Geochemical characteristics of water-dissolved gases and implications on gas origin of Sinian to Cambrian reservoirs of Anyue gas field in Sichuan Basin, China

The Anyue field is a supergiant gas field which was discovered recently in the Sichuan Basin, China where the Sinian Dengying Formation and the Cambrian Longwangmiao Formation are principal gas reservoirs. Gas in the Anyue field contains mainly methane (>98%) and a low content of heavy hydrocarbons, with minor H2S component. Reservoirs commonly contain bitumen and produce formation water. It is currently suggested that natural gas in the Anyue field is derived from the secondary cracking of crude oil. However, carbon isotopic ratio of methane is significantly less negative than that of bitumen, which contradicts the isotopic signature oil cracking process would predict. Besides, this phenomenon also cannot be explained by the process of thermochemical sulphate reduction (TSR), because there is no remarkable correlation between the δ13C1 values and H2S contents as suggested in previous studies. Both free gas and water-dissolved gas from the Anyue gas field were analyzed in this study for their stable isotopes. Results show that the δ13C1 of the gas derived from the formation water is much less negative than that of free gas. Therefore, it is inferred that the less negative δ13C1 values in the free gas reservoir are attributable to addition of natural gas that is previously dissolved in formation water. Geological setting of the gas reservoirs in Dengying and Longwangmiao formations of the Anyue gas field is favorable for the formation and preservation of water-dissolved gas. In addition, both formations had experienced significant structural uplifting before the gas reservoirs were formed. Reduced temperature and pressure in the formations by geological uplifting could cause super-saturation of methane in the formation water, and as a consequence, water-dissolved methane gas could exsolve from water phase into gas phase. Therefore, it is concluded that natural gas in the Anyue field is a mixture of free gas and gas exsolved from the formation water. As a result, the carbon isotope of methane gas in the Anyue field became less negative than that of a single free gas component would predict

Formation mechanism of tight coal-derived-gas reservoirs with medium-low abundance in Xujiahe Formation, central Sichuan Basin, China

Although Xujiahe Formation source rocks in the central Sichuan Basin, China were determined to have low gas-generation intensity, several large-scale gas fields have been found associated with this formation. Thus origins and formation mechanisms of natural gas in the Xujiahe Formation have attracted attentions of many researchers. In this study, geochemistry techniques were deployed to analyze natural gas and formation water in the Xujiahe Formation tight gas reservoir, central Sichuan Basin. By considering geologic background of the gas reservoir, its formation mechanism was investigated. Research results show that the Xujiahe Formation reservoir contains an independent petroleum system, with its natural gas exclusively originated from coal-measure source rocks in the Xujiahe Formation. The formation water was determined to be CaCl2 type with high salinity. H and O isotope values are largely deviated from those of meteoric water line, indicating favorable preservation conditions for the formation water. The Xujiahe Formation is composed of multiple coal-measure source rocks and superimposed by tight sandstones. The well-developed formation water provides favorable conditions for generating water-dissolved gas. Structural movements during the Himalayan period induced significant uplifting of the central Sichuan Basin with overlying formations denudated. Consequently, natural gas dissolved in formation water experienced depressurization and exsolution. The released natural gas formed free gas phase in structural highs or provided additional natural gas supplies to existing gas reservoirs

Geochemical evidence for in situ accumulation of tight gas in the Xujiahe Formation coal measures in the central Sichuan Basin, China

