Abstract: PVT experiment is a conventional method used to determine the phase characteristics of oil and gas at different pressures and temperatures, which helps oil exploration and development workers to more accurately and quickly determine the physical parameters of oil and gas. At present, there are still two unresolved problems in the PVT experiment of condensate gas. One is that a check is carried out only on the monotonicity and ranges of similar experimental data, and there is a lack of a checking method suitable for different PVT experiment data. The other is that the volume factor of condensate oil and dissolved gas-oil ratio cannot be directly measured by experiments, while the phase simulation software adopts the method of fitting before calculation, and many uncertainties still exist. In view of above problems, based on the principle of phase separation volume equilibrium under standard conditions, in combination with equal composition expansion and equal volume depletion experiment conditions, the paper establishes the material balance equation and material balance equation for both equal composition expansion experiment and equal volume depletion experiment on condensate gas, respectively. Compared with the commercial phase state simulation software, for the condensate gas with high condensate oil content, the relative errors of relevant parameters under different depletion pressures calculated by the laboratory material balance equation are as follows:1.9 % for retrograde condensate saturation, 2.8 % for condensate volume coefficient, and 6.3 % for the solution gas-oil ratio in condensate oil, indicating that the both are in good agreement with each other. Three application examples demonstrating that the laboratory material balance equation plays an important part in the basic research on condensate gas reservoir development are listed as below:(1)Based on the routine checking of similar experimental data, the matched checking process for different experimental data can be further achieved. (2)Without adding any new experimental equipment and experimental procedures, the condensate oil volume coefficients and solution gas-oil ratios can be simply calculated while checking the quality of experimental data. (3)Considering the influence of the pressure stages of equal volume depletion experiments, dynamic indicators for the natural depletion of constant-volume condensate gas reservoirs can be predicted.

Key words: condensate gas, laboratory, material balance, condensate oil properties, data checking, dynamic prediction

摘要： PVT实验用来测定油气在不同压力和温度下的相态特征,是一种可以帮助石油勘探开发工作者更准确、快速测定油气物性参数的常规方法。对于凝析气PVT实验尚存在2个未解决的难题:①对实验数据的检查,局限于同类实验数据的单调性和数据范围,缺乏不同类实验数据之间的匹配性检查手段;②实验无法直接测取凝析油体积系数和溶解气油比,而相态模拟软件采用先拟合再计算的方法,存在诸多不确定因素。针对这两个难题,依据标准状况条件下分相体积平衡原理,结合等组成膨胀实验和等容衰竭实验条件,建立了凝析气等组成膨胀实验物质平衡方程式和等容衰竭实验物质平衡方程式。与商业化相态模拟软件相比,对于高凝析油含量凝析气,实验室物质平衡方程式计算各级衰竭压力下相关参数的相对误差分别为:反凝析液饱和度为1.9 % ;凝析油体积系数为2.8 % ;凝析油溶解气油比为6.3 % ,二者吻合度高。通过3个应用实例的分析,体现出实验室物质平衡方程式在凝析气藏开发基础研究中的重要作用:①在同类实验数据常规检查基础上,可进一步实现实验数据的匹配性检查;②不需新增任何实验设备和实验流程,在对实验数据做出质量甄别的同时,实现凝析油体积系数和溶解气油比的简单求取;③考虑等容衰竭实验压力级数的影响,实现定容凝析气藏衰竭开发动态指标预测。

关键词: 凝析气, 实验室, 物质平衡, 凝析油性质, 数据检查, 动态预测