Simulation of natural gas hydrate formation skeleton with the mathematical model for the calculation of macro-micro parameters

Abstract

The quantitative relationship among the four process parameters (bentonite, binders, pressure, and time) of artificial core preparation, two macroscopic physical parameters (permeability and porosity), and three microscopic pore parameters (average pore and throat diameters and pore throat ratio) are investigated through multiple sets of experiments. Further, this research considers the natural gas hydrate formation skeleton in the Mount Elbert Well on Alaska North Slope as the simulated object. The optimal artificial core formula with permeability and porosity similar to the in situ hydrate formation skeleton was optimized by an orthogonal test, the fitting function relationships among these three aspects were obtained, and a relationship model was established.The results demonstrated that the permeability and porosity of the optimal formula are extremely close to the natural formation skeleton, and the microscopic pore morphology is similar to that of the natural cores. The established relationship model can be used to accurately estimate the permeability, porosity, and pore and throat diameters using the four process parameters; in turn, the process parameters also can be estimated. The digital simulation preparation technology of the natural gas hydrate formation skeleton developed in this work can accurately and quickly estimate the macro-micro physical parameters of the artificial hydrate formation skeleton. Further, it can also prepare 60-cm-long cores that can be used in the subsequent experimental study of the physical property response in hydrate formation drilling, playing an important role for the simulation of natural formation skeletons.