A new technique to determine excessive water and gas production mechanisms as seen in petroleum production wells has been developed and verified.
Based on systematic numerical simulation studies on reservoir water coning and channeling, it was discovered that log-log plots of WOR (Water/Oil Ratio) vs time or GOR (Gas/Oil Ratio) vs time show different characteristic trends for different mechanisms. The time derivatives of WOR and GOR were found to be capable of differentiating whether the well is experiencing water and gas coning, high-permeability, layer breakthrough or near wellbore channeling.
This technique was applied on wells in several fields in Texas, California, the Gulf coast and Alaska Plots using the actual production history data determined the production problem mechanisms. Together with well tests and logs, the technique was used to select well treatment candidates and to optimize treatments to enhance the return of investment.
Over the last 30 years, technical efforts for water control were mainly on the development and implementation of gels to create flow barriers for suppressing water production. various types of gels were applied in different types of formations and to solve different types of problems.1,2 Quite often, excessive water production mechanisms were not clearly understood or confirmed. Although many successful treatments were reported, the overall treatment success ratio remains low.3
Through these field trials, the art of treatment job execution was progressively improved. Good practices in the process of candidate selection, job design, gel mixing and pumping and job quality control were recognized and adapted. More effectlve tools and placement techniques were also used. The desire to define different types of excessive water production problems began to surface.