Line extension part of Colombian production surge

John Skalski
Oleoducto Central S.A.
Santafé de Bogatá, Columbia

Shipments began this month along Oleoducto Central S.A. (Ocensa), the nearly 500 mile (800 km ), 30 and 36-in. oil pipeline from central Colombia (Fig. 1 [25,746]) to a Caribbean Sea export site.

Start-up follows installation of 700 km of new pipeline (Phase 2) to complement a 100-km segment installed in 1993-94 (Phase 1).

Volumes approaching 320,000 b/d are departing the initial Cusiana pump station for the trip to the Cove?as terminal and offshore tanker-loading facility. At full capacity by yearend, the new Ocensa system will combine with another 24-in. oil pipeline to carry 556,000 b/d (Fig. 2 [25,008]).

Ownership

Ocensa is a limited liability company formed in Colombia in October 1994 by six companies to build, own, and operate the oil pipeline-transportation system. Producer ownership is split among Empresa Colombiana de Petroleos, Colombian state oil company, producer (25%); BP Colombia Pipelines, producer (15.2%); Total Pipeline Colombia, producer (15.2%); and Triton Pipeline Colombia, producer (9.6%).

Known as the Canadian Group, operator-owners are IPL Enterprises Colombia (17.5%) and TCPL (Bermuda) (17.5%). Main offices are in Santafe de Bogot , the country's capital.

Percentages also represent participation by each company in the building of the system, the budget for which exceeded $2 billion (U.S.).

In addition to the transportation system, the producers have a budget of more than $7 billion for upstream field development of the Cusiana/Cupiagua project. This development includes well sites, flow lines, and central processing.

A smaller (24 in.) system has been operating from Vasconia to Coveñas for the same shippers in the same area moving approximately 160,000 b/d from Cusiana field to offshore loading. Ocensa Operations (Canadian Group) took over the operation of this system in October 1995.

The combined existing system and the new system will be controlled remotely from the Ocensa facilities in Bogot .

The company's goals focus on the need to operate an expanding oil-pipeline system to meet objectives of today's shippers in addition to those of future shippers as new oil fields develop, all to world-class standards.

The structure of the company permits operator/investor Canadian Group to set initiatives via incentives agreed to by the producers to operate a successful batched-oil, open-market transportation system without direct involvement by the producers and partners of today.

Ocensa Operations employs more than 120 persons, of whom less than 10% are North American expatriates.

Expanded system

The new transportation system is made up of more than 700 km of 30 and 36-in. fusion bond epoxy (FBE) and extruded polyethylene-coated pipe, four pump stations, and an offshore tanker loading unit (TLU).

The pipeline routing profile (Fig. 3 [22,185]) shows that, although the initiating station is at an elevation of approximately 400 m above sea level, the oil must then be pumped to overcome an elevation of more than 2,800 m above sea level and then returned to sea level at the tanker loading unit.

More than 104,000 hp have been installed in the first 87 km of the nearly 800 km pipeline system, including the 100 km of 30-in. line of the existing system.

The pipeline begins in the Cusiana fields in central Colombia (Fig. 1) and travels west to the pump stations of El Porvenir and Miraflores and through the pressure- regulating station of La Belleza.

At La Belleza, oil begins its downward flow through the existing 100-km section to Vasconia and continues via gravity to the northwest through the existing station at Caucasia to the coast of Colombia at Coveñas. There a new terminal has been constructed to receive the oil and load tankers in the Gulf of Morrosquillo at 60,000 bbl/hr via a newly constructed 11.4 km, 42-in. subsea pipeline to the new TLU (Table 1 [92,003]).

Ocensa pipeline system construction was managed by BP Exploration (BPX) Colombia with the construction management team's staff made up of BPX and representatives of Ocensa partners.

A feasibility study was completed in March 1993 and in December 1993 all participants established and approved a Statement of Requirements which set the standards and concepts for design, construction, and operation of the new system. A budget of $1.3 billion was set for the 1996/98 work. In May 1994, engineering was awarded to Brown & Root, Houston.

