Search

In this study, we apply advanced numerical optimization techniques to extend the work of Imhof and Sharma (2005, 2006) to integrate geological and geophysical data and infer the sedimentary parameters that produce a match to seismic data. In particular, we seek to match not just event timing (phase) but also reflection strength (amplitude). This inverse problem of quantitatively matching present-day measurements of structure, stratigraphy, petrology and/or fluids is inherently ill-posed and computationally difficult. In our approach we automatically adjust parameters, which control numerical forward models such as numerical basin models, petrophysical models, and seismic acoustic models, to match observed seismic data and observed stratigraphy. Note that the problem we tackle is more complex than traditional seismic inversion, which “just” estimates the velocity and reflectivity model that fits the seismic data. Here we also estimate the geological layer composition, as well as rock physics parameters controlling the relationships defining the bulk rock density and velocity.

4-D seismic reservoir simulation combines the analysis of 4-D (time-lapse) seismic changes measured in an oil and gas field with 3D elastic seismic modeling, reservoir characterization and fluid flow simulation to better understand drainage patterns of oil, gas and water into wells and to identify bypassed pay. We have solved this poorly constrained, inverse problem and arrived at a selfconsistent reservoir simulation that minimizes error and predicts 4-D seismic changes similar in space, time, and magnitude to those observed in a complex, intertwined, turbidite channel reservoir in the South Timbalier 295 field, Gulf of Mexico. Particle flow produced from the seismic reservoir simulation predicts that drainage was complex, with a pressure drop in the reservoir to below the bubble point producing a gas cap nearby the producing wells. Brightened seismic amplitudes both downdip and updip of the wells indicate that the gas coming out of solution filled the most permeable of the tubular turbidite channels. Poor oil migration downdip suggests the need for water injection, which the operator instituted in 1997 to recover this downdip oil and repressurize the reservoir. Additional production drilling must be placed precisely to target the tubular turbidite channels not filled with gas. The seismic reservoir simulation suggests that this enhanced recovery strategy should be successful. As we get better and better at 4-D seismic reservoir simulation, we should get more and more of the original oil-in-place from complex reservoirs.

One of the most important features of time‐dependent reservoir characterization is the added additional constraints that can be incorporated to update the initial reservoir model. Uncertainty of the model may be gradually reduced as the iteration of time‐dependent reservoir characterization continues.