Abstract: The Bozi block of Tarim Oilfield is a typical tight sandstone condensate gas reservoir with serious wax plugging. So it is necessary to study the phase behavior and the wax deposition pattern of well fluids in Bozi gas reservoir, which will provide the phase enveloping diagram of the condensate gas and then help to control the paraffin deposition. In this study, the PVT tester and the self-designed microscopic solid deposition tester are used to get the phase enveloping line of the condensate gas. Such testing methods allow us to monitor phase changes of “ gas-liquid-solid" system at different temperatures and pressures. In addition, the real reservoir conditions can be visually simulated. The result shows that the phase behaviors of the waxcontaining condensate gas is extremely complex. Under different temperatures and pressures, gas phase, gas-liquid, gas-solid,and gas-liquid-solid multiphase appear. The main wax components of Bozi 104 well are C16 ~ C30, and their content is 0.111 % mol. The wax precipitation temperature is 15. 4° C, the maximum instantaneous wax deposition volume is 0. 2258 % ,and its cumulative volume is 9. 49% . When the pressure is above the dew point, the solid wax is not dominated by the condensate oil but by long plate-like coarse wax crystals. When the pressure is below the dew point, the solid wax is condensed from the gas. The wax is soluble to the condensate oil. Then a transparent colloidal, glassy block material are formed, which have a strong binding effect on the condensate oil.

Key words: condensate gas, visualization, phase behavior, wax deposition law, wax crystal morphology

摘要： 塔里木油田博孜区块属于典型致密砂岩凝析气藏，存在较为严重的蜡堵问题。因此需要对博孜区块井流物进行气藏条件下的相态与析蜡规律的实验研究，获得凝析气相态包络线相图，为凝析气井防蜡工艺提供理论支撑。文章通过可视化PVT测试仪和自主研发可视化显微固相沉积测定仪，在测试凝析气相态包络线的同时可直观观察凝析气随温度、压力变化时“气 －液 －固”三相相变形态，具有模拟气藏条件下可视化的优点。结果表明，含蜡凝析气的相态特征极为复杂，在不同温度、压力条件下，有气相、气 －液两相、气 －固两相、气 －液 －固三相等多相态变化。博孜104井凝析气中主要结蜡成分 C16～C30之间，以片状粗晶蜡为主，摩尔含量为0.111％，而地面凝析油析蜡点为 15.4 ℃，最大瞬时析蜡量 0.2258 ％，累积析蜡量9.49 ％。露点以上的气相析蜡形成的固相物质不受凝析油影响，以长型片状粗蜡晶为主；露点以下产生的固相析蜡受凝析油溶剂影响，析蜡与凝析油互溶形成透明胶状、玻璃块状物质，对凝析油具有较强束缚作用，降低凝析油流动性。

关键词: 凝析气, 可视化, 相态, 析蜡规律, 蜡晶形态