Effect of Free Ammonium on Performance Destabilization of Drilling Fluid and
Chemical Remedial Measures

Zhou Jian1, Wu Weilin2, Liu Haobing3, Liu Xin4, Luo Xiao1*, Lu Fuwei1, Hu Sanqing1
Page No. 22-30

While long-term storage of amine-based inhibitors was injected into the drilling fluid, many
problemswould come out such as increased fluid loss and wellbore instability.Ammonia was added
to the inhibitor to simulate the free ammonium in the amine-based inhibitor, and the effect of free
ammonium on destabilization performance of drilling fluid was investigated.The results showed that
the inhibitor had no damage to the performance of the drilling fluid when the ammonium ion
concentration was not more than 0.185 mmol/L. When the ammonium ion was higher than 0.301
mmol/L, the filter cake became thicker and the water loss increased greatly.The free ammonium
component of the displacement inhibitor is neutralized with acetic acid and its potassium salt.The
results show that the same molar concentration of potassium acetate as the free ammonium can
produce an ion exchange effect with free ammonium.The addition of the corresponding
concentration of potassium acetate to the amine-based inhibitor containing free ammonium restores
the fluid loss and can be used to urgently treat amine-based inhibitors with unstable field
properties.
Keywords : amine-based inhibitor; free ammonium; well wall instability; potassium acetate; ion
exchange