A New Method for Research on Unsteady Pressure Dynamics and Productivity of Ultralow-Permeability Reservoirs

In the numerous low-permeability reservoirs, knowing the real productivity of the reservoir became one of the most important steps in its exploitation. However, the value of permeability interpreted by a conventional well-test method is far lower than logging, which further leads to an inaccurate skin factor. This skin factor cannot match the real production situation and will mislead engineer to do an inappropriate development strategy of the oilfield. In order to solve this problem, key parameters affecting the skin factor need to be found. Based on the real core experiment and digital core experiment results, stress sensitivity and threshold pressure gradient are verified to be the most influential factors in the production of low-permeability reservoirs. On that basis, instead of a constant skin factor, a well-test interpretation mathematical model is established by defining and using a time-varying skin factor. The time-varying skin factor changes with the change of stress sensitivity and threshold pressure gradient. In this model, the Laplace transform is used to solve the Laplace space solution, and the Stehfest numerical inversion is used to calculate the real space solution. Then, the double logarithmic chart of dimensionless borehole wall pressure and pressure derivative changing with dimensionless time is drawn. The influences of parameters in expressions including stress sensitivity, threshold pressure, and variable skin factor on pressure and pressure derivative and productivity are analyzed, respectively. At last, the method is applied to the well-test interpretation of low-permeability oil fields in the eastern South China Sea. The interpretation results turn out to be reasonable and can truly reflect the situation of low-permeability reservoirs, which can give guidance to the rational development of low-permeability reservoirs.

Lung diffusing capacity for nitric oxide measured by two commercial devices: a randomised crossover comparison in healthy adults

In Europe, two commercial devices are available to measure combined single-breath lung diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) in one maneuver. Reference values were derived by pooling datasets from both devices, but agreement between devices has not been established.We conducted a randomised crossover trial in 35 healthy adults (age 40.0±15.5 years, 51% female) to compare DLNO (primary endpoint) between MasterScreen™ (Vyaire Medical, USA) and HypAir (Medisoft, Belgium) devices during a single visit under controlled conditions. Linear mixed models were used adjusting for device and period as fixed effects and random intercept for each participant.Difference in DLNO between HypAir and MasterScreen was 24.0 mL·min−1·mmHg−1 (95% CI 21.7 to 26.3). There was no difference in DLCO (−0.03 mL·min−1·mmHg−1, 95% CI −0.57 to 0.12) between devices while alveolar volume (VA) was higher on HypAir compared to MasterScreen™ (0.48 L, 95% CI 0.45 to 0.52). Disparity in the estimation of VA and the rate of NO uptake (KNO=DLNO/VA) could explain the discrepancy in DLNO between devices. Disparity in the estimation of VA and the rate of CO uptake (KCO=DLCO/VA) per unit of VA offset each other resulting in negligible discrepancy in DLCO between devices. Differences in methods of expiratory gas sampling and sensor specifications between devices likely explain these observations.These findings have important implications for derivation of DLNO reference values and comparison of results across studies. Until this issue is resolved reference values, established on the respective devices, should be used for test interpretation.

A User Experience and eHealth Literacy Inspection of a Lab Test Interpretation Mobile App for Citizens

People are increasingly able to access their laboratory (lab) results using patient-facing portals. However, lab reports for citizens are often identical to those for clinicians; without specialized training they can be near impossible to interpret. In this study, we inspected a mobile health application (app) that converts traditional lab results into a citizen-centred format. We used the Health Literacy Online (HLO) checklist to inspect the app. Our inspection revealed that most of the app’s strengths were related to its Organization of Content and Simple Navigation and most of its weaknesses were related to Engage Users. We also identified several usability and user experience (UX) issues that were beyond the purview of the HLO checklist. Although this app represents an important step towards making lab results universally accessible, we identified several opportunities for improvements that could increase its value to citizens.

Neuropsychological Assessment of the Aging Physician: A Review & Commentary

Late-career physicians (LCPs) are at risk for cognitive changes that may affect their ability to practice medicine. This review aggregates and discusses research that has examined cognitive functioning among physicians, typically when clinically referred for various medical and psychological reasons that may interfere with their ability to practice medicine. Special consideration is devoted to the role of approaches for examining cognitive functioning (e.g., cognitive screening, cognitive testing, & neuropsychological assessment), normative challenges, and cultural factors that should be considered when evaluating a physician. Based on published studies, there is evidence supportive of the use of cognitive testing and neuropsychological assessment among physicians in a fitness for duty setting. However, prospective studies designed to identify physicians at-risk (i.e., to prevent medical error) are lacking. Additional research is warranted to establish physician-based normative reference groups and aid in test interpretation and prognostication. Moreover, given limitations associated with cognitive testing in isolation, there is a potential role for comprehensive neuropsychological assessment to identify cognitive changes in physicians and provide a supportive pathway to preserve physicians’ ability to practice medicine.