Modeling Fishbones Using the Embedded Discrete Fracture Model Formulation: Sensitivity Analysis and History Matching

Abstract

Abstract The fishbones technology is a new well stimulation technique developed to increase well productivity index and improve reservoir connectivity to the well, being an alternative to hydraulic fracturing. This technique consists of creating several branches (holes) in the well using acid injection (dissolution and diversion). Those branches have small diameter and an average length of 40 feet. Main advantages of this technology over hydraulic fracturing are the competitive price and reduced operation time. In this paper we aim at modeling fishbones using the embedded discrete fracture model (EDFM), originally developed to model conductive faults and fractures. An EDFM preprocessing code was rewritten and extended to generate non-neighboring connections (NNC) between matrix, fractures and well connections; the NNCs were exported and used as input for a numerical simulator capable to handle NNCs. We modified the EDFM preprocessing code to adequately model fishbones. Each fishbone branch is treated as a fracture with dimensions equivalent to the branch dimensions (radius and length). The use of appropriate equations based on Peaceman's equation allows to model fishbones as equivalent fractures. Our new approach was used to perform sensitivity analysis (one at a time method) of the reservoir properties and the number of fishbones' branches for a case of primary oil production. A history match of the results of the first pilot using the fishbone technology was performed using an automated algorithm. Triple porosity cases were also evaluated and a good agreement between simulation and production data was obtained. A sensitivity analysis using design of experiments and the regression technique was used to compare the application of fishbones in different reservoirs (isotropic, anisotropic, and fractured) under primary oil production. The results of the simulations show that the fishbones is a promising stimulation technology that should be further evaluated.