Measurement of Tensile Characteristics of Methane Hydrate and Extraction of DEM Model Parameters

Knowingthe tensile response of methane hydrate (MH) is essentialfor understanding the mechanical behavior of hydrate-bearing sandlayer and is also necessary for enhancing gas production using hydraulicfracturing. In this study, the tensile response of MH with no sandparticles was measured and the parameters necessary for a discreteelement method (DEM) were extracted from the experimental results.First, powdered MH was filled into small and large cups, the MH inthe two cups were integrated as one MH sample by annealing, and theMH samples were subjected to tensile experiments. The reason two cupswere used is that we wanted to identify the area of the fracture plane,which is the same as the top surface area of the small cup. We alsomeasured the MH content and filling ratio by decomposing the samplesand by measuring the weight and volume of the samples, respectively.The results indicated that the tensile Young's modulus of MHwas between 6 and 48 MPa and its tensile strength ranged from 0.14to 1.14 MPa depending on the filling ratio. It was also shown thatthe higher the filling ratio, the larger the tensile strength. Next,we considered continuum MH as an aggregate of virtual particles anddeveloped an MH particle bond model. By performing a series of DEMsimulations of tensile experiments and comparing with the experimentalresults, we obtained the parameters of the DEM bond model for thevirtual MH particles, such as a suitable radius of 0.5 & mu;m, abond Young's modulus of 750 MPa, and a bond tensile strengthof 3000 MPa.