大涝坝凝析气藏高含蜡凝析油注气石蜡析出分析

Analysis on Paraffin Deposition of High-Waxy Condensate Oil with Gas Injection in Condensate Gas Reservoirs of Dalaoba Gas Field, Tarim Basin

以塔里木盆地大涝坝高含蜡凝析气藏地层流体作为研究对象,利用可连接高温高压DBR-PVT测试装置的激光测试仪和在线过滤器,展开凝析油析蜡点和在线析蜡量实验测试,同时注入气进行多次向后接触后析蜡点测试,结合石蜡析出理论计算模型的计算结果进行对比分析。结果表明:以石蜡组分作为可调参数进行析蜡点、析蜡量模拟与实验测试结果能很好的契合,将流体中石蜡组成物质的量分数代入理论模型进行计算,能很好地预测流体多次向后接触前、后的析蜡点和析蜡量;同时,基于此流体体系进行模拟计算,给出了DL4井注入气不同接触次数后流体组成变化和不同温度下析蜡量变化趋势,注入气体主要以抽提作用为主,导致流体重质组分含量增加且析蜡点上升。所得结果可为凝析气藏进行注气前、后析蜡量计算提供依据。

In order to study formation fluids in the high-wax condensate gas reservoirs in Dalaoba gas field, experiments and tests are car-ried out for wax appearance temperature（WAT）and on-line wax precipitation amount of condensate oil with a laser test device and in-linefilters connected to high-temperature and high-pressure DBR-PVT tester. Meanwhile, gas is injected to test WAT after multiple backwardcontacts. The paper compares the results with those obtained from the theoretical calculation model for paraffin deposition. The analysisshows that if paraffin components are considered as adjustable parameters, the modeling results of WAT and wax precipitation amountcould match with the experimental results very well. If the mole fractions of paraffin components are put into the theoretical model, WATand wax precipitation amount before and after multiple backward contacts could be well predicted. Using this fluid system to perform mod-eling and calculation, the changes of fluid compositions with different contact frequencies and wax precipitation amount at different temper-atures can be obtained after gas injection in Well DL4. The injected gas mainly plays the role of extraction, which will result in the increaseof heavy component content in the fluid and the rise of WAT. The results can provide basis for calculation of wax precipitation amount be-fore and after gas injection in condensate gas reservoirs.