Disproportionate permeability reduction in commingled reservoirs: Fluid deployment and post-treatment productivity
Master thesis
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http://hdl.handle.net/11250/2416812Utgivelsesdato
2016-06Metadata
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Sammendrag
Water shutoff (WSO) treatments are traditionally used to manage unwanted water production and improve oil recovery in mature oilfields. WSOs are engaged in selected type of water production types and totally block both water and oil flow. Polymers or gelant fluids can be used as an alternative (and attractive) option in which these chemicals are injected into the formation aimed to lower the water phase relative productivity compared to the oil one. This process is called disproportionate permeability reduction (DPR). These chemical treatments, WSO or DPR, as opposed to mechanical ones, can be placed near wellbore or deeper in the formation. Their placement into the formation is very important and affects both treatment and post-treatment performance. This work aims to provide improved analytical tools for designing and evaluating the performance of a DPR treatment.
A radial piston-like displacement model for non-Newtonian fluid injection into the multilayered reservoirs will be developed first. Most of the previous relevant research work for two phase flow in the porous media is based on the linear system of the Buckley-Leverett model. More realistic formation characteristic are much more complicated than the one considered in the classical Buckley-Leverett model. For example, injection fluids can be non-Newtonian and the injection geometry to be not linear but radial. Therefore, the second part of this work is to develop an analytical models for non-Newtonian fluid displacement in a radial system and also consider the effects from polymer retention phenomena and presence of damage (skin) zones near the wellbore. The Buckley-Leverett model developed obeys mass conservation very well during the computation of the solution and the performance results of DPR treatment with a piston-like multilayered model also verifies the validation of the radial Buckley-Leverett model with multiple layers.
Several parameters such as skin damage, retention coefficients, pressure constraints, average reservoir pressure and DPR properties are investigated through modelling results to evaluate DPR treatment design. These results show that skin has a visible effect on the differential pressure during injection, relative injectivity and relative productivity index. Injection pressure constraints will lead to a longer injection process and decrease the relative injectivity. Average reservoir pressure impacts on oil production rate after the DPR treatment process. Also, a strong DPR permeability reduction can lower the watercut more efficiently. Finally, polymer retention coefficient does not affect the treatment performance significantly.
Beskrivelse
Master's thesis in Petroleum engineering