Hydrocarbon Gas Production Research Articles

Development of a Graded Early Warning Index System and Identification of Critical Temperatures for Coal Spontaneous Combustion Using Composite Gas Characteristics.

Conventional single gas alarm method and coal spontaneous combustion three-stage alarm method have become increasingly inadequate to meet complex underground conditions. To address this issue, this study focuses on the coal in the goaf of the Z109 working face in the Donggucheng Mine as the research object. Through program-controlled heating experiments, the production of carbon monoxide and hydrocarbon gases during the coal oxidation process was determined, and the variation characteristics of gas ratios with temperature were further analyzed. The coal spontaneous combustion process was subdivided into seven small stages, and a quantitative composite parameter coal spontaneous combustion grading warning system was formulated. Based on its characteristics, measures to be taken under different warning levels were proposed, and it was determined that 120, 140, and 160 °C are the key temperatures for coal spontaneous combustion prevention and control in the Z109 working face of Donggucheng Mine. By using numerical simulation, the optimal nitrogen injection position for the working face was determined and the on-site fire prevention and extinguishing measures were optimized, providing insights into the establishment of a coal mine spontaneous combustion warning system.

PALEOFACIES — BASIS OF RESERVOIR DEVELOPMENT DESIGN

Apt-Alb-Cenomanian age rocks (K1a-al + K2s) within the northern part of the West Siberian oil and gas province (OGP) are the main commercial gas production target in the Russian Federation. However, at present there are certain prerequisites and significant reserves to increase the raw hydrocarbon base and gas production in the central regions of Western Siberia. For further study of the geological structure of these sediments in order to assess their oil and gas potential, it is necessary to set up and carry out complex geological, geophysical and special studies (including sedimentological identification of sediments, detailed reconstruction of paleogeographic sedimentation settings, paleofacial analysis of rocks, petrophysical support of the works). This will make it possible to increase the accuracy and reliability of the planned works on oil and gas prospecting and exploration, as well as to carry out a qualitative forecast of the area development of promising complex reservoir rocks, to perform a full calculation of the initial geological reserves of hydrocarbons for a number of new objects (including PK5, PK7, PK8) and to build highquality geological and hydrodynamic models of hydrocarbon deposits necessary for the design of their further development.A detailed analysis of the primary geological and geophysical materials at our disposal has shown that during the formation of the Pokur Formation in the Middle Ob oil and gas bearing area (OGO) there were heterogeneous conditions of sedimentation — from purely continental to coastal-marine. High lithologic and facies heterogeneity of the studied sediments is observed everywhere. These circumstances complicate the processes of detailed correlation in these sediments, and in some cases — unrealized in practice even within one exploration area. Stratification of productive strata is the most important part of oil and gas prospecting and exploration. According to the results of our studies, the upper strata are most well traced (in some cases up to the hypsometric level of PK3-4 strata occurrence). Their confident area correlation makes it possible to identify smaller stratigraphic subdivisions (packs) in these strata and to determine the paleofacial genesis of these sediments.

Microscopic mechanism for CO2-assisted co-gasification of polyethylene and softwood lignin: A reactive force field molecular dynamics study

Co-gasification of biomass and waste plastic to produce syngas and value-added products is an attractive technology for renewable energy utilization and waste disposal. CO2 as a gasifying agent has received much attention as it can act as carbon source and oxidant in the reaction. In this paper, the feasibility and characteristics of CO2-assisted co-gasification of polyethylene and softwood lignin were explored. Simulation results showed that the lignin macromolecule began to decompose through C–O–C bond breaking and the PE chain gradually decomposed through C–C bond breaking. CO2-assisted co-gasification showed a negative synergistic effect on gas yield at the early stage, which delayed the reaction, but showed a positive synergistic effect at the late stage. The reaction between CO2 and carbon-containing fragments greatly promoted CO production. The hydrogen and hydrocarbon radicals from PE were actively involved in H2 and hydrocarbon gas production. Compared with O2-assisted co-gasification, the CO2-assisted and CO2/O2-assisted co-gasification yielded more CO, hydrocarbon gases and combustible gases and increased the lower heating value of gas product. This work sheds light on the underlying mechanisms of CO2-assisted co-gasification of polyethylene and softwood, and would be helpful for the development of this technology.