Pipe and pumps

The design is based on ANSI B31.4, as no comparable standard exists in Colombia.

The pipe for the project was ordered in December 1994 from three mills in Japan: Sumitomo Corp. and affiliates, Itochu Corp., and Nissho IWAI Corp., all in Tokyo.

Pipe started arriving in Colombia at the port of Santa Marta where Bredero Price Colombia B.V., on behalf of the three pipe mills, established a coating plant to apply the fusion bond epoxy (FBE) coating and extruded polyethylene coating (PE) on the 12 and 18-m, 30 and 36-in. Grade X-70 steel pipe.

Wall thicknesses vary from 0.375 to 0.938-in. in consideration of the extreme terrain and resulting hydraulics. The 12-m, 30 and 36-in. FBE + PE (three-part system) coated pipe was selected for the mountainous 218 km section between Cusiana and La Belleza (Fig. 4 [19,114 bytes]).

The 18 m and some 12-m joints were coated with FBE for the section north of Vasconia to the coast, a less mountainous region.

The three main pump stations already existed but required major expansion to achieve the new flow rates. Additional tankage and horsepower was required (Fig. 3).

Materials for the project have come from around the world:

Such major items as main line pumps and diesel drivers were supplied by Machinery Corp. of America, Lafayette, Ind. The Cusiana electric-driven pumps were supplied by Ansaldo Ross Hill, Leeds, U.K., with booster and shipping pumps supplied by Sulzer (U.K.) Pumps Ltd., Leeds, and BW/IP International Inc., Tulsa.
The 22 station and main line gate valves were supplied by Grove Italia, Voghera, and the 91 main line gate valves were supplied by Daniel Valve Co., Houston. The 36 check valves were supplied by Tom Wheatley Valve Co., Houston, and the tanker loading unit was supplied by Bluewater Terminal Systems, Hoofddorp, The Netherlands.

The routing of the new system in general parallels the existing system with some deviations due to space limitations on the mountain ridges and unstable terrain on the 45-90° slopes.

The remote main line gate valves are installed in concrete bunkers and 3/4-in. steel plate shelters for security. The valve operators are solar powered, electric-over-hydraulic operators. Solar power is also used to power the supervisory control and data-acquisition (scada) system equipment at these valve sites.

Construction

Pump-station construction was managed by Distral S.A., Bogot . The pipelines were being constructed by two companies:

Techint-Cotecol, a Colombian company established by Techint International Construction Co., Buenos Aires, for the south section (224 km) between Cusiana and La Belleza with two spreads working towards Miraflores from each end (one 36-in., 137-km spread and one 30-in., 87-km spread). All crossings are open cut (Fig. 5 [16,744 bytes]). Laying rates reached 20-40 joints/day over mountainous terrain, using manual and semiautomatic welding. Because of the many steep slopes, special crews (up to 12) were established to tackle the joint-by-joint construction program. Slopes of up to 85° were overcome with cables, anchors, and conventional excavators and equipment to install the buried system.
Saipem S.p.A., Milan, for the Vasconia-Coveñas section (476 km of 30 in.), three spreads working with automatic welding in high production region of Caucasia to Coveñas Manual welding was employed in the hilly terrain towards Vasconia (Fig. 6 [12,921 bytes]). Four river crossings of approximately 1,200 m each were directionally drilled. One airport landing strip (1 km) was directionally drilled.

Average production using automatic welding was 100 joints/day; manual welding achieved 20 joints/day.

John Skalski is currently seconded to Ocensa construction as manager for pipeline construction, pipeline south. Before working in Colombia for Ocensa, he was employed by Interprovincial Pipe Line (IPL), Edmonton. Skalski is a mechanical engineering graduate from the University of Saskatchewan and a member of the Association of Professional Engineers, Geologists & Geophysicists of Alberta.