Minifract test analysis from a case study in the Oligocen formation Truong Nguyen Huu
Petrovietnam University
Abstract
The minifrac test also called DFIT (Diagnostic fracture injection test) supports a method to determine some important parameters such as fracture efficiency, fracture closure pressure, fluid leak coefficient, and fracture geometry before conducting the main hydraulic fracture treatment design, such as pad volume and slurry volume. In reality, there are some factors including formation properties such as porosity of formation, permeability of formation, total compressibility of formation, and frac-fluid rheology, fluid volume, and injection rate that affect the results of Mini fracture test. The method injected with small volumes of frac fluid with low viscosity such as linear gel, slick water into the formation to propagate fracture dimensions for creating small fracture volumes such as fracture height, fracture length, and fracture width. Since the injection is stopped, the pressure drops or fall-off is carried out to monitor. The surface pressure or the bottom hole pressure is decreased because these pressures depend on the leakage of fluid through the surface fracture area, and then the leakage coefficient, fracture efficiency, fracture geometries, closure pressure, and spurt loss have been determined by Nolte^s G function, log-log plot, or square root of time analysis. This paper presents the methodology for analyzing pressure decline to obtain crucial factors and then applies a case study to the Oligocene formation in the White Tiger field, and presents the effects of rheological properties of facturing fluid, wall building coefficient on Minifrac test results. Before conducting a Mini fracture test simulation, linear gel is tested in the laboratory by low pressure low temperature (LPLT) filtration to achieve the wall building coefficient.
