Academia - A discussion of how soap is used to revive mature oil fields.
Most reservoirs in the US under operation by small producers have become mature due to extended waterflooding. In fact, an estimated 80% of the total number of oil wells in the US are now classified as “marginal.” The mature reservoirs accessed by these wells usually have a high water cut, in the range of 80% to 90%. Also, the industry typically leaves about 65% of oil behind after many years of waterflooding because of reservoir heterogeneity and incomplete sweep of the formation. Excessive water production becomes a major problem as these oil fields mature. High volumes of water production result in increased levels of corrosion and scale, increased load on fluid-handling facilities, increased environmental concerns, and eventually well abandonment (with associated workover costs). Consequently, producing zones are often abandoned in an attempt to avoid water contact, even when the intervals still retain large volumes of recoverable hydrocarbons. Controlling water production has been a challenging goal for most oil producers.