Sarir Field - Post-Discovery

Post-Discovery

C-1-65 had an oil column exceeding 76 m, above predicted closure for its shallow reflection structure. Although seismic maps gave structural indications, details were unreliable at the reservoirs top 1676 m below. Thus, while the second and third wells were drilled, a seismic refraction survey was shot. It gave control over the basement structure, but since the first four wells proved reservoir sands varied from 141-410m in thickness over a relatively short distance, the survey gave little control over the trapping structure. Seismic maps on both horizons and subsurface information showed the reservoir structure and helped limit drilling in dry holes.

After discovery continuous drilling occurred with up to five rigs at a time. Initially, short outsteps up to 4 km were made, followed by bolder drilling to confirm reserves and justify costs for a 516 km oil pipeline to Tobruk. Once confirmed, C-1-65 was steadily drilled on a 2 km grid spacing. At this time, two smaller fields were discovered: Sarir North and L-65.

In May 1965 five infill wells were sabotaged. The incident occurred during the reign of King Idris before the 1969 coup led by Colonel Qaddafi. The wild wells were not reported in the news media and the perpetrations not revealed. Until the Persian Gulf War of 1991 this was the largest simultaneous well fire ever. In recognition of the number and ferocity of the blowouts BP called for the fire fighter Red Adair plus his lieutenants Boots & Coots. On arrival the crew drove around the field to assess the task. One of the wells had not caught fire but was erupting crude. Living up to his larger than life reputation mirrored by John Wayne in the film Hellfighters Adair approached the well and closed the undamaged master valve saying (reputedly) “one down four to go”. On return to the main camp he informed BP that he could cap the wells unaided and dispatched Boots & Coots back to Houston. He extinguished the fires in 3 weeks.

Initial production from the main Sarir oil wells averaged 8,000 bbl/d (1,300 m3/d), with some achieving rates of 20,000 bbl/d (3,200 m3/d). Since Sarir does not have a gas cap and GORs vary between 60-225 static ft³ per barrel, pressure maintenance was an issue. Fresh water was used, available from about 46 m to 518 m. Some areas used downhole pumps to maintain production. Desalters were also added, since the large salt amounts entrained in crude production were untolerable by many refineries.