Yuling Tan - Academia.edu (original) (raw)

Papers by Yuling Tan

ACS Omega

Shale gas has become an important natural gas resource in recent years as the conventional oil an... more Shale gas has become an important natural gas resource in recent years as the conventional oil and gas resources are depleting. Shale gas content is one of the most important parameters for reserve calculation and sweet-spot prediction. The traditional core recovery method is widely used to determine gas content. However, the estimation of lost gas content is the main factor of error and difficulty. Large errors and uncertainties occur when using the widely used methods, such as the United States Bureau of Mines (USBM) method. Hence, a more accurate method is required. In this work, a full-process model is developed in COMSOL Multiphysics to describe the lost gas with time during the core recovery process as well as the desorption stage after the core is covered. In this method, by setting the initial gas pressure and flow parameters and matching the desorbed gas volume and considering variable diffusivity with respect to temperature, the initial gas content and the gas lost with respect to time are calculated. Overall, 10 field data are tested using this full-process model, and the USBM method is also applied to compare the results. It is found that if the ratio of lost gas volume estimated using the USBM method to the desorbed gas volume of the field data is lower than 2.0, the USBM method underestimates the lost gas compared to the full-process method; if the ratio is about 2.0, the results from the USBM and the full-process methods are comparable; and if the ratio is close to 3.0, the USBM method tends to overestimate the lost gas. The modeling results indicate that this proposed full-process method is more theoretically sound than the USBM method, which has high uncertainties depending on the number of desorbed gas data points used. Nevertheless, this proposed method requires a large number of parameters, leading to the difficulty in finding true parameters. Therefore, an optimization algorithm is required. In summary, this study provides theoretical support and a mathematical model for the inversion calculation of lost gas during shale core recovery. It is helpful to evaluate the resource potential and development economics of shale gas more accurately.

Proceedings of the 2017 7th International Conference on Education, Management, Computer and Society (EMCS 2017), 2017

Geofluids, 2021

In this work, a triple-porosity, two-phase flow model was established to fill the knowledge gap o... more In this work, a triple-porosity, two-phase flow model was established to fill the knowledge gap of previous models focusing on gas production characteristics while ignoring the impacts of water injection. The proposed model considers the water flow in the fracture systems and clay minerals and the gas flow in the organic matter, inorganic pore, and fracture systems. The proposed model is solved using a finite element approach with COMSOL Multiphysics (Version 5.6) and verified with field data. Then, the evolutions of the intrinsic and relative permeabilities during water injection and gas production are examined. Furthermore, the impacts of water injection time and pressure are investigated. Good verification results are obtained; the goodness-of-fit value is 0.92, indicating that the proposed model can replicate both the water stimulation and the gas production stages. The relative gas permeability declines during water injection but recovers in the gas depletion stage. Furthermore...

Studies in Mathematical Sciences, 2012

This paper proposed the optimal portfolio model maximizing returns and minimizing the risk expres... more This paper proposed the optimal portfolio model maximizing returns and minimizing the risk expressed as CvaR under the assumption that the portfolio yield subject to multivariate t distribution. With Fuzzy Mathematics, we solve the multi-objectives model, and compare the model results to the case under the assumption of normal distribution yield, based on the portfolio VAR through empirical research. It is showed that our returns and risk are higher than M-V model. Key words : Multivariate t distribution; The optimal portfolio; VAR; CVAR; Multi-objectives programming; Fuzzy mathematics

This paper proposed the optimal fund investment portfolio model maximizing both expected return a... more This paper proposed the optimal fund investment portfolio model maximizing both expected return and skewness as well as minimizing the variance. We use fuzzy mathematics method to solve the multi-objectives model, and a numerical example of Chinese fund market is used to illustrate that the method can be efficiently used in practice.

