基于光纤监测的段内多簇暂堵方案优化

Optimization of In-Stage Multi-Cluster Temporary Plugging Scheme Based on Optical Fiber Monitoring

  • 摘要: 为了实现段内簇间均匀改造,需要对优势进液簇进行暂堵。目前主要根据室内暂堵试验制定暂堵方案,但室内暂堵试验条件与实际压裂工况有一定差距,导致暂堵效果不理想。为给段内多簇压裂暂堵方案优化提供依据,优选新疆油田一口水平井(A井),针对5个压裂段设计了12套暂堵方案,利用管外光纤监测技术监测段内各射孔簇在暂堵前后进液量的变化,据此判断暂堵效果。A井实施12套暂堵方案后,未监测到簇间转向分流现象,说明暂堵无效。分析导致暂堵无效的原因为:暂堵球直径与孔眼直径不匹配;孔眼朝向具有随机性,高边孔眼难以封堵;为避免射孔刺断光纤,选用了圆形通孔的破裂盘,但对暂堵球封堵孔眼不利。为此,提出了暂堵方案改进措施:采用直径与孔眼直径相同的暂堵球封堵孔眼,并添加纤维和小粒径暂堵剂或采用绳结暂堵剂;进行定向射孔,射低边孔;采用锥形孔的破裂盘。

     

    Abstract: It is necessary to temporarily plug the dominant fluid inlet cluster to achieve uniform transformation between clusters in stages. The current temporary plugging schemes are mainly developed based on the indoor temporary plugging test. However, there is a certain gap between the indoor temporary plugging test conditions and the actual fracturing conditions, resulting in an unsatisfactory temporary plugging effect. In order to provide a basis for optimizing in-stage multi-cluster fracturing temporary plugging schemes, a horizontal well of the Carboniferous system in Xinjiang Oilfield was selected, and 12 sets of temporary plugging schemes were designed for five fracturing stages to plug holes or fracture. The out-of-pipe optical fiber monitoring technology was used to monitor the changes in fluid intake of each perforation cluster in stages before and after temporary plugging, and the temporary plugging effect was judged accordingly. After the implementation of 12 sets of temporary plugging schemes in Well A, no diversion between clusters was detected, indicating the ineffectiveness of temporary plugging. The inefficiency is attributed to factors such as the mismatched diameter of the plugging ball with the hole and the random hole orientation, making it challenging to block high-edge holes. In order to avoid perforating the optical fiber, the ruptured disc is a circular through-hole structure, which is not conducive to blocking the hole with the temporary plugging ball. Therefore, improvement measures of temporary plugging schemes were proposed: applying temporary plugging balls with a diameter the same as the hole to block the hole; adding fibers and temporary plugging agents with small particles or using rope temporary plugging agents; making low-edge holes shot through directional perforation; utilizing a tapered hole structure for the ruptured disc.

     

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