Abstract
A model with short computational time has previously been developed to predict the rate-dependent gas/oil ratio (GOR) from a horizontal well. The oil flow towards the wellbore is based on a one-dimensional model by Konieczek. The model performs remarkably well for medium-time production optimization (weeks, months), while the predictions during the first days after a large change in the production can be poor. An improved one-dimensional model for the flow towards the wellbore is proposed, where the oil flow is treated as a superposition of three terms:
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1)
Radial flow towards the wellbore and towards a mirror well.
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Flow to correct for modified boundary conditions due to the radial flows.
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Flow due to height variations of the gas/oil contact (GOC).
The new model takes care of the current short term and near-well deficiencies: Effect of 2D flow close to the wellbore, gas breakthrough due to viscous gas fingering, and horizontal/vertical anisotropy. Based on analysis and preliminary testing the new model should have equally good medium and long term capabilities and considerably improved short term and near-well behaviour, compared to the present implementation.
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Open Access This is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (https://creativecommons.org/licenses/by-nc/2.0), which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
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Halvorsen, S.A., Mjaavatten, A. & Aasheim, R. Improved near-well approximation for prediction of the gas/oil production ratio from oil-rim reservoirs. Comput Geosci 16, 231–246 (2012). https://doi.org/10.1007/s10596-011-9250-6
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DOI: https://doi.org/10.1007/s10596-011-9250-6