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- Kyuro Sasaki is a professor of Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University(K... moreKyuro Sasaki is a professor of Department of Earth Resources Engineering, Faculty of Engineering, Kyushu University(KU), Japan since 2005. He had taught at Mining College, Akita University for 20 years, and moved to KU. He holds BS, MS and PhD degrees from Hokkaido University, Sapporo, Japan. His research interests are mineral resources production, fluid mechanics and heat & mass transfer phenomena in Mining and Petroleum Industries. He has published several papers on SAGD, Methane Hydrate Production Method and Enhanced Coal Bed Methane Recovery, CO2 Geological Storage, Spontaneous Combustion of Coal and Mine Ventilation, etc. He recently forcuses on studying Geological CO2 Storage and CO2 Monitoring System.edit
Majority of the population in Pepel depend on groundwater for domestic and other purposes. However, in spite of the high potential of groundwater in this region and the number of boreholes drilled by Aid Agencies, study reveals that there... more
Majority of the population in Pepel depend on groundwater for domestic and other purposes. However, in spite of the high potential of groundwater in this region and the number of boreholes drilled by Aid Agencies, study reveals that there is still a serious problem with adequate availability and quality of groundwater supply. Watersamples from 35 selected borehole wells were collected from June – September 2016. Water samples were collected from each well for quality analyses within Pepel, Port Loko districts for Physicochemical and bacteriological analysis. The parameters tested are pH, Temperature, Color, Total Dissolved Solid, Conductivity,Calcium, Nitrate, Manganese, Chloride, Fluoride, Iron, Copper, Turbidity and Sulfate. The result obtained was compared with World Health Organization (WHO) standards for water quality. Results have shown that boreholes in Pepel have high average yield of (2.04 m3/hr. The productivity of the boreholes in Pepel cansupply enough water to the locals in the area and that most of the physical parameters are within acceptable WHO limits for drinking water quality. The entire water samples that were analyzed for chemical parameters indicated that the samples did not exceed the acceptable WHO limits. More than half of the borehole watersamples 19 (54 %) out 35 boreholes showed lower pH values that are below WHO recommended pH limits of 6.5-8.5, while 17 (46% ) out 35 boreholes fall within WHO recommended pH limits. This shows that many of the sample borehole waters from the study areas indicated a tendency to towards acidity. Thus, these water sources are acidic. The acidity of water may be attributed to marshy and sandy sulphate soils. Acids lower pH and bases increase pH of water. Fluctuation in pH reflects the biological activity and changes in the natural chemistry of waters, as well as pollution. However, 67% of the wells yielded water of good bacteriological quality.
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Swelling control is an elaborated balancing of solid-liquid ratios in the mud, influencing crucial physio-chemical features. Mechanical swelling control methods showing limitations drove recent researchers to consider chemical agents,... more
Swelling control is an elaborated balancing of solid-liquid ratios in the mud, influencing crucial physio-chemical features. Mechanical swelling control methods showing limitations drove recent researchers to consider chemical agents, including polyvinyl alcohol (PVOH). PVOH is known to have a swelling ability to improve mud rheology. The present study investigates the synergy of PVOH and Bentonite in an aqueous environment by analyzing the effluents samples. Three types of PVOH were selected: a standard PVOH and two modified PVOHs (a non-ionic group PVOH and a cationic group PVOH-3 attached to the carbon backbone. Except for the control sample (sample without polymer), PVOHs were added to different mud samples at ranging concentrations of 0.1 wt.% to 0.5 wt.%; each has a bulk volume of 400 ml. Each mud sample was filtrated at room temperature under an applied pressure of 1.28 MPa for 5 hours. The samples’ effluents were then analyzed for polymer adsorption. Preliminary filtration t...
