超低渗透油藏水平井缝间异步周期注采补能技术

Inter-fracture asynchronous periodic injection-production energy supplement technology for horizontal wells in ultra-low permeability reservoirs

由于超低渗透砂岩油藏水平井缺乏补充能量的有效手段,为此提出水平井同井缝间轮换注采工艺。该工艺管柱由丢手接头、Y445封隔器、Y341封隔器、单向配注器、单向配产器、脱卡器组成,可实现部分压裂缝注水、部分压裂缝采油,在同一口水平井内实现分段异步注采补能。缝间异步注采增油是水驱、弹性驱、渗吸多种驱动机理综合作用的结果,相比传统的面积注水井网,更容易形成有效驱动。研究表明:水平井同井缝间异步周期注采补能方法采用水力压裂裂缝注水,油藏吸水面积大幅度增加;流场形状由径向渗流转变为线性渗流;缩短注入端与采出端的距离,提高了驱替压力梯度,有效渗透率也随之增大,这些机制综合作用起到了增油的效果。现场试验表明,水平井同井缝间异步周期注采补能方法能有效提升单井产量,可在超低渗砂岩油藏规模推广。

Since horizontal wells in ultra-low permeability sandstone reservoirs lack effective means of energy supplement, an alternate injection-production process between fractures in same horizontal well was proposed. The process string is composed of release sub, Y445 packer, Y341 packer, one-way injection dispenser, one-way production dispenser, and card stripper, which can realize water injection in partial fractures and oil production in other partial fractures. Therefore, the staged asynchronous injection-production energy supplement can be realized in a same horizontal well. Asynchronous injection-production and oil-increasing between fractures is the result of the combined action of multiple driving mechanisms, including water flooding, elastic flooding, and imbibition. Compared with the traditional area water injection well pattern, it is easier to achieve more effective flooding effect. The research shows that: for the inter-fracture asynchronous periodic injection-production energy supplement method in the same well, the water in injected in to the hydraulic fracturing fractures, which greatly increases the water absorption area in the reservoir;the shape of the flow field changes from radial flow to linear flow;the distance between the injection end and the production end is shortened,which increases displacement pressure gradient and effective permeability. The combined effect of these mechanisms plays an important role in increasing oil production. Field tests show that the inter-fracture asynchronous periodic injection-production energy supplement method in same horizontal well can effectively improve single-well production, and can be popularized to ultra-low permeability sandstone reservoirs on a large scale.