射流式水力降压钻井机理与参数研究  

Mechanism and parameter study of jet hydraulic drilling for decreasing bottomhole pressure

作　　者：于水杰[1,2] 李根生[1] 罗洪斌[1] 黄中伟[1] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国石化国际石油勘探开发公司,北京100191

出　　处：《石油钻采工艺》2009年第2期11-14,共4页Oil Drilling & Production Technology

基　　金：教育部科技重大项目(No.306003);教育部“长江学者与创新团队”项目(No.IRT0411)资助

摘　　要：窄密度窗口是钻井工程设计中的一个难点。为解决这一问题,提出了一种射流式水力降压原理,利用高速射流产生的抽吸力降低井底压力(循环当量密度),并介绍了工具设计的基本思路。射流式水力降压工具由主副流道组成,副流道流体在喷嘴处的高速低压区对环空产生抽吸作用。通过计算,降压效果随无量纲面积比、排量和喷嘴直径的增大而增大,随钻井速度的增大而降低。在分流量5%、钻井液密度1.25 g/cm3时,最大能降低井底压力1.5 MPa。该研究为射流式水力降压钻井应用打下了基础。Narrow window between fracture and pore pressure brings huge difficulty to drilling engineering. To solve the problem, a new jet hydraulic principle to decrease bottomhole pressure is proposed in this paper, i.e., using the suction power resulted from high speed jet to decrease bottomhole pressure （equivalent circulation density）. And the basic idea of drilling tool design is introduced. The jet hydraulic bottomhole pressure decreasing tool includes main and secondary flow path. Drilling fluid flowing through the secondary path exerts sucking effect on annular at the high velocity and low pressure part of the nozzle. Calculation shows that the pressure decreasing effect gets better as the dimensionless nozzle-to-throat ratio, the flow rate, and the nozzle diameter increase, but it gets worse as the drilling rate increases. The bottomhole pressure decreases by 1.5 MPa at the most in the condition that the flow ratio between main and secondary flow path is 5% and the mud density is 1.25 g/cm^3.

关 键 词：射流式 水力降压 循环当量密度 钻井机理 参数计算 

分 类 号：TE248[石油与天然气工程—油气井工程]