Modeling fluid flow in porous media is often ignores diffusion forces with the assumption that viscous transport is the predominant controller. Several researchers have questioned this assertion, but have never proposed a real alternative model. Involvement of diffusion forces in such tight mediums can no longer be ignored with the creeping of Unconventional Reservoirs (UCRs) production to the oil and gas market. This work presents a new detailed fluid flow model, incorporating a cyclic gas injection (gas huff and puff) case study, while including the influence of diffusion, viscous and inertia forces.Diffusion is a critical component in the fluid flow of tight UCRs. Diffusion effect is predominating the nano scale, whereas becomes less essential in macro and micro scales. A model for single-phase fluid flow in tight UCRs was previously produced by modifying the flow Forchheimer’s equation. The new modification addresses the fluid transport phenomena into three scales incorporating a diffusion term. In this study, a new multiphase liner model, numerically solved, has been developed and deployed for a gas huff and puff project. The new model has been numerically validated and verified using synthetic data and huff and puff case study.Ideally, the new model suits fluid flow in tight UCRs. The modified Forchheimer’s model presented is solved using the MATLAB numerical method for linear multiphase flow. For the huff &amp; puff case, very simple profiles and flow dynamics of the main flow parameters have been established and a thorough parametric analysis and verifications were performed. It has been observed that the diffusion system becomes more prominent in regulating flow velocity with low permeability of the formation rock and low viscosity of the flowing fluid. A detailed sensitivity analysis to validate the current model, including both rock and fluid properties, was performed and fine-tuned to comply with the case of cyclic gas injection. The findings indicate a behavioral alignment with a previous hypothesis that matches actual reservoir behavior.To explain fluid flow in tight unconventional reservoirs for a cyclic gas injection, a new robust fluid flow model has been introduced. The model involves viscous, inertial and diffusion forces and supposed to operate in the macro, micro and nano scales tainting in tight UCRs. The new UCRs model is expected to gain much of applications for cyclic gas injection (huff &amp; puff) projects.

A Unique Approach in Modelling Flow in Unconventional Reservoirs With Viscous, Inertial and Diffusion Forces Contributions.

Paper Proceedings: https://asmedigitalcollection.asme.org/OMAE/OMAE2021/volume/85116

OMAE 2021

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