Hydrocarbon gas huff-n-puff optimization of multiple horizontal wells with complex fracture networks in the M unconventional reservoir

The oil production of the multi-fractured horizontal wells (MFHWs) declines quickly in unconventional oil reservoirs due to the fast depletion of natural energy. Gas injection has been acknowledged as an effective method to improve oil recovery factor from unconventional oil reservoirs. Hydrocarbon gas huff-n-puff becomes preferable when the CO2 source is limited. However, the impact of complex fracture networks and well interference on the EOR performance of multiple MFHWs is still unclear. The optimal gas huff-n-puff parameters are significant for enhancing oil recovery. This work aims to optimize the hydrocarbon gas injection and production parameters for multiple MFHWs with complex fracture networks in unconventional oil reservoirs. Firstly, the numerical model based on unstructured grids is developed to characterize the complex fracture networks and capture the dynamic fracture features. Secondly, the PVT phase behavior simulation was carried out to provide the fluid model for numerical simulation. Thirdly, the optimal parameters for hydrocarbon gas huff-n-puff were obtained. Finally, the dominant factors of hydrocarbon gas huff-n-puff under complex fracture networks are obtained by fuzzy mathematical method. Results reveal that the current pressure of hydrocarbon gas injection can achieve miscible displacement. The optimal injection and production parameters are obtained by single-factor analysis to analyze the effect of individual parameter. Gas injection time is the dominant factor of hydrocarbon gas huff-n-puff in unconventional oil reservoirs with complex fracture networks. This work can offer engineers guidance for hydrocarbon gas huff-n-puff of multiple MFHWs considering the complex fracture networks.

Effects of nutrient injection on the Xinjiang oil field microbial community studied in a long core flooding simulation device.

Microbial Enhanced Oil Recovery (MEOR) is an option for recovering oil from depleted reservoirs. Numerous field trials of MEOR have confirmed distinct microbial community structure in diverse production wells within the same block. The variance in the reservoir microbial communities, however, remains ambiguously documented. In this study, an 8 m long core microbial flooding simulation device was built on a laboratory scale to study the dynamic changes of the indigenous microbial community structure in the Qizhong Block, Xinjiang oil field. During the MEOR, there was an approximate 34% upswing in oil extraction. Based on the 16S rRNA gene high-throughput sequencing, our results indicated that nutrition was one of the factors affecting the microbial communities in oil reservoirs. After the introduction of nutrients, hydrocarbon oxidizing bacteria became active, followed by the sequential activation of facultative anaerobes and anaerobic fermenting bacteria. This was consistent with the hypothesized succession of a microbial ecological "food chain" in the reservoir, which preliminarily supported the two-step activation theory for reservoir microbes transitioning from aerobic to anaerobic states. Furthermore, metagenomic results indicated that reservoir microorganisms had potential functions of hydrocarbon degradation, gas production and surfactant production. Understanding reservoir microbial communities and improving oil recovery are both aided by this work.

Comparison of co-refining of fast pyrolysis oil from Salix via catalytic cracking and hydroprocessing

Lignocellulosic biomass from energy crops, i.e., short rotation coppice willows such as Salix spp., can be used as feedstock for production of transportation biofuels. Biomass conversion via fast pyrolysis followed by co-refining with fossil oil in existing refinery infrastructure could enable a fast introduction of large-scale production of biofuels. In this study, Salix was first liquefied using ablative fast pyrolysis in a pilot scale unit. The resulting pyrolysis oil, rich in oxygenates, was thereafter co-refined in 20 wt% ratio with fossil feedstock using two separate technologies, a fluidized catalytic cracking (FCC) laboratory unit and a continuous slurry hydroprocessing pilot plant.In the FCC route, the pyrolysis oil was cracked at 798 K using a commercial FCC catalyst at atmospheric pressure, while in the hydroprocessing route, the oil was processed at 693 K and a hydrogen pressure of 15 MPa in the presence of an unsupported molybdenum sulfide catalyst. Both routes resulted in significant deoxygenation (97 wt% versus 93 wt%). It is feasible to co-refine pyrolysis oil using both methods, the main difference being that the hydroprocessing results in a significantly higher biogenic carbon yield from the pyrolysis oil to liquid and gaseous hydrocarbon products (92 wt%) but would in turn require input of H2. In the cracking route, besides the liquid product, a significant part of the biogenic carbon ends up as gas and as coke on the catalyst. The choice of route depends, among other factors, on the available amount of bio-oil and refining infrastructures.

