Wences P. Gouveia

On the inversion of time‐lapse seismic data

As the number of time-lapse (4D) seismic applications increases; so do the prospects for quantitative estimates of dynamic reservoir properties, such as fluid saturation and pressure, based on time-lapse seismic data. These estimates can be obtained by the application of appropriate rock physics models that map seismic-derived estimates of timelapse Pand S-impedance changes to changes in the dynamic properties. Therefore, it is important that reliable 4D impedance models are available for this process. There are, however, a number of ways to estimate impedance change from 4D seismic data. The purpose of our study was to assess the merits of different inversion workflows by using a synthetic 4D data set and comparing models resulting from the inverse calculations with actual impedance models. This study demonstrates the importance of coupling the inversion of base and monitor surveys to mitigate the impact of inherent non-uniqueness in seismic data inversion. The results from uncoupled inversions can mislead time-lapse interpretation and compromise reservoir management decisions.

The CWP object‐oriented optimization library

The CWP Object‐Oriented Optimization Library (COOOL) consists of a collection of C++ classes (encapsulations of abstract ideas), a variety of optimization algorithms implemented using these classes, and a collection of test functions, which can be used to evaluate new optimization algorithms.

Jotun 4D: Characterization of fluid contact movement from time-lapse seismic and production logging tool data

Time-lapse (or 4D) seismic is a reservoir monitoring technology that has matured to the point where it can be considered a reliable reservoir surveillance tool. By analyzing differences of multiple seismic surveys acquired over a producing reservoir and by integration with conventional reservoir monitoring tools, 4D seismic data can provide valuable insight on dynamic reservoir properties such as fluid saturation, pressure and temperature. Many published case studies demonstrate that 4D seismic technology can optimize reservoir management and improve production efficiency. In this paper we describe the application of time-lapse seismic methods to the Norwegian North Sea Jotun Field to determine the extent of the oil-water contact (OWC) movement during the first three years of production.

Integration of Time-Lapse Seismic and Production Logging Data: Jotun Field, Norway

Time-lapse (4D) seismic data acquired over the Norwegian North Sea Jotun Field is used to monitor water sweep in the Paleocene-age Heimdal reservoir. Inversion of the seismic differences provides a direct measure of the impedance increase associated with water displacing oil. This highresolution image of water sweep is consistent with production logging tool (PLT) data acquired in seven wells in the field. Combined with integrated reservoir facies interpretations and with other production data, the 4D data successfully derisked several proposed infill well locations and has identified new workover candidates and drilling opportunities in the field. The results of this work demonstrate the strength of applying multidisciplinary team efforts and partner cooperation to optimize asset value through tailored data acquisition programs and drilling.