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Ammonium ion which is a positively charged polyatomic cation has been widely used as clay control agent. As this ion has similar characteristics to potassium ion including ionic diameter and hydration number, ammonium ion should be able to displace divalent ion bridging between oil and rock surface during Multi-component Ion Exchange (MIE) mechanism as same as potassium ion. This study is performed to evaluate the effectiveness of ammonium ion compared to potassium ion and sodium ion. The result shows that both ammonium ion and potassium ion which are similar in hydrated properties can displace divalent ion better than sodium ion as well as deionized water. From coreflood experiment, there is a relationship between number of divalent ions in effluent and oil recovery factor. The higher the amount of divalent ions in effluent, the more oil is recovered. It is also observed that portion of calcium ion expelled from rock surface is increased when monovalent is present in injected water. From this study, it can be concluded that hydrated properties of monovalent ion in injected water affects the MIE mechanism. Small amount of ammonium ion can be added into injected water to improve the effectiveness of the mechanism. |
