Wang Jintang, Xu Jiaqi, Bai Yujing, Xu Hao, Liao Bo, He Guolei, Li Yiyao, Li Wenbiao
State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao, 266580, China.
School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, 266580, China.
Sci Rep. 2024 Sep 30;14(1):22678. doi: 10.1038/s41598-024-73445-1.
Natural gas hydrate is a promising unconventional natural gas source due to its high energy density and huge global reserves. During exploitation, the drilling fluid may invade the hydrate formation and induce hydrate decomposition, causing reservoir damage. Herein, a novel reservoir protectant made by bio-degradable temporary plugging material (BDTPM) was developed in the form of polymer-ceramic composite microcapsules. As an additive to the drilling fluid, the BDTPM can minimize drilling fluid intrusion by plugging the reservoir during drilling and afterwards maximize permeability recovery by degrading the material. The particle size distribution was in the range of 1-130 μm. The optimal mass ratio between modified ceramic particles, ethyl cellulose and epoxy resin was found to be 4:2:1. The plugging rate was 100% when ethyl cellulose and epoxy resin were mixed to coat the ceramic particles to form BDTPM, and the plugging performance was the best. At a temperature close to the typical hydrate reservoir environment (5 °C), 0.02 wt% low-temperature complex enzyme can degrade BDTPM, and the permeability recovery rate is 64.66%. The efficient reservoir protectant developed in this work could play an important role in the successful drilling of natural gas hydrate reservoirs.
天然气水合物因其高能量密度和巨大的全球储量，是一种很有前景的非常规天然气资源。在开采过程中，钻井液可能侵入水合物地层并导致水合物分解，造成储层损害。在此，一种由可生物降解的临时封堵材料（BDTPM）制成的新型储层保护剂以聚合物 - 陶瓷复合微胶囊的形式被开发出来。作为钻井液的添加剂，BDTPM在钻井过程中通过封堵储层可使钻井液侵入最小化，之后通过材料降解使渗透率恢复最大化。粒径分布在1 - 130μm范围内。发现改性陶瓷颗粒、乙基纤维素和环氧树脂之间的最佳质量比为4:2:1。当乙基纤维素和环氧树脂混合以包覆陶瓷颗粒形成BDTPM时，封堵率为100%，且封堵性能最佳。在接近典型水合物储层环境的温度（5℃）下，0.02 wt%的低温复合酶可降解BDTPM，渗透率恢复率为64.66%。这项工作中开发的高效储层保护剂在天然气水合物储层的成功钻探中可发挥重要作用。