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The early Middle Miocene Ngrayong Formation, an important reservoir of North East Java Basin, is well exposed in the central anticlinal part of Madura Island. The purpose of current study is to classify the depositional environments of... more
The early Middle Miocene Ngrayong Formation, an important reservoir of North East Java Basin, is well exposed in the central anticlinal part of Madura Island. The purpose of current study is to classify the depositional environments of the study area based on the characteristics and geometry of sedimentary facies. In the Madura island, the thicker clastics and deeper carbonates of Ngimbang Formation and Kujung Formation of Late Oligocene-Early Miocene deposited in the northeast-southwest asymmetrical half grabens. After the deposition of Kujung Formation, the basin morphology developed nearly eastwest trending shelf edge and the deposition of Tuban Formation began. The fine grained complex of Tuban Formation was followed by the Ngrayong Sandstones deposition. The depositional model of Ngrayong Formation is being producing of wide variety of depositional environments. Large scale cross-bedded sandstones and bioturbated massive sandstones with thin to medium bedded argillaceous limesto...
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Abstract Fundamentally, recovery methods of untapped crude oils require injection of foreign material(s) in the reservoir, which subsequently promote(s) the displacement of residual oil. In chemical enhanced oil recovery (EOR), the... more
Abstract Fundamentally, recovery methods of untapped crude oils require injection of foreign material(s) in the reservoir, which subsequently promote(s) the displacement of residual oil. In chemical enhanced oil recovery (EOR), the microscopic sweep efficiency depends primarily on achievement of a low interfacial tension. The present work investigates into the surface tension and phase behavior properties of microemulsion developed from a contact between a dimeric ammonium salt surfactant achieve an ultra-low interfacial tension (IFT) was compared with a conventional polysorbate surfactant commonly used in chemical EOR. At fairly low concentration, dimeric surfactants achieved an IFT of order of 10 −3 mN/m. Salinity tolerance and IFT were significantly altered not only by the heaviness i.e. API of the crude, but also by the reservoir conditions. Moreover, alkane carbon number (ACN), introduced in this work, revealed that modeling a micellar slug formulation solely based on chemical composition of the crude and/or its nature could be misleading. Presence of divalent ions was found to promote the increase in IFT rather to a shift to a lower value. Also, a relative low adsorption of micellar slug was found in both dolomite and Berea sandstone. However, active head of the dimeric surfactant showed a preferential attachment to carbonate rock while low interactions were observed for sandstone. Lastly, the present study has highlighted an inhibiting acidity activity for dimeric ammoniums salt surfactants.
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ABSTRACT Herein is investigated the potential of CO2-triggered and thermo-responsive gel as plugging agent for heterogeneous sandstone formations. The gel starts to swell from a silica-based nanofluid solution at a temperature as high as... more
ABSTRACT Herein is investigated the potential of CO2-triggered and thermo-responsive gel as plugging agent for heterogeneous sandstone formations. The gel starts to swell from a silica-based nanofluid solution at a temperature as high as 55 oC. Spectral characterization, the rheological properties, adsorption characteristics, and oil recovery efficiency from modelled heterogeneous formations are studied. The spectral characterization revealed that CO2 bubbling during gel preparation controls the partition of hydrolyzed monomers during the polymerization by silica nanoparticles. The gelation time and the gel rheological properties depend both on the formation temperature, the presence in salts. For either parameter investigated, calcium and sulfate salts have the most prominent effect. The oil recovery depends not only on the permeability distribution but also on the mitigation of the polymer adsorption. The application of CO2-triggered gels could be effective in formation with contrasted permeability but fails to give promising results for homogeneous formations.
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The dynamic varied elastic modulus and damping coefficient of underground goaf are most important factors which describes the goaf absorption ability on seismic wave energy. This numerical simulation study have focused on the effect of... more
The dynamic varied elastic modulus and damping coefficient of underground goaf are most important factors which describes the goaf absorption ability on seismic wave energy. This numerical simulation study have focused on the effect of goaf area on earthquake-wave propagation and seismic response on the ground surface in a coal mine area. The laboratory measurements were carried out by 135 porous samples cases consisting rocks and coal particles 0.12–0.25 mm in size to estimate the dynamic elastic modulus and damping coefficient of the fragmented rock masses. In this simulation, a new model on damping coefficient of longitudinal and transverse waves has been presented in considering rock size (D), effective stress (σe), porosity (φ) and compaction time (t). The empirical correlation between the damping coefficient and effective stress (depth) as well as the compaction time of the goaf area has been derived and used for each goaf and strata grid blocks in the simulation. The results showed that the peak ground acceleration (PGA) above the goaf area exhibits 9–20% reduction compared to that of unexcavated condition (original coal seam), and around 10–35% seismic energy is trapped in the goaf area as goaf varied from 100 to 700 m. In the meantime, the peak ground displacement (PGD) is amplified up to seven times for the goaf depth ranging from 100 to 700 m compared to that of the unexcavated condition. Both PGA and PGD above goaf area are smaller than those above the undisturbed coal seam.
