Hydrocarbon and Non-Hydrocarbon Gas in Salt Environments, A Contribution to Gas Genesis Understanding: ABSTRACT

Free residual gas after laparoscopy may cause shoulder pain, decreasing patient satisfaction with the procedure. We analyzed the correlation between postoperative residual carbon dioxide gas and shoulder pain, explored the peri- and postoperative factors associated with residual carbon dioxide and determined the effects of the use of a drainage tube. A cohort of 326 patients who underwent laparoscopic adnexal surgery between March 2005 and June 2018 at a teaching hospital in Korea was retrospectively analyzed through a medical records review. The enrolled patients were divided into 1-, 2-, and 3-port groups. The right volume, left volume, and total volume of residual gas were calculated using a formula based on measurements obtained from chest X-rays. Continuous variables were compared using Student t tests. Categorical variables were compared with the chi-square test or Kruskal–Wallis test. The total volumes of postoperative residual carbon dioxide gas were significantly different between the 1- and 2-port groups and between the 1- and 3-port groups (157.3 ± 179.2 vs 25.1 ± 92.3 mL and 157.3 ± 179.2 vs 12.9 ± 36.4 mL, respectively). The volume of residual gas and the time to the first passage of gas were positively correlated. The total volume of residual gas was more strongly correlated with the operative wound pain score than with the shoulder pain score. Additionally, the pre- and postoperative white blood cell counts, postoperative hospitalization duration, residual carbon dioxide volume, and shoulder pain score were significantly different between patients with and without a drainage tube. Although the volume of residual gas was not correlated with the shoulder pain score, the author found that both were lower in patients with a drainage tube than in those without, indicating that a drainage tube could be safely used to decrease residual gas volume and the shoulder pain score without increasing the risk of postoperative infection.

Several biological and physico-chemical processes lead to the transformation of organic matter (OM) from simple organic compounds to a complex macromolecule and a mixture of hydrocarbons during the geological evolution of sedimentary rocks. These changes are controlled by biological activity in the early stages of burial, and by temperature and pressure in the later stages. The increasing temperature and pressure conditions with burial is termed as maturation, in which biomolecules are converted into petroleum. Three consecutive stages of maturation namely: diagenesis, catagenesis and metagenesis produce irreversible changes in the composition of sedimentary OM. The bulk characteristics (such as elemental composition) of OM starting from its deposition to the formation of oil and gas are well understood in the past using traditional methods such as source rock analyzer (SRA). However, a large knowledge gap still exists in understanding the processes involved in the transformation and evolution of OM during maturation at the molecular level. Understanding the molecular level properties of shale OM is important for precise estimation of hydrocarbons, increasing efficiency of HC recovery and production, designing effective CO2 sequestration and waste disposal strategies, and understanding mechanisms of contaminant release and sorption. The primary objective of my PhD dissertation is to understand evolution of sedimentary OM at molecular scale in Marcellus Shale. The Marcellus Shale is the largest natural gas producing reservoir in the United States and has been extensively drilled in the past decade. The amount of natural gas extracted from the reservoir has almost tripled due to advancements in horizontal 3 drilling technologies. As a result, thousands of wells have been drilled in areas of Pennsylvania, Ohio and West Virginia covering a wide range of maturation (from early oil window to overmature window) and paleo-depositional environments. Drilling of these wells provides access to several thousand feet deep core samples for biogeochemical analysis. In my study, I utilized core samples of Marcellus shale with variable maturity (ranging from 0.8 VRo to 3 VRo) and depositional environment. The variability in sources of OM, paleo-redox conditions and thermal maturation was determined using pyrolysis and biomarker proxies especially in samples from mature part of the basin. Once the information about source of OM and maturation was established, kerogen was extracted from the Marcellus Shale maturity series. Chemical composition and structural properties of the extracted kerogen was determined using advanced spectroscopic techniques. Using the distribution and changes in structural parameters of kerogen, an understanding

This article analyzes the volatility of retrograde condensate when a gas condensate field is exposed to dry natural gases containing carbon dioxide (CO₂), which is associated with some of its advantages over other non-hydrocarbon gases.
 The indicators of the process of impact on the bottomhole zone of a producing gas condensate well by "dry" gas enriched with carbon dioxide are studied, taking into account the influence of the physicochemical and thermodynamic properties of the gas condensate system, as well as the thermobaric conditions of the process itself.
 "Dry" hydrocarbon gas containing carbon dioxide more actively evaporates retrograde condensate compared to other non-hydrocarbon gases. However, to increase the efficiency of this process, one should take into account the number of injected gas contacts and the temperature of the bottomhole zone.

