WASHINGTON — Despite conservation and other strategies, the United States has grown increasingly dependent on foreign oil and should take steps to protect itself against future supply disruptions, a report to Congress said Oct. 29.Many of the easier ways of achieving oil savings already have been taken. They include switching to other fuels for utilities, industry, and the residential and commercial sectors. Future efforts may be more difficult and costly, said the report by the congressional Office of Technology Assessment. The report was an update of a 1984 OTA analysis and the new study found the situation has worsened. The United States "is more dependent on oil imports and less prepared to respond to a severe oil supply disruption than it was just seven years ago." The report said most analysts feel oil shortfalls due to war or other disruptions are "much less likely than they were in the 1970s," but substantial shortages are still possible. With many of the easier opportunities already taken to replace previous uses of oil and to improve energy efficiency, the focus shifts to two sectors "where oil replacement poses significant technical challenges - transportation and industry," OTA said. "Nevertheless, OTA believes that opportunities remain to reduce oil import vulnerability." The OTA suggested several goals to ease import dependence and increase energy efficiency, including limiting net oil imports to not more than 50 percent of annual consumption and promoting efforts to diversify oil sources outside the Middle East. Other goals include increasing US energy efficiency by 2 percent a year and moving toward a post-fossil fuel economy by reducing carbon intensity by 10 percent in each of the next two decades.