Development of a true triaxial device for hydraulic fracturing experiments

Abstract

[Abstract] We present the design, mechanical modeling and testing of a low-cost true triaxial (TT) device aimed at the development of hydraulic fracturing experiments in rocks up to stress-es of 60 MPa acting over the faces of 150 mm-edge cubic samples. The system is de-signed around a structural steel high-strength frame, two commercial low-profile hydraulic cylinders, one hydraulic hand pump and a servo-controlled hydraulic press. The low-profile cylinders act as horizontal stress actuators while the hydraulic press provides with the vertical stress component. We describe the general outline of the system and we pro-vide details about the selected components employed. The mechanical modeling of the frame shows that the strength and stiffness of the frame is sufficient for the intended use and we summarize some of the operative testing being developed at present. We include also some considerations regarding the preparation of samples prior to hydraulic fracturing testing as well as some related recommendations. The system is presented as an introduc-tory approach to more sophisticated TT testing systems but is has the capability to incorpo-rate further improvements and/or upgrades to cope with more advanced experimental tasks.