The study of accumulation mechanisms of tight gas has attracted much attention in recent years. One of the focuses is whether natural gas can migrate on a large scale in tight reservoirs. In this work, geochemical parameters (such as C1/C1+, C1/(C2+ C3), C1+, δ13C1, δ13C2, iC4/nC4, iC5/nC5) of the tight gas reservoirs in the central Sichuan Basin, China have been studied to characterize the accumulation mechanisms in these fields. Results show that the tight gas accumulation in the Xujiahe Formation in the central Sichuan is in situ, and natural gas has not experienced large-scale migration. In gases from the central Sichuan Basin, δ13C1 ranges from −44.1‰ to −37.1‰ with an average of −40.1‰, and C1/C1+ ranges from 0.80 to 0.97 with an average of 0.91. While in the gases from the western Sichuan Basin, δ13C1 is between −35.5‰ and − 30‰ with an average of −32.2‰, and C1/C1+ ranges from 0.95to 0.99with an average of 0.98. Based on geochemical indicators of natural gas, the gases of Xujiahe Formation in the Central Sichuan Basin originated from the local coal measures of the Xujiahe Formation in horizontal direction with little contribution from the western Sichuan. In central Sichuan Basin, there is also no horizontal migration of natural gas in the same formation between adjacent gas fields. Vertically, the Xujiahe Formation is an independent gas generating system and has no relationship with the underlying Mid-Lower Triassic formations and the Jurassic natural gas formation above it. The δ13C2of Xujiahe Formation in central Sichuan ranges from −28.3‰ to −25.9‰, with an average of −27.5‰. However, the δ13C2 of Lower Jurassic above Xujiahe Formation ranges from −36.8‰ to −30.5‰, with an average of −33.0‰. Under the Xujiahe Formation, the δ13C2 in Leikoupo Formation ranges from −35.5‰ to −32.1‰, with an average of −33.1‰, and in Jialingjiang Formation ranges from −34.6‰ to −33.2‰, with an average of −33.8‰. There is also a clear distinction in the geochemical characteristics of natural gas between the upper and lower gas reservoirs in the Xujiahe Formation, indicating that there is no obvious vertical migration of natural gas. Geochemical evidence shows that there is no large-scale gas migration in the Xujiahe Formation. The tight gas is generated in situ and accumulated in the formation in the central Sichuan Basin

Tracing interaction between hydrocarbon and groundwater systems with isotope signatures preserved in the Anyue gas field, central Sichuan Basin, China

Anyue gas field is a large gas field located in the central Sichuan Basin, China. Although many studies have been carried out previously, the formation mechanism of this field is unclear and currently under debate. To better understand the accumulation history, the role that groundwater plays in transporting hydrocarbons within sedimentary basins and water-gas interactions, stable and noble gas isotopes were measured in thirteen free gas samples from the Anyue gas field. In addition, nine formation water samples and five reservoir bitumen samples were analyzed for stable carbon isotopes. δ13C(CH4) values in the gas samples range from −35.0 to −32.6‰, showing evidence of thermogenic origin. δ13C values among three different types of samples (free gases, water-dissolved gases and reservoir bitumen) show a pattern that cannot be explained by oil cracking followed by free gas accumulation. It suggests the occurrence of gas-groundwater interaction in the Anyue field. Free gas samples can be divided into 2 distinct groups by their geographical locations and stratigraphical source formations. 3He/4He ratios (R/Ra) in group 1 and group 2 samples range from 0.0118 to 0.0132 and 0.0115 to 0.0256, respectively, indicating He is mainly derived from the crust. 20Ne/22Ne and 21Ne/22Ne ratios suggest a mixing between the air and crust sources. 40Ar/36Ar ratios ranging from 1658 to 2109 and 2168 to 5973 in group 1 and group 2 samples, respectively, are significantly higher than the air value of 298.6. In comparison, heavier noble gas (Kr and Xe) isotopic compositions are predominantly air-like. The relative enrichment of 4He and 21Ne* in group 1 samples can be possibly explained by preferential release of light noble gases in a low temperature environment. Samples in group 2 show a good fit to the solubility-controlled Rayleigh fractionation model, suggesting the presence of an open system degassing of gases from the groundwater. The excess heavy noble gases in natural gas samples can be attributed to the addition of sedimentary components from the source rocks during geological evolution. 4He groundwater ages considering in-situ production and external flux indicate the addition of young groundwater into the Anyue gas field. Low gas-groundwater ratios and high CH4/36Ar ratios suggest that only a small portion of the gases in the current Longwangmiao reservoir of Anyue gas field has been in contact with the relatively young groundwater. Based on the noble gas and stable carbon isotope results in all samples, we propose a two-stage gas and groundwater interaction process during the gas preservation and accumulation history in the Anyue gas field in China

