Experimental Research On Simulated Natural Gas Hydate Bearing Sediments

Research on the reservoir properties of hydrate bearing sediments is a key point in gas hydrate development. Formations of gas hydrate influence the properties of hydrate bearing sediments, and thus affect the acoustic velocity, resistivity and permeability of sediments. Experiments with different hydrate saturations were conducted to measure the properties of simulated hydrate bearing sediments and the effects of gas hydrate were considered. The experiment devices were designed big with ambient and axial pressure to simulate in-sit hydrate sediments. Cementation effect of hydrates was introduced to Wylie equation. Solid hydrates fill the voids between sand grains and change the cementation condition of the formation, which can impact the propagation of sounds. The revised equation fit the experimental data well. Salt-removing effect and the block effect of hydrate change the mineralization and connectivity of pore fluids, and thus impact the resistivity of hydrate sediments. Experimental equation was proposed based on experimental data between resistivity and hydrate saturation. The paper pointed that the solidness and cementing effect of gas hydrate changes the explanation parameters in Archie's formula, which makes the Archie's formula did not fit the experimental data well. The permeability experiments were conducted and the exponent formula was proved in the calculation of permeability of hydrate bearing sediments. Experimental relationships in traditional petroleum industry should be validated or revised in hydrate bearing sediments to make a good result. The data and conclusions of this paper will give some supports in the explanation of hydrate bearing sediments.