|PRODUCTS AND SERVICES|
|The tracking of fluid drainage over
time is a required condition for efficient reservoir
monitoring. 4D (time-lapse) seismic differencing
holds great promise as the keystone to an e-based
integrated reservoir management strategy that is able to
image changes not only within a reservoir but within the
stack of reservoirs that make up most of the oil and gas
fields of the world. Yet there are major components
of 4D sesimic monitoring that are only just being
developed by the industry. Field acquisition is
still centered on reacquisition using 3D methodologies;
processing and interpretation are focused on
normalization and differencing of time lapse data itself;
and seismic modeling is 1D and 2D, acoustic, and built
around one reservoir at a time.
CES technologists foresaw a market need for a rapid analysis and interpretation toolkit for quickly differencing two vintages of 3D seismic surveys (the RAI software now being marketed by Western Geophysical, recently acquired by Baker-Hughes International). That product helped Western acquire a significant number of field reshoot jobs, particularly in the North Sea, and compete successfully in the newly emerging 4D seismic market. Schlumberger, in particular, was surprised by Western's software lead.
Three years ago, we also understood the need to integrate into an e-based management system the observed 4Dseismic differences with reservoir simulator predictions and production histories of fluid withdrawal in fields. If quantitative reservoir management were to truly come about, the engineering geological and geophysical worlds would have to be combined into what is now being called an "earth model" solution. That is, the observed seismic changes over time must be reconciled with the known fluid withdrawal information and the complexity of the permeability pathway information if successful predictions of future drainage were to be optimized.
Western concurred, and we launched a very ambitious seismic e-reservoir modeling software development project code-named "SeisRes". Not only would the reservoir stack be simulated from a fluid flow perspective, but the drainage changes would be fed into a 3D, elastic seismic modeling program that could simulate seismic amplitude changes accurately enough to be realistically compared to real 4D seismic field data differences. An optimizer would then reconcile the differences between the differences. That is, the time-lapse differences between observed and computed seismic and fluid flow models and data would converge to the best view of the real changes occurring in oil and gas fields that the industry has so far been able to produce.