Abstract:
Operational problem of CaCO3 scale has been experienced for many oil-wells in
Zamrud field. Some CaCO3 scales encountered in tubing and other in artificial lift.
This problem increased operating cost of work over job to pull out the artificial lifts
which were stuck by CaCO3 scale. In order to clean up the perforation zone with
high skin effect contributed by CaCO3 scale, acidizing using 15% HCl was
conducted, but the production time was very short and the oil-wells were needed
to be re-acidized. In order to get longer production life of treatment, the growth of
CaCO3 scale is needed to be inhibited after acidizing job. Downhole scale
squeeze treatment (DSST) has good performance with step of crystal growth
retardation, crystal nucleation inhibition, and crystal dispersion. Scale inhibitor
which was pumped is 10% Gyptron IT-256, with active content of bishexamethylene
triamine penta(methylene phosphonic acid) tested using
dynamic scale loop to determine minimum inhibitor concentration, which is
necessary step in the evaluation process. For many oil-wells, DSST show a
good performance indicated by longer production with almost constant watercut.
Good understanding of type of scale inhibitor which was used and the
characteristic of content of positive and negative ion in formation water as well as
mineralogy of perforated zone in oil wells enables of remedy other oil wells in
different fields with variety of mineralogy and bottom-hole temperature
