Physical simulating experiments of hydrajet perforating and fracture initiation process

Key words:  jets  hydrajet perforating  fracture initiation  simulating experiment  cavity shape

Abstract:

Experimental researches were introduced by selected samples from Chang 6 formation of Changqing Oilfield, and the process of hydrajet perforating and fracture initiation process was simulated by using field parameters，jetting tools and e-quipmenls. The tested samples were all cut by special tools. The experimental results show that the whole jetting hole is of tear-drop shape，and it includes four parts of casing perforation, entrance sputtering section，cement reduction and main section. When fracture initiated, a slim channel with gladiate shape is added in the end of the hole. The sample will fracture when jetting velocity is high enough in test condition, which indicates that the pressure in jetting hole increases obviously with the jetting velocity increase. The jetting flow erodes out a slim channel along crack propagate direction when fractures initiate, which makes the jetting hole length increase doubly, and is beneficial to enhance penetration efficiency. Individual channels are connected by crack when fractures initiate，which indicates that jetting hole can guide the fracture initiation and extension near the well bore in test condition.