Simulation of microwave’s heating effect on coal seam permeability enhancement
|نوع نگارش مقاله||
scopus – master journals – JCR
۴٫۲۷۶ در سال ۲۰۲۰
۲۶ در سال ۲۰۲۱
۰٫۹۰۱ در سال ۲۰۲۰
|شاخص Quartile (چارک)||
Q1 در سال ۲۰۲۰
خرید محصول توسط کلیه کارت های شتاب امکان پذیر است و بلافاصله پس از خرید، لینک دانلود محصول در اختیار شما قرار خواهد گرفت و هر گونه فروش در سایت های دیگر قابل پیگیری خواهد بود.
فهرست مطالب مقاله:
As hydraulic fracturing was forbidden in some countries due to possible negative environmental impacts and enhanced coalbed methane (ECBM) was restricted by in-situ conditions, microwave heating was pro- posed to enhance coalbed permeability. One of the mechanisms of improving coal permeability with microwave irradiation is that thermal expansion caused by microwave heating. To study the influence of microwave’s heating effect of coal samples, the simulations were conducted using a coupled electro- magnetic, thermal and mechanical model in this paper. The temperature, Von-Mises stress and strain dis- tribution of coal sample are recorded every 10 s. The permeability distribution is also obtained based on the relationship between strain and permeability from articles. It was found that volume average temper- ature, stress, strain and permeability increase almost linearly with time. The average permeability increased from 1.65 ۱۰ ۱۶ m2 to 3.63 ۱۰ ۱۶ m2 under 2.45 GHz and 500 W microwave radiation after 300 s. The significant increase proved microwave to be effective in coal seam permeability enhancement.
|بخشی از متن مقاله:|
Gas drainage has been widely adopted in mine production. The exploitation of coalbed methane (CBM) is not only important to coal mine safety production, but also significant to energy conser- vation and environment protection [1–۴]. The enhancement of coal seam permeability is one of the most crucial problems in gas drai- nage. The most commonly used method to achieve permeability enhancement is hydraulic fracturing and enhanced coalbed methane (ECBM). However, hydraulic fracturing is environmen- tally harmful, and ECBM is restricted by field conditions and not effective for certain cases. Therefore, alternative methods were sought to address this problem as well. In recent years, microwave was proposed to enhance coal seam permeability due to its pene- trability and heating effect.
Several experiments were carried out to study microwave’s effect on coalbed permeability enhancement. Li’s NMR tests
indicated that pore size of coals, as well as the total pore volume, increase under microwave irradiation . Kumar found that cleat volume of unconfined coal sample increased from 1.8% to ۱۶٫۱% and concluded that microwave can be applied in enhancing the connection between wellbore and fracture system in coal seams .
Beyond that, numerical simulations were also introduced to microwave’s heating effect on coal sample . Lin investigated the influence of microwave frequency, microwave power, coal per- mittivity and coal size on coal’s microwave heating effect . How- ever, all these models only studied the microwave heating effect of coal sample, while neglecting the accompanying thermal stress and its influence on coal seam permeability.
The aim of this paper is to study the microwave’s heating effect on coal samples and to investigate the accompanying thermal stress’s effect on permeability. A coupled electric, heat transfer and mechanics model was built with COMSOL Multiphysics. The electric field and thermal field were coupled with microwave heat- ing effect. The thermal field distribution and thermal stress of coal sample were obtained when microwave frequency and power determined. Then, the permeability of coal sample can be calcu- lated using the relations between stress and permeability. The results show that microwave has significant effect on enhancing permeability of coal.
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