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Geomechanics and Engineering
  Volume 20, Number 6, March25 2020, pages 537-546
DOI: https://doi.org/10.12989/gae.2020.20.6.537
 


Geomechanical properties of synthesised clayey rocks in process of high-pressure compression and consolidation
Taogen Liu, Ling Li, Zaobao Liu, Shouyi Xie and Jianfu Shao

 
Abstract
    Oil and natural gas reserves have been recognised abundantly in clayey rich rock formations in deep costal reservoirs. It is necessary to understand the sedimentary history of those reservoir rocks to well explore these natural resources. This work designs a group of laboratory experiments to mimic the physical process of the sedimentary clay-rich rock formation. It presents characterisation results of the physical properties of the artificial clayey rocks synthesized from illite clay, quartz sand and brine water by high-pressure consolidation tests. Special focus is given on the effects of illite clay content and high-stress consolidation on the physical properties. Multi-step loaded consolidation experiments were carried out with stress up to 35 MPa on mixtures constituting of the illite clay, quartz sand and brine water with five initial illite clay contents (w=85%, 70%, 55%, 40% and 25%). Compressibility and void ratio were characterised throughout the physical compaction process of the mixtures constituting of five illite clay contents and their water permeability was measured as well. Results show that the applied stress induces a great reduction of clayey rock void ratio. Illite clay contents has a significant influence on the compressibility, void ratio and the permeability of the physically synthesized clayey rocks. There is a critical illite clay content w=70% that induces the minimum void ratio in the physically synthesised clayey rocks. The SEM study indicates, in the high-pressure synthesised clayey rocks with high illite clay contents, the illite clay minerals are located in layers and serve as the material matrix, and the quartz minerals fill in the inter-mineral pores or are embedded in the illite clay matrix. The arrangements of the minerals in microscale originate the structural anisotropy of the high-pressure synthesised clayey rock. The test findings can give an intuitive physical understanding of the deep-buried clayey rock basins in energy reservoirs.
 
Key Words
    artificial clayey rocks; property characterisation; low permeability; clay content; porosity reduction
 
Address
Taogen Liu: 1.) School of Civil Engineering and Architectural Engineering, Nanchang Institute of Technology, 330029 Nanchang, China
2.) Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, College of Resources and Civil Engineering, Northeastern University, Shenyang, 110819, China
3.) University of Lille, LaMcube (FR2016), 59650, Villeneuve d\'Ascq, France

Ling Li: 1.) School of Civil Engineering and Architectural Engineering, Nanchang Institute of Technology, 330029 Nanchang, China
2.) University of Lille, LaMcube (FR2016), 59650, Villeneuve d\'Ascq, France

Zaobao Liu, Shouyi Xie and Jianfu Shao: 1.) Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,
College of Resources and Civil Engineering, Northeastern University, Shenyang, 110819, China
2.) University of Lille, LaMcube (FR2016), 59650, Villeneuve d\'Ascq, France
 

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