油砂SAGD开发过程中面临的夹层问题

麦凯河油藏岩心资料表明油砂储层含有不等厚度、延伸范围和频率的低物性夹层,其对SAGD生产动态和蒸汽腔发育特征的影响成为关注的焦点。为此,根据夹层含量和分布位置划分四类SAGD井组;以此为研究对象,开展三维数值模拟研究沿程和垂向剖面蒸汽腔发育特征,并利用二维数值模拟对夹层位置、厚度和宽度等因素进行敏感性分析。研究认为,相比井组上方夹层,井间夹层对SAGD生产动态不利影响更大;延长预热时间并不能改善SAGD开发效果;夹层主要是阻碍了蒸汽上升通道以及冷凝蒸汽和加热原油的泄流通道,导致沿程蒸汽腔发育不均匀。

Shale Layers Issues in Oil Sands SAGD Process

Core data of Makay River reservoir shows there are shale layers of varying thickness, lateral extent and frequency, and their impact on SAGD performance and steam chamber growth becomes the focus of most concern. For all this, SAGD well pairs can be divided into four categories according to frequency of shale layers and relative position to the injector. Focused on these four kinds of SAGD well pairs, the effect of shale layers on steam chamber development was studied by 3D numerical simulation, and sensitivity analysis was developed to study location, thickness and lateral extent of shale layers by 2D numerical simulation. The results demonstrate that Shale layers between the injector and producer are more harmful to SAGD performance than that over well pair. Prolong the heating time cannot improve SAGD performance. Shale layers mainly block the flow path of steam moving upwards or heated oil and condensed steam draining downwards, making it extremely difficult to forming relatively uniform steam chamber along the wellbore.