Experimental Study of the Perforation Effect on Hydraulic Fracturing Under Triaxial Stresses Using Physical Modeling

Mohammad Darbor¹; Hadi Shakeri¹; Lohrasb Faramarzi²

¹ Dept. of Mining, Sahand University of Technology, Tabriz, Iran

² Dept. of Mining, Isfahan University of Technology, Iran

Doi:10.29252/ANM.2019.10976.1369

Abstract

Hydraulic fracturing is one of the most important methods for the propagation of oil and gas reservoirs, which is used to increase the inflow to well bore in low permeability formations. Various parameters such as in-situ stress field, joints and natural fractures of the formation, the fluid rheology, the mechanical properties of the formation, injection fluid flow and perforation affect the hydraulic fracturing pressure. In this research, a triaxial machine was designed and built for experimental investigation of the hydraulic fracturing in conditions close to the field conditions, so that all three of the main stresses in field conditions are applied in laboratory tests. Then, the influence of different perforation parameters such as perforation geometry (including length, diameter and shape), phase of perforation (in both vertical and horizontal wells) and minimum horizontal stress in the presence of perforation, using 38 artificial specimens (plaster + sand) with dimensions of 10×10×10 cm, was considered on the geometry and breakdown pressure, pressure-time diagram, and the development of micro-cracks. The results showed that increasing the perforation diameter, changing the perforation angle to the maximum horizontal stress and increasing the minimum horizontal stress in the case of reverse fault, rises the breakdown pressure.

Keywords: Hydraulic Fracturing; In-situ Stresses; Perforation Geometry; Perforation Phase Angle; Breakdown Pressure