Petrophysical Characterization and Fluids Transport in Unconventional Reservoirs, 2019

Coal permeability is one of the most important reservoir properties for coalbed methane (CBM) pro... more Coal permeability is one of the most important reservoir properties for coalbed methane (CBM) production. Coalbed permeability is sensitive to stress and is also affected by sorption induced swelling/shrinkage. Analytical models are preferred in understanding the coal permeability behavior and are easy to use in reservoir simulations of CBM production. The widely applied assumptions in these analytical permeability models are constant vertical stress and uniaxial strain conditions. However, literature work using coupled geomechanical and reservoir simulations show that the uniaxial strain condition might be a good approximation but the constant vertical stress condition is not. Therefore, in this chapter, we consider that the deformation of roof rock will act to hold part of the overburden load and we propose a permeability model based on the nonconstant vertical stress condition. The model results show the same results as the literature results using coupled geomechanical and reser...

Journal of Natural Gas Science and Engineering, 2021

Abstract Shale gas is becoming more important in clean energy supply. There is original water con... more Abstract Shale gas is becoming more important in clean energy supply. There is original water content in shale pores under reservoir condition. In addition, the introduction of water-based fracturing fluid during hydraulic fracturing process also changes the shale reservoir water saturation. Water saturation has a profound impact on the gas effective permeability and its anisotropy, thus on shale gas production. Previous experimental studies on gas effective permeability were mostly on dry samples. Due to the great difficulty in gas-water two-phase flow experiment, there are very few experiments to study the impact of shale water saturation on gas permeability. How water content affects gas effective permeability is not well understood. This work proposes an experimental method to investigate the effect of water saturation on stress-dependent gas permeability. Moreover, the experimental method and gas permeability results are compared between this work and literature. An integrated permeability model considering the impact of water saturation is proposed. It is found that the water content has significant impact on gas effective permeability and the impact is more significant for low permeability samples.

This publication, Irrigation and Water Relations, is the fifth in a fourteen-part series of Unive... more This publication, Irrigation and Water Relations, is the fifth in a fourteen-part series of University of California Cooperative Extension online publications that comprise the Small Grain Production Manual. The other parts cover specific aspects of small grain production practices in California:

Journal of Natural Gas Science and Engineering, 2021

Proppants hold fractures open and increase fracture conductivity but must survive and remain func... more Proppants hold fractures open and increase fracture conductivity but must survive and remain functional during pressure drawdown. The shale reservoir usually suffers a high effective stress during gas depletion whilst most previous experiment works are conducted under a relative low stress level. In this work, permeability evolution was explored in a proppant-supported natural fracture of Longmaxi shale from the Sichuan Basin, China under a large effective stress range (1.5-59.5 MPa). Proppant performance was examined via continuous permeability measurements and by optical microscopy and laser-classifier measurements of particle size distributions (PSD) recored both pre-and post-loading. The permeability of the propped shale fracture is two orders of magnitude higher than that of the non-propped fracture and strongly controlled by the proppant behaviour. Surprisingly, overall permeability of the proppant pack decreases with an increase in thickness of the enclosed proppant. The decrease in the permeability with high stresses is largest for unpropped fractures and decreases with an increase in the number of layers. Most important, the mean compressibility of the non-propped and propped fracture is not constant but reduces with an increase in confining stress. This indicates that the compaction, crushing, embedment and repacking of the proppant particles, because of high effective stress, resulting in a decrease in the porosity of the proppant pack further reducing the compressibility and permeability of the supported fracture.

