Enterprise Products Partners LP, Teppco Partners LP and a unit of Marquard & Bahls AG plan to build a $1.8 billion Texas oil port that will be the biggest US crude-import terminal when it opens in 2010. The facility, known as Texas Offshore Port Systems, or TOPS, will take deliveries from tankers 36 miles (58 kilometers) offshore and pump the oil to onshore refineries through a subsea pipeline. TOPS will mostly handle light crude shipments from West Africa and the Gulf for Texas-based gasoline producers, said Dan Duncan, the Houston billionaire who controls Enterprise. The port will cut costs for refiners who now rely on barges to haul oil to inland ports. It will also be less susceptible to fog that hinders deliveries. “This is going to relieve bottlenecks and allow for more efficient routing of crude oil to refineries,'' Darren Horowitz, an analyst at Raymond James & Associates Inc., said in a telephone interview. “It's really going to improve the efficiency'' of importing crude. Demand for the port's capacity will be driven by environmental rules that are making it harder and costlier for refiners to ship crude through the Houston Ship Channel and other waterways in smaller vessels, Duncan told investors and analysts on Monday on a conference call. Exxon Mobil Corp., the world's biggest oil refiner, and Motiva Enterprises LLC, a joint venture of Saudi Aramco and Royal Dutch Shell Plc, have already agreed to lease 40 percent of the port's capacity. Enterprise rose 41 cents, or 1.5 percent, to $28.67 at 10:56 a.m. in New York Stock Exchange composite trading. Teppco gained 2 cents to $30.33. The subsea pipeline will cross onshore at Freeport, Texas, and extend along the coast to a 3.9-million-barrel storage facility at Texas City. A second pipeline will run 75 miles from Texas City to a new storage center near Port Arthur, Texas, which will hold about 1.2 million barrels. TOPS will be 80 percent larger than the biggest existing US oil port, the Louisiana Offshore Oil Port known as LOOP. It will be able to handle shipments from the world's largest supertankers that can haul 3 million barrels each, supplanting LOOP's monopoly on the US market for such deliveries. Duncan, ranked the 39th richest American last year by Forbes magazine, is chairman and the biggest holder of Enterprise and its general partner, Enterprise GP Holdings LP. Duncan is also the largest investor in Teppco, controlling an 18 percent stake based on a Feb. 28 public filing. Duncan, 75, started Enterprise in 1969 with one truck, two partners and $10,000. Forbes estimated Duncan's fortune at $8.2 billion. Enterprise, Teppco and Marquard's Oiltanking Holdings America will contribute $600 million each to the project and own equal stakes.