A Three-Fold Classification of Tight Gas Based Primarily on Dynamic Relationship Between Gas Charging History and Reservoir Tightening Process and its Application
Lei Zhang1, 2, 3, *, Lunwei Zhu1, 3, Jianian Shen1, 3, Qifei Huang2
Identifiers and Pagination:Year: 2015
First Page: 51
Last Page: 57
Publisher Id: TOPEJ-8-51
Article History:Received Date: 18/8/2014
Revision Received Date: 17/11/2014
Acceptance Date: 16/12/2014
Electronic publication date: 12/3/2015
Collection year: 2015
open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Building upon the foundation of the prior investigations, a three-fold classification of tight gas reservoirs is proposed in this paper which is based primarily on dynamic relationship between gas charging history and reservoir tightening process, coupled with tectonic evolution, source-reservoir relationship, migration and charging pattern. The three categories of tight gas are: (1) “pre-existing” basin-centered gas reservoir, in which the reservoir sands experienced earlystage tightening processes, occurring before peak gas generation, expulsion from source rock, and charging of reservoir; (2) “pre-existing subsequent-improved” tight gas reservoir, in which the reservoir sands were also tightened before gas charging and then underwent reservoirs improvement mainly caused by the tectonic activities; and (3) “subsequentconventional” tight gas reservoir where reserved sands were tightened after the peak of gas generation, expulsion from source rock, and charging of reservoir. This type of tight gas initially formed conventional gas accumulation during gas charging of reservoir, and subsequently modified to tight gas reservoir. All the three categories of tight gas have different geological conditions of gas accumulation and gas accumulation patterns, which can be used as characteristics to classify these tight gas systems, and thus have distinctive control on regional gas distribution. The results of applying this tight gas classification for an actual basin show that correctly distinguishing these three kinds of tight gas reservoirs from each other could contribute greatly to the exploration and development of tight gas reservoirs.