Oil producers in many areas of the country are finding that drilling horizontal wells--starting a well downward, then angling out through the length of the reservoir--can significantly increase the flow of crude oil, often restoring economic life to an aging field. But since horizontal drilling is not yet a precise science and is more expensive than vertical drilling, operators must have confidence that it will actually produce the predicted results before investing in the technology. Stanford University researchers are assessing the performance of horizontal wells through sophisticated modeling and reservoir analyses. The goal is to develop modeling and simulation techniques that will provide operators with the quantitative tools to predict horizontal well performance in a variety of reservoir types and conditions. Using Stanford's computer modeling of complex reservoir structures and large-scale flow experiments at the Marathon Research Center that simulate reservoir conditions, the University researchers hope to develop an accurate set of specifications that will allow operators to determine whether horizontal wells make technical and economic sense for their specific fields. The results could be a major step forward in the widespread acceptance of a technology that will boost the nation's oil production