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Abstract The CO2 diffusion coefficients in crude oils were measured from curves of oil-swelling vs. elapsed time with CO2 dissolution in the oils. The oil swelling was measured with CO2 up to a pressure of 10 MPa at 50 °C. The swelling... more
Abstract The CO2 diffusion coefficients in crude oils were measured from curves of oil-swelling vs. elapsed time with CO2 dissolution in the oils. The oil swelling was measured with CO2 up to a pressure of 10 MPa at 50 °C. The swelling coefficient and diffusion coefficient of CO2 and CH4 gases in the oil column were compared with CH4 gas. The diffusion coefficient of the heavy oil was evaluated as approximately 1.1–1.6% of that of bitumen. The swelling factors increased with pressure, and the diffusion coefficients in CO2 supercritical range were more than twice as high as those in the CO2 gas phase. An empirical equation to estimate gas solubility in crude oils vs. API gravity has been presented as well. Gas diffusion coefficients were shown to relate to oil viscosity based on the Stokes-Einstein formula and a new correlation between the two with the absolute average deviation (AAD%) of about 15.5%, derived.
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One of the most important factors of the successful production, transportation and utilization of the highly viscous oil such as bitumen is viscosity reduction. Several approaches including emulsification of bitumen as dispersed particle... more
One of the most important factors of the successful production, transportation and utilization of the highly viscous oil such as bitumen is viscosity reduction. Several approaches including emulsification of bitumen as dispersed particle in the continuous aqueous phase containing surfactant have been investigated and practised. However, recent progress in heavy oil emulsification has witnessed the use of polymeric surfactants. The use of this type of surfactants have been supported by observations including the ability to form emulsion which is easy to brake and environmental friendly compared to the low molecular weight surfactants. The present effort therefore seeks primarily to investigate the suitability of a hydrophilic polymeric surfactant in viscosity reduction of the bitumen. It has been observed that the sample of polymeric surfactant employed is able to significantly reduce the viscosity of the original sample of bitumen and stabilized the emulsion formed.
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Environmental information is important for understanding how our planet is changing and what is the role of human activities in the process of this change. Access to quality environmental information is crucial for developing relevant... more
Environmental information is important for understanding how our planet is changing and what is the role of human activities in the process of this change. Access to quality environmental information is crucial for developing relevant policies and appropriate practical responses for the global and regional environmental problems. Environmental information systems have been developed for many years to facilitate environmental information creation, organization and access; however, the boundaries of environmental information research are beyond dealing with just the systems and can cover various topics under the broad discipline of environmental information science. This article reviews the concept of the science of environmental information and the topics that might be included in it.
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Surfactant injection is one of the most effective EOR techniques. Chemical surfactants however pose a few problems such as their high cost and low-degradability. We study on the utilization of biomass such as agricultural fertilizer... more
Surfactant injection is one of the most effective EOR techniques. Chemical surfactants however pose a few problems such as their high cost and low-degradability. We study on the utilization of biomass such as agricultural fertilizer mainly comprising the residue of squeezed beer yeast for EOR as an alternative of chemical surfactants because crude oil can be completely miscible with the fertilizer solution. The fertilizer can be stably supplied at a low cost because it is a waste of beer brewing industry and is only used for an animal feed additive so far. Its retail price is approximately 1 USD/kg in Japan. We semi-quantitatively estimated the interfacial tension (IFT) between the fertilizer solution and crude oil by the oil displacement test. Concentration of the fertilizer was varied between 10 to 50 g/L. The fertilizer solution to which sodium chloride was added at a concentration of 10 to 40 g/L was hydrothermally treated at 60, 80, 100 or 120 ºC for 10, 20, 30, 45 or 60 minute...