Maintenance Chemotherapy With Chinese Herb Medicine Formulas vs. With Placebo in Patients With Advanced Non-small Cell Lung Cancer After First-Line Chemotherapy: A Multicenter, Randomized, Double-Blind Trial

Background: Chinese Herb Medicine Formulas (CHMF) was reported to improve the quality of life (QoL) in advanced NSCLC patients. The present study was designed to investigate whether maintenance chemotherapy plus CHMF in patients would improve QoL and progression-free survival (PFS).Methods: Seventy-one patients were enrolled from 8 medical centers in China, and were randomly assigned to a maintenance chemotherapy plus CHMF group (n = 35) or a maintenance chemotherapy plus placebo group (n = 36). The outcome measures included PFS, Karnofsky performance status (KPS) scores, QoL (assessed with the lung cancer symptom scale (LCSS) questionnaire), and adverse events (AEs).Results: Patients in the CHMF group showed significant improvements in median PFS (HR = 0.55, 95% CI 0.28–0.88, P = 0.019), KPS scores (P = 0.047), fatigue (cycle [C] 3: P = 0.03), interference with daily activities (C3: P = 0.04) and dyspnea (C2: P = 0.03) compared with patients in the placebo group. Compared with the placebo group, the incidence of AEs decreased in the CHMF group, including loss of appetite (C2: P = 0.011, C4: P = 0.004) and dry mouth (C4: P = 0.011).Conclusion: The essential finding of our study is that maintenance chemotherapy combined with CHMF may prolong PFS, relieve symptoms, improve QoL and alleviate the side effects

Designing biomass lignins for the biorefinery

4 páginas.- 3 figuras. 17 referencias.- Comunicación oral presentada en el 16th European Workshop on Lignocellulosics and Pulp (EWLP) Gothenburg, Sweden, June 28 – July 1, 2022As ever more component monomers are discovered, lignin can no longer be regarded as deriving from just the three canonical monolignols. Pathway intermediates and additional products of truncated biosynthesis are now established lignin monomers. The array of acylated monolignols continues to expand. Game-changing findings have demonstrated that phenolics from alternative pathways, including flavonoids and hydroxystilbenes, are also involved in lignification, expanding the traditional concept. Beyond the basic science intrigue, these findings propound exciting new avenues for valorizing lignins, or for producing more readily extractable or depolymerizable lignins, in crop and bioenergy plants.We further acknowledge lots of colleagues and collaborators, and funding from the Swiss National Science Foundation (Synergia) grant # CRS115_180258, and the DOE Great Lakes Bioenergy Research Center (DOE BER Office of Science DE-SC0018409).N

Geochemical characteristics of natural gases from different petroleum systems in the Longgang gas field, Sichuan Basin, China

Located in the Sichuan Basin, China, the Longgang gas field consists of three vertically developed petroleum systems with the Triassic Leikoupo Formation as a dividing interface. There is one marine petroleum system below the interface and one continental petroleum system above it. The marine petroleum system is composed of coal measures, the main source rock in the Longtan Formation, and marine reef reservoirs in the Changxing and Feixianguan formations. The continental petroleum system can also be subdivided into two sets. One is the Xujiahe petroleum system sourced from the Xujiahe coal measures in the Upper Triassic formation. The other is a Jurassic petroleum system that is sourced from Jurassic lacustrine black shales. The gas pools in the marine system contain H2S gas. The gases are very dry and the δ13C1 and δ13C2 values display less negative values with an average of −29.2 and −25.0‰, respectively. The gases are humic origin generated at highly to over mature stages from coal measures of the Longtan Formation. The natural gas in the continental petroleum system does not contain H2S. The natural gases from the Xujiahe petroleum system are mainly wet gases with a few dry gases, and belong to typical humic type sourced from coal measures of the Xujiahe Formation. All the gases from this Jurassic petroleum system are wet gases and the alkane gases show more negative carbon isotopic values typical of sapropels. These are derived from the lower Jurassic lacustrine black mudstone. The three sets of petroleum systems in the Longgang gas field are vertically well separated. Each system has its own source rock, and there are no gases from other sources despite multiple tectonic events in the past. The reservoirs had been in a relatively stable tectonic condition with excellent seals by cap rocks during the gas accumulation period

