Experiences Of Downhole Scale Squeeze Treatment To Solve Problem Of Caco3 Scale In Zamrud Field, Indonesia

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