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Primarily designed to provide hydrodynamic friction between mechanical parts of a mechanical engine, lubricating oils are hydrocarbon mixtures composed of base oils and chemical enhancers or additives. The degradation of a lubricant... more
Primarily designed to provide hydrodynamic friction between mechanical parts of a mechanical engine, lubricating oils are hydrocarbon mixtures composed of base oils and chemical enhancers or additives. The degradation of a lubricant should be regarded as a result of depletion in its additives. Through an extensive analysis of various grades of car engine oils, this work intended to elucidate the chemical mechanisms responsible of depletion in additives , thus loss of efficiency. Using both analytical tools and traditional oil condition monitoring techniques, performance enhancers degradation was found to be induced by a complex tribo-chemistry process occurring within the engine. Furthermore, physical conditions existing within were believed to promote oxidation processes that yielded acidic materials causing lubricant performance alteration. Triggered by wear metals, it has been established that conversion of antioxidant additives along with inhibition of antiwears were primary rea...
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... The GIS Model for Geothermal Resources Exploration (GM-GRE) combines the results of geological, geochemical and geophysical studies. ... 2), which are (from southwest to northeast): the Zagros Active Folded Belt, the Sanandaj Sirjan... more
... The GIS Model for Geothermal Resources Exploration (GM-GRE) combines the results of geological, geochemical and geophysical studies. ... 2), which are (from southwest to northeast): the Zagros Active Folded Belt, the Sanandaj Sirjan Orogenic Belt, Central Iran, the Alborz ...
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The present work highlights the capacity of disparate lattice Boltzmann strategies in simulating natural convection and heat transfer phenomena during the unsteady period of the flow. Within the framework of Bhatnagar-Gross-Krook... more
The present work highlights the capacity of disparate lattice Boltzmann strategies in simulating natural convection and heat transfer phenomena during the unsteady period of the flow. Within the framework of Bhatnagar-Gross-Krook collision operator, diverse lattice Boltzmann schemes emerged from two different embodiments of discrete Boltzmann expression and three distinct forcing models. Subsequently, computational performance of disparate lattice Boltzmann strategies was tested upon two different thermo-hydrodynamics configurations, namely the natural convection in a differentially-heated cavity and the Rayleigh-Benard convection. For the purposes of exhibition and validation, the steady-state conditions of both physical systems were compared with the established numerical results from the classical computational techniques. Excellent agreements were observed for both thermo-hydrodynamics cases. Numerical results of both physical systems demonstrate the existence of considerable di...
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Most coal mines are in the seismic intensity 7(12 degree evaluation or even higher in China. Large-scale mined-out spaces formed in the strata have been increased, because of excessive coal mining exploitation. The seismic response of... more
Most coal mines are in the seismic intensity 7(12 degree evaluation or even higher in China. Large-scale mined-out spaces formed in the strata have been increased, because of excessive coal mining exploitation. The seismic response of mine surface will be different from other places because of the impact of the mined-out area on the seismic wave’s propagation. This paper studies the seismic response acceleration, peak acceleration and displacement at the ground surface above unstable and compacted mined-out areas by FLAC3D numerical models for various conditions. The results of the numerical simulation are consistent with the surface seismic response of Zhaogezhuang Mine in the Tangshan earthquake, 1976. It has been shown that the seismic damage to the surface above the mined-out area especially to the surface above the boundary of the mined-out area was slightly less than those in other places at the ground surface, and the seismic damage to the surface which is 2-3 times the size ...
In this study, an operation research on the performances of Tomakomai CCS project has been carried out for investigating the permeability uncertainty and the failures on CO 2 operation and transportation. Firstly, economical effects of... more
In this study, an operation research on the performances of Tomakomai CCS project has been carried out for investigating the permeability uncertainty and the failures on CO 2 operation and transportation. Firstly, economical effects of estimation error in aquifer permeability were investigated by using a reservoir block modeling based on numerical simulation results on CO 2 injection rate. Secondary, economic loss resulted from failure of CO 2 injection was evaluated by assuming periodical injection halts. It is clear that CO 2 buffers, such as sphere gas tanks, should be installed to store CO 2 on the CCS process which can temporarily store CO 2 after it is captured when a trouble on transportation or injection processes occurs. Without a buffer, releasing the captured CO 2 to the atmosphere due to system failure or trouble in injection will add to capture costs, or will result in carbon tax or opportunity loss on CCS. The larger size of CO 2 buffer volume can potentially withstand...
