Naturally fractured hydrocarbon reservoir simulation by elastic fracture modeling

Accurate fluid flow simulation in geologically complex reservoirs is of particular importance in construction of reservoir simulators.General approaches in naturally fractured reservoir simulation involve use of unstructured grids or a structured grid coupled with locally unstructured grids and discrete fracture models.These methods suffer from drawbacks such as lack of flexibility and of ease of updating.In this study,I combined fracture modeling by elastic gridding which improves flexibility,especially in complex reservoirs.The proposed model revises conventional modeling fractures by hard rigid planes that do not change through production.This is a dubious assumption,especially in reservoirs with a high production rate in the beginning.The proposed elastic fracture modeling considers changes in fracture properties,shape and aperture through the simulation.This strategy is only reliable for naturally fractured reservoirs with high fracture permeability and less permeable matrix and parallel fractures with less cross-connections.Comparison of elastic fracture modeling results with conventional modeling showed that these assumptions will cause production pressure to enlarge fracture apertures and change fracture shapes,which consequently results in lower production compared with what was previously assumed.It is concluded that an elastic gridded model could better simulate reservoir performance.

Evaluation of Myocardial Strain and Aortic Elasticity in Patients with Bicuspid Aortic Valve

This study evaluated the myocardial strain and aortic elasticity in patients with bicuspid aortic valve（BAV） and then investigated the relation between them. Thirty-nine patients（30 males; mean age 44±19 years; range 6 to 75 years） with BAV were recruited as BAV group, and 29 age- and sex-matched healthy controls（21 males; mean age 42±11 years; range 20 to 71 years） served as control group. Aortic strain, distensibility and stiffness index were derived using M-mode echocardiography. Left ventricular global myocardial strain was acquired with speckle-tracking echocardiography. Correlation between aortic elasticity and myocardial strain was also analyzed. The results showed that aortic stiffness was higher（17.5±14.0 vs. 5.3±2.7, P〈0.001）, and aortic strain（4.9±4.7 vs. 11.0±4.1, P〈0.001） and distensibility（1.8±2.1 vs. 3.7±1.6, P〈0.001） were lower significantly in BAV group than in control group. Global circumferential strain（–19.1±4.2 vs. –22.5±3.7, P〈0.001）, radial stain（29.8±14.9 vs. 38.0±8.8, P〈0.001） and longitudinal stain（–18.4±3.4 vs. –20.8±3.5, P〈0.001） were significantly lower in BAV group than in control group. There was weak association between aortic elasticity and myocardial strain. These findings indicated BAV patients manifest reduced myocardial strain which had weak relationship with aortic elastic lesion.

Ferroelectric solid solutions with perovskite- and columbite-type components: From structures formation to domain and hysteresis phenomena

The paper reports results on the complex study on ferroelectric ceramics that represent solid solutions containing components with a perovskite-type or columbite-type structure.Solid solutions of a three-component(1−x−y)NaNbO_(3)−xKNbO_(3)−yCdNb_(2)O_(6) system are manufactured at x=0.05-0.20 and y=0.10.Domain structures in ceramic grains are studied.The consistency between experimental and calculated results is examined for coexisting phases split into non-180°domains(mechanical twins)in the solid solution with x=0.15.A correlation between the internal structure(crystal,domain,granular,and defect)and fundamental elec­tromechanical and polarization properties is stated for the studied three-component solid solutions.