Improved methods for water shutoff. Semi-annual report, May 1, 1996--September 30, 1996

In the United States, more than 20 billion barrels of water are produced each year during oilfield operations. Today, the cost of water disposal is typically between $0.25 and $0.50 per bbl for pipeline transport and $1.50 per bbl for trucked water. Therefore, there is a tremendous economic incentive to reduce water production if that can be accomplished without significantly sacrificing hydrocarbon production. For each 1% reduction in water production, the cost-savings to the oil industry could be between $50,000,000 and $100,000,000 per year. Reduced water production would result directly in improved oil recovery (IOR) efficiency in addition to reduced oil-production costs. A substantial positive environmental impact could also be realized if significant reductions are achieved in the amount of water produced during oilfield operations. In an earlier project, we identified fractures (either naturally or artificially induced) as a major factor that causes excess water production and reduced oil recovery efficiency, especially during waterfloods and IOR projects. We also found fractures to be a channeling and water-production problem that has a high potential for successful treatment by gels and certain other chemical blocking agents. By analogy, these blocking materials also have a high potential for treating narrow channels behind pipe and small casing leaks. We also determined that the ability of blocking agents to reduce permeability to water much more than that to oil is critical to the success of these blocking treatments in production wells if zones are not isolated during placement of the blocking agents