Identifying Optimal Operating Envelope in Horizontal Wells Producing from Dual Permeability Media

Abstract

In this paper, we present an integrated workflow utilizing a numerical model to identify optimal operating envelope for horizontal wells producing from dual permeability media. A synthetic dual permeability numerical model comprised of critical components namely: fracture and matrix permeabilities, matrix-fracture conductivity (shape factor), and fracture distribution based on Discrete Fracture Network (DFN) scheme was built. In addition, two horizontal producers completed with Inflow-Control – Devices (ICDs) and as open-hole respectively, are also connected to the model. Rigorous sensitivity analysis is implemented on these key parameters using the dynamic model under Equalspacing sampling scheme with well oil rate as the objective function. Range of values on each variable are typical for naturally fractured reservoirs. In addition, detailed sensitivity on ICD parameters such as flow resistance ratings are performed. Results from the analysis are presented in cumulative probability function identifying most likely, pessimistic and optimistic values. Among all the variables, Matrix-fracture transmissibility has most impact. Unfortunately, it is often neglected when designing horizontal wells in dual permeability reservoirs. Current practice pays most attention on permeability contrast lack of consensus in the industry on best technique for its estimation. Most common methodologies applied are Kazemi and Warren-Roots. Nevertheless, it plays a critical role in describing dual permeability subsurface flow mechanism. Most significantly, it is widely acknowledged that beaning up choke sizes enhances production performance of wells connected to dual permeability. However, in this study, we have been able to establish operating limits for this phenomenon. Matrix-fracture transmissibility could significantly influence a producer, which has not intersected high permeability streaks. Our study clearly demonstrates this observation using high-resolution dual permeability dynamic model. In addition, by performing multi-variate characterization, we establish operating envelope for optimizing well production performance in dual media systems through choke size settings.