Energy & Fuels, 2020

Hydraulic fracturing enhances the recovery of gas from ultralow permeability shales, into which w... more Hydraulic fracturing enhances the recovery of gas from ultralow permeability shales, into which water-based fracturing fluids, proppants, and activators are typically injected. However, the impacts of the existing complex multidomain response of a heterogeneous mineral and organic matrix and fractures on the resulting heterogeneity of reservoir transport properties caused by the hydraulic fracturing remain poorly understood. To address this defect, a multidomain multiphysics model is constructed to represent a two-phase flow within a three-component heterogeneous solid system (mineral and organic matrix and fractures) representing the functional complexity of the medium. This model partitions the shale reservoir into a stimulated reservoir volume (SRV) enclosed within an unstimulated reservoir volume (USRV). Different from the previous work, the shape of the SRV is treated as the spheroid instead of the rectangular shape and the size can be determined from the spatial distribution of microseismic events rather than artificially assumed. A two-phase flow model is established for both regions with the impacts of the effective stress variation on the fracture permeability considered and solved with a finite element formalism. The fidelity of the model is first verified using two field data sets from the Barnett and Marcellus shales with good fits achieved against time histories of production. Numerical studies then investigate the impacts of relevant parameters on shale gas production behavior; specially, the impacts of the effective stress and the existence of proppants are first reported. The variations in relative permeability and intrinsic permeability within the SRV are shown to dominate the early-time response of the gas flow rate. The long-term response is mainly dependent on the mass supply from the matrix system and the encapsulating USRV region. The effectiveness of hydraulic fracturing optimized as the SRV region is maximally extended in the horizontal direction and where the increase in permeability is a convex function against a concave function. The distal transport and placement of the proppant remarkably enhance the gas production rate and resist its decline as a result of the evolving high formation stress developed by pressure drawdown. For the selection of proppant type and placement, the resulting permeability and compressibility are of complementary importance as the first controls the initial gas flow rate, whereas the second determines the permeability trend with time. Proppant permeability decreases near-linearly for a constant compressibility but exponentially where compressibility is updated to represent the true response of the proppant pack. The proposed model applies a new approach for optimizing the hydraulic fracturing process and for analyzing the shale gas production behavior.

Journal of Natural Gas Science and Engineering, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

SPE Asia Pacific Oil and Gas Conference and Exhibition, 2018

Cooper Basin is one of the most important onshore oil and gas producing basins in Australia. It a... more Cooper Basin is one of the most important onshore oil and gas producing basins in Australia. It also has the most prospective unconventional tight gas and shale gas opportunities. As tight sandstones or gas shales have low permeability, understanding the permeability behaviour is important for the production of these gas resources. In this work, tight sandstone and shale samples were obtained from an exploration well in the Cooper Basin, Australia, and they were cut into cubic samples with about 30 mm on each side using a wire saw. The cubic sample was then placed in a 3D printed membrane, therefore, permeability along each directional axis can be measured. Methane was used to characterise the permeability. Effects of gas pressure and effective stress were studied with gas pressure up to 9.5 MPa and effective stress up to 7.0 MPa. The results shows that the shale has strong permeability anisotropy at different direction. The sandstone sample also showed anisotropic behaviour, but no...

International Journal of Environmental Research and Public Health, 2019

Air pollution has become a global environmental challenge and poses major threats to human health... more Air pollution has become a global environmental challenge and poses major threats to human health, particularly for the aging population. However, few studies have investigated the effects of air pollutants on human longevity, especially based on the total regional quantities and sources. Based on investigation of the spatiotemporal variations of three air pollutants (PM10, SO2, and NOx) and three longevity indicators (centenarian ratio, centenarity index, and aging tendency), this study aims to identify the relationship between air pollution and regional longevity in Guangxi Province. Air pollutant and population data from 109 counties and areas of Guangxi were collected from environmental research reports and statistical yearbooks. Cluster and outlier analysis was used to detect the regions with high and low clusters of the longevity indicators and air pollutants. Geographically weighted regression analyses were performed to determine the relationship between longevity and air pol...

Energy & Fuels, 2019

The impact of moisture on gas adsorption capacity reduction on coal has been well recognized and ... more The impact of moisture on gas adsorption capacity reduction on coal has been well recognized and empirical correlations are widely used to quantitatively evaluate the moisture effect. However, few studies are found on fundamental modelling of moisture effect on gas adsorption capacity. In this work, two theoretical models on basis of the extended Langmuir theory (EL based) and the ideal adsorbed solution theory (IAS based) were developed to account for the gas adsorption capacity with different pressures and moisture contents. With the parameters determined from the gas adsorption on dry samples and water adsorption on samples under atmospheric condition, both models are able to predict the gas adsorption capacity under combined effect of gas pressure and moisture content. The models were verified through a set of experimental data from a coal sample from Australia and they were further applied to describe the methane adsorption behaviour on a coal sample from New Zealand. The results demonstrate that both models can reasonably predict the gas adsorption capacity on moist coal samples. Although one more parameter is required, the IAS based model could match the experimental data with higher accuracy. The research findings in this work contribute to a better understanding of the fundamentals of gas adsorption characteristics on moist coal.

