Experimental study on the effect of temperature and pressure on CH4 breakthrough pressure in unsaturated low-permeability sandstone

Abstract

Breakthrough pressure plays an important role in gas reservoir exploitation and caprock sealing evaluation.In order to simulate the effects of temperature and pressure on CH4 breakthrough pressure in low-permeability sandstones, a step-by-step method was used to conduct CH4 breakthrough experiments on an unsaturated low-permeability sandstone from the Ordos Basin under different combinations of temperature and pressure.The results show that with the increase of temperature or pressure, the breakthrough pressure and time of CH4 show a downward trend, and the pressure change has a more significant impact on the breakthrough process of CH4.It was found that the effect of temperature and pressure on the breakthrough pressure of CH4 is due to the change of interfacial tension and contact angle, and then controls the breakthrough pressure.In addition, it was found that the breakthrough pressure decreases with the increase of the two-phase viscosity ratio; the higher the temperature and pressure, the smaller the breakthrough pressure.Therefore, within this P-T range, for the unsaturated low-permeability sandstone reservoir, the higher the temperature and pressure, the more favorable for gas reservoir development; for the unsaturated low-permeability sandstone caprock, the lower the temperature and pressure, the better the sealing property of the cap rock and the safer the caprock.

Keywords

• temperature and pressure
• breakthrough pressure
• methane
• step-by-step method
• low-permeability sandstone