The Possibility to Estimate In Situ the Porosity of Permafrost: A Preliminary Study

Knowledge of permafrost’s ice and unfrozen water content is critical for predicting the permafrost behavior during ice–water–ice transition. This is especially relevant when ice and permafrost are melting in many regions under the influence of global warming. It is well-known that only a part of the formation's pore water turns into ice at 0 ^oC. After the further lowering the temperature, the water phase transition continues, but at gradually decreasing rates. Thus, the porous space is filled with ice and unfrozen water. The laboratory data show that frozen formations' mechanical, thermal, and rheological properties strongly depend on the moisture content. Hence, porosity and temperature are essential parameters of permafrost. In this paper, it is shown how, and by combining research in three fields: (1) geophysical exploration, (2) numerical modeling, and (3) temperature logging, it is possible to estimate in-situ the porosity of permafrost. To demonstrate the procedure, five examples of numerical modeling (where all input parameters are specified) are given. This investigation is the first attempt to analyze the permafrost’s porosity in situ quantitively.