Cenozoic Eridanos Delta Hydrocarbon System
gas technology Cenozoic Eridanos Delta Hydrocarbon System
Shallow (<1 km) gas accumulations Shallow gas – what do we know Seismic amplitude data of the Eridanos delta, on the Dutch shelf were recognized Shallow gas occurs in unconsolidated, showing reflection anomalies (‘bright spots’) indicative of shallow gas accumulations. in the 1970s but were never Cenozoic sediments on the Dutch continen- tal shelf, particularly in shallow marine to developed because of low reservoir continental (deltaic) deposits of the pressures and unconsolidated Plio-Pleistocene Eridanos delta. The sand issues. Current interest in shallow marine to continental deposits these accumulations comes forth accumulated both from deep thermogenic from a stronger demand on the gas sources and from biogenic sources in market and the availability of newer shallower strata. They are either structur- ally trapped in anticlines associated with production techniques. Therefore, rising salt domes or occur in stratigraphic many operators re-explore the or depositional traps. The gas accumula- potential of the North Sea’s shallow tions may be economically attractive, gas. Currently five such operators especially if located near existing infra- are pooling data in a TNO joint structures. The Dutch thermogenic, industry sponsor project. biogenic and mixed shallow gas systems are highly dynamic. Gas chimneys, acoustic turbidity and blanking, pockmarks and stacked bright spots, as well as methane dissolved in groundwater, all indicate ongoing and/or recent migration and leakage of shallow gas. Shallow gas gas technology
Locality of the Tertiary- Pleistocene Eridanos river (yellow) and delta (orange) system.
production in the Dutch offshore is still This will be achieved by constructing a 3D, limited by a lack of familiarity with the basin-scale reservoir model of the shallow shallow gas systems, especially with gas systems contained in the Cenozoic respect to the unclear relationship between Eridanos delta. Key external controls will anatomy of the delta and charging/ be linked directly to depositional elements trapping conditions at specific stratigraphic (fans, valley fills, clinoforms and topsets) intervals. calibrated by extensive well data, providing bio- and chronostratigraphic, geochemical Key questions and paleoenvironmental information. The Direct hydrocarbon indicators for shallow established reservoir model—in combina- gas occurrences include bright spots and tion with reconstruction of the areas of several other types of velocity anomalies, origin of biogenic and thermogenic gases which are well known by offshore operators and the charging, preservation and as they may strongly affect the correct pressure conditions in these reservoirs— imaging of deeper subsurface (energy forms the basis for improved prediction of absorption, ray distortion, etc). Their study other potential shallow gas occurrences and characterization have important offshore the Netherlands, either economic industry applications, both in geohazard profitable or hazardous. identification and in exploration of deeper levels. E&P would clearly benefit from an TNO increased understanding of how the TNO is one of Europe’s largest independent distribution of these environments is companies in the areas of technology related to external (climate, tectonics, development and technical consultancy. sea-level) and internal (delta-lobe switch- TNO employs over 4,000 scientists in a TNO.NL ing, avulsion) processes. A sequence-strati- wide range of economical sectors, graphic framework should provide critical including energy, mobility, industrial information about the architecture and innovation, information society and reservoir properties of these not yet defence. We have over 70 years of well-understood reservoirs and the experience in: continuity of sealing clays. −− Advisory, independent from commercial interests Objectives −− Development of innovative technologies The main objective of the study is to in close collaboration with major develop a workflow that assesses the industrial parties and universities. potential of seismic bright spots as −− Knowledge transfer programs for indicators for shallow gas occurrences. industry and universities worldwide.
We distinguish ourselves by our independ- TNO Mapped bright spots ent position and capability to address Dr. Johan ten Veen Legend Bright spots challenging technological issues with Princetonlaan 6 Shallow gas field Extend of mapped area multi-disciplinary teams of highly qualified 3584 TA UTRECHT scientists. We develop technology, on the basis of top quality scientific knowledge, T +31 88 866 45 32 into practical applications with industrial M +31 6 12 89 54 27 use. As an independent company TNO is E [email protected] not active in the production or commerciali- zation of its innovations. TNO.NL/energy