C. Gastaldi, L. Ben Brahim
The present study quantifies the benefits of integrating, by means of geostatistics, 3D seismic attributes and well data to predict reservoir properties and reduce volume uncertainties. Indeed, there is, on hydrocarbon fields, a clear complementarity between well data (which are few, biased in location but accurate) and 3D seismic data (which are dense, regularly sampled but noisy and ambiguously related to reservoir parameters).
The link between geological properties and 3D seismic attributes was optimised, after careful study of data histograms and variograms, by filtering out the high frequency variations of the 3D seismic attributes. Data variograms contribute to the description of the reservoirs anisotropy. Geological predictions errors were quantified by some tests. Using 3D seismic attributes to guide the kriging of well data values, brought a 50% reduction of predictions errors.
Similarly, conditional simulations results, summarised in expectation curves, showed a significant reduction of the exploration uncertainties. These uncertainties are quantitatively described by isoprobability maps.
An application of this methodology on a real case will be presented.
This study illustrates the benefit of integrating 3D seismic attributes with well data to reduce field uncertainties. Geostatistics acts as the vector for data integration. It provides the mathematical framework to quantify uncertainties, leading to a better assessment of the Exploration and Development risks. This data integration has great cost savings potential, in particular in the delineation phase of a field, and will play an important role in certification exercises.
AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France