light hydrocarbon in S1 during coring and sample storage. Special programed pyrolysis results of twenty-eight core samples, along with a routine source rock screening pyrolysis dataset of 68 samples, from a recent shale oil study well of the Eocene Qianjiang Formation in Jianghan Basin, China were analyzed to demonstrate the application of proposed methods. We showed that (a) by reassembling corresponding activation energies, the original S1 curve can be split into groups of similar thermal evaporative property, resulting in a composition classification of free hydrocarbons in S1 when it was converted back to temperature domain; (b) a full correction on the gaseous and light hydrocarbon loss in S1 permits a more precise estimation of oil composition as well as total resource; (c) the resulting oil composition grouping provides information for inferring the fraction of extractable hydrocarbon; d) oil composition varies considerably among the samples within a stratigraphic interval of 20 m. Samples from intra salt organic-rich lamina show different compositional characteristics with much less abundance in gaseous and volatile oil compounds; while samples from inter salt interval contain large portion of volatile and light oil, indicating a promising production zone.
•Thermal evaporative kinetics of S1 curve was used to characterize oil composition groups•Oil compositional grouping provides essential information for assessing oil mobility and extractable oil resource•Phase analysis based correction of evaporative loss in S1 led to insights for realistic oil composition characterization
Shale oil resources have been discovered in argillaceous dolomite in the Lower Member of Paleogene Xingouzui Formation (LXF) of the Jianghan Basin, opening up a new field of shale oil exploration and ...development. Previous studies have mainly focused on the evaluation of reservoir quality, but the research on the enrichment mechanisms of organic matter (OM) in argillaceous dolomite is very limited or unknown. On the basis of organic geochemical and mineralogical data, combined with sedimentological analyses, the factors controlling the differential enrichment of OM in the LXF Member II oil Bed argillaceous dolomite are studied. The results show that the average TOC content of the samples is greater than 1.0%, which could be regarded as good source rocks. The kerogen type is mainly type II, with a small amount of type I and type III, and most of the samples are in the low-mature stage. Vertically, the development of the LXF Member II oil Bed argillaceous dolomite can be divided into three stages: the lower section (LS) has TOC content ranging from 0.57 to 4.95%, the middle section (MS) has a higher TOC content, between 0.55 and 9.52%, and the TOC content of the upper section (US) is relatively low, between 0.41 and 3.49%. The distribution of biomarkers showed that both higher plants and aquatic organisms contributed to the OM accumulation. The parameters of biomarkers such as pristane/phytane (Pr/Ph), gammacerane/C30 hopane (G/H), extended tricyclic terpane ratio (ETR) and their degree of dispersion, as well as sedimentological characteristics, indicate that the LS was deposited in a stratified deep waterbody with anoxic bottom water, the MS was deposited in a saline stratified moderate-deep waterbody with anoxic bottom water, and the US was deposited in a disturbed saline waterbody. Different sedimentary environments controlled the source of OM, the effectiveness of nutrients recycling and preservation conditions, which jointly affect the enrichment of OM. The stratified moderate-deep waterbody with anoxic bottom water and no physical disturbances, coupled with low terrigenous organic matter (TOM) inputs and the contribution of algae and other phytoplankton, are the best conditions for the enrichment of OM in argillaceous dolomite.
•The LXF argillaceous dolomite shows good potential for shale oil exploration.•Physical disturbances are unfavorable for OM enrichment.•Stratified water column with low TOM input favor OM enrichment.•Key factors controlling OM enrichment at different stages are distinct.
Migrated hydrocarbons occur commonly in liquid-rich source rock reservoirs and can distort analytical results of programed pyrolysis. Disregarding the effect may result in unreliable data ...interpretation and inappropriate hydrocarbon generation kinetics. This paper proposes a method based on kerogen kinetics for characterizing the impacts, estimating the severity and subsequently minimizing the effects by removal of the migrated components from the oil-stained samples through a numerical approach. The restored hydrocarbon pyrograms are then used for recalculation of relevant Rock-Eval parameters and proper construction of generation kinetic models. The proposed methods and workflow were applied to the source rock samples from the Qianjiang Formation, a confined source rock system imbedded in salt layers, where contamination from migrated hydrocarbons is common. An additional Rock-Eval dataset consisting of whole-rock samples and post-solvent extracted replicates was used to validate the methods. The validation results show that the proposed numerical approach is a cost-effective alternative to the traditional laboratory solution.
•Migrated hydrocarbons in source rock reservoir distort analytical results of Rock-Eval pyrolysis.•Disregarding the effect results in unreliable data interpretation, overestimation of generation potential and inappropriate kinetics.•New method removes effectively the migrated hydrocarbons from pyrograms, providing a cost-effective alternative for additional post-solvent extracted experiment
The rapid development of global urbanization and industrialization not only promotes a significant improvement in the level of socio-economic development, but also exacerbates the complexity and ...vulnerability of regional land resource utilization, resulting in frequent land use conflicts and seriously constraining the sustainable development of regional socio-economic and ecological environment. Taking Funan County as an example, based on interpretation data of Landsat TM/ETM remote sensing image data from 1980 to 2020, this paper analyses the temporal and spatial evolution characteristics of land use conflict in Funan County from 1980 to 2020 using the ArcGIS spatial analysis method, land use conflict measurement model, geographically weighted regression and geographical detector and then deeply analyses the main factors affecting land use conflict in Funan County and its driving mechanisms. In descending order, land use types undergoing the most change include cultivated land, urban and rural construction land, grassland, forestland and water area. The results of land use change are mainly the occupation of cultivated land by construction land, water area and forestland. Overall land use conflict in Funan County is serious with approximately 80 % of land use in the county in conflict, the severe land use conflict is mostly concentrated in urban and township built-up areas, and there is an increase trend year by year. Land use conflict is the result of multiple factors. Policy, economic development, and the social population and natural environment are the key driving factors behind land use conflict, which have a significant impact on the direction, location, scale and rate of land use transfer.Accurately identifying regional land use changes and conflicts and exploring the driving mechanism behind land use conflicts are of great significance for achieving the sustainable development of regional social economies and ecological environments.
