AN ANALYTICAL MODEL TO DETERMINE THE MAXIMUM ALLOWABLE POINT SOURCE HEATING WITH MINIMAL RISK TO PHASE-CHANGE OF LIQUIDS IN BRAIN TISSUE

Author(s):  
Smreeti Dahariya ◽  
Amy Rachel Betz
2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Yongsheng Tan ◽  
Qi Li ◽  
Haitao Li ◽  
Xiang Zhou ◽  
Beibei Jiang

Abstract Acid treatment is an important measure to improve production for horizontal wells of carbonate reservoirs. Acid injection profile of horizontal wells (AIPHWs) is the most critical indicator of the success of the acidification. Currently, most previous works studied AIPHW based on the point source method. However, an inherent singularity exists in the point source solution, and hence, the calculation speed is too slow or the solution does not converge. To solve this problem, a semi-analytical model (coupling the wellbore flow model and reservoir seepage model) by the volumetric source method is presented to determine AIPHW in carbonate reservoirs. In this new coupled model, the permeability heterogeneity, formation contamination, acid-induced wormhole formation, and wellbore pressure drop are all considered. The results of the validations show that the results from the proposed method match well with the model results from the literature. Then, the effects of the acid injection flowrate, acid injection time, and permeability heterogeneity on the AIPHW are studied. According to the sensitivity analysis, we find that the disequilibrium degree of AIPHW becomes stronger as acid injection flowrate increases, acid injection time increases, and permeability heterogeneity coefficient increases. This study provides a guide for the design of horizontal well acidification and the evaluation of acid treatments of horizontal wells in carbonate reservoirs.


Author(s):  
B. Rajendran ◽  
J. Karidis ◽  
M-H. Lee ◽  
M. Breitwisch ◽  
G. W. Burr ◽  
...  

2013 ◽  
Vol 1545 ◽  
Author(s):  
Yejun Zhu ◽  
Baoling Huang ◽  
Jingshen Wu

ABSTRACTThe concept of low carbon, energy saving and sustainable design has been widely accepted all over the world. As a matter of fact, large amount energy is consumed to control the indoor environment to maintain a comfortable ambience for living and working. To increase the energy utilization efficiency, phase change material (PCM), which can store and release heat through phase change, has been recognized as an excellent candidate for green building. Analytical model is of great importance to describe and predict heat transfer with phase change. The classic Stefan problem solution is quite suitable for crystalline materials, which requires the input of certain phase change temperature. However, many PCMs widely used, like paraffin, are semi-crystalline materials, which have a much larger phase changing temperature range compared with small molecule crystalline materials. It is important to appropriately model the phase change of semi-crystalline polymers for the application of PCM. Furthermore, in large spatial scale prediction, widely used semi-infinite plane model is usually quite suitable to explain initial heat transfer. Unfortunately, semi-infinite plane is not the same as real situation. In this paper, by using the temperature at the end of the phase change as the equivalent melting temperature, a heat transfer model for semi-crystalline organic PCM is constructed. Meanwhile, this model concerns the phase change in a limited region. This model can serve as a fast tool to predict the one-dimensional heat transfer with phase change in an explicit form. The model is validated by the results of simulations and experiments reported in the literature.


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