Recent developments in seismic exploration and reservoir characterization

The exploration, appraisal and production of oil and gas reserves are supported by a variety of sophisticated measurements that contribute to characterizing the geometry and flow properties of hydrocarbon reservoirs. Acoustic measurements ranging from high resolution ultrasonics to lower resolution (but higher range) seismics play important roles in this characterization. This paper describes, in particular, how seismics have been transformed by the development and acceptance of 3-D techniques which have helped improve the success rate of new wells from 10-20% to 60-80%. Moreover, information from seismic signals, which include sound speed, impedance maps, amplitude and phase changes, can be linked to important rock parameters (e.g., rock type, porosity, and hydrocarbon saturation) and to changes in these parameters over time by comparing repeated seismic surveys separated by months or years. Many consider this process, becoming known as 4-D seismics, to represent the next revolution in using seismic techniques. The success of this may be invaluable to finding much by-passed oil and gas in already produced fields, which could have enormous impact on the supply of oil and gas and its costs