Experimental Study of the Pore Structure and Permeability of Coal by Acidizing

Bo Zhao, Guangcai Wen, Haitao Sun and Xusheng Zhao
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Bo Zhao: College of Resources and Environment Science, Chongqing University, Chongqing 400030, China
Guangcai Wen: College of Resources and Environment Science, Chongqing University, Chongqing 400030, China
Haitao Sun: Gas Research Branch, China Coal Technology and Engineering Group Chongqing Research Institute, Chongqing 400037, China
Xusheng Zhao: Gas Research Branch, China Coal Technology and Engineering Group Chongqing Research Institute, Chongqing 400037, China

Energies, 2018, vol. 11, issue 5, 1-15

Abstract: The permeability of coal reservoirs prominently determines methane flow in reservoirs. A large amount of coal reservoirs containing methane, however, have low permeability because pores in reservoirs are sealed. To solve this issue, we investigated the pore structure and permeability law of coal through contrastive analysis of the microstructure and macrostructure before and after acidizing, using ASAP 2020 and triaxial servo-controlled seepage equipment. An analysis of the experimental data revealed the mechanism and the key parameters of acidizing, such as acid mass fraction and acidizing time. In addition, we hold that the optimal mass fraction for the test specimens is about 12~15%. Furthermore, the acid reaction is divided into three stages according to characteristics of the reaction progress. An analysis of the reaction kinetics of “ HCl-HF ” states that the significant factors will impact the process of reaction, like the composition of coal, surface area of the acid-coal reaction, mass fraction of acids, and environment of the reaction system. The results provide a new idea and research method for further enhancing permeability and gas extraction.

Keywords: acidizing; coal; specific surface area; pore volume; permeability; HCl-HF system (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2018
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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