It could be argued today that oil companies would be better described as water companies. Total worldwide oil production averages some 75 million barrels per day (BOPD) and, while estimates vary, this is associated with the production of 300-400 million barrels of water per day (BWPD). These values of approximately 5-6 barrels of water for every barrel of oil are quite conservative. In the United States, where many fields are depleted, the ratio of water-to-oil production is closer to 9-to-1. In some areas around the world, fields remain on production when the ratio is as high as 50-to-1.
Water production is always a harbinger of problems in an oil well. It can cause scaling problems in susceptible wells, induce fines migration or sandface failure, increase corrosion of tubulars, and kill wells by hydrostatic loading, amongst other things. Thus, while water production is an inevitable consequence of oil production, it is usually desirable to defer its onset, or its rise, for as long as possible.
Numerous strategies, both mechanical and chemical, have been employed over the years in attempts to achieve this. Simple shut-off techniques, using cement, mechanical plugs and cross-linked gels have been widely used. More exotic concepts, like relative permeability modification (RPM), have also been applied with varying degrees of success.
This paper reviews the traditional techniques and proposes some new methodologies and technologies that can be used in the design of RPM treatments, in particular. New insights offered in this paper have been gained from the design and analysis of various experimental treatments around the world.
The paper includes several of these, as case histories, to support the concepts and conclusions.