Accurate Forecasts of Stress Accumulation during Slurry Injection Operations

I. M. Mohamed; G. Block; S. M. Kholy; O. Abou-Sayed; A. Abou-Sayed
Presented at 50th U.S. Rock Mechanics/Geomechanics Symposium, Houston, Texas, June 2016.


Slurry injection is commonly used to dispose of oilfield wastes during the drilling and production phases of a well. Waste types include drill cuttings, drilling fluids, produced sands, and other types of wastes produced during production. Although slurry injection is most effective when hydraulic fractures are created, safe operations demand that the fractures remain contained below one or more confining layers that are situated above the permitted injection zone. This paper outlines how numerical simulations of 3D fracture propagation can be used to accurately forecast and monitor fracture containment in support of ongoing injection operations. In particular, simulation results are used to determine the accumulation of stress caused by ongoing deposition of solids within the fractures and near the wellbore. Five case studies highlight both the numerical methods and best practices for safely operating slurry injection wells. Field observations of pressure-fall off data and extrapolated near-well stress and fracture lengths are found to match closely with numerical results. Recent advances using cloud-based diagnostics of well performance also enable using real-time slurry rheology, injection rate and pressure data to drive numerical fracture simulations to predict how operational decisions impact fracture geometry and subsurface reservoir properties.