Hydrocarbon indication in Rio Bonito Formation sandstone: Implication for CO2 storage in São Paulo, Brazil

São Paulo State has witnessed CO2 storage-based investigations considering the availability of suitable geologic structures and proximity to primary CO2 source sinks related to bioenergy and carbon capture and storage (BECCS) activities. The current study presents the hydrocarbon viability evaluations and CO2 storage prospects, focusing on the sandstone units of the Rio Bonito Formation. The objective is to apply petrophysical evaluations with geochemical inputs in predicting future hydrocarbon (gas) production to boost CO2 storage within the study location. The study used data from eleven wells with associated wire-line logs (gamma ray, resistivity, density, neutron, and sonic) to predict potential hydrocarbon accumulation and fluid mobility in the investigated area. Rock samples (shale and carbonate) obtained from depths >200 m within the study location have shown bitumen presence. Organic geochemistry data of the Rio Bonito Formation shale beds suggest they are potential hydrocarbon source rocks and could have contributed to the gas accumulations within the sandstone units. Some drilled well data, e.g., CB-1-SP and TI-1-SP, show hydrocarbon (gas) presence based on the typical resistivity and the combined neutron-density responses at depths up to 3400 m, indicating the possibility of other hydrocarbon members apart from the heavy oil (bitumen) observed from the near-surface rocks samples. From the three-dimensional (3-D) model, the free fluid indicator (FFI) is more significant towards the southwest and southeast of the area with deeper depths of occurrence, indicating portions with reasonable hydrocarbon recovery rates and good prospects for CO2 injection, circulation and permanent storage. However, future studies based on contemporary datasets are required to establish the hydrocarbon viability further, foster gas production events, and enhance CO2 storage possibilities within the region.

Atomically Dispersed Au-Assisted C-C Coupling on Red Phosphorus for CO2 Photoreduction to C2H6.

Single-atom catalysts have exhibited great potential in the photocatalytic conversion of CO2 to C2 products, but generation of gaseous multi-carbon hydrocarbon products is still challenging. Previously, supports of a single atom consist of multiple elements, making C-C coupling difficult because the coordination environment of single-atom sites is diversified and difficult to control. Here, we steer C-C coupling by implanting an Au single atom on the red phosphorus (Au1/RP), support with uniform structure composed of a single element, lower electronegativity, and better ability to absorb CO2. The electron-rich phosphorus atoms near the Au single atoms can function as active sites for CO2 activation. The Au single atom can effectively reduce the energy barrier of C-C coupling, boosting the reaction kinetics of the formation of C2H6. Notably, the C2H6 selectivity and turnover frequency of Au1/RP reach 96% and 7.39 h-1 without a sacrificial agent, respectively, which almost represents the best photocatalyst for C2 chemical synthesis to date. This research will provide new ideas for the design of high-efficiency photocatalysts for CO2 conversion to C2 products.

Optimising ex-situ catalytic fast pyrolysis of pine wood at pilot scale: Impacts on the energy content, chemical composition and stability of the liquid fuel product

A central composite design was used to optimise the yield and higher heating value (HHV) of the liquid fuel produced through ex-situ catalytic fast pyrolysis of pine wood. The variables were the temperature and loading of H-ZSM-5 zeolite catalyst. GC/MS, 1H NMR and stability tests were undertaken to compare the fuel properties of organic phases with similar HHVs, generated from catalytic treatments at low (≤ 370 °C) and high (≥ 470 °C) temperatures. When targeting an HHV of 32 MJ/kg, higher yields were obtained at low temperature and high catalyst loading, despite higher coke yield. Treatment at low temperature preserved more alkyl groups and made the fuel less aromatic (−13 % of aromatic hydrogen and lower content of Crich hydrocarbons). Undesirable catalytic cracking of alkyl groups at higher temperature was evidenced by a 60 % increase in the production of hydrocarbon gases. Despite a higher oxygen content, the fuel produced at low temperature was also found to be more stable.

