Summary
Development of the Greater Plutonio field complex in Angola Block 18 has been supported by 4D since the first monitor survey was acquired in 2009. Existing 4D data over the field had been considered to be of high quality. Here we develop a processing flow including ?S?R (the sum of the mis-positioning of the sources and receivers from baseline to monitor survey) thresholding and parallel pairwise binning with transfer operators to further improve the quality of the 4D products, while optimizing the 4D quality for all six possible time steps between the baseline and three monitor surveys.
Introduction
The Greater Plutonio development lies in Block 18, offshore Angola. It consists of 5 fields, each with 3 to 5 reservoir sections which sit in water depths of 1200 to 1500 m. It has been on production since Q4/2007. Oil is processed and exported via an FPSO.
The development is actively supported by 4D narrow azimuth towed streamer seismic data. The acquisition program to date has consisted of a baseline survey acquired in 2000 with subsequent monitor surveys acquired in 2009, 2011 and 2013. The favorable rock properties and geometry of the fields result in considerable value being gained from the 4D products. The key technologies adopted to date in extracting value from the 4D data have been steerable streamers and sources, TTI anisotropic velocity model building and imaging, and multi-vintage parallel 4D processing (Jackson and Riviere, 2013). A typical example of the 4D data quality seen at Greater Plutonio is shown in Figure 1.
4D data from the processing associated with Monitor 1 and 2 had been considered to be of high quality with low NRMS levels and interpretable 4D difference products. A desire to further improve the 4D data quality was none the less driven by a need to ensure that the influence of 4D data can be sustained beyond the early field development phase. Achieving this would provide data of sufficient quality to support base management decisions as the field matures and development well programs are completed.
