Abstract
There is a huge potential for using CO2 gas to recover additional oil after water flooding in reservoir chalk. However, the injection of CO2 into chalk reservoirs will disturb the chemical equilibrium between formation water, injection water and chalk. A proper understanding of these CO2-induced interactions and the resulting changes in the physical properties at representative reservoir conditions is required. Unfortunately, reliable chemical data are rare because data cannot be acquired directly at reservoir conditions with present-day techniques. In published experiments, water samples are in many cases obtained at atmospheric conditions with the aid of a back-pressure regulator. Thus, water samples are not representative of in situ reservoir conditions and if proper care is not taken, the collected data cannot be used to judge the magnitude of the chemical reactions taking place at reservoir conditions. However, in some cases water obtained at laboratory conditions can give information on in situ reservoir conditions by using geochemical speciation models to account for dissolved gases that are lost from the effluents during sampling (Bachu & Adams 2003).
Highlights
There is a huge potential for using CO2 gas to recover additional oil after water flooding in reservoir chalk
Water the samples were saturated with synthetic formation water samples are not representative of in situ reservoir conditions (FW)
All plugs had a diameter of 3.81 cm and a length of and if proper care is not taken, the collected data cannot be approximately 7.5 cm; plugs with similar petrophysical propused to judge the magnitude of the chemical reactions taking erties (Table 1) were used to check the reproducibility of the place at reservoir conditions
Summary
There is a huge potential for using CO2 gas to recover additional oil after water flooding in reservoir chalk. The injection of CO2 into chalk reservoirs will disturb the chemical equilibrium between formation water, injection injected fluids. In this way, we can validate the sampling procedure and investigate how the measured parameters (pH, CO2 pressure, calcium (Ca) and bicarbonate (HCO3–) concentrations) compared with the calculated parameters. A proper understanding of these CO2induced interactions and the resulting changes in the physical properties at representative reservoir conditions is required
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