Systematic study of low temperature cracking of low-density polyethylene with ZSM-5

The viability of cracking low-density polyethylene (LDPE) over H-ZSM-5 catalysts at reaction temperatures below 300 °C was demonstrated using ZSM-5 catalysts with varying textual properties and acid site content. While ZSM-5 made from standard syntheses could catalyze LDPE cracking it was found that increasing the external surface area of H-ZSM-5 from 24 m2/g to 325 m2/g resulted in a dramatic increase in LDPE conversion. For all catalysts the products were permanent hydrocarbon gas products in the C1–C5 range. H-ZSM-5 prepared in nanosheet and nanosphere morphologies achieved 64 wt% and 58 wt% LDPE conversion, respectively, compared to a standard H-ZSM-5 sample with micron-sized crystals that achieved 28 wt% conversion after 8 h at 250 °C under inert conditions. It was also found that strong Brønsted acid sites were necessary for high conversion of LDPE in this temperature regime as shown by the relatively weaker solid acid catalysts Al-MCM-41 and B-MFI converting negligible LDPE under the same reaction conditions. Lastly, a low molecular weight model molecule (n-tetracosane) was tested to gain insight into the cracking mechanism of LDPE over MFI catalysts. The findings in this work point to new approaches for catalyst design to achieve low temperature LDPE depolymerization.

Multi-scale structural inheritance of fracture systems pattern in coal-bearing measures of the Lorraine-Saar coal Basin

The Lorraine-Saar Basin (LSB) is one of the major Paleozoic coalfields of Western Europe that has been shapedover two centuries as a heartland of underground coal mining and associated industrial activities in the transborderarea of France and Germany. The Basin still has considerable coal reserves accumulated in numerous laterally continuous coal seams that were affected by processes of thermogenic production of gaseous hydrocarbons during post-Carboniferous burial and related coalification. The LSB stands out by its up to 6 km sedimentary column and its inversion resulting in Paleozoic erosion in the range of 750 m (French part of the Basin) and pre-Mesozoic (Permian) erosion between 1800 and 3000 m (German part of the Basin). Historically, coal production in the Lorraine and the Saar portions of the entire Basin was associated with numerous mining hazards because of the high methane content in coal seams. The LSB has the potential to host an enormous unconventional resource base including coalbed methane (CBM). Coal mines here are no longer operated to produce coal; however, methane generated in deep compartments is venting here via fracture swarms to the Earth’s surface. Cutting natural methane emissions throughout CBM production within coal-bearing terrains is a crucial opportunity for slowing global warming rates. Nearly all CBM plays worldwide are affected in some way by natural multiscale fracture sets ranging from large fault zones to closely spaced joints, micro-shears, or cleat sets in coal seams. The LSB is not excluded indeed from this trend because of the long-term experience of geological exploration during extensive coal mining in the past. Characterization of structural patterns of fracture networks at different scales is a pragmatic process boosting the reliable perception of the performance of coalbed methane gas reservoirs. The focus of this contribution is to get an insight into the style and kinematic description of the multi-scale fault and cleat patterns in the LSB based on results of subsurface and underground geological mapping, and X-ray computer tomography. It will benefit the right mindset to ensure proper technical decisions for efficient exploration and exploitation of CBM reservoirs in the Basin.

Molecular and isotopic compositions of hydrocarbon gases generated from anomalously 13C-enriched sapropelic sedimentary organic matter in lacustrine basins

For lacustrine basins, the enrichment of 13C in sedimentary organic matter is closely related to the growth of plankton biological productivity. Consequently, there are many cases where the sapropelic organic matter is more 13C-enriched than the humic organic matter. However, the geochemical characteristics of the pyrolysis products produced by 13C-enriched lacustrine sapropelic organic matter are less discussed. Herein, two lacustrine sapropelic kerogen samples with remarkably different carbon isotopic ratios (–23.2‰ and –28.4‰) and a coal sample (–25.6‰) were performed by a closed and dry pyrolysis system at temperatures ranging from 300 °C to 600 °C. The results indicated that the carbon isotopic compositions of hydrocarbon gas products were significantly affected by the initial carbon isotopic composition of their sources. At similar simulated temperatures, the carbon isotopic compositions of methane generated from the 13C-enriched sapropelic sample and the coal sample were more consistent. However, owing to the difference in their gas-generation mechanism, the natural gas generated from the coal sample had a more 13C-enriched isotopic composition of ethane (δ13C2) and a higher dryness, particularly at higher maturity levels. The hydrogen isotopic composition of methane (δ2HC1) was markedly enriched in deuterium as the thermal maturity increased and may have been independent of the genetic type and salinity. Therefore, we used the “Dryness vs. δ2HC1” and “δ13C2 vs. δ2HC1” diagrams to confirm the genetic type of natural gas in lacustrine basins.

