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SAGD开采预热之前对稠油储层进行基于剪切扩容(剪胀)和张性扩容的微压裂改造有利于提高SAGD循环预热效率及蒸汽腔发育速度。微压裂阶段的稠油处于未流动状态,注水导致油砂骨架被剪胀或等向撑开,体应变变为负值,压缩系数(绝对值)增大,且压缩系数越大代表油砂储层具有更高的扩容量和更好的可注性。论文针对微压裂阶段储层压缩系数的定义、计算及测试等问题,以新疆风城陆相储层重1区齐古组为研究对象,通过油砂体积压缩实验,开展微压裂注水阶段储层压缩实验机理研究,评价考虑不同注压、注液温度等条件下油砂体积变形及压缩规律。实验结果表明,对于剪切扩容,油砂软化前的压缩系数随着平均有效应力增加而增加,软化后则正好相反;减小有效围压,降低注液温度,增加单向变形,压缩系数增大。对于张性扩容,平均有效应力越小,温度越低,压缩系数越大。该研究成果能够为评价微压裂过程中的储层可注性提供指导。
Prior to SAGD pre-heating, micro-fracturing rebuilding of heavy oil reservoirs based on shear expansion (dilatancy) and tension expansion is beneficial to improve SAGD cycle preheating efficiency and steam chamber growth rate. The heavy oil in the microfracturing stage is in a non-flowing state. Water injection causes the oil sand skeleton to dilate or isotropically, the body strain changes to a negative value, the compression coefficient (absolute value) increases, and the larger the compression factor, the oil sands The reservoir has higher capacity and better annotation. In this paper, according to the definition, calculation and test of reservoir compression coefficient in microfracturing stage, the Qigu Formation, a district of windwind terrestrial reservoir in Xinjiang, is selected as the research object. Through the experiment of volumetric compression of oil sand, Study on mechanism of reservoir compression experiment, evaluate volume deformation and compression law of oil sand under different conditions of injection pressure and injection temperature. The experimental results show that for shear expansion, the compressibility coefficient of oil sand before softening increases with the increase of average effective stress, and the opposite is true after softening; the effective confining pressure is reduced, the injection temperature is decreased, the unidirectional deformation is increased, the compressibility is increased Big. For tensile expansion, the average effective stress is smaller, the lower the temperature, the greater the compression coefficient. The results of this study can provide guidance for evaluating reservoir annability during microfracturing.