Experimental and theoretical quantification of the relationship between electrical resistivity and hydrate saturation in porous media

FUEL

卷:269

Article

Jin, Yurong^1,2  Li, Shuxia¹  Yang, Daoyong² 

[1] China Univ Petr East China, Coll Petr Engn, Qingdao 266580, Peoples R China

[2] Univ Regina, Petr Syst Engn, Fac Engn & Appl Sci, Regina, SK S4S 0A2, Canada

关键词: Methane hydrate;    Electrical resistivity;    Porosity;    Tortuosity;    Archie formula;   

DOI  :  10.1016/j.fuel.2020.117378

来源: Elsevier

【 摘 要 】

An equivalent resistivity model is proposed and validated to determine hydrate saturation based on the experimentally measured resistivity. Experimentally, hydrate with different saturations is formed in an artificial sandpack to measure pressure, temperature, and resistivity as a function of time. The resistivity evolution includes induction of nucleation, large-scale hydrate nucleation, and hydrate rearrangement. Theoretically, a mathematical model on the basis of the parallel circuit principle is developed to quantify the relationship between resistivity and hydrate saturation by taking sand skeleton, temperature, brine salinity, and formation tortuosity into account. The formation tortuosity is expressed as a function of water relative permeability which can be determined by incorporating the existing semi-empirical models. In addition, the cementation exponent and saturation index in the Archie formula are empirically obtained by nonlinearly regressing the experimental measurements, while the sand skeleton resistivity, the correlation coefficient of formation tortuosity, and hydrate saturation index are introduced and determined in the equivalent resistivity models. It is found that the equivalent resistivity models are in a better agreement with the experimental measurements, while the Archie formula introduces an obviously larger error at higher hydrate saturation. Furthermore, it is recommended to use the dynamic porosity expressed as a function of hydrate saturation when characterizing the electrical properties and three-phase flow in porous media. Also, the equivalent resistivity models are found to have a less dependence on the accuracy of porosity compared with the Archie's formula.

【 授权许可】

Free