Medicine, 2019

Objective: Previous studies have reported an association between cyclooxygenase-2 (COX-2) polymor... more Objective: Previous studies have reported an association between cyclooxygenase-2 (COX-2) polymorphism and gastric cancer (GC) susceptibility, but their results are controversial. This meta-analysis was intended to evaluate the relationship between the COX-2 rs20417 polymorphism and GC susceptibility in different ethnic groups. Methods: We searched PubMed, EMBASE, Web of Knowledge, and the Chinese Biomedical Database (CBM) for relevant casecontrol studies published up to October 6, 2018, which reported an association between the COX-2 rs20417 polymorphism and gastric cancer risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of this association. Results: 15 papers detailing case-control studies were included in the analysis, which included a total of 2848 GC cases and 4962 healthy controls. The meta-analysis results indicated that the COX-2 rs20417 polymorphism was associated with increased GC susceptibility under allele (G vs C: OR = 1.67, 95%CI = 1.19-2.35, P = .003), heterozygous (GG vs CG: OR = 1.44, 95%CI = 1.03-2.02, P = .034), dominant (GC+CC vs GG: OR = 1.66, 95%CI = 1.18-2.34, P = .004), homozygous (GG vs CC:OR = 2.20, 95%CI = 1.07-4.54, P = .033), and recessive models (CC vs GG+CG:OR = 2.05, 95%CI = 1.09-3.85, P = .025). An analysis of ethnic subgroups revealed that the COX-2 rs20417 polymorphism was significantly associated with GC susceptibility in Asians under all 5 models (G vs C:

Autism Research, 2019

Food allergies are frequently reported to co-occur with autism spectrum disorder (ASD), but the p... more Food allergies are frequently reported to co-occur with autism spectrum disorder (ASD), but the prevalence of this cooccurrence remains uncertain. In the present study, we examined parent-reported prevalence of co-occurring food allergy and ASD in a nationally representative sample of US children ages 2-17 in the National Health Interview Survey, study years 2011-2015. All analyses used survey weights to account for the complex sampling design. In the analytic sample of 53,365 children ages 2-17, there were 905 children with parent-reported ASD (prevalence of 1.7%) and 2,977 children with parent-reported food allergy (prevalence of 5.6%). Parent-reported food allergies were nearly 2.5 times more common in children with ASD (prevalence of 13.1%) than in children without ASD (5.4%). These results indicate that food allergies commonly co-occur with ASD, which may have etiological implications. Autism Res 2019, 00: 1-4.

International Journal of Coal Geology, 2019

Unconventional natural gas, including coalbed methane and shale gas, has become important natural... more Unconventional natural gas, including coalbed methane and shale gas, has become important natural gas resources. Coal and shale reservoirs are characterised by low porosity and low permeability and difficult for gas production. These reservoirs are also considered as fractured reservoirs, i.e. the natural fracture/cleat system in coals and bedding direction microfractures in shales. Permeabilities of these reservoirs are sensitive to stress change. During gas production, the pressure drawdown significantly increases effective stress, and thus decreases the absolute permeability. The relationship between permeability and stress is characterised by fracture compressibility, which is difficult and costly to be obtained from the field, but can be acquired easily from laboratory measurement. In this review article, the laboratory methods to obtain fracture compressibility were reviewed. Literature data on fracture compressibility for coals and shales were collated and the relationships between fracture compressibility and pressure, stress and rock properties were discussed. It is found that fracture compressibility is higher for coals than for shales, and the fracture compressibility for proppant supported fracture is even lower than that for the same shale or coal. Moreover, fracture compressibility is variable depending on gas type, gas pressure, and stress. Fracture compressibility has no correlation with absolute permeability in general, but has a weak positive correlation for the same sample.