Laboratory and theoretical constraints on the generation and composition of natural gas

Late Triassic-early Jurassic silica rocks are widely developed in Northeast China. To evaluate the silica rock hydrocarbon generating capacity, we have simulated the hydrocarbon evolution process by thermal simulation experiments and analyzed the hydrocarbon generation characteristics. The experiments were carried out at six temperature points 250, 270, 290, 310, 330, and 350°C, and the content of the gaseous and liquid products was measured. The experiments results showed that the organic-rich siliceous rocks are characterized by a relatively high hydrocarbon-generating capacity. The gaseous products are generated at different temperatures, while natural gas is mainly generated when the peak period of oil generation is completed. Natural gas includes hydrocarbon and non-hydrocarbon gases. Hydrocarbon gases include methane, ethane, propane, butane, pentane, and other heavy hydrocarbon gases. Non-hydrocarbon gases include hydrogen, nitrogen, carbon monoxide, and carbon dioxide. Carbon dioxide is the main component of the gas products, followed by hydrogen, methane, nitrogen, and other gases, but the total content of other gases is extremely low. Carbon dioxide generated during all stages of the oil generation process accounts for the vast majority, but in geological conditions, it will eventually be consumed by hydration. Nitrogen is mainly produced in the early stage. The content of hydrogen and hydrocarbon gases increases with increase in temperature, but hydrogen is usually depleted in the actual reservoir due to its strong chemical activity.

Deep oil and gas, as an important part to make up the energy-deficient. A series of breakthroughs had been made in their exploration and development in the past few years. However, the effects of deep fluids during hydrocarbon formation and evolution are still an ambiguous problem. Therefore, to investigate the effect of water pressure (PW) on hydrocarbon generation and thermal evolution of type-I, type-II, and type-III kerogens in a deeper stratum, three series of pyrolysis experiments were conducted on three samples with different kerogen types (types II1, I, and III in TC, YMS, and XJ samples, respectively) in a high-temperature, high-pressure simulator. The type-I kerogen was pyrolyzed with 5, 20, 35, 50, 65, and 80 MPa water pressure at 375 °C for 48 h, whereas the type-II and type-III kerogens were pyrolyzed with 10, 20, 30, 40, 50, and 60 MPa water pressure at 350 °C for 48 h. The results showed that there was a threshold pressure PW affecting liquid hydrocarbons. In addition, before the threshold pressure, PW played a role in promoting, but then it was the inhibiting. For gaseous hydrocarbons, while the pressure effects and results were the same as with liquid hydrocarbons in TC samples under the near-critical or critical state, they had no obvious effects in YMS and XJ samples before the critical state, which proved that the organic matter (OM) evolution was associated with the state of fluid in the reaction system and the effects were stronger when the fluid was under the near-critical or critical state than when it is not under this state. The reasons could be concluded as follows: (1) the different properties of water, as the ionization product constant of water (K(w)) was higher in TC samples and may provide more H+ to participate in the OM reactions compared to YMS and XJ samples. Moreover, the particular characteristics of intersolubility with organic solvent occurred under near-critical or critical states, resulting in the more water-soluble hydrocarbons being expelled in TC samples. (2) Chemical mechanism: based on the first-order reaction equation for oil–gas generation and essential characters of samples and experiments, it can be concluded that the influence degree of PW on OM evolution was related to the type of OM, the thermal maturity as well as the nature of water. (3) Physical mechanism: the vapor in free space and generated hydrocarbons in pores were in a dynamic balance state, which also resulted in the existence of threshold pressure PW affecting OM evolution. Therefore, understanding the effects of PW on OM evolution would help us to study the oil–gas generation accurately in actual geology and help preferably in oil–gas exploration and exploitation.

