Experimental study on hydraulic isolation mechanism during hydra-jet fracturing

摘要

Horizontal wells with multiple hydraulic fractures are common occurrence application in petroleum industry all of the word. Hydraulic fractures are usually created by applying high pressure fracturing fluid to the sections of the well bore where the fractures designed to propagate. Mechanical isolation is wildly used to separate the wellbore sections, during the fracturing process. Recently, hydraulic isolation is used for the same purpose in some applications where the mechanical isolations may lead to unsuccessful fracturing processes. This paper presents the experimental study on the mechanism of the hydraulic isolation. Several parameters, such as tubing pressure, annular pressure, nozzle diameter, and area ratio, have been investigated to explore the impact of this mechanism. The dimensionless approach was used to analyze data to understand the behavior of hydraulic isolation. Three dimensionless parameters were defined, including low-pressure ratio, area ratio and damping factor. Results have shown that linear relationships on log-log plot of low-pressure ratio and damping factor may exist. Furthermore, the value of low-pressure ratio is enlarged by decreasing damping factor and increasing area ratio. This study indicates the feasibility to obtain better hydraulic isolation by increasing tubing pressure and selecting a larger nozzle diameter.