Co-feeding of vacuum gas oil and pinewood-derived hydrogenated pyrolysis oils in a fluid catalytic cracking pilot plant to generate olefins and gasoline.

Background: The Waste2Road project exploits new sustainable pathways to generate biogenic fuels from waste materials, deploying existing industrial scale processes. One such pathway is through pyrolysis of wood wastes. Methods: The hereby generated pyrolysis liquids were hydrogenated prior to co-feeding in a fluid catalytic cracking (FCC) pilot plant. So-called stabilized pyrolysis oil (SPO) underwent one mild hydrogenation step (max. 200 °C) whereas the stabilized and deoxygenated pyrolysis oil (SDPO) was produced in two steps, a mild one (maximum 250 °C) prior to a more severe process step (350 °C). These liquids were co-fed with vacuum gas oil (VGO) in an FCC pilot plant under varying riser temperatures (530 and 550 °C). The results of the produced hydrocarbon gases and gasoline were benchmarked to feeding pure VGO. Results: It was proven that co-feeding up to 10 wt% SPO and SDPO is feasible. However, further experiments are recommended for SPO due to operational instabilities originating from pipe clogging. SPO led to an increase in the hydrocarbon gas production from 45.0 to 46.3 wt% at 550 °C and no significant changes at 530 °C. SDPO led to a rise in gasoline yield at both riser temperatures. The highest amount of gasoline was produced when SDPO was co-fed at a 530°C riser temperature, with values around 44.8wt%. Co-feeding hydrogenated pyrolysis oils did not lead to a rise in sulfur content in the gasoline fractions. The highest values were around 18 ppm sulfur content. Instead, higher amounts of nitrogen were observed in the gasoline. Conclusions: SPO and SDPO proved to be valuable co-refining options which led to no significant decreases in product quality. Further experiments are encouraged to determine the maximum possible co-feeding rates. As a first step, 20-30 wt% for SPO are recommended, whereas for SDPO 100 wt% could be achievable.

Catalytic and Kinetic Study of the CO2 Hydrogenation Reaction over a Fe–K/Al2O3 Catalyst toward Liquid and Gaseous Hydrocarbon Production

CO2 hydrogenation toward gaseous and liquid hydrocarbons has been experimentally studied over a Fe–K/Al2O3 catalyst in a fixed-bed reactor. At 15 bar, 300 °C, 2080 N mL/gcat/h, and H2/CO2 ratio of ...

Carbon-Negative Scenarios in High CO2 Gas Condensate Reservoirs

A gas condensate reservoir in Northern Croatia was used as an example of a CO2 injection site during natural gas production to test whether the entire process is carbon-negative. To confirm this hypothesis, all three elements of the CO2 life cycle were included: (1) CO2 emitted by combustion of the produced gas from the start of production from the respective field, (2) CO2 that is separated at natural gas processing plant, i.e., the CO2 that was present in the original reservoir gas composition, and (3) the injected CO2 volumes. The selected reservoir is typical of gas-condensate reservoirs in Northern Croatia (and more generally in Drava Basin), as it contains about 50% CO2 (mole). Reservoir simulations of history-matched model showed base case (production without injection) and several cases of CO2 enhanced gas recovery, but with a focus on CO2 storage rather than maximizing hydrocarbon gas production achieved by converting a production well to a CO2 injection well. General findings are that even in gas reservoirs with such extreme initial CO2 content, gas production with CO2 injection can be carbon-negative. In almost all simulated CO2 injection scenarios, the process is carbon-negative from the time of CO2 injection, and in scenarios where CO2 injection begins earlier, it is carbon-negative from the start of gas production, which opens up the possibility of cost-effective storage of CO2 while producing natural gas with net negative CO2 emissions.

