聚合物堵剂对窜槽的封堵效果

Plugging Law of Polymer Plugging Agent in Channeling Model

时光

SHI Guang

随着油田深入开发，受增产、增注措施和储层物性影响，水泥环窜槽井数逐渐增多。窜槽打乱了原有开发 层系，造成严重层间干扰。分析聚合物堵剂在窜槽中的封堵规律是实现高效封堵的关键。利用水泥环窜槽封堵 物理模拟装置，以窜槽模型的突破压力、微观结构及岩心的分流率作为评价手段，从窜槽结构、注入轮次、注入速 率3 个角度分析水泥环封窜规律。研究结果表明，在一定的实验条件下，窜槽模型的结构直接影响了封窜效果， 窜槽裂缝宽度越宽，封堵效果越差，窜槽内的堵剂会出现无法紧密贴合缝壁或断裂等情况，当窜槽裂缝宽度为 1.5 mm时，突破压力仅为11.46 MPa；大部分堵剂流经裂缝进入了高渗层，分流率大于80%。注入轮次也是影响 封窜效果的重要参数之一，对于结构复杂的窜槽则需要多轮次的封窜才能保证效果，当注入轮次提高到3 次时， 突破压力达到了14.33 MPa。降低注入速率可以改善堵剂对低渗层的污染，当注入速率为0.25 mL/min 时，低渗 透岩心的分流率可降低至10.8%。本文探索了聚合物堵剂对水泥环窜槽的封堵规律，对窜槽井的封窜具有重要 的指导意义。

With the continuous development of oil field，the number of channeling wells gradually increased due to the change of the reservoir physical properties and the measures for increasing production and injection. The exploration-layer system which is interrupted by the channeling causes serious interlayer interference. The key to achieving effective plugging is to analyze the sealing laws of chemical plugging agent in channeling. In this paper，a set of physical simulation equipment was developed to simulate the sealing process of cement sheath channeling. The sealing laws of cement sheath was analyzed from channeling structure，injection cycle and injection rate，based on the breakthrough pressure，microstructure of channeling model and diversion rate of core. The experimental results showed that，the structure of the channeling model directly affected the channeling sealing effect. The wider the crack width was，the worse the plugging effect was. At worst，the plugging agent could not closely fit the wall of the fracture or plugging agent broke at the upper part of the model. When the channeling crack width was 1.5 mm，the breakthrough pressure was only 11.46 MPa. Most of the plugging agent flowed through the fracture and entered the high permeability layer，which made the diversion rate greater than 80%. Injection cycle was also one of the important parameters that affect the sealing effect of channeling. A complicated channeling required multiple cycles of sealing to ensure the effect. When the injection rounds were increased to three cycles，the breakthrough pressure reached 14.33 MPa. The decrease of injection rate could reduce the pollution of plugging agent to low permeability layer. When the injection rate was 0.25 mL/min，the diversion rate of low permeability core could be reduced to 10.8%. The research on the sealing law of cement sheath channeling had important guiding significance for sealing of channeling well.

10.19346/j.cnki.1000-4092.2023.02.014