适用于高温高盐油藏裂缝封堵的沥青黏结体系研制及性能

Performance Evaluation of Asphalt Bonding System Applied to BlockHigh Temperature and High Salinity Reservoir Fractures

为解决高温高盐裂缝油藏的气窜问题,采用黄原胶作为携带液悬浮剂,以沥青和核桃壳两种惰性材料作为封堵主剂,在确定主剂粒径范围及悬浮剂浓度后,设计正交试验方案探索核桃壳加量、沥青加量及其软化点对裂缝岩心封窜效果的影响及最优组合。结果表明:对裂缝岩心封窜效果的影响依次为核桃壳含量>沥青含量>软化点;通过对正交试验最优方案进行验证,在高温(130℃)、高盐(223.07 g/L)的环境下,体系对2 mm的网状裂缝岩心达到了86.24%以上的封堵率。针对最优方案封堵后的微观形貌观察显示,软化后沥青发挥其“变形虫”特性,对周边核桃壳颗粒进行了黏结,充填核桃壳架桥形成的孔隙,确保封堵层不被高压流体冲垮或被裹挟,增强封堵性能。沥青-核桃壳体系具有良好的抗温、抗盐能力,且颗粒粒径、浓度、沥青软化点等关键因素可根据实际环境酌情调整,对解决恶劣油藏环境的气窜问题提供了参考。

In order to solve gas channeling problem in high-temperature and high-salinity fractured reservoir,a new blocking system was introduced that use xanthan gum as the suspending agent and walnut shell and asphalt as the main blocking agent.After the particle size range and concentration of suspending agent were determined,the systematic orthogonal experiment was designed to research the impacts of concentrations of walnut shell and asphalt and the softening point of asphalt on blocking effects,and to obtain the optimum scheme.The experimental results showed that the influence sequence of the above three factors was walnut shell concentration>asphalt concentration>asphalt softening point.In addition,by verifying the optimum scheme which was obtained from direct-vision analysis,the plugging ratio of this agent can reach more than 86.24%for 2 mm fractured core in high temperature(130℃)and high salinity(223.07 g/L)environment.The morphology observations of the optimum scheme showed that the softened asphalt demonstrated its‘amoeba’characteristic and bonded with the surrounding walnut shells.The asphalt filled in the pore which was formed by bridging walnut shells to guarantee the blocking layer not collapsed or carried by high-pressure airflow.The asphalt-walnut shell system has good resistance to high-temperature and high-salinity,and key factors such as the size and concentration of particles,asphalt softening point can be adjusted appropriately in an actual environment.It provides a reference for solving gas channeling problem in reservoirs which have serious environments.