American Rock Mechanics Association
June 28, 2015
Fracturing experiments were conducted on cylindrical Berea sandstone samples using Synthetic-Based Mud (SBM) with a new experimental set-up (UT Mudfrac). Several injection cycles were carried out on each rock sample to measure the Fracture Initiation Pressure (FIP) and the stable Fracture Propagation Pressure (FPP) at various confining pressures. The measured FIP values were compared – and found to be in good agreement – with Rummel’s model for FIP. The stable FPPs were measured using SBM with and without Lost Circulation Material (LCM), and compared with the large-scale fracturing experiments conducted at the Drilling Engineering Association (DEA) 13 investigation. Excellent agreement between DEA 13 and UT Mudfrac results was found. Our study shows that the stable FPP value changes linearly with the minimum horizontal stress (Sh) over a wide range of values. In addition, for a borehole diameter equal to – or greater than – 0.5 inch, the stable FPP value is apparently not affected by the borehole size. The experimental approach presented here can be used to predict stable FPP values for arbitrary in-situ stresses, borehole size, and fluid formulation.
Authors: Omid Razavi, Karimi Vajargah, Eric Van Oort, Munir Aldin, Sudarshan Govindarajan, MetaRock Laboratories, Inc.