Pyrolysis Fourier transform infrared spectroscopy (pyrolysis FTIR) is a potential sample selection method for Mars Sample Return missions. FTIR spectroscopy can be performed on solid and liquid samples but also on gases following preliminary thermal extraction, pyrolysis or gasification steps. The detection of hydrocarbon and non-hydrocarbon gases can reveal information on sample mineralogy and past habitability of the environment in which the sample was created. The absorption of IR radiation at specific wavenumbers by organic functional groups can indicate the presence and type of any organic matter present.Here we assess the utility of pyrolysis-FTIR to release water, carbon dioxide, sulfur dioxide and organic matter from Mars relevant materials to enable a rapid habitability assessment of target rocks for sample return. For our assessment a range of minerals were analyzed by attenuated total reflectance FTIR. Subsequently, the mineral samples were subjected to single step pyrolysis and multi step pyrolysis and the products characterised by gas phase FTIR.Data from both single step and multi step pyrolysis-FTIR provide the ability to identify minerals that reflect habitable environments through their water and carbon dioxide responses. Multi step pyrolysis-FTIR can be used to gain more detailed information on the sources of the liberated water and carbon dioxide owing to the characteristic decomposition temperatures of different mineral phases. Habitation can be suggested when pyrolysis-FTIR indicates the presence of organic matter within the sample. Pyrolysis-FTIR, therefore, represents an effective method to assess whether Mars Sample Return target rocks represent habitable conditions and potential records of habitation and can play an important role in sample triage operations.

The Australian sheep industry aims to increase the efficiency of sheep production by decreasing the amount of feed eaten by sheep. Also, feed intake is related to methane production, and more efficient (low residual feed intake) animals eat less than expected. So we tested the hypothesis that more efficient sheep produce less methane by investigating the genetic correlations between feed intake, residual feed intake, methane, carbon dioxide, and oxygen. Feed intake, methane, oxygen, and carbon dioxide were measured on Merino ewes at postweaning (1,866 at 223 d old), hogget (1,010 sheep at 607 d old), and adult ages (444 sheep at 1,080 d old). Sheep were fed a high-energy grower pellet ad libitum for 35 d. Individual feed intake was measured using automated feeders. Methane was measured using portable accumulation chambers up to 3 times during this feed intake period. Heritabilities and phenotypic and genotypic correlations between traits were estimated using ASReml. Oxygen (range 0.10 to 0.20) and carbon dioxide (range 0.08 to 0.28) were generally more heritable than methane (range 0.11 to 0.14). Selecting to decrease feed intake or residual feed intake will decrease methane (genetic correlation [] range 0.76 to 0.90) and carbon dioxide ( range 0.65 to 0.96). Selecting to decrease intake ( range 0.64 to 0.78) and methane ( range 0.81 to 0.86) in sheep at postweaning age would also decrease intake and methane in hoggets and adults. Furthermore, selecting for lower residual feed intake ( = 0.75) and carbon dioxide ( = 0.90) in hoggets would also decrease these traits in adults. Similarly, selecting for higher oxygen ( = 0.69) in hoggets would also increase this trait in adults. Given these results, the hypothesis that making sheep more feed efficient will decrease their methane production can be accepted. In addition, carbon dioxide is a good indicator trait for feed intake because it has the highest heritability of the gas traits measured; is cheaper, faster, and easier to measure than feed intake and has strong phenotypic and genetic correlations with feed intake. Furthermore, selection for feed intake, feed efficiency, methane, and carbon dioxide can be done early in sheep at postweaning age or hoggets. This early selection reduces the generation interval for breeding, thereby increasing response to selection.

Solubility of hydrocarbon and non-hydrocarbon gases in aqueous electrolyte solutions: A reliable computational strategy

Evolution of organic matter in lignite-containing sediments revealed by analytical pyrolysis (Py–GC–MS)