ACS Omega

Shale gas has become an important natural gas resource in recent years as the conventional oil an... more Shale gas has become an important natural gas resource in recent years as the conventional oil and gas resources are depleting. Shale gas content is one of the most important parameters for reserve calculation and sweet-spot prediction. The traditional core recovery method is widely used to determine gas content. However, the estimation of lost gas content is the main factor of error and difficulty. Large errors and uncertainties occur when using the widely used methods, such as the United States Bureau of Mines (USBM) method. Hence, a more accurate method is required. In this work, a full-process model is developed in COMSOL Multiphysics to describe the lost gas with time during the core recovery process as well as the desorption stage after the core is covered. In this method, by setting the initial gas pressure and flow parameters and matching the desorbed gas volume and considering variable diffusivity with respect to temperature, the initial gas content and the gas lost with respect to time are calculated. Overall, 10 field data are tested using this full-process model, and the USBM method is also applied to compare the results. It is found that if the ratio of lost gas volume estimated using the USBM method to the desorbed gas volume of the field data is lower than 2.0, the USBM method underestimates the lost gas compared to the full-process method; if the ratio is about 2.0, the results from the USBM and the full-process methods are comparable; and if the ratio is close to 3.0, the USBM method tends to overestimate the lost gas. The modeling results indicate that this proposed full-process method is more theoretically sound than the USBM method, which has high uncertainties depending on the number of desorbed gas data points used. Nevertheless, this proposed method requires a large number of parameters, leading to the difficulty in finding true parameters. Therefore, an optimization algorithm is required. In summary, this study provides theoretical support and a mathematical model for the inversion calculation of lost gas during shale core recovery. It is helpful to evaluate the resource potential and development economics of shale gas more accurately.

Proceedings of the 2017 7th International Conference on Education, Management, Computer and Society (EMCS 2017), 2017

Geofluids, 2021

In this work, a triple-porosity, two-phase flow model was established to fill the knowledge gap o... more In this work, a triple-porosity, two-phase flow model was established to fill the knowledge gap of previous models focusing on gas production characteristics while ignoring the impacts of water injection. The proposed model considers the water flow in the fracture systems and clay minerals and the gas flow in the organic matter, inorganic pore, and fracture systems. The proposed model is solved using a finite element approach with COMSOL Multiphysics (Version 5.6) and verified with field data. Then, the evolutions of the intrinsic and relative permeabilities during water injection and gas production are examined. Furthermore, the impacts of water injection time and pressure are investigated. Good verification results are obtained; the goodness-of-fit value is 0.92, indicating that the proposed model can replicate both the water stimulation and the gas production stages. The relative gas permeability declines during water injection but recovers in the gas depletion stage. Furthermore...

Studies in Mathematical Sciences, 2012

This paper proposed the optimal portfolio model maximizing returns and minimizing the risk expres... more This paper proposed the optimal portfolio model maximizing returns and minimizing the risk expressed as CvaR under the assumption that the portfolio yield subject to multivariate t distribution. With Fuzzy Mathematics, we solve the multi-objectives model, and compare the model results to the case under the assumption of normal distribution yield, based on the portfolio VAR through empirical research. It is showed that our returns and risk are higher than M-V model. Key words : Multivariate t distribution; The optimal portfolio; VAR; CVAR; Multi-objectives programming; Fuzzy mathematics

This paper proposed the optimal fund investment portfolio model maximizing both expected return a... more This paper proposed the optimal fund investment portfolio model maximizing both expected return and skewness as well as minimizing the variance. We use fuzzy mathematics method to solve the multi-objectives model, and a numerical example of Chinese fund market is used to illustrate that the method can be efficiently used in practice.

