Design and Installation of the Santa Ynez Unit Pipelines

Abstract The Santa Ynez Unit Expansion project offshore Santa Barbara, California, includes the installation of two new platforms in water depths exceeding 1000ft. The pipelines connecting the new structures, Harmony in 1200 ft andHeritage in 1070 ft, to the existing Hondo platform in 850 ft and to theonshore facilities required the resolution of such technical challenges as:installation of 20" pipelines in water depths of 1260 ftinstallation of a new riser on platform Harmony in 1200 ft water depthmitigation of a 20" diameter pipeline span of a subsea canyon in 1230 ftwater depth.diverless connection of three 20" pipelines to risers The SYU pipelines were successfully installed in early 1992. This paperprovides the technical approaches and results obtained during the design andinstallation of these pipelines. Description of Santa Ynez Unit Expansion Project Oil production from the Santa Ynez Unit started in 1981 from the Hondoplatform in 850 ft water depth. Oil is pumped to the "OS&T"(Offshore Storage and Treatment) facility, a converted tanker moored in 485 ftwater depth, for export using shuttle tankers. The SYU Expansion projectprovides for the addition of two platforms and a production treating facilityin Las Flores Canyon, near Santa Barbara, California. Oil emulsion from the three platforms is commingled on Harmony and pumped toshore through a 20" ANSI 600# pipeline system. After separation andtreatment water from the emulsion is pumped back to Harmony for disposal. Produced gas from the Harmony platform is planned to be pumped to Hondo fortransmission to shore through an existing 12" pipeline. The field layout isshown in Figure 1, and pipeline data is provided in Table 1.