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A novel experimental methodology based on nuclear magnetic resonance (NMR) is proposed to examine sensitivity damage mechanisms in clay-containing reservoirs. We successfully implemented this methodology for Nanyang tight oil reservoir. By performing experiments under conditions of different brine salinities and pH values, the degrees of potential salt and alkali sensitivity damage were determined first; thereafter, the damage mechanisms were identified by analyzing the NMRT2spectra and (magnetic resonance) MR images. TheT2spectra clearly showed the quantitative exchange between small pores and big pores, and the changes in pore size at different positions in the core were visualized in the MR images obtained before the centrifugation of the core. To understand the behavior of clay size variation and clay migration in the damage process, the core was centrifuged, leaving only the clay bound water in the core, and then MR images were acquired again. The salt sensitivity damage mechanisms of clay swelling and clay migration and alkali sensitivity damage mechanism of clay dispersion and migration in Nanyang tight oil reservoir were effectively identified. Additionally, owing to the use of core-scale MR images, the sensitivity damage processes at the reservoir scale could be interpreted well. [ABSTRACT FROM AUTHOR]

Objective: To study the impact of interposed abdominal pulling-pressing cardiopulmonary resuscitation (IAPP-CPR) for patients with cardiac arrest (CA)., Methods: A prospective study was conducted. A total of 122 CA patients admitted to Department of Emergency of Shandong Provincial Mining Industry Group Company Central Hospital from July 2013 to December 2017 were enrolled. They were divided into standard cardiopulmonary resuscitation (S-CPR) group (n = 62) and IAPP-CPR group (n = 60) according to order of admission. The patients in S-CPR group received external cardiac compression, open airway, endotracheal intubation, mechanical ventilation, routine drug rescue, and defibrillation when ventricular fibrillation was found. And the patients in IAPP-CPR group received the IAPP-CPR on the basis of the routine chest compression. During the relaxation period, the patients were subjected to abdominal lifting and compressing with amplitude of 4-5 cm, frequency of 100 times/min, and the time ratio of lifting to compressing was 1:1. The data of demographics and clinical signs of patients were collected. The markers of respiratory and circulatory performance of all patients after CPR were determined. The rates of restoration of spontaneous circulation (ROSC), successful resuscitation, and the prognosis were recorded. With the success of CRP as the dependent variable, the factors with statistical significance showed by univariate analysis were used as the independent variable to carry out two classification Logistic regression analysis for screening the influence factors of CPR success. Receiver operating characteristic (ROC) curve was plotted to analyze the predictive value of various factors on the success of CPR., Results: 122 patients were enrolled in the analysis. Compared with the S-CPR group, heart rate (HR), mean arterial pressure (MAP), arterial partial pressure of oxygen (PaO 2 ), and end-tidal carbon dioxide partial pressure (P ET CO 2 ) were significantly increased at 30 minutes after CPR in IAPP-CPR group [HR (bpm): 66.3±11.5 vs. 53.1±12.6, MAP (mmHg, 1 mmHg = 0.133 kPa): 65.4±6.5 vs. 53.2±5.4, PaO 2 (mmHg): 77.7±11.8 vs. 61.8±14.3, P ET CO 2 (mmHg): 45.5±9.6 vs. 31.8±8.2, all P < 0.05], and arterial partial pressure of carbon dioxide (PaCO 2 ) and lactic acid (Lac) were significantly lowered [PaCO 2 (mmHg): 46.7±6.2 vs. 57.9±9.5, Lac (mmol/L): 2.1±1.5 vs. 4.4±2.2, both P < 0.05]. The time of CA to ROSC in IAPP-CPR group was significantly shorter than that in S-CPR group (minutes: 6.3±1.8 vs. 11.2±1.4, P < 0.05), the ROSC rate and CPR success rate were significantly higher than those in S-CPR group [ROSC rate: 61.7% (37/60) vs. 43.5% (27/62), CPR success rate: 40.0% (24/60) vs. 21.0% (13/62), both P < 0.05], and 24-hour survival rate and survival and discharge rate of patients were significantly higher than those in the S-CPR group [24-hour survival rate: 46.7% (28/60) vs. 29.0% (18/62), survival and discharge rate: 20.0% (12/60) vs. 11.3% (7/62), both P < 0.05]. Logistic regression analysis showed that PaO 2 , PaCO 2 and P ET CO 2 were the factors that affect the success of CPR [PaO 2 : β= -3.76, odds ratio (OR) = 0.23, 95% confidence interval (95%CI) = 0.12-0.86, P = 0.031; PaCO 2 : β= 1.41, OR = 4.09, 95%CI = 1.70-9.82, P = 0.002, P ET CO 2 : β= 0.78, OR = 2.18, 95%CI = 1.42-3.35, P = 0.000]. ROC curve analysis showed that the above three factors had good predictive value for the success of CPR. The predictive value of PaCO 2 and P ET CO 2 were better, the area under ROC curve (AUC) was 0.93 and 0.92, respectively, when the cut-off values was 46.7 mmHg and 48.8 mmHg, the sensitivity was 92.0%, 88.0%, respectively, and the specificity was both 94.3%., Conclusions: PaO 2 , PaCO 2 and P ET CO 2 are the factors that influence the success of CPR. PaCO 2 and P ET CO 2 have great value in predicting the success of CPR. Compared with the S-CPR group, IAPP-CPR group results in better hemodynamic and pulmonary ventilation effects, and remarkably improve ROSC and successful resuscitation. IAPP-CPR has obvious clinical value for CA patients.