Fiscal measurement and the effects of atmospheric pressure variation: Small deviations and large risks

The production and transport of liquid and gaseous hydrocarbons have always been the object of studies to improve technologies and procedures, as they involve large volumes and high-value goods. There are several procedures, rules and regulations applied to the measurement of fluid flow, but its applicability may involve significant operating costs. The balance between requirements and costs led to the use of gauge pressure transmitters instead of absolute pressure gauges and assuming a constant atmospheric pressure value for parameterization of compensation algorithms. This solution simplifies the calibration process but can potentially impact measurement uncertainties because atmospheric pressure is not constant. This work quantifies these impacts and concludes that, for gas systems operating below 2000 kPa, the use of absolute pressure transmitters or the incorporation of in-line atmospheric pressure gauges is recommended. Above this value, the effects of atmospheric pressure variation do not have as much impact, but even in these cases the final uncertainty estimate of the measured gas volume must consider this source of additional uncertainties.

Conversion of Polyethylene Waste into Gaseous Hydrocarbons via Integrated Tandem Chemical–Photo/Electrocatalytic Processes

The chemical inertness of polyethylene makes chemical recycling challenging and motivates the development of new catalytic innovations to mitigate polymer waste. Current chemical recycling methods yield a complex mixture of liquid products, which is challenging to utilize in subsequent processes. Here, we present an oxidative depolymerization step utilizing diluted nitric acid to convert polyethylene into organic acids (40% organic acid yield), which can be coupled to a photo- or electrocatalytic decarboxylation reaction to produce hydrocarbons (individual hydrocarbon yields of 3 and 20%, respectively) with H2 and CO2 as gaseous byproducts. The integrated tandem process allows for the direct conversion of polyethylene into gaseous hydrocarbon products with an overall hydrocarbon yield of 1.0% for the oxidative/photocatalytic route and 7.6% for the oxidative/electrolytic route. The product selectivity is tunable with photocatalysis using TiO2 or carbon nitride, yielding alkanes (ethane and propane), whereas electrocatalysis on carbon electrodes produces alkenes (ethylene and propylene). This two-step recycling process of plastics can use sunlight or renewable electricity to convert polyethylene into valuable, easily separable, gaseous platform chemicals.

Simulating Coal Permeability Change as a Function of Effective Stress Using a Microscale Digital Rock Model

Investigating the coal microstructure under the influence of effective stress is vital for evaluating hydrocarbon gas production and CO2 geo-storage potential of deep coal seams. While several theo...

Determining new way to detect hydrocarbon polluted water at vertical and horizontal spaces

Abstract Remote and proximal sensing are important tools to discover surface and ground natural resources such as water, wealthy minerals, and hydrocarbons. The results of this study rely on discovering the ability of water detector Aqua to detect many products of hydrocarbons and polluted water with hydrocarbon at different vertical and horizontal spaces on and under the ground. The importance of this discovery is helping to sense and detect the accurate location and underground depth of hydrocarbons and water pollution with hydrocarbons as quickly and efficiently as possible by using Aqua device. Many laboratory experiments were carried out by Aqua on different gaseous, liquid, and solid hydrocarbon products. Field experiments were achieved to test the ability of the device to detect polluted water with hydrocarbons at different distances and depths. Verification of the results was also carried out when measuring hydrocarbon concentration of several samples at the laboratory via the analytical method, relationship between lab measurements of these samples and outcomes of Aqua has significant correlation and determination.

Molecular dynamics simulation of thermal degradation of silicone grease using reactive force field

AbstractSilicone grease, consisting of polydimethylsiloxane (PDMS) chains and silica, has been widely used in electrical power systems; this causes thermal aging of silicone grease at high temperatures. In this study, the thermal degradation process of silicone grease was analyzed at different temperatures using reactive force field (ReaxFF). The effects of different factors, such as silica surface chemistry and oxygen content, on the final products have been studied. The results showed that the final products can be divided into two main categories: small gaseous molecules and large‐molecule products. The number of gaseous hydrocarbon products and their unsaturation increased with increasing temperature. The large‐molecule products were consisted of silica and surrounding PDMS chains, which were broken and reorganized during the thermal degradation process. The time interval required for the formation of the large‐molecule products is larger when silica with a modified surface is used. The addition of oxygen during thermal degradation provided a new decomposition route. The O/Si ratio in the residue of silica grease increased while the C/Si ratio decreased with the increasing oxygen content. A new method for the generation of SiO2 residues in a sufficient oxygen environment was proposed based on the reactions between oxygen and Si–CH3.