基于机械比能的非常规油气藏水平井水力压裂分段分簇设计方法

The Clustering Design Method of Hydraulic Fracturing on Horizontal Wells in Unconventional Reservoirs Based on Mechanical Specific Energy

中国海洋及陆地赋存有丰富的非常规油气资源,由于这类储层岩性致密,需要采用水平井及体积压裂技术提高产能,而水平井水力压裂分段分簇设计直接决定着岩体内多个裂缝的起裂与扩展,不合理的设计将导致仅有部分裂缝开启并延伸,进而导致产能的降低。机械比能参数很好地体现了岩石的破裂强度及地应力差,与裂缝的起裂扩展有密切关系,因此将机械比能引入分段分簇设计中。文章深入分析了机械比能的物理含义,考虑作用到井底的真实钻压与扭矩,在机械比能基本模型的基础上对钻压、扭矩、转速进行修正,建立了机械比能的修正模型,并提出了采用机械比能参数进行分段、采用欧式贴近度进行分簇的压裂设计方法。结合H4井进行了基于机械比能的分段分簇设计,该井现场施工后产量高于邻井,初步证明了该分段分簇设计方法的有效性和适应性。

The oceans and continents in China are rich in unconventional oil and gas reservoirs,due to the tight lithology of these reservoirs,horizontal wells and volume fracturing technologies are required to improve productivity.The design technology of segmentation and clustering in the process of hydraulic fracturing on horizontal wells directly determines the initiation and expansion of multiple fractures in the rock mass.The unreasonable design of segmentation and clustering will lead to the opening and extension of only part of the fractures,thus reducing productivity.The mechanical specific energy(MSE)parameter reflects the rock fracturing strength and in-situ stress difference,which is closely related to the fracture initiation and propagation.This paper deeply analyzes the physical meaning of MSE,which reflects not only geological characteristics,but also engineering characteristics.Considering the real WOB and torque acting on the bottom hole,the wellhead WOB,torque and rotational speed are corrected,a correction model of mechanical specific energy is established.On the basis of mechanism analysis,the new idea of segmentation and clustering design technology is put forward:using the MSE parameters to segment,and using the Euclidean Closeness to determine perforation cluster points.The segmentation and clustering design is carried out in Well H4,and the production of which after on-site construction is higher than that of adjacent wells,which preliminary proves the effectiveness of the intelligent segmentation and clustering design method.