Optimization of Hydrocarbon Production from Unconventional Shale Reservoirs using Numerical Modelling

Abstract

The success of unconventional hydrocarbon extraction depends on the effective stimulation of reservoir rocks. Industry practice is to conduct a large number of field trials requiring high capital investment and long cycle-time. The workflow outlined in this paper, using best available reservoir data in combination with best available simulation models offer a cheaper and faster alternative approach for optimization of the complete design and for the improvement of production. Integrating subsurface characteristics, well completion, well operation, diagnostic and well performance analysis by using asset specific data, the development of an optimal completion design is possible. This results in the reduction of field trials, which is primarily necessary for achieving the optimal completion design. In addition, it provides valuable insights for further data acquisition to evaluate and forecast performance of the well. This paper introduces the workflow to model, calibrate and optimize the landing and orientation of the well including hydraulic fracturing stimulation design for naturally fractured unconventional shale reservoirs. For fracture simulation, the paper introduces an approach for parametric coupled hydro-mechanical 3D Finite Element (FEM) modeling, including non-linear material modeling of fracture propagation in sedimentary rocks. In order to calculate production out of the created fracture network, estimation of accessible connected hydrocarbons is calculated. For calibration and optimization purposes, automated sensitivity studies for uncertainty variations of the reservoir parameters as well as engineering and operational parameters are performed and are evaluated relative to the resulting Stimulated Reservoir Volume (SRV), Accessible Hydrocarbon initially in Place (AHCIIP) and Estimated Ultimate Recovery (EUR). The current version of this technology does not handle proppant transport and placement. Instead, assumptions are made for proppant acceptance in the fracture network and used in estimating the proppant accepting simulated rock volume, connected hydrocarbons, and hydrocarbon production. Further enhancement of the FEM workflow to capture 3D proppant transport and placement is under development and will be a major update in the upcoming hydraulic fracture simulator version.