So called “Semi dolerite” is represented by sills and dykes of seven masses. The writer classified those dolerites geologically and petrologically in two groups, namely Semi dolerite and Nagasawa dolerite. Semi dolerite intrudes in the lower part of Nagao formation and the upper part of Semi formation as sill form, but rarely in Nozoki formation in dyke form. Then, Nagasawa dolerite intrudes in the lower part and extrudes in the middle part of Nagasawa formation. Sills and dykes of Semi dolerite show chilled margins at the lower and upper contact with the intruded sediments. The thickness of the largest sill is 24.4 meters, while its chilled base is 0.8 meters and its upper chilled margin is 0.5 meters thick. When the thickness of sill is over about 20 meters, the petrographyic and chemical compositions vary remarkably from the margins to the central and upper part in one sill, by differentiation “in situ”. The writer found a differentiation sequences in Semi dolerite sill as follows, namely, chilled margins, normal dolerite, felsic dolerite (dioritic laver in the upper part), dolerite pegmatite and granophyric segregation vein. Nagasawa dolerite sills 18.6 meters in thickness, and the grain size is relatively small and uniform throughout the whole body. As a characteristic nature, it includes numerous xenocryst of quartz, skeleton like plagioclase and hornblende like matters. The chemical composition of Nagasawa dolerite, comparing with the felsic differentiates of Semi dolerite, has the next characteristics: SiO2 component of the latter is equall to the one of the former, while Fe2O3+FeO component is poor, and A12O3 and MgO components are richer in the latter than in the former. Judging from the chemical composition as well as the mineralogical compositions, Nagasawa dolerite is believed to have been derived from the original magma of Semi type dolerite not by the differentiation process, but by the assimilation of the felsic materials as probably the granitic materials.

Hydrocarbon yield evolution characteristics and geological significance in temperature-pressure controlled simulation experiment

Ongoing climate change is making the large pool of organic matter (OM) stored in Arctic permafrost vulnerable to mobilization; thus, garnering a deeper understanding of molecular transformations within the abundant pool of soil OM, specifically humic substances, is crucial. Here we present the first high‐resolution mass‐spectrometry examination of molecular compositions of humic acid (HA) and fulvic acid (FA) isolated from organic‐rich deep yedoma (Pleistocene age ice‐rich permafrost) and alas (thermokarst deposit formed during permafrost thaw) cores. The FA fractions were dominated by oxygen‐rich unsaturated compounds, whereas the HA fractions were mostly composed of relatively reduced saturated and aromatic moieties. A substantial increase in contribution of both CHO‐only and N‐containing aliphatic compounds was observed in the HA fractions of the yedoma OM with depth, whereas the alas HA fractions were depleted in aliphatics but enriched with condensed and hydrolyzable tannins. The observed differences in compositional space of the immobile OM stored in the deep yedoma versus alas deposits were consistent with evolution of OM during thermokarst lake genesis, implying intense microbial degradation of N‐rich OM released from the yedoma deposits and accumulation of highly degraded, plant‐derived OM. The patterns of molecular transformations of OM were apparent in compositional space of the least degraded HA fractions as compared to much more oxidized FA fractions. This shows great promise of molecular exploration of the alkali‐extracted OM, comprising up to 50% of the total organic carbon in deep permafrost both for paleoreconstructions and predictions of climate feedback to released OM due to permafrost thaw.

New insights into the role of system sealing capacity in shale evolution under conditions analogous to geology: Implications for organic matter evolution and petroleum generation

Compositions of non-hydrocarbon and noble gases in natural gas samples collected from the Kuqa Depression, Tabei Uplift Belt, North Depression, Tazhong Uplift, and Southeast Depression in the Tarim Basin, China were analyzed to investigate the origin of the natural gases. The results show that the largest component of the natural gases is hydrocarbon gas with a concentration of 33.46% to 99.26%. The non-hydrocarbon gases are mainly composed of CO2 and N2 with concentrations of 0.01% to 17.95% and 0.1% to 52.45%, respectively. The helium content varies from 0.005% to 0.30%. The 3He/4He ratio varies from 0.01 Ra to 0.55 Ra (where Ra denotes atmospheric 3He/4He ratio = 1.4 × 10–6), and the 4He/20Ne ratio varies from 8.3 to 7400. Most of the 3He/4He values are below 0.1 Ra. The low 3He/4He ratios indicate crustal radiation to be the main source of the helium. There are no positive correlations between the 3He/4He ratio and helium abundance, non-hydrocarbon abundance, heat flow, and the age of reservoir formations. The ratios of 3He/4He are related to the time or stage of the natural gas accumulation. The ratios of 3He/4He in the reservoirs that were filled in the later stage (Himalayan period) are lower than those in the reservoirs that were filled in the earlier stage (Yanshan period).