Hydraulic fracturing in a penny-shaped crack. Part II: Testing the frackability of methane hydrate-bearing sand

• Published in: Journal of Natural Gas Science and Engineering
• Main Authors: Too, Jun Lin, Cheng, Arthur, Khoo, Boo Cheong, Palmer, Andrew, Linga, Praveen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2018
• Subjects: Methane hydrate
• Online Access: https://oceanrep.geomar.de/id/eprint/47060/; https://oceanrep.geomar.de/id/eprint/47060/1/Too_Part2.pdf; https://doi.org/10.1016/j.jngse.2018.01.046

Highlights • Methane hydrate in sand with hydrate saturation 50–75% can be artificially fractured using hydraulic fracturing. • The apparent fracture toughness was determined to range between 0.3 and 1.4 MPa√m. • Linear regression suggests that cementing structure began to exhibit when hydrate saturation above 40%. Abstract This work examines the susceptibility of methane hydrate in sand to fracture. The task is made difficult because of two challenges: (1) the means to conduct hydraulic fracturing experiments under high pressure and low temperature conditions, and (2) the formation of high saturation hydrate-bearing sand. The apparent fracture toughness ( ) of a material is usually determined via conducting standard tests such as three-point bend on notched beams or pull test on compact specimens. In Part I, Too et al. (2018), hydraulic fracturing in a penny-shaped crack was found able to determine and estimate the tensile strength of frozen sand. As such, experiments were conducted using the similar approach on the synthesized high saturation methane hydrate-bearing sand specimens (approximately 50–75%) with sample size of 80 mm in diameter and 150 mm in length. The range of determined is between 0.3 and 1.4 MPa√m while the tensile strength estimated ranges between 6 and 12.5 MPa for the hydrate saturation range. The possibility of creating artificial fractures in synthetic methane hydrate-bearing sand may present an opportunity to improve the gas production from natural occurring hydrate-bearing sand.