Threshold pressure of sandstone is of great importance in water jet drilling, which is regarded as an economical method to enhance the oil productivity. However, the effect of the parameters on threshold pressure jetted by water, which helps decide the pump pressure in the field test and guide the feeding velocity, remains unknown. In this paper, two nozzles are chosen as the jetting tools, after which the structure of the nozzles are revealed. Artificial sandstones with various properties are made as rock samples, and then the threshold pressure of the rock samples is tested comparatively by self-made experimental system. The results are analyzed by dimensionless method and data analysis software, until then a simple regression equation is presented in this paper and the experimental data and prediction data fit well. From the analysis, threshold pressure is proportional to 0.84 power of compressive strength, which indicates its major role of contribution, while the porosity and permeability play a subtle role in threshold pressure There is a little difference of the minor factors of threshold pressure between the nozzles, which is correlated with the rock breaking mechanism by water jet. Rock breaking velocity is also discussed in this paper. The results presented in this paper can provide guidelines for the applications of water jet drilling.

砂岩的阈值压力在水射流钻井中非常重要，被认为是提高石油生产率的一种经济方法。但是，这些参数对水喷射阈值压力的影响尚不清楚，这有助于确定现场测试中的泵压并指导进料速度。在本文中，选择两个喷嘴作为喷射工具，然后揭示喷嘴的结构。将具有各种特性的人造砂岩制成岩石样品，然后通过自制的实验系统对岩石样品的阈值压力进行比较测试。通过无量纲方法和数据分析软件对结果进行分析，直到本文提出一个简单的回归方程，并且实验数据和预测数据拟合得很好。根据分析，阈值压力与抗压强度的0.84幂成正比，表明其主要作用，而孔隙率和渗透率在阈值压力中起微妙的作用。喷嘴之间的阈值压力的次要因素差异很小，这与喷水的破岩机制。本文还讨论了破岩速度。本文介绍的结果可为水射流钻井的应用提供指导。这与喷水的破岩机理有关。本文还讨论了破岩速度。本文介绍的结果可为水射流钻井的应用提供指导。这与喷水的破岩机理有关。本文还讨论了破岩速度。本文介绍的结果可为水射流钻井的应用提供指导。