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Hybrid CO 2 EOR using polymer‐assisted carbonated low salinity waterflood to improve CO 2 deliverability and mobility
Author(s) -
Lee Ji Ho,
Kim Tae Hong,
Lee Kun Sang
Publication year - 2018
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1752
Subject(s) - brine , enhanced oil recovery , salinity , petroleum engineering , chemical engineering , viscosity , wetting , polymer , materials science , chemistry , geology , composite material , organic chemistry , engineering , oceanography
A hybrid polymer‐assisted carbonated low‐salinity waterflood (PCLSWF) is a low‐salinity waterflood‐based enhanced oil recovery (EOR) co‐injecting CO 2 and polymer. In the hybrid process, the low salinity of make‐up brine enhances CO 2 deliverability into a reservoir due to the salting‐out phenomenon. This PCLSWF introduces the following synergetic effects: 1) wettability modification; 2) decreasing oil viscosity; 3) increasing brine viscosity. These effects are evaluated in core‐ and pilot‐scaled systems. First, the PCLSWF induces ion‐exchange of Ca 2+ and improves wettability following MIE (multi‐components ionic exchange) theory. The wettability modification effect is enhanced in the pilot‐scaled system because the low pH of the PLCSWF dissolves more cemented calcite mineral producing Ca 2+ and resulting in more ion‐exchange of Ca 2+ . Secondly, a lot of dissolved CO 2 in brine is transferred into oil, consequently decreasing the viscosity and density of oil. Finally, polymer injection increases the viscosity of the displacing fluid. Although it undergoes mechanical and chemical degradation, it still improves mobility ratio and sweep efficiency. In the pilot‐scaled system, the PCLSWF enhances oil recovery up to 12%, 6%, and 2% over the low salinity waterflood (LSWF), low salinity polymer flood (LSPF), and carbonated low salinity waterflood (CLSWF) respectively. The optimization process maximizes the efficiency of the PCLSWF, and it is recommended that tertiary PCLSWF is deployed following the secondary CLSWF. The optimized injection design of the PCLSWF increases the net present value up to 18% more than the LSWF. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd.