2/4-14 R

General

Well 2/4-14 R was designed to re-establish full well control of the uncontrolled flow in well 2/4-14 by using both well 2/4-14 R and 2/4-15 S. The RKB with Neddrill Trigon is 37 m, but all depths in this account are relative to the RKB of Treasure Saga (26 m) for easier comparison with other the well bores and re-entries involved in the blow out.

Since the underground blow out occurred in well 2/4-14 in January 1989 various surveys and analyses had been conducted to monitor any flow of gas into shallow strata in the area. Gas bubbles from the site of the 2/4-13 well head were first time reported from ROV surveys in August 1989. A Sidescan Sonar Search was performed in the period from late June 1989 up to late March 1990. No gas leakage was detected by this method. A seismic surveillance study was performed in the 2/4-14 area by Read Well Services A/S in order to monitor the noise and acoustic activity caused by possible cracking due to migration of hydrocarbons into the shallow sand layers. Four seismometers were placed on the seafloor from 21 September to 2 October 1989. Analysis of these data proved seismic activity, possibly due to the pressure build-up and release of energy related to the hydrocarbon accumulation in the sand layers. Geochemical analyses of gas samples from wells 2/4-13, 2/4-14, and 2/4-15 were conducted. Variable mixes of shallow (biogenic) with deep reservoir (thermogenic) gasses were found in the samples, with the highest proportion of thermogenic gas in the depression of well 2/4-13. Seismic shallow anomalies corresponding to sands at 828, 492 and 445 m were mapped in March 1990, indicating recipients for leaking hydrocarbons.

The 2/4-14 R well program covers the phase from where the 7" liner has been set, cemented, logged and successfully pressure tested in well 2/4-15 S.

Operations and results

Jack-up rig Neddrill Trigon arrived the 2/4-14 location on 21 March 1989. A sub sea snubbin