CO2 assisted steam flooding in late steam flooding in heavy oil reservoirs

To improve the oil recovery and economic efficiency in heavy oil reservoirs in late steam flooding,taking J6 Block of Xinjiang Oilfield as the research object,3D physical modeling experiments of steam flooding,CO2-foam assisted steam flooding,and CO2 assisted steam flooding under different perforation conditions are conducted,and CO2-assisted steam flooding is proposed for reservoirs in the late stage of steam flooding.The experimental results show that after adjusting the perforation in late steam flooding,the CO2 assisted steam flooding formed a lateral expansion of the steam chamber in the middle and lower parts of the injection well and a development mode for the production of overriding gravity oil drainage in the top chamber of the production well;high temperature water,oil,and CO2 formed stable low-viscosity quasi-single-phase emulsified fluid;and CO2 acted as a thermal insulation in the steam chamber at the top,reduced the steam partial pressure inside the steam chamber,and effectively improved the heat efficiency of injected steam.Based on the three-dimensional physical experiments and the developed situation of the J6 block in Xinjiang Oilfield,the CO2 assisted steam flooding for the J6 block was designed.The application showed that the CO2 assisted steam flooding made the oil vapor ratio increase from 0.12 to 0.16 by 34.0%,the oil recovery increase from 16.1%to 21.5%,and the final oil recovery goes up to 66.5%compared to steam flooding after perforation adjustment.

Characterization of Malalignment between Atrial and Ventricular Septa in Overriding/Straddling Tricuspid and Mitral Valves

Objective:Overriding/straddling of an atrioventricular valve is a consequence of atrial-ventricular septal malalignment.We sought to characterize the malalignment by analogizing it to a flap-door and using structured approach.Methods:The echocardiograms and magnetic resonance images of 35 patients with overriding/straddling tricuspid or mitral valve were evaluated to assess the following modifiers;the malaligned part of the septum,the reference structure,and the mechanism,direction and severity of malalignment.Results:The pathology included classic overriding tricuspid valve in 15,classic overriding mitral valve in 12,and overriding tricuspid valve with left juxtaposition of atrial appendages in 8.In classic overriding tricuspid valve,the ventricular septum was hinged to the anterior interventricular groove and its insertion to the posterior interventricular groove was displaced toward the right ventricle.The VSD primarily involved the inlet but also extended toward the anterior interventricular groove.In classic overriding mitral valve,the ventricular septum was hinged to the posterior interventricular groove and crux cordis.Its insertion to the anterior interventricular groove was displaced toward the left ventricle.The VSD primarily involved the anterior part but also extended toward the inlet.Overriding tricuspid valve with left juxtaposition of atrial appendages had a mild degree of malalignment with displacement/rotation of the atrioventricular junction.Evenly spaced short-axis images were most helpful in characterizing the pathology.Conclusions:Overriding/straddling atrioventricular valves can be easily understood by analogizing the atrial-ventricular septal malalignment to a flap-door and describing the pathology in a structured manner.Contrary to what has previously been known,the VSD is not limited to the inlet or outlet part of the ventricular septum.

New Insights into Sinus Venosus Defects from Cross-Sectional Imaging

Sinus venosus defects include two varieties,superior and inferior sinus venosus defects.The superior sinus venosus defect is characterized by abnormal communication between two closely related venoatrial structures:1)the normally positioned superior vena cava-right atrium complex and 2)the right pulmonary vein-left atrium complex that is displaced leftward,forward and upward.Inferior sinus venosus defects primarily involve the inferior vena cava-right atrial junction while the right pulmonary vein-left atrial junction can also be affected.Because of the rarity and wide variation of the defects,the morphological characterization of sinus venosus defects is inconsistent among investigators and often inaccurate.Modern imaging technologies with high spatial and temporal resolutions have allowed accurate and detailed assessment of the pathological anatomy in larger numbers of cases.In this pictorial essay,we revisit the established and controversial features of the sinus venous defects using twodimensional(2D)and three-dimensional(3D)images obtained by magnetic resonance(MR)or computed tomography(CT)with brief discussion on imaging and treatment strategies.

The Overriding Interest

Twenty years ago,far-sighted leaders of China and the Association of Southeast Asian Nations(ASEAN)launched a dialogue that deep-ened mutual understanding and trust,and helped forge close cooperation between the two sides.Since then,China and ASEAN have bolstered part-nerships

某些特殊形式的同位概念

但除了这种语法概念的同位语句外,英语中还有某些语法上不是同位语而实际含义上却具有同位概念的语言现象,应引起我们在学习和实际使用时的注意。本文想就这个问题作一点介绍。