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A CO2-ECBMR numerical modeling has been build for the Mao Khe coal seam in Vietnam. The numerical simulations for sensitivity studies on the dominant factors for CH4 production, such as permeability, CO2 injection rate and well spacing... more
A CO2-ECBMR numerical modeling has been build for the Mao Khe coal seam in Vietnam. The numerical simulations for sensitivity studies on the dominant factors for CH4 production, such as permeability, CO2 injection rate and well spacing have been carried out by giving CO2 and CH4 adsorption capacities and viscocities of CO2 and water as a function of the coal seam temperature (40 to 65 °C). Finally, the numerical simulations with fivespot model have been presented to evaluate CO2 injectivity and CH4 productivity by changing the well spacing. The results show that CO2 injection is roughly proportional to number of injectors, however the time of the maximum CH4 production rate is delayed with 5-spots unit area. From view of economical evaluation, drilling cost of wells and well spacing are important parameters to decide the optimum production scheme. (Received May 6, 2010; accepted September 6, 2010)
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Large volumes of unconventional fossil resource are untapped because of the capillary forces, which kept the oil stranded underground. Furthermore, with the increasing demand for sustainable energy and the rising attention geared towards... more
Large volumes of unconventional fossil resource are untapped because of the capillary forces, which kept the oil stranded underground. Furthermore, with the increasing demand for sustainable energy and the rising attention geared towards environment protection, there is a vital need to develop materials that bridge the gap between the fossil and renewable resources effectively. An intensive attention has been given to nanomaterials, which from their native features could increase either the energy storage or improve the recovery of fossil energy. The present chapter, therefore, presents the recent advancements of nanotechnology towards the production of unconventional resources and renewable energy. The chapter focuses primarily on nanomaterials applications for both fossils and renewable energies. The chapter is not intended to be an exhaustive representation of nanomaterials, rather it aims at broadening the knowledge on functional nanomaterials for possible engineering applications.
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The underlying effect of preflush salinity and silica nanofluid (Si-NF) on oil production is examined. The influence of salinity on the stability of Si-NFs is studied. A series of sand-pack floodings evaluating oil production was... more
The underlying effect of preflush salinity and silica nanofluid (Si-NF) on oil production is examined. The influence of salinity on the stability of Si-NFs is studied. A series of sand-pack floodings evaluating oil production was conducted at different concentrations of preflush salinity (0 to 4 wt.%), followed by the injection of a Si-NF (0.5 wt.%) at the trail of which postflush water was injected. The effluent water and solids were collected and analyzed using X-ray fluorescence (XRF). Interfacial tension (IFT) and contact angle measurements were conducted on the Si-NF in the presence of salinity to confirm the effect. The Si-NF became unstable and formed precipitate in the presence of salinity. The sand-pack flooding showed that when the preflush salinity was increased, the displacement efficiency (ED) using the Si-NF and postflush injection was increased (ED = 44%). The XRF of the precipitated effluent revealed that the preflush salinity and Si-NF caused mineral leaching, which...
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In this investigation, an environmentally benign and efficient way for gasification of low-rank coal under CO2 rich condition, rapid heating, and high pressure was investigated. Series of experimental and simulation studies were carried... more
In this investigation, an environmentally benign and efficient way for gasification of low-rank coal under CO2 rich condition, rapid heating, and high pressure was investigated. Series of experimental and simulation studies were carried out to compare the combustion characteristics of the Shandong (SD) low rank coal and Datong (DT) bituminous coal. It was found that the gasification potential of the SD coal sample was higher than that of the DT coal sample under the conditions investigated. A gasification model was developed and validated to predict the gasification characteristics of the low rank coal based on the experimental and the gasification kinetic parameters. It was found that the gasification conditions resulting in effective gasification of the low rank coal (in terms of CH4, CO and H2 gases production) are 100% CO2 concentration, 37.5 J/s heating rate, and 0.5 – 1 MPa pressure range.