Petrophysical Characterization and Fluids Transport in Unconventional Reservoirs, 2019

Coal permeability is one of the most important reservoir properties for coalbed methane (CBM) pro... more Coal permeability is one of the most important reservoir properties for coalbed methane (CBM) production. Coalbed permeability is sensitive to stress and is also affected by sorption induced swelling/shrinkage. Analytical models are preferred in understanding the coal permeability behavior and are easy to use in reservoir simulations of CBM production. The widely applied assumptions in these analytical permeability models are constant vertical stress and uniaxial strain conditions. However, literature work using coupled geomechanical and reservoir simulations show that the uniaxial strain condition might be a good approximation but the constant vertical stress condition is not. Therefore, in this chapter, we consider that the deformation of roof rock will act to hold part of the overburden load and we propose a permeability model based on the nonconstant vertical stress condition. The model results show the same results as the literature results using coupled geomechanical and reser...

Journal of Natural Gas Science and Engineering, 2021

Abstract Shale gas is becoming more important in clean energy supply. There is original water con... more Abstract Shale gas is becoming more important in clean energy supply. There is original water content in shale pores under reservoir condition. In addition, the introduction of water-based fracturing fluid during hydraulic fracturing process also changes the shale reservoir water saturation. Water saturation has a profound impact on the gas effective permeability and its anisotropy, thus on shale gas production. Previous experimental studies on gas effective permeability were mostly on dry samples. Due to the great difficulty in gas-water two-phase flow experiment, there are very few experiments to study the impact of shale water saturation on gas permeability. How water content affects gas effective permeability is not well understood. This work proposes an experimental method to investigate the effect of water saturation on stress-dependent gas permeability. Moreover, the experimental method and gas permeability results are compared between this work and literature. An integrated permeability model considering the impact of water saturation is proposed. It is found that the water content has significant impact on gas effective permeability and the impact is more significant for low permeability samples.

This publication, Irrigation and Water Relations, is the fifth in a fourteen-part series of Unive... more This publication, Irrigation and Water Relations, is the fifth in a fourteen-part series of University of California Cooperative Extension online publications that comprise the Small Grain Production Manual. The other parts cover specific aspects of small grain production practices in California:

Journal of Natural Gas Science and Engineering, 2021

Proppants hold fractures open and increase fracture conductivity but must survive and remain func... more Proppants hold fractures open and increase fracture conductivity but must survive and remain functional during pressure drawdown. The shale reservoir usually suffers a high effective stress during gas depletion whilst most previous experiment works are conducted under a relative low stress level. In this work, permeability evolution was explored in a proppant-supported natural fracture of Longmaxi shale from the Sichuan Basin, China under a large effective stress range (1.5-59.5 MPa). Proppant performance was examined via continuous permeability measurements and by optical microscopy and laser-classifier measurements of particle size distributions (PSD) recored both pre-and post-loading. The permeability of the propped shale fracture is two orders of magnitude higher than that of the non-propped fracture and strongly controlled by the proppant behaviour. Surprisingly, overall permeability of the proppant pack decreases with an increase in thickness of the enclosed proppant. The decrease in the permeability with high stresses is largest for unpropped fractures and decreases with an increase in the number of layers. Most important, the mean compressibility of the non-propped and propped fracture is not constant but reduces with an increase in confining stress. This indicates that the compaction, crushing, embedment and repacking of the proppant particles, because of high effective stress, resulting in a decrease in the porosity of the proppant pack further reducing the compressibility and permeability of the supported fracture.

