Over 60% of the original oil in a place (OOIP) is retained in a reservoir after conventional methods have been exploited. Application of enhanced oil recovery (EOR) technology gives an additional chance to get out possibly about 20% more oil from the reservoir. The use of watersoluble polymers improves the water-oil mobility ratio, therefore, the displacement efficiency increased, and leads to enhanced oil recovery. High-molecular-weight polyacrylamide group is widely and successfully used in EOR. But no commercial polymer composition can be used in conditions of high temperature and hardness brine offshore reservoirs yet. To avoid the time consumption and high expense for selection and synthesis of the appropriate-structural polymer for EOR application, we attempt to find additives to enhance the thermal stability of polymer solutions. In this paper, we report the results of improved viscosity stability of diluted polymer/ seawater solutions aged at reservoir conditions for 31days by adding graphite-oxide particles (GOs). In the presence of 300 ppm of GOs, the viscosity stability of 1700 ppm acrylamide-based polymer in sea water solution increases from 92 °C to 135 °C. FESEM pictures show good distribution of GOs in polymer network, which is a result of integration of functional groups in GOs surfaces and hydrophilic polymer chains.

Highlights Pneumopericardium is a rare laparoscopic complication, mostly subclinical. Chest pain and dyspnea might be the manifestation of pneumopericardium, however, of harmful cardiopulmonary conditions as well. Conservative managements are efficient in hemodynamically stable.

Abstract:This paper describes a solution to the T-joint problem in matching 2D fragments of an object. Matching fragments of an object is useful for solving puzzles or reassembling archaeological fragments. Many factors, such as the number of pieces and the complex shapes of pieces make this a difficult problem. Various approaches to this problem exist. This paper presents an approach to solving the T-joint problem, which comes up in assembling fragments. The work described in this paper starts with a 2D object that should be easy to extend to 3D problems.

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