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The present study investigated the ability of a thermophilic anaerobic microbe (herein coded as AR80) for MEOR with the further objective to quantify the uncertainty of production forecast in terms of the cumulative probability... more
The present study investigated the ability of a thermophilic anaerobic microbe (herein coded as AR80) for MEOR with the further objective to quantify the uncertainty of production forecast in terms of the cumulative probability distribution. A series of core flood experiments conducted in water-flooded Berea sandstone showed that up to 51% of initial oil-in-place was recovered when the plugs were treated with AR80 and shut-in for 14 days. Mainly, the oil recovery mechanisms were attributed to viscosity enhancement, wettability changes, permeability and flow effects. Matching the laboratory data using artificial intelligence: the optimized cumulative oil recovery could be achieved at an enthalpy of 894.2 J/gmol, Arrhenius frequency of 8.3, residual oil saturation of 20%, log of capillary number at microbe flooding stage of −1.26, and also depicted a history match error less than 3%. Therefrom, a sensitivity analysis conducted on reservoir shut-in period effect on oil recovery reveale...
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The present work investigates the effects of kaolinite on viscosity and surface tension of water-in-oil (W/O) emulsions formed from an Omani heavy crude oil and steam. In Oman, steam flooding is widely used as tertiary means to recover... more
The present work investigates the effects of kaolinite on viscosity and surface tension of water-in-oil (W/O) emulsions formed from an Omani heavy crude oil and steam. In Oman, steam flooding is widely used as tertiary means to recover untapped heavy oils. However, the production of sludge along with residual oil is one of the major issues faced in the field. An Omani heavy oil (API gravity of 21.5°) enriched with kaolinite at the fixed concentration of 10 wt % was used to form W/O emulsions by steam injection. Rheological properties of generated emulsions were investigated over the temperature range of 30–80 °C. Not only was the presence of fine particles (kaolinite) found to alter the viscosity of W/O emulsions (about 20% lower than that without kaolinite), but also kaolinite clay particles induced a thixotropic behavior of W/O emulsions. The latter observation was thought to be subsequent to a chemistry occurring upon the contact between kaolinite particles and condensed water. At a fixed concentration...
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Primarily designed to provide hydrodynamic friction between mechanical parts of a mechanical engine, lubricating oils are hydrocarbon mixtures composed of base oils and chemical enhancers or additives. The degradation of a lubricant... more
Primarily designed to provide hydrodynamic friction between mechanical parts of a mechanical engine, lubricating oils are hydrocarbon mixtures composed of base oils and chemical enhancers or additives. The degradation of a lubricant should be regarded as a result of depletion in its additives. Through an extensive analysis of various grades of car engine oils, this work intended to elucidate the chemical mechanisms responsible of depletion in additives , thus loss of efficiency. Using both analytical tools and traditional oil condition monitoring techniques, performance enhancers degradation was found to be induced by a complex tribo- chemistry process occurring within the engine. Furthermore, physical conditions existing within were believed to promote oxidation processes that yielded acidic materials causing lubricant performance alteration. Triggered by wear metals, it has been established that conversion of antioxidant additives along with inhibition of antiwears were primary re...
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Transportating and stockpiling low-rank coals are puts them under risk of spontaneous combustion, because they are very easy to get self heating ignition after drying or removing moisture due to high moisture and oxygen contents. In this... more
Transportating and stockpiling low-rank coals are puts them under risk of spontaneous combustion, because they are very easy to get self heating ignition after drying or removing moisture due to high moisture and oxygen contents. In this study, the modified concept of Equivalent Oxidation Exposure-time (EOE-Moisture time) has been presented for row-rank coals. The equations for the EOE-Moisture time have been formulated by considering moisture content and oxidation capacity in low temperature range to predict the heat generating rate as functions of coal moisture saturation and oxygen concentration in the pile. Numerical simulations were carried out by applying the EOE-Moisture time on self-heating of low rank coal by changing the coal stockpile size. It has been shown based on the numerical simulations that the temperature rising rate of the pile is increased with lower initial moisture saturation of low rank coal. It has been shown that coal including a large percent of moisture i...