Energy & Fuels, 2020

Hydraulic fracturing enhances the recovery of gas from ultralow permeability shales, into which w... more Hydraulic fracturing enhances the recovery of gas from ultralow permeability shales, into which water-based fracturing fluids, proppants, and activators are typically injected. However, the impacts of the existing complex multidomain response of a heterogeneous mineral and organic matrix and fractures on the resulting heterogeneity of reservoir transport properties caused by the hydraulic fracturing remain poorly understood. To address this defect, a multidomain multiphysics model is constructed to represent a two-phase flow within a three-component heterogeneous solid system (mineral and organic matrix and fractures) representing the functional complexity of the medium. This model partitions the shale reservoir into a stimulated reservoir volume (SRV) enclosed within an unstimulated reservoir volume (USRV). Different from the previous work, the shape of the SRV is treated as the spheroid instead of the rectangular shape and the size can be determined from the spatial distribution of microseismic events rather than artificially assumed. A two-phase flow model is established for both regions with the impacts of the effective stress variation on the fracture permeability considered and solved with a finite element formalism. The fidelity of the model is first verified using two field data sets from the Barnett and Marcellus shales with good fits achieved against time histories of production. Numerical studies then investigate the impacts of relevant parameters on shale gas production behavior; specially, the impacts of the effective stress and the existence of proppants are first reported. The variations in relative permeability and intrinsic permeability within the SRV are shown to dominate the early-time response of the gas flow rate. The long-term response is mainly dependent on the mass supply from the matrix system and the encapsulating USRV region. The effectiveness of hydraulic fracturing optimized as the SRV region is maximally extended in the horizontal direction and where the increase in permeability is a convex function against a concave function. The distal transport and placement of the proppant remarkably enhance the gas production rate and resist its decline as a result of the evolving high formation stress developed by pressure drawdown. For the selection of proppant type and placement, the resulting permeability and compressibility are of complementary importance as the first controls the initial gas flow rate, whereas the second determines the permeability trend with time. Proppant permeability decreases near-linearly for a constant compressibility but exponentially where compressibility is updated to represent the true response of the proppant pack. The proposed model applies a new approach for optimizing the hydraulic fracturing process and for analyzing the shale gas production behavior.

Journal of Natural Gas Science and Engineering, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

SPE Asia Pacific Oil and Gas Conference and Exhibition, 2018

Cooper Basin is one of the most important onshore oil and gas producing basins in Australia. It a... more Cooper Basin is one of the most important onshore oil and gas producing basins in Australia. It also has the most prospective unconventional tight gas and shale gas opportunities. As tight sandstones or gas shales have low permeability, understanding the permeability behaviour is important for the production of these gas resources. In this work, tight sandstone and shale samples were obtained from an exploration well in the Cooper Basin, Australia, and they were cut into cubic samples with about 30 mm on each side using a wire saw. The cubic sample was then placed in a 3D printed membrane, therefore, permeability along each directional axis can be measured. Methane was used to characterise the permeability. Effects of gas pressure and effective stress were studied with gas pressure up to 9.5 MPa and effective stress up to 7.0 MPa. The results shows that the shale has strong permeability anisotropy at different direction. The sandstone sample also showed anisotropic behaviour, but no...

International Journal of Environmental Research and Public Health, 2019

Air pollution has become a global environmental challenge and poses major threats to human health... more Air pollution has become a global environmental challenge and poses major threats to human health, particularly for the aging population. However, few studies have investigated the effects of air pollutants on human longevity, especially based on the total regional quantities and sources. Based on investigation of the spatiotemporal variations of three air pollutants (PM10, SO2, and NOx) and three longevity indicators (centenarian ratio, centenarity index, and aging tendency), this study aims to identify the relationship between air pollution and regional longevity in Guangxi Province. Air pollutant and population data from 109 counties and areas of Guangxi were collected from environmental research reports and statistical yearbooks. Cluster and outlier analysis was used to detect the regions with high and low clusters of the longevity indicators and air pollutants. Geographically weighted regression analyses were performed to determine the relationship between longevity and air pol...

Energy & Fuels, 2019

The impact of moisture on gas adsorption capacity reduction on coal has been well recognized and ... more The impact of moisture on gas adsorption capacity reduction on coal has been well recognized and empirical correlations are widely used to quantitatively evaluate the moisture effect. However, few studies are found on fundamental modelling of moisture effect on gas adsorption capacity. In this work, two theoretical models on basis of the extended Langmuir theory (EL based) and the ideal adsorbed solution theory (IAS based) were developed to account for the gas adsorption capacity with different pressures and moisture contents. With the parameters determined from the gas adsorption on dry samples and water adsorption on samples under atmospheric condition, both models are able to predict the gas adsorption capacity under combined effect of gas pressure and moisture content. The models were verified through a set of experimental data from a coal sample from Australia and they were further applied to describe the methane adsorption behaviour on a coal sample from New Zealand. The results demonstrate that both models can reasonably predict the gas adsorption capacity on moist coal samples. Although one more parameter is required, the IAS based model could match the experimental data with higher accuracy. The research findings in this work contribute to a better understanding of the fundamentals of gas adsorption characteristics on moist coal.

