摘要
针对我国西部油田储层厚（200～300m）、泥夹层多且厚度不均（0．5～5m），分层压裂时小井眼多层封隔器下入困难及后期修井难度大等问题，采用纵向一体化穿层压裂；但由于泥夹层多、穿层难、水力裂缝如何最大程度串通储层在理论和技术上成为一大难点。基于流固耦合及岩石弹塑性断裂力学理论，建立巨厚多层一体化穿层压裂三维有限元数值模型，对泥夹层层厚、层数及射孔位置对水力裂缝垂向扩展形态的影响进行分析。结果表明，在储层厚度及注入排量一定的条件下，泥夹层较多时（≥4层），裂缝能有效穿透的泥夹层层厚〈3m；泥夹层较少时（≤2层），能有效穿透的泥夹层层厚〈5m。各泥夹层处的扩展缝宽随着夹层层厚的增加而减小。高含泥井段砂地比〈75％时，对裂缝垂向扩展的阻碍作用较大，作业时应避免在高含混岩层内射孔．应加强彝秒岩层上射孔，提升一体化压裂效果．结果显示，模型分析与微地震现场监测结果相符。
In the light of problems like thick reservoir （200 ～ 300 m）, ample muddy interbedding with uneven thickness （0. 5 ～ 5 m）, difficulty in packer tripping-in and upper workover in slim hole during multi-layered fractu- ring, vertical integrative cross-layer fracturing is applied. However, as there exist many muddy interbeds and layer- crossing is difficult, how to make hydraulic fracture furthest connect reservoirs becomes a major difficulty both in theory and in practice. A 3D finite element numerical model for huge-thickness multi-layer integrative cross-layer fracturing is established. Thickness and number of muddy interbeds, the effect of perforation position on vertical ex- tensive pattern of hydraulic fractures are then analyzed. The results show that if reservoir thickness and infill rate are constant, fractures can effectively penetrate less than 3 m with more muddy interbeds （ 〉 4 layers） ; and this number is less than 5 m with less muddy interbeds （ ≤2 layers）. With the increase of interbed＇ s thickness , the width of extensive fractures in muddy interbeds decreases. When sand-mud ratio of high-muddy interval less than 75%, it generates high resistance to the extension of fractures. Perforation in high-muddy layers should be avoided. Perforation in sand layers is preferred, so as to enhance the effect of integrative fracturing.
出处
《科学技术与工程》
北大核心
2014年第9期34-38,共5页
Science Technology and Engineering
基金
国家科技重大专项(2011ZX05046-3)资助
关键词
巨厚储层
泥夹层
一体化压裂
穿层压裂
裂缝形态
reservoir with huge thickness muddy interbed integrative fracturing fracture pattern
