Numerical simulation study of oil-based cuttings re-injection induced fractures

Abstract

Cuttings re-injection is an effective method to solve the accumulation of solid waste such as oil-based cuttings in offshore oil and gas fields, which has the advantages of low cost, high efficiency, and environmental safety. But, the slurry leakage events occur frequently due to the poor understanding of the fracture initiation and extension of cuttings re-injection in existing studies. This paper develops a rock cuttings intermittent re-injection simulator based on the open-source hydraulic fracturing software Pyfrac. The impact of different construction and formation parameters on the propagation of induced fractures was investigated through numerical simulations. The simulation results show that Young’s modulus, Poisson’s ratio and the magnitude of in-situ stress have less influence on the final scope of the fractures. The difference in-situ stress between the re-injection layer and the compartment, the viscosity of the re-injection fluid and the re-injection interval time have significant impacts on the length and height of the fracture. Therefore, in the actual construction process, the liquid viscosity and interval time can be adjusted to obtain the different scopes of induced fractures.