Although several researches have been conducted for CO 2 injection in shale gas reservoirs, there is definite lack of study that concentrates on the multi-component transport and geomechanical effect. This paper presents shale gas model for CO 2 injection considering dissolution, molecular diffusion and stress-dependent permeability as well as multi-component adsorption. Based on information of Barnett shale reservoir, a simulation model is constructed for CO 2 flooding. Extended Langmuir isotherm is used to simulate the competitive sorption among the molecules involved. Gas solubility is represented by Henry's law. Co-and counter-diffusive transportsare depicted by Sigmund correlation. Stress-dependent permeability in shale reservoir is considered by exponential correlation with the linear-elastic constitutive model. In the proposed model, the mechanisms and parameters which could influence on CO 2 injection are studied. A series of reservoir simulations based on these effects are performed to study effective injection of CO 2 .Mechanisms of CO 2 injection in shale gas reservoir contribute to both enhanced CH 4 recovery and storage of CO 2 . Desorption of CH 4 in the model with the multi-component adsorption is activated by competitive sorption with the CO 2 which is preferentially adsorbed over CH 4 with a ratio up to 5:1. Molecular diffusion enables CO 2 to displace CH 4 in ultra-low matrix permeability condition. The model with molecular diffusion presents wide spread CO 2 in the reservoir compared with the model not considering molecular diffusion. Because of ultra-low permeability of shale reservoir, effect of diffusion is higher than conventional reservoirs so that it should be considered in the CO 2 injection model of shale reservoir. CO 2 injection supports the reservoir pressure so that effect of stress-dependent permeability is mitigated compared with primary recovery model. In this model, CO 2 injection improves shale gas recovery about 12%. The CO 2 injected in the reservoir exists as a super-critical phase, adsorption trapping, and dissolution trapping of 45.8, 46.5, and 3.6%, respectively. According to reservoir and fracture parameters, amount of each state would be changed. The sensitivity analysis for either enhanced CH 4 recovery or CO 2 storage is conducted to investigate the critical parameters that control these CO 2 -EGR process and CO 2 storage, respectively.This work presents study for mechanisms of CO 2 injection in shale gas reservoir taking account of multi-component adsorption, dissolution, molecular diffusion, and geomechanical effect and sensitivity analysis for uncertain parameters of the shale reservoir. The investigation is important for better understanding and design of CO 2 injection in order to enhance CH 4 recovery and CO 2 storage.
S E T T I N G : Eleven referring hospitals in South Korea. O B J E C T I V E :To compare therapeutic responses in chronic obstructive pulmonary disease (COPD) subgroups, classifi ed by diffusing capacity of the lung for carbon monoxide (DL CO ) and lung volume. D E S I G N : A total of 130 stable male COPD patients were classifi ed into four subgroups according to baseline DL CO and residual volume/total lung capacity (RV/TLC) ratio. We compared therapeutic responses to short acting β 2 -agonist (SABA) and 3-month combined inhalation of long-acting β 2 -agonist (LABA) and corticosteroid among patients with these subgroups. CHRONIC obstructive pulmonary disease (COPD) is characterised by chronic airfl ow limitation that is not fully reversible. 1 COPD is not a single disease but rather a group of conditions with variable clinical, physiological and radiographic manifestations. 2 S U M M A R YThe Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines recommend different treatment strategies based on the severity of airfl ow limitation, as assessed by post-bronchodilator forced expiratory volume in 1 second (FEV 1 ) values. 1 Although FEV 1 is useful in the diagnosis and physiological staging of COPD, arbitrary stratifi cations of SDL and YMO contributed equally to this article.
THE DEVELOPMENT of pulmonary hypertension (PH) is often observed in advanced chronic obstructive pulmonary disease (COPD) and indicates a poor prognosis, with a 5-year survival rate of 20-36%. 1,2 PH primarily occurs in COPD patients with severe hypoxaemia; fortunately, however, the PH is typically mild. 3 Hypoxaemia increases pulmonary artery pres- S U M M A R Ysure (PAP) through hypoxic pulmonary vasoconstriction and vascular remodelling. 4 However, there is a poor correlation between lung function parameters and PAP, suggesting that factors other than airway obstruction and/or loss of alveolar surface may play a role in its aetiology.Recent studies have shown that a proportion of patients with only moderate airway obstruction have severe PH. 5,6 Disproportionate PH in COPD patients seems best defi ned as at least moderate elevation in SDL and YMO contributed equally to this article.
Whether indoor painting aggravates preexisting allergic diseases remains unclear. We aimed to evaluate the impact of new classroom painting on aggravation of asthma, allergic rhinitis (AR), and atopic dermatitis (AD) in children. Studied school was previously painted with conventional water-based paint 20 years ago and had natural ventilation system. We identified a total of 172 children aged 10-12 years with allergic diseases in 17 classrooms, which were allocated to newly painted rooms with low-volatile organic compounds (VOC), water-based paint, or existing rooms. After painting, there was no intervention or internal airflow to influence indoor air environment in both classrooms. We prospectively assessed the symptom severity and serious events of allergic diseases between both classrooms at baseline and after one and eight weeks after painting. At one and eight weeks, there were no significant changes in the Childhood Asthma Control Test scores, the fractional nitric oxide levels, lung function in asthmatic children in either classroom. There were also no significant changes in the severity score of AR or AD, or serious events in all allergic diseases. These findings suggest classroom painting with this new paint at the levels encountered in this study might not be a major aggravating factor for school-aged children with allergic diseases.
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