sp8b00075_si_001.pdf (1.71 MB)
Effects of Phosphonate Structures on Brine–Biotite Interactions under Subsurface Relevant Conditions
journal contribution
posted on 2018-07-12, 00:00 authored by Lijie Zhang, Doyoon Kim, Young-Shin JunPhosphonates have been widely used
as scale inhibitors in energy-related subsurface operations, where
their performance is greatly affected by interactions with rocks and
minerals. However, information about commonly used phosphonate scale
inhibitor–shale interactions is limited. In this study, using
Fe-bearing mica (biotite) as a model phyllosilicate mineral, the effects
of three common phosphonates, namely, iminodi(methylene)phosphonate
(IDMP), nitrilotris(methylene)phosphonate (NTMP), and diethylenetriaminepenta(methylene)phosphonate
(DTPMP), were studied at 95 °C and 102 atm CO2. During
the experiments (0–70 h), IDMP remained stable, while NTMP
and DTPMP were degraded and released phosphate, formate, and new phosphonates
with smaller molecular weights. As a result of the differences in
complexation capability, IDMP, with the fewest phosphonate functional
groups, promoted biotite dissolution mainly through surface complexation
and DTPMP, with the most functional groups, promoted biotite dissolution
mainly through aqueous complexation. Furthermore, the presence of
phosphonates enhanced secondary precipitation of P-, Fe-, and Al-bearing
minerals, and their phosphonate structures affected the morphologies,
phases, and distributions of secondary precipitates. Owing to
phosphonate–biotite interactions (mainly as a result of surface
adsorption), the biotite surfaces became much more hydrophilic. This
study provides new insights into structure-dependent phosphonate–mineral
interactions, and the results have important implications for the
safety and efficiency of energy-related subsurface operations.