针对非均质油藏双水平井SAGD扩容启动后水平段动用不均匀的问题,从改善渗流条件和优化驱动机理两方面出发,提出直井辅助SAGD水平井扩容启动的复合扩容新工艺。通过地质力学有限元方法与热采油藏数值模拟模型的耦合,分析了疏松砂岩地质力学扩容储层物性参数及流体流动行为变化,预测了采用新工艺扩容后注蒸汽热采开发效果。研究结果表明:直井辅助SAGD扩容应采用水平井先扩容、直井后扩容的实施顺序,避免直井先扩容情况下造成扩容位置局部窜通,利于形成均匀复合扩容带;直井扩容带宽度对于水平井轨迹与地应力方向的夹角敏感,水平井轨迹与最大水平应力平行时扩容带宽度最大;直井与水平井扩容带能否连接,和水平井轨迹与地应力方向的夹角无直接关系,直井和SAGD水平井之间的距离越大,扩容带的连接就越困难。与传统SAGD工艺相比,直井辅助扩容后,SAGD水平井重力泄油和直井蒸汽吞吐可发挥协同作用,增产效果显著。研究成果可为SAGD扩容启动现场实施提供指导。
In order to solve the problem of uneven production in horizontal interval after the start of SAGD dilation of dual horizontal wells in heterogeneous reservoir, a new composite dilation technology of vertical well assisted SAGD dilation in horizontal well was proposed from two aspects of improving seepage conditions and optimizing driving mechanism. By coupling the geomechanical finite element method with the numerical simulation model of thermal recovery in oil reservoir, the changes of physical parameters and fluid flow behavior of the geomechanical dilation reservoir of loose sandstone were analyzed, and the development effect of thermal recovery with steam injection after dilation by the new technology was predicted. The study results showed that the vertical well assisted SAGD dilation should be conducted in the order of horizontal well first and vertical well later, so as to prevent local channeling in the dilation position caused by vertical well dilation first, which was conducive to the formation of uniform composite dilation zone; the width of dilation zone of vertical well was sensitive to the angle between horizontal well track and in-situ stress direction, and the width of dilation zone was the largest when the horizontal well track was parallel to the maximum horizontal stress; whether vertical well connected to the dilation zone of horizontal well was not directly related to the angle between horizontal well track and in-situ stress direction; the greater the distance between the vertical well and the SAGD horizontal well, the more difficult it was to connect the dilation zone. Compared with the traditional SAGD technology, after the vertical well assisted dilation, the gravity drainage of the SAGD horizontal well and the steam huff and puff of vertical well could work together, and the effect of increasing production was significant. The study results can provide guidance for the on-site implementation of SAGD dilation.
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