柯克亚凝析气藏注气前缘突破判断、调整及注气效果

柯克亚凝析气田西五一（3）凝析气藏循环注气先导试验区从1994年9月开始注气，至1999年8月结束，因所用注采井网多是利用现有老井组成，各单井注采井距、储层物性等方面都存在较大差异，各采气井气窜时间也不同。为提高循环注气的整体开发效果，如何判断注气前缘是否突破并对采气井进行调整显得尤为重要。在西五一（3）先导试验区注气实践中，通过对井口油压、气油比、井流物中C^＋₅的变化进行规律性总结，结合干气波及系数归纳出了4种方法，并对单井、井组气窜进行综合了判断。根据判断结果，进行注气量、采气量和井网调整，地层中的反凝析现象得到了明显改善，气油比上升减缓甚至下降。试验区注气期间累积采凝析油7.0183×10⁴t，凝析油采出程度达39.2%，比衰竭式开采的采收率21％提高了18.2个百分点，采收率得到了明显的提高。

JUDGMENT AND ADJUSTMENT OF GAS-INJECTION FRONT AND RESULTS OF GAS INJECTION IN AKEYA CONDENSATE RESERVOIRS

Gas injection in the pilot testing zone for cycle gas injection of Xiwu-3 condensate reservoir in Akeya condensate field began in Sep., 1994 and ended in Aug., 1999. Since the injection/production well pattern was formed mostly by the old existing wells, the space between the wells and the reservoir physical property of each well was very different, and the time when gas channeling happens was also different for each production well. To improve the development results of the cycle gas injection, it is very important how to judge if the gas-injection front was broken, and adjust the production of gas wells. In the gas-injection practice of the pilot testing zone for Xiwu condensate reservoir, with summing the changing law of the wellhead surface-tubing pressure, the gas/oil ratio, and the C_ 5+ content of the well fluid, the 4 methods are derived combining the conformance factor of dry gas. And the judgment of gas channeling is conducted comprehensively for single well and well group. According to the judgment results, the gas-injection volume, the gas production and the well pattern are adjusted. So, the retrograde condensation situation of the formations is improved obviously. The gas/oil ratio ups slower and even downs. The cumulative production of condensate oil is 70,183 t during the gas-injection period in the testing zone. The recovery level of condensate oil reaches to 39.2%, which is 18.2 percent more than 21% of the recovery factor by natural depletion.