CASE HISTORY - HDX XREAM Mark II

Ninian Central Well:

This well was drilled using oil-based mud as an oil producer in 1998. The well under produced estimated output since being drilled, with production at a rate of 1550 bpd of oil and 2424 bpd water. The cause of the low production was unknown, but it was suspected drilling fluids solids such as barite was the main problem as sag and loss of weight during the drilling of the reservoir was experienced. In addition barium, strontium sulphate and carbonate scales common to the field may have been impairing production due to the high water cut.

Since the exact nature of the impairment was unknown, an HDC variant targeting scale as well as mud grade barite – HDC Mark I, was selected for treatment of the production interval. Because the well had significant water cut, it was decided to bull head the HDC to the target and allow it to soak across the interval (inside and outside) for a period of 12 hours. (BHT 115°C – depth 18,500')

The well was brought back on line, resulting in a rapid increase in production. No emulsions or any solids were seen on returns.

Immediately after flowing, oil production increased to 2245 bpd with water up to 4997 bwpd. The well stabilized with a continuing oil production of 2340 bpd and water falling back to 3984 bwpd, with the water cut continuing to fall.

The net increase in oil production stabilized at a 51% increase.

Subsequent analysis of the initial dissolver returns indicated over 156 kilograms of mud grade barium sulphate had been dissolved plus an additional 50 kilograms of unspecified barium scale. This analysis was conducted by OCT Aberdeen on behalf of the Operators.