An essential key to a successful waterflooding project is a well-planned and well-executed program of surveillance and monitoring. Production curves are very valuable tools for monitoring and detecting changes in well and reservoir performance. Production performance can provide clues as to the nature of reservoir behavior. To be meaningful, production curves require accurate and regular production well tests since fluids produced from the field are annually allocated to individual wells based on these tests. It is important to consider the following items in the design and implementation of a comprehensive waterflood surveillance program.

• Accurate record-keeping of each injector's and producer's data performance in terms of:

  • -Injection and production rates

  • -Bottom hole pressures

  • -Fluid profiles, for example, water and oil cut, WOR, GOR, etc.

• Monthly comparison of actual and predicted performance

• Estimate of sweep efficiency and oil recovery at various stages of depletion

• Performance and operating conditions of facilities

• Accurate and detailed reservoir description

• Water quality and treating

• Economic surveillance

• Diagnosis of existing/potential problems and their solutions

As a general objective, a surveillance program should allow for the maximum oil recovery to be achieved at the lowest WOR and operation cost. From a reservoir viewpoint, this can be achieved by maximizing the water recovery factors, which are primarily controlled by the three main efficiency factors (EA, EY, and ED) with a minimum amount of injected water. There are useful plotting and diagnostic techniques and procedures that are designed to supplement prediction methods and assist in quantifying the flood performance.