Statoil is working with UK company Reservoir Imaging Ltd (RIL) on the development of a programme to improve the quality and consistency of its 4-D seismic acquisition projects. The aim is to maximize the value of 4-D seismic as a tool for monitoring the performance of oil and gas reservoirs, which in turn could potentially lead to the production of untapped reserves.

RIL, based in Edinburgh, Scotland, has just completed an initial project to provide quality control (QC) and analyze all the 4-D seismic surveys commissioned by Statoil in 2006. Data from 19 legacy 4-D surveys carried out in previous years were also included in the analysis. The 10 projects from the 2006 4-D campaign involved many different geological and environmental conditions and a variety of seismic acquisition methods. One of the key goals was to provide consistent quality control across all the surveys so that outcomes of each project could be compared and highlight where adjustments were required. During the 2006 surveys, navigation data from the operating vessels was transmitted from the field to the shore at regular intervals so that RIL could process the data and generate a standard set of 4-D attributes.

A major element of RIL’s approach was to develop what is believed to be the only comprehensive GIS database that isolates contributing elements of a 4-D seismic survey in sufficient detail to allow accurate statistical analysis and comparison of surveys. Information on such factors as the acquisition technology, survey geometry, steering and feathering of towed streamers, etc. can all be crucial parameters in the planning and execution of 4-D surveys to ensure they can be repeated as exactly as possible over time.

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