Int. J. of Oil, Gas and Coal Technology   »   2016 Vol.11, No.2

 

 

Title: Distinct performance characters and inducing mechanisms of CO2 and N2 enhanced coalbed methane recovery

 

Authors: Jian Hou; Jintao Wu; Kang Zhou

 

Addresses:
State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao, Shandong 266580, China; College of Petroleum Engineering, China University of Petroleum, Qingdao, Shandong 266580, China
College of Petroleum Engineering, China University of Petroleum, Qingdao, Shandong 266580, China
College of Petroleum Engineering, China University of Petroleum, Qingdao, Shandong 266580, China

 

Abstract: The distinction of performance characters and inducing multiple mechanisms in CO2 and N2 enhancement are ambiguous, even though the different stimulation performances have been discussed in existing studies. This article establishes an essential mathematical model and a comparison of the recovery dynamics with CO2 and N2 injection is conducted. The results indicate that the distinct characters of CO2 and N2 enhancement derive mainly from the different properties of porosity, permeability and gas sorption. The N2 injection appears more time efficient. The variation of porosity and permeability plays more complex roles when CO2 is injected as the coal seam is divided into two regions of gas concentration, pressure and cleat permeability. The influence of the coal seam and gas properties is discussed. The parameters related to the porosity and permeability variation and gas sorption inflict quite different influences between CO2 and N2 injection, while the coal seam intrinsic properties impact similarly. [Received: November 22, 2013; Accepted: September 7, 2014]

 

Keywords: enhanced coalbed methane recovery; ECBM; performance characters; mathematical modelling; numerical simulation; CO2 injection; carbon dioxide; N2 injection; nitrogen; recovery dynamics; porosity; permeability; gas sorption; coal seams; gas concentration; pressure; cleat permeability.

 

DOI: 10.1504/IJOGCT.2016.074285

 

Int. J. of Oil, Gas and Coal Technology, 2016 Vol.11, No.2, pp.204 - 227

 

Available online: 21 Jan 2016

 

 

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