COMPACTION, ROCK PROPERTIES AND AVO MODELING IN THE GOLIAT FIELD, SW BARENTS SEA : A petrophysical approach
The PDO approved Goliat Field, situated on the Finnmark Platform in SW Barents Sea region represents the first oil field to be developed on the Norwegian Barents shelf. Cenozoic exhumation still poses significant challenges in developing frontier exploration models due to its effects on the differen...
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| Format: | Master Thesis |
| Language: | English |
| Published: |
2011
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| Online Access: | http://hdl.handle.net/10852/12628 http://urn.nb.no/URN:NBN:no-27847 |
| Summary: | The PDO approved Goliat Field, situated on the Finnmark Platform in SW Barents Sea region represents the first oil field to be developed on the Norwegian Barents shelf. Cenozoic exhumation still poses significant challenges in developing frontier exploration models due to its effects on the different elements in a petroleum system. Understanding the nature of the transition from mechanical to chemical compaction, the degree of overconsolidation and AVO modeling of selected reservoir intervals is the main theme of this work. Data from six wells, laboratory compaction curves and published shale compaction trends have been used to evaluate the rock properties as a function of depth. AVO synthetic single interface models have been carried out using Hampson-Russel. Experimental laboratory compaction data coupled with compaction trends in the Goliat Field indicate that the amount of exhumation ranges between 700 – 1500m. An integration of the Vp-depth trend together with a porosity-shear modulus cross plot, show that the transition from mechanical to chemical compaction for siliciclastic rocks occurs at approximately 600m BSF. This temperature controlled transition represents a silica phase transformation. The Chemical compaction trends show a smaller change in Vp with depth