ABSTRACT

Low Salinity water and Polymer injection are as two well known Enhanced Oil Recovery (EOR) technologies. The concept of Low Salinity Water (LSW) flooding has been documented as a promising water-based enhanced oil recovery method. In the same way, many experimental studies have been proven the effect of Low Salinity Water injection to increase oil recovery by mobilizing the residual oil saturation. So far, the two methods have been deeply studied and tested singularly and their effectiveness in oil recovery has been demonstrated but the synergy between these two techniques is still not clear and needs more investigation. This study presents experimental investigations of the potential effect by injection of Polymer in combination with Low Salinity in the terms of oil recovery in a sandstone reservoir.

In this work, we report core-flooding experiments carried out on mixed-wet sandstone core plugs to investigate the efficiency of Low Salinity, Polymer and Low Salinity Polymer (LSP) flooding. The core samples were aged with a crude reservoir oil at 76°C and 90°C for around four weeks before the tests.

This EOR combination resulted to enhance recovery efficiency compared to apply Low Salinity or Polymer flooding separately. Consequently, in addition to incremental oil recovery as outcome of this synergy, the use of Low Salinity Polymer (LSP) flooding with respect to Polymer flooding demonstrated significant benefits in the terms of considerably lower amount of polymer required to make the solution therefore leading to cost reduction.

Combined injection of Polymer and Low Salinity can be implemented to enhance oil recovery in favorable conditions. The reducing the polymer amount is proven an important factor for full field application. Therefore, the synergy effect of these EOR techniques will have valuable potential for full field development strategies.

INTRODUCTION

Naturally, reservoirs produce hydrocarbons to maximum of 20 % of total oil/gas in place. This means that further production will only be possible through an Enhanced Oil Recovery (EOR) strategy.

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