Open Access

ARTICLE

Research on Influence Rules of Pore Structure on Water & Polymer Flooding using Etched Glass Micro-model

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1 Enhanced Oil Recovery Institute, China University of Petroleum, Beijing 102249.
2 Key Laboratory of Petroleum Engineering, Ministry of Education, Beijing 102249, China.
3 Petroleum Engineering Istitute, He’nan Oil Field, Nanyang, 473132.

Structural Longevity 2013, 10(1), 59-70. https://doi.org/10.3970/sl.2013.010.059

Abstract

In this paper, visual micro-model technology has been applied to investigate the influence rules of pore structure on water and polymer flooding, by observing multiphase flow in porous media under the ZEISS 2000-C microscopy. To make the transparent etched glass micro-model representative, the image of target reservoir layer from Shuanghe Oil field, was selected by using laser confocal scanning technology. To ensure effective flow, pore channels with dead-end were gotten through artificially, then the fine-adjustment-image was etched into two glass plates and a specific cementing process was used. The main characteristic of this micro-model is that it preserves the typical pore structure and can be observed at the pore level clearly.
As an enhanced oil recovery technology, polymer injection has been studied and applied for some time; however, the mechanism about how polymer flows in heterogeneity reservoir with high water-cut is not very clear. Total 4 micro-models with 600 md permeability, oil-wet, were used for displacing test at room temperature. Two parameters: pore-throat ratio (PTR) and coordination number (CN) were used to describe heterogeneity of model, and each model was different with others in these 2 parameters. The result shows that owing to the "macro holes surrowned by keyholes” mechnism, large amount of oil was left behind after water flooding. The bigger the value of PTR, the more the residual oil exists; polymer solution with higher-viscosity can enlarge sweeping volumn and reduce the amount of residual oil at the same time by draging oil droplets into oil threads and peeling oil film; fixing permeability, the less the PTR, the biger EOR can polyer flooding get; with the same PTR, the bigger the CN, the higher the EOR. Polymer flooding is with great application prospect in high water-cut Shuanghe oil field.
This study also shows that displacing experiments on these glass-etched micromodels do provide visual results, which revealing the flow procedure of water and polymer flooding in porous media with typical structure of target reservoir. However, the artifically-fine conductivity is less real to the sandstone realistically, so the combined results from both glass and sandstone micro-model are more valuable.

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