| Title | Production Improvement Through Scale Removal by Condensate Injection in Darajat Geothermal Field Indonesia |
|---|---|
| Authors | M. Ramos SURYANTA, Christovik H. SIMATUPANG, Cedric CEASE, Dian K. HADI, Glenn U. GOLLA |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | condensate injection, scale clean out, PD pump and gravity assisted injection |
| Abstract | Condensate injection to remove wellbore scale and to improve production were tried in numerous geothermal fields (some of them are Salak, Geyser, etc). This is the first time that this was done at Darajat field. It was also attempted to improve on this process by injecting hot condensate and possibly increasing its pH to accelerate the dissolution of the scale. Ring gauge/go devil history of DRJ-AA indicated that scale was identified in the wellbore starting around 2008. The presence of this scale was accompanied by a higher decline in the well’s production thus making this well one of the candidates for well remediation or work-over. During the preparations to plug and abandon a power plant condensate injector, there was a need to find a temporary injector to take the condensate while engineering work was being done to transfer all condensate to an edge-field injector. This operational opportunity was then translated into a plan of removing the scale and improving production by injecting DRJ-AA with power plant condensate. This was a common practice for scaled-up wells at Salak Field, another Chevron-operated geothermal facility in West Java. The process was to be improved by heating up the condensate using the same well’s steam. This was proposed to be done using a positive displacement (PD) pump, injecting at a rate in which there is still positive well head pressure (around 3-5 barg). The steam from the reservoir will then pre-heat the condensate before it reaches the shallowest scale detected in the well which was above the top of the liner. This remedial well work was executed in two stages, namely, a short-period (8 hours) “hot condensate” injection stage by utilizing PD pumps and a long-period (~2 months) cold condensate injection with the well head pressure at vacuum conditions. Results show that the condensate injection successfully cleaned out some of the scale and improved productivity of DRJ-AA. Subsequent ring gauge surveys resulted to similar-sized tools (used before the well clean-out) reaching deeper indicating a decrease in the wellbore scale. DRJ-AA’s original production of 7 - 11 kg/s increased to 16 - 19 kg/s. Geochemistry showed that the produced fluids from DRJ-AA increased in boron and decreased in NCG suggesting boiling of the condensate that was injected during the well clean-out. |