A new water-oil ratio improvement chemical has been developed which, when applied to producing wells, may substantially improve profitability by decreasing water production and permitting additional oil to be produced. The material, which is polymeric- has a different conformation and polymer-rock interaction them previously used materials. This new polymeric water-oil Ratio Control Agent will be referred to as VORCA, which is, an acronym for use in this paper only. The performance of WORCA is not significantly altered by mechanical shear, exposure to oxygen, acids, oils, or other normally encountered oil field fluids.
Laboratory result show a significant decrease in relative permeability to water after the UOHCA has been applied to a simulated producing formation. Consequent improvement of oil relative to that of water is improved. These taste also indicate that wash off is minimal after the material is placed.
Application to a production well is quite simple. An aqueous dilution of the base material is introduced into the formation at less than fracturing pressure. Normally, a rig is not required. No waiting or down-time is necessary. The well may be returned to production immediately.
Development field applications have been very encouraging. There has been either (1) marked decrease in water production, (2) a lowered fluid level while pumping the well, (3) an increase in oil production 0r (4) all of these.
Water production from oil wells is almost unavoidable in water drive reservoirs. The industry traditionally has lived with this problem by either separating and disposing of the produced water or by squeezing with a plugging agent to restrict water entry. The introduction of strict governmental regulations to control the disposal of product water has rapidly increased the cost of handling this water. For example, in one field, the cost to life, separate, and dispose of the produced water is $1.5 per barrel.
The encroachment of water usually causes a significant decrease in oil production. Normally, as the degree of water saturation increases, the relative oil permeability is reduced. In many cases, the relative oil permeability of a typical cases, the relative approaches when the degree of water saturation is greater than about 40–60 %.
A high degree of water saturation near the wellbore may be due to water coning, water fingering, communication with a water zone through high permeability streaks, fissures and/or fractures. As the degree of water saturation increase, water is produced instead of oil. This water may actually "kill" the oil producing zones or portions of zones which are in the same completion.
The high producing rate of water may have other problems associated with it. E.g. increased corrosion, sand production, emulsion formation, disposal. Etc.
Historically there have been two general methods of creating undesired water production. If the region of water production is well defined and can be isolated, the treatment of that region only with a material which will "set-up" to irreversibly plug the matrix is the preferred method.