An experimental investigation into hydraulic fracture propagation—Part 1. Experimental facilities

Abstract

Since the development of hydraulic fracturing to enhance the production of oil or gas from a well, many fracture propagation models have been put forward. However, practical methods of evaluating the theoretical and numerical models have been few. For the above reasons, a set of hydraulic fracture tests was conducted on 350 × 305 × 305 mm and 610 × 584 × 305 mm gypstone blocks to produce experimental data for verification of hydraulic fracturing numerical models and evaluation of hydraulic fracturing theories for stress measurements. This paper, the first part of a series of publications, provides a general description of the experiments. It illustrates fabrication and properties of the artificial rock—gypstone, the test frame which applies the three principal stresses on specimens, the pump system that exerts bottomhole pressure on specimens, specimen size, well size, layout of wells and sealing of wells. Following that, instrumentation of the experiments (injection rate, bottomhole pressure, stresses, deformation of specimens) and testing procedures are presented. Finally, one representative experimental result is shown, and the effect of specimen size on breakdown pressure is examined by comparison of hydraulic fracture tests conducted in 305 × 305 × 305 mm with 610 × 584 × 305 mm block specimens. The experimental results show that this system is suitable for hydraulic fracture tests. No effect of specimen size on breakdown pressure is found for 305 × 305 × 305 mm block specimens.