Technologies for sand and water control have been developed, patented and successfully field tested in the Kern River Field, Bakersfield, California, using a modified furan resin. These chemical resin systems are stable to temperatures over 700F, are inert to oil field chemicals, are environmentally safe, involve very low material and placement costs, are applicable to wells with almost any downhole temperature, and require production interruptions of a few hours rather than days.
The sand control technology involves consolidating formation sand during a steam stimulation of a well by injecting the treatment chemical mixed with catalyst into the steam. The result is a consolidation that can be completed in less than two hours without affecting gross production. The second technology is a process for fluid isolation. This method involves placing the resin, with an internal catalyst, into the wellbore. The resin then penetrates out into the formation and polymerizes into an impervious plug, thereby preventing fluids from entering the well from the treated zone.
The research leading to the development of these chemical sand and fluid isolation technologies began in the laboratory with the evaluation of currently used chemical systems for sand control ranging from latex rubbers to plastics including conventional furan resins. These systems were found lacking because they are susceptible to thermal and chemical degradation.
The lack of thermal and chemical stability of most polymer systems is caused by the relatively short length of the polymer's molecular chain. To overcome this problem a modified furan resin system was developed. Water is produced as a by-product of the polymerization of a furan resin. As the polymerization proceeds, the water inhibits the further growth of the polymer. Therefore, an ester was added to react with and remove the water. This facilitates the formation of very large polymer molecules that are both chemically and thermally stable.
A second consideration for in-situ sand control applications is to minimize the reduction in permeability caused by the chemical coating the sand grains. For this reason an acid catalyzed aerosol of furfuryl alcohol (FA) is created by injecting the chemical into the steam stream during a steam stimulation of a well. The aerosol nature of the process insures a very thin coating on the sand, which maximizes permeability.
The process does not create a permanent consolidation. A compromise was made between a permanent consolidation that would have a larger permeability reduction and a temporary but more highly permeable consolidation. The low cost of the system offers the opportunity for reapplication as necessary. The highly permeable consolidation results in higher potential production compared to more permanent chemical sand control methods.
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