Seismic is a preliminary method of geophysical exploration that provides an advantage over the geological aspects of the reservoir. However, the latter is growing “4D seismic”. In this article we will explain this new technology and how is it different from conventional “3D seismic” and its inputs for oil tankers.
What is the 4D Seismic?
The 4Dseismicor “3D repetitive” or “Constant listening” is indeed an improvement of 3D seismic activity by integrating time in the construction of images. It allows detection and estimation of the changes in the basement that occurred during time evolution of the middle. In particular, in industry, monitoring can improve our understanding of an oil/gas reservoir or a CO2 storage site. For example, repeated acquisitions allow tracking the evolution of the injected fluid fronts, optimizing fluid injection programs into improved hydrocarbon recovery.
What is the difference between 3D seismic and 4D seismic?
When sources and sensors are deployed on a single line (x) on the surface of the soil (or ocean), a 2D image is spoken (x, z). By extension, we talk about a 3D image when sources and sensors are deployed on a surface (x, y). 3D imaging (x, y, z) naturally characterizes geological structures and their extensions, which is important information for oil exploration.
Conventional oil and gas tanks operate over decades. The latter evolve slowly during their production. To characterize the evolution of these tanks over time (t), seismic monitoring 4D (x, y, z, t) is used to repeat a 3D acquisition on the same field. In practice, the conditions are never strictly identical, which is the greatest difficulty in processing and analyzing these data. Thus, seismic 4D is used to transform static data into dynamic data.
The benefits of 4D seismic
The 4D seismic inputs are colossal, not only to continuously monitor the oil fields, but to control fluid injection (water, steam, carbon dioxide or methane) in undrained tablecloths or compartments, thus increasing production rates by around 20%.
The 4D Seismic is a big step by oil giants; it would give a real boost to the oil industry. This project will allow oil companies to make their products profitable and to drastically reduce the number of explorations and the risks of associated accidents.