- Copyright © 2001 Society of Exploration Geophysicists
There is a widely discussed vision that by the end of this decade permanent sensors systems in wells will be common components of instrumented oil fields and will provide data for more effective asset management and operations. In this scenario, seismic sensors, seismic sources, and a variety of nonseismic sensors will be unobtrusively and permanently distributed throughout the development infrastructure. When activated, these systems will constantly monitor the properties and performance of the reservoir and the dynamic changes that occur as production, stimulation, and EOR processes are applied. That is the vision. Let us look at where we are today.
To date, several hundred pressure sensors have been permanently installed in wells. Other deployed sensors measure temperature, production, pH, fluid composition, mechanical noise from electrical submersible pumps (ESP), and the noise of abrasion caused by produced sand (Table 1).
Time-lapse (TL) reservoir monitoring from the borehole is in its infancy. Most successful deployments have been experimental proof-of-concept tests using retrievable (wireline) arrays to monitor CO2 and steam floods and to listen passively to the reservoir. Only a few of these examples are time-lapse or have utilized permanent borehole sensors.
Since its introduction in the late 1980s, more than 70 surface and ocean bottom cable (OBC) time-lapse seismic surveys have been acquired globally in a wide range of geologic and reservoir settings. These monitor a wide range of oil-field operations including fluid contact movements, waterflood, steam flood and CO2 flood effectiveness. With many case histories on file and with more projects being undertaken, the value created by 4-D seismic is being demonstrated.
The acceptance of 4-D as a reservoir management tool, with its application in areas of high cost and low margin, is creating the appropriate business elements to stimulate commercial development …