Objectives and problems to be solved: The overall objective of the ATLASS project is to reduce the number of unnecessary production wells within a hydrocarbon reservoir and increase the hydrocarbon recovery rate by identification of bypassed reserves. Sub-objectives to achieve this goal are: - to improve quantitative interpretation tools for time lapse seismic data- to develop methods so that untrained sections of hydrocarbons can be identified- to improve placement of wells by using new time lapse analysing techniques- estimate volumes of bypassed oil or gas- provide guidelines on how to obtain precise information about production changes within a hydrocarbon reservoir- ultimately to improve recovery factors and extraction of hydrocarbons Existing techniques for gathering information on how a hydrocarbon reservoir is being drained are based on a mathematical model simulation. This model is continuously being updated as new wells are drilled into the reservoir. Seismic data is the most efficient tool to obtain reservoir information between wells, and if the acquisition of seismic data is repeated after some years of production, it is possible to interpret seismic changes in terms of production related effects. Some recent case studies (Duri, Gullfaks and Draugen) show that this qualitative interpretation (being able to discriminate between touched and untouched areas within the reservoir) technique has proved to be of commercial benefit to the actual fields. Description of work: The aim is to extend the qualitative approach into a quantitative interpretation, which means to estimate changes in pay thickness, discriminate between various production effects (pressure versus fluid saturation), determine shape and velocities of water fronts. If we achieve to fill the gap between qualitative and quantitative interpretation of time-lapse seismic data, we will have an extremely important tool for reservoir management. We will undertake the following approach:- Establish experimental rock physics database linking seismic parameters to reservoir production parameters
- Develop methods for distinguishing production effects from seismic time-lapse data.
- Develop methods for quantifying and increasing seismic repeatability. This is one of the major obstacles for quantitative use of time-lapse data.
- Quantify the additional information added to the time-lapse analysis technique by seabed seismic datasets. By development of these four main items, our ambition is to achieve an improved management of hydrocarbon reservoirs. Expected results and exploitation plans In addition to presentation at conferences, publication in scientific and trade journals, the results of the project are to be disseminated to Energy companies through the marketing departments of the respective partners.
Some key results from the ATLASS project are: -A new method for removing acquisition footprints from 4D seismic data-Method for discrimination between velocity and compaction changes;
- A new method for removing water layer multiples from 4D seismic data;
- Development of laboratory equipment for acoustic monitoring of long core flooding;
- Methodology for combined use of 4C and streamer data;
- Guidelines for how to assess uncertainties in quantitative time lapse analysis;
- New insight into key issues controlling the repeatability of 4D seismic data Most of the above mentioned techniques have been tested on real field examples, with good results. This means that some of the key results obtained in the project already have been transferred into valuable results for the industry.
Funding SchemeCSC - Cost-sharing contracts
2600 GA Delft
20097 San Donato Milanese
2280 AB Rijswijk Zh