Dairy Manure as a Potential Feedstock for Cost-Effective Cellulosic Bioethanol

This study investigated sulfite pretreatment to overcome recalcitrance of lignocelluloses (SPORL) pretreatment and subsequent enzymatic digestibility of undigested dairy manure to preliminarily assess its potential use as an inexpensive feedstock for cellulosic bioethanol production. The sulfite pretreatment was carried out in a factorial analysis using 163 to 197 °C for 3 to 37 min with 0.8% to 4.2% sulfuric acid combined with 2.6% to 9.4% sodium sulfite. These treatments were compared with other standard pretreatments of dilute acid, and hot and cold alkali pretreatments. This comparative study showed that the sulfite pretreatment, through its combined effects of hemicellulose and lignin removal and lignin sulfonation, is more effective than the diluted acid and alkali pretreatments to improve the enzymatic digestibility of dairy manure

Genetic Types, Distribution Patterns and Enrichment Mechanisms of Helium in China’s Petroliferous Basins

Helium is a strategic resource with many scientific, technical and industrial applications. However, despite its importance and scarcity, there is a lack of understanding on its origin, migration and accumulation processes. In view of this, the distribution patterns and enrichment mechanisms of helium are studied based on systematic analysis of the genetic types of helium in petroliferous basins in China. The helium in the petroliferous basins in China is mainly radiogenic, which involves the decay of U and Th. As expected, we found that, in one gas field, the helium content in natural gas increases with the age of reservoir rock, and in the same layer of the same structure within one reservoir, the helium content in natural gas in high altitude part of the structure is higher than that in the lower part. Enrichment of helium is closely related to old deep groundwater. The helium produced by radioactive decay in old strata is dissolved in water and transported and enriched through water migration. Due to large uplift of the structure during the Himalayan period, the helium dissolved in water was exsolved and accumulated with natural gas in the trap above the water. And thus, the helium-rich natural gas reservoirs formed. So, the helium contents in natural gas fields increase gradually along the flow direction of groundwater. The area with large range of uplift often shows higher helium content. This study not only provides a basis for the study of helium enrichment research, but also provides a new idea for industrial helium resource exploration

Geochemical evidence of water-soluble gas accumulation in the Weiyuan gas field, Sichuan Basin

At present, there are several different opinions on the formation process of the Weiyuan gas field in the Sichuan Basin and the source of its natural gas. In view of the fact that the methane carbon isotope of the natural gas in the Weiyuan gas field is abnormally heavy, the geologic characteristics of gas reservoirs and the geochemical characteristics of natural gas were first analyzed. In the Weiyuan gas field, the principal gas reservoirs belong to Sinian Dengying Fm. The natural gas is mainly composed of methane, with slight ethane and trace propane. The gas reservoirs are higher in water saturation, with well preserved primary water. Then, it was discriminated from the relationship of H2S content vs. methane carbon isotope that the heavier methane carbon isotope of natural gas in this area is not caused by thermochemical sulfate reduction (TSR). Based on the comparison of methane carbon isotope in this area with that in adjacent areas, and combined with the tectonic evolution background, it is regarded that the natural gas in the Weiyuan gas field is mainly derived from water-soluble gas rather than be migrated laterally from adjacent areas. Some conclusions are made. First, since methane released from water is carbon isotopically heavier, the water-soluble gas accumulation after degasification results in the heavy methane carbon isotope of the gas produced from Weiyuan gas field. Second, along with Himalayan movement, great uplift occurred in the Weiyuan area and structural traps were formed. Under high temperature and high pressure, the gas dissolved in water experienced decompression precipitation, and the released natural gas accumulated in traps, consequently leading to the formation of Weiyuan gas field. Third, based on calculation, the amount of natural gas released from water which is entrapped in the Weiyuan gas field after the tectonic uplift is basically equal to the proved reserves of this field, confirming the opinion of water-soluble gas accumulation after degasification