Investigation of Low-Salinity Waterflooding in Secondary and Tertiary Enhanced Oil Recovery in Limestone Reservoirs

详细信息    查看全文

• 作者：Asghar Gandomkar ; Mohammad Reza Rahimpour
• 刊名：Energy & Fuels
• 出版年：2015
• 出版时间：December 17, 2015
• 年：2015
• 卷：29
• 期：12
• 页码：7781-7792
• 全文大小：535K
• ISSN：1520-5029

文摘

Improved oil recovery from oil-wet low-permeability limestone reservoirs is a great challenge by altering the reservoir rock wettability. The purpose of this study is to compare the results of low-salinity waterflooding in secondary and tertiary modes to decrease the residual oil saturation from limestone reservoirs. Three different stock-tank crude oils and limestone cores are used in this study. All of the coreflooding experiments were performed at 60 掳C and 2000 psi by injection of actual formation and seawater, with brine solutions containing single-component salt, such as MgSO₄, KCl, Na₂SO₄, CaCl₂, MgCl₂, and NaCl, with a wide range of salinity levels. During low-salinity flooding in secondary recovery, the dominant displacement-suggested mechanism is snap-off, which results in an oil recovery factor with different values for the various wettability conditions. The most interesting result is that tertiary low-salinity recovery was never observed in these coreflooding experiments. The measured effect of tertiary low-salinity waterflooding from limestone core experiments was rock dissolution, as a result of surface reactions, and an increase in water relative permeability.