2020-02-28 3:27:06
Enmax Technology (Shanghai) Company Ltd., Shanghai, China
EnmaxOnline >> Cases Studies & Reports >> Case Histories >> CNOOC Bohai/Ba&Sr Scale/Downhole CPRS
CNOOC Bohai/Ba&Sr Scale/Downhole CPRS

Location: Well No.:SZ36-1-J10, SZ36-1Platform 
Operator: CNOOC Bohai Oil Company
Before installation
  • Production started on Dec. 14, 1997 with ESP.  The oil production was stabilized above 100 m3/d after acidizing in 1998;
  • Since mid April, 2005, EPS failed frequently due to scale buildup;
  • A magnetic scale tool was run into the well, but it did not work, failed in a short time, less than 3 months;
  • It was concluded that such a frequent pump inspection and repair was mainly caused by the downhole scale buildup, which resulted pump failure and reduced production;
  • Scale analysis indicated that the main composition of  scale is Ba0.75Sr0.25SO4, up to 98%;
  • Barium(Ba) and Strontium (Sr) scale, which is the most difficult scale  to deal with.

After the installation
  • The ESP was repaired on May 4, 2006, and a Enmax CPRS downhole unit was run into the well with the ESP;
  • After the installation of Enmax CPRS downhole tool, Enmax Shanghai was advised that the production had been stabilized at 250 m3/d, with a crude production of 80 m3/d, and no more EPS failure because of scale buildups;
  • Till the report date, Oct. 16th, 2008, continuous production for 892 days, no breakdown;
  • Within 892 days, EPS repair related cost saving > 7,700,000 RMB, Oil production increase >16,500.000 RMB;
  • This downhole CPRS unit is still working in this well today.