Long Exposure Chelating Acid Treatment to Release ESP Stuck Pump

In October 2019, electrical submersible pump (ESP) XY-107 experienced an overload shutdown. Troubleshooting actions have been conducted such as reverse rotation, used rocking method, voltage boost, inject gas through the annulus, and even fluid circulation, yet still failed to reactivate the well. Pump stuck condition was suspected and urgently need a solution. A study was performed to determine the cause of pump stuck. XY-107 is produced from limestone formation, therefore suggesting possibility of scale deposit formation in this well. Upon physical inspection inside the well's flowline, lump of deposit was recovered and suspect similar material could have occurred inside the pump. Rig intervention is a common solution for the ESP pump stuck condition. However, it required high cost (around 80,000 USD) and a longer well service job period up to 5 days. With scale deposit as the suspect, an unconventional solution was proposed to soak the well with acid to dissolve stuck-material by rigless operation. It was much cheaper than rig intervention (only about 4,000 USD) and with a shorter time of 1 day. Yet, acid selection is critical to avoid material damage during operation. Since conventional acid system is known to be corrosive to the metal components, hazardous, and difficult to handle; chelating acid was chosen as an alternative since it is known as a metal-friendly and able to dissolve carbonate and iron deposit. Treatment to address pump stuck situation was executed in March 2020. The chemical treatment was injected by pumping and circulating chelating solution from tubing to the annulus. ESP then soaked for 48-hours long. The treatment has successfully revived the well. It produced with no significant issue for 8 months and even double the oil production. This successful treatment proves chelating technique is safer for ESP and able to regain well production. Significant cost saving up to 76,000 USD was realized by avoiding rig intervention and shortening time of well services. Detailed study, laboratory testing, treatment procedure, and further analysis are discussed in this paper. Chelating acidizing is an uncommon acid system to stimulate carbonates and sandstone in our operating area. Since its successful performance during the trial, more acid campaign using chelating was conducted to enhance oil production. However, this acid system was never been tried as a solution treatment for pump stuck condition and the case of well XY-107 was the first time in the company's history.

Geometallurgy of Trace Elements in the Hrazdan Iron Deposit

This study presents an evaluation of arsenic and other trace metals in the Hrazdan Iron-Ore project in Armenia using a methodology typically associated with Geometallurgical characterization. The principal host of the trace elements is pyrite and oxidized equivalents. Pyrite is a mineral of elemental concern as it has the potential to generate acidic pH in water that it contacts and thus mobilize metals of concern. In the Hrazdan deposit, there is a general excess of neutralizing carbonate minerals that result in adequate buffering of generated acid and limiting the mobility of metal cations in solution. However, metalloids that form oxyanions species such as those of arsenic or chromium tend to be more mobile in neutral to alkaline mine drainage. From the geometallurgical assessment of the mine waste, the results of the geochemical testwork can be explained and the information used to assess potential issues with mine waste storage, timing of metal release and provide a baseline for mitigation strategies.