A new method for the estimation of lost gas during the measurement of the gas content of coal

Meng Lu, Tom Blasingame (Editor), Zhejun Pan, Ray Johnson Jr (Editor), Luke D Connell, Ye Lu

Research output: Chapter in Book/Report/Conference proceedingConference PaperOther

3 Citations (Scopus)


n this text, the authors present a study on estimating the lost gas during the retrieval process of coal sample within wellbores. A new method is proposed because the traditional ones often give inaccurate predictions. To this end, the major sources of errors with those routine methods are first discussed briefly, and modifications are made accordingly in the present method to improve the accuracy of prediction. This new method takes into account these aspects: (1) Both the advection and diffusion effects are included in the proposed flow equation; (2) the present model uses the actual shape of the core sample (say, a cylinder) rather than a simplified 1D spherical object; and (3) a fully numerical scheme is developed in which the actual retrieval history is used to specify the boundary conditions of the core sample. When the relevant sorption isothermal curve for the coal is known, the proposed model contains three parameters to be determined, which refer to the effective permeability, the effective diffusion coefficient, and the initial gas content or the initial gas pressure. The three parameters are determined through best matching the experimental data with the aid of an artificial-neural-network (ANN) technique. Two application examples are presented in this study. One is with a benchmark laboratory test, and the other is with a standard field case studied by means of an established method. It is shown with the two examples that the present method can give accurate predictions for the lost gas volume concerned, and offers some important advantages that the traditional ones do not have.
Original languageEnglish
Title of host publicationSPE Asia Pacific Unconventional Resources Conference and Exhibition
Subtitle of host publication9-11 November, Brisbane, Australia
PublisherSociety of Petroleum Engineers
Pages1 - 15
Number of pages15
ISBN (Electronic)9781613993880
Publication statusPublished - 2015
EventSPE Asia Pacific Unconventional Resources Conference and Exhibition - Brisbane QLD Australia, Brisbane, Australia
Duration: 9 Nov 201511 Nov 2015


ConferenceSPE Asia Pacific Unconventional Resources Conference and Exhibition

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