Medicine, 2019

Objective: Previous studies have reported an association between cyclooxygenase-2 (COX-2) polymor... more Objective: Previous studies have reported an association between cyclooxygenase-2 (COX-2) polymorphism and gastric cancer (GC) susceptibility, but their results are controversial. This meta-analysis was intended to evaluate the relationship between the COX-2 rs20417 polymorphism and GC susceptibility in different ethnic groups. Methods: We searched PubMed, EMBASE, Web of Knowledge, and the Chinese Biomedical Database (CBM) for relevant casecontrol studies published up to October 6, 2018, which reported an association between the COX-2 rs20417 polymorphism and gastric cancer risk. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of this association. Results: 15 papers detailing case-control studies were included in the analysis, which included a total of 2848 GC cases and 4962 healthy controls. The meta-analysis results indicated that the COX-2 rs20417 polymorphism was associated with increased GC susceptibility under allele (G vs C: OR = 1.67, 95%CI = 1.19-2.35, P = .003), heterozygous (GG vs CG: OR = 1.44, 95%CI = 1.03-2.02, P = .034), dominant (GC+CC vs GG: OR = 1.66, 95%CI = 1.18-2.34, P = .004), homozygous (GG vs CC:OR = 2.20, 95%CI = 1.07-4.54, P = .033), and recessive models (CC vs GG+CG:OR = 2.05, 95%CI = 1.09-3.85, P = .025). An analysis of ethnic subgroups revealed that the COX-2 rs20417 polymorphism was significantly associated with GC susceptibility in Asians under all 5 models (G vs C:

Autism Research, 2019

Food allergies are frequently reported to co-occur with autism spectrum disorder (ASD), but the p... more Food allergies are frequently reported to co-occur with autism spectrum disorder (ASD), but the prevalence of this cooccurrence remains uncertain. In the present study, we examined parent-reported prevalence of co-occurring food allergy and ASD in a nationally representative sample of US children ages 2-17 in the National Health Interview Survey, study years 2011-2015. All analyses used survey weights to account for the complex sampling design. In the analytic sample of 53,365 children ages 2-17, there were 905 children with parent-reported ASD (prevalence of 1.7%) and 2,977 children with parent-reported food allergy (prevalence of 5.6%). Parent-reported food allergies were nearly 2.5 times more common in children with ASD (prevalence of 13.1%) than in children without ASD (5.4%). These results indicate that food allergies commonly co-occur with ASD, which may have etiological implications. Autism Res 2019, 00: 1-4.

International Journal of Coal Geology, 2019

Unconventional natural gas, including coalbed methane and shale gas, has become important natural... more Unconventional natural gas, including coalbed methane and shale gas, has become important natural gas resources. Coal and shale reservoirs are characterised by low porosity and low permeability and difficult for gas production. These reservoirs are also considered as fractured reservoirs, i.e. the natural fracture/cleat system in coals and bedding direction microfractures in shales. Permeabilities of these reservoirs are sensitive to stress change. During gas production, the pressure drawdown significantly increases effective stress, and thus decreases the absolute permeability. The relationship between permeability and stress is characterised by fracture compressibility, which is difficult and costly to be obtained from the field, but can be acquired easily from laboratory measurement. In this review article, the laboratory methods to obtain fracture compressibility were reviewed. Literature data on fracture compressibility for coals and shales were collated and the relationships between fracture compressibility and pressure, stress and rock properties were discussed. It is found that fracture compressibility is higher for coals than for shales, and the fracture compressibility for proppant supported fracture is even lower than that for the same shale or coal. Moreover, fracture compressibility is variable depending on gas type, gas pressure, and stress. Fracture compressibility has no correlation with absolute permeability in general, but has a weak positive correlation for the same sample.