Abstract

Temperature losses along a well string are investigated for the case of dry steam injection in order to determine the possibility of its delivery to the well bottom without condensation. It is assumed that in the rock, the temperature increases with increasing depth according to the geothermal gradient, the steam flow is constant, the steam at the head has a high temperature and is dry, containing no water droplets. On the way to the bottom, the steam temperature decreases, but does not yet reach the saturation point. Heat loss into rock is calculated using the generally accepted formula. The position of the point where steam condensation begins in the well is determined. Calculations are carried out for the most probable flow rates in the fields: 25, 50, 75, and 100 t/day. The heat capacity of dry steam is considered constant, which is acceptable only for low pressures, up to 3–4 MPa. In this case, a formula is proposed for the steam temperature distribution throughout the well string and the problem is solved analytically. However, at elevated pressures, it is necessary to take into account the thermal dependence of the heat capacity of steam and use a numerical method to find the temperature distribution. Based on the calculated variants, a conclusion is made about the possibility of supplying the amount of phase transition heat to the reservoir in full. If the reservoir is highly permeable and lies close to the surface, then we can hope for complete delivery of the phase transition heat to the reservoir. At formation depths greater than 500 m, steam is completely condensed in the well string. The heat of the phase transition enters the rock.

中文翻译：

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油藏干蒸汽注入井内不凝结问题

摘要

针对干蒸汽注入的情况，研究了沿井管柱的温度损失，以确定其在不冷凝的情况下输送到井底的可能性。假设岩石中，根据地温梯度，温度随着深度的增加而升高，蒸汽流量恒定，头部的蒸汽温度高且干燥，不含水滴。在到达底部的过程中，蒸汽温度降低，但尚未达到饱和点。岩石的热损失是使用普遍接受的公式计算的。确定井中蒸汽冷凝开始点的位置。计算油田最可能的流量：25、50、75 和 100 吨/天。干蒸汽的热容被认为是恒定的，仅在低压（最高 3-4 MPa）下才可接受。在这种情况下，提出了整个井柱中蒸汽温度分布的公式，并通过解析解决了该问题。然而，在高压下，有必要考虑蒸汽热容的热依赖性，并使用数值方法来找到温度分布。根据计算的变量，得出了向储层完全供应相变热量的可能性的结论。如果储层具有高渗透性并且靠近地表，那么我们可以希望将相变热量完全传递到储层。在地层深度大于 500 m 时，蒸汽在井柱中完全凝结。相变的热量进入岩石。