Jianghan Basin is the largest terrestrial saline lake basin in China, with the largest salinization area in the Paleogene. Research on salt rhythmite formations is crucial for petroleum exploration ...in salt lake basins. With alternating dry and wet climates, the difference in the organic matter (OM) provenance and enrichment remain controversial. In this study, petrology, element geochemistry, and molecular geochemical analyses were performed for the Qianjiang Formation to determine the depositional environment and provenance of its OM. The response of OM enrichment in the saline lake to the alternating dry and wet climates was reassessed. Three lithofacies associations (LAs) were designated: (1) LA1 was rich in argillaceous dolomite and argillaceous limestone with high total organic carbon (TOC); (2) LA3 was interbedded argillaceous glauberite and argillaceous dolomite with low TOC; (3) LA2 was a mixture of the above minerals with moderate TOC values. LA1 was deposited during desalination with a reducing environment and water stratification. The ∑C21-/∑C22+, C29/C30 hopane and maceral indicate the OM of LA1 derive from algae. Compared with LA1, LA2 was deposited with higher salinity and less algae. LA3 was deposited during intense evaporation, high salinity, and a disturbed environment. The OM sources of LA3 include higher plants and low aquatic organisms. Dry and wet climates control changes in organic enrichment. Hypersalinity is unfavorable to algae but beneficial to preservation. The stratified deep water is conducive to the accumulation of OM. The desalination is a crucial period for organic matter enrichment in the saline lake.
•Desalination is a crucial period for organic matter enrichment in saline lake.•Mechanisms of organic matter accumulation are different in dry and wet climates.•Hypersalinity is unfavorable to algae but beneficial to preservation.
Organic-rich lacustrine shales are widely developed in China, and they have long been simply regarded as homogeneous source rocks, which restricts the understanding of intrasource oil accumulation. ...At present, the study of the LXF (Lower Member of the Xingouzui Formation) in the Jianghan Basin as an unconventional oil reservoir is still in its infancy, and the hydrocarbon accumulation mechanism is still unclear. Geochemical and mineralogical studies were carried out on a suite of samples from the 100-m-thick sequence, i.e., LXF II Oil Bed, by using XRD, SEM, MICP, and Rock-Eval pyrolysis. The results show that the II Oil Bed is rich in carbonate and poor in clay, so it shows a good fracturing tendency. The high degree of heterogeneity in mineral composition leads to frequent interbedding of different lithofacies. In the II Oil Bed, intercrystalline pores, interparticle pores, and intraparticle pores are developed, and micro-fractures are often observed. However, the main pore types, pore size distribution, and connectivity are quite different among lithofacies, and the carbonate-rich lithofacies have better reservoir capacity. The OM (organic matter) abundance of the II Oil Bed varies greatly and generally ranges from fair to very good. Coupled with its early-mature to mature Type II OM, it is considered to have the characteristics required for oil generation. Comprehensive analysis shows that the II Oil Bed has good shale oil exploration prospects, and the enrichment of shale oil in the sequence is the result of multiple factors matching. Firstly, high organic matter abundance is the material basis for shale oil enrichment. Secondly, thermal maturity is a prerequisite, and the difference in burial depth leads to the differential enrichment of shale oil in different areas. Thirdly, pores and micro-fractures developed in shale not only provide space for hydrocarbon storage, but also form a flow-path network. Finally, multi-scale intrasource migrations are key processes ranging from the scale of lithofacies to the intervals, which further results in the differential shale oil enrichment in different lithofacies and intervals. Considering the hydrocarbon generation capacity and reservoir quality, the prospective depth for shale oil exploration in the study area is >1350 m. The findings of this study can help in the better-understanding of the shale oil enrichment mechanism, and the optimization of future exploration strategies.
Macrophages are one of the important cells in immune system. In this article, we aim to explore the regulatory role of miR-455-3p on proliferation and osteoblast differentiation of RAW264.7 cells.
...Expression levels of genes and proteins in cells were tested via qRT-PCR and western blot. The targeted correlation between miR-455-3p and PTEN was identified by luciferase analysis. MTT assay and flow cytometry were applied to detect the proliferation and apoptosis of cells. Osteoclastogenesis was completed by stimulating RAW 264.7 cells with RANKL. Tartrate-resistant acid phosphatase (TRAP) activity in different groups of cells were assessed.
Firstly, we determined that up-regulation of miR-455-3p promoted the proliferation and inhibited apoptosis of RAW 264.7 cells. MiR-455-3p deficiency played opposite effect in RAW 264.7 cells. Additionally, osteoclastogenesis-related factors (TRAP, CTSK and NFATc1) expression levels were remarkably up-regulated in miR-455-3p-mimic group of RAW264.7 cells treated with RANKL, but decreased in inhibitor group. Luciferase assay proved that miR-455-3p targeted PTEN. We took a further step and found overexpression of PTEN significantly inhibited the increased proliferation and osteoblast differentiation of RAW264.7 cells induced by miR-455-3p.
Our findings supported basic to explore the molecular mechanism of proliferation and osteoblast differentiation of RAW264.7 cells.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
