In the cold regions, warm mud is usually used to drill deep wells. This mud causes formation thawing around wells, and as a rule is an uncertain parameter. For frozen soils, ice serves as a cementing material, so the strength of frozen soils is significantly reduced at the ice–water transition. If the thawing soil cannot withstand the load of overlying layers, consolidation will take place, and the corresponding settlement can cause significant surface shifts. Therefore, for long-term drilling or oil/gas production, the radius of thawing should be estimated to predict platform stability and the integrity of the well. It is known that physical properties of formations are drastically changed at the thawing–freezing transition. When interpreting geophysical logs, it is therefore important to know the radius of thawing and its dynamics during drilling and shut-in periods. We have shown earlier that for a cylindrical system the position of the phase interface in the Stefan problem can be approximated through two functions: one function determines the position of the melting-temperature isotherm in the problem without phase transitions, and the second function does not depend on time. For the drilling period, we will use this approach to estimate the radius of thawing. For the shut-in period, we will utilize an empirical equation based on the results of numerical modelling.

中文翻译：

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多年冻土地区的钻井：解冻带的动态

在寒冷地区，通常使用温暖的泥浆钻深井。这种泥浆导致井周围地层融化，通常是一个不确定的参数。对于冻土，冰作为胶结材料，因此在冰水过渡处冻土的强度显着降低。如果解冻的土壤不能承受上覆层的荷载，就会发生固结，相应的沉降会导致地表发生明显的位移。因此，对于长期钻井或油气生产，应估计解冻半径以预测平台稳定性和井的完整性。众所周知，地层的物理性质在解冻-冻结转变过程中发生了巨大的变化。在解释地球物理日志时，因此，了解钻井和关井期间的解冻半径及其动态非常重要。我们之前已经表明，对于圆柱系统，Stefan 问题中相界面的位置可以通过两个函数来近似：一个函数确定没有相变的问题中熔化温度等温线的位置，第二个函数不取决于时间。对于钻井期间，我们将使用这种方法来估计解冻半径。对于关井期，我们将利用基于数值模拟结果的经验方程。第一个函数确定熔融温度等温线在没有相变的问题中的位置，第二个函数不依赖于时间。对于钻井期间，我们将使用这种方法来估计解冻半径。对于关井期，我们将利用基于数值模拟结果的经验方程。第一个函数确定熔融温度等温线在没有相变的问题中的位置，第二个函数不依赖于时间。对于钻井期间，我们将使用这种方法来估计解冻半径。对于关井期，我们将利用基于数值模拟结果的经验方程。