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Carbon capture and storage (CCS) is an established and verified technology that can implement zero emissions on a large enough scale to limit temperature rise to below 2 °C, as stipulated in the Paris Agreement. However, leakage from CCS... more
Carbon capture and storage (CCS) is an established and verified technology that can implement zero emissions on a large enough scale to limit temperature rise to below 2 °C, as stipulated in the Paris Agreement. However, leakage from CCS sites must be monitored to ensure containment performance. Surface monitoring of carbon dioxide (CO2) concentrations at onshore CCS sites is one method to locate and quantify CCS site leakage. Employing soil accumulation chambers, we have established baseline data for the natural flux of CO2 as a threshold alert to detect CO2 leakage flux to ensure the safety of onshore CCS sites. Within this context, we conducted on-site CO2 measurements at three different locations (A, B, and C) on the INAS test field at the Ito campus, Kyushu University (Japan). Furthermore, we developed a specific measurement system based on the closed-chamber method to continuously measure CO2 flux from soil and to investigate the correlation between CO2 flux from the soil surf...
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Surfactin, which is an anionic bio-surfactant, can be effective for enhanced oil recovery because it decreases interfacial tension between oil and water. However, it forms precipitation by binding with divalent cations. This study... more
Surfactin, which is an anionic bio-surfactant, can be effective for enhanced oil recovery because it decreases interfacial tension between oil and water. However, it forms precipitation by binding with divalent cations. This study examined the countermeasure to prevent surfactin from forming precipitation for applying it to enhanced oil recovery. Alcohols, chelating agents, a cationic surfactant and an ion capturing substance were selected as the candidates for inhibiting surfactin from forming precipitation. Citric acid and trisodium citrate were selected as promising candidates through the measurements of turbidity of the mixture of the candidate, surfactin and calcium ions. Those chemicals also had a function as a co-surfactant for surfactin. However, the permeability of the Berea sandstone core into which the solution containing surfactin and trisodium citrate was injected was decreased significantly, whereas citric acid could be injected into the core without significant permea...
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CO2 microbubbles have recently been used in enhanced oil recovery for blocking the high permeability zone in heterogeneous reservoirs. Microbubbles are colloidal gas aphrons stabilized by thick shells of polymer and surfactant. The... more
CO2 microbubbles have recently been used in enhanced oil recovery for blocking the high permeability zone in heterogeneous reservoirs. Microbubbles are colloidal gas aphrons stabilized by thick shells of polymer and surfactant. The stability of CO2 microbubbles plays an important role in improving the performance of enhanced oil recovery. In this study, a new class of design of experiment (DOE)—definitive screening design (DSD) was employed to investigate the effect of five quantitative parameters: xanthan gum polymer concentration, sodium dodecyl sulfate surfactant concentration, salinity, stirring time, and stirring rate. This is a three-level design that required only 11 experimental runs. The results suggest that DSD successfully evaluated how various parameters contribute to CO2 microbubble stability. The definitive screening design revealed a polynomial regression model has ability to estimate the main effect factor, two-factor interactions and pure-quadratic effect of factors...
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This paper examined the reservoir souring induced by the sulfate-reducing bacteria (SRB) inhabiting the reservoir brine of an oilfield in Japan. Although the concentration of sulfate of the reservoir brine was lower than that of seawater,... more
This paper examined the reservoir souring induced by the sulfate-reducing bacteria (SRB) inhabiting the reservoir brine of an oilfield in Japan. Although the concentration of sulfate of the reservoir brine was lower than that of seawater, which often was injected into oil reservoir and induced the reservoir souring, the SRB inhabiting the reservoir brine generated hydrogen sulfide (H2S) by using sulfate and an electron donor in the reservoir brine. This paper therefore developed a numerical simulator predicting the reservoir souring in the reservoir into which the reservoir brine was injected. The results of the simulation suggested that severe reservoir souring was not induced by the brine injection; however, the SRB grew and generated H2S around the injection well where temperature was decreased by injected brine whose temperature was lower than that of formation water. In particular, H2S was actively generated in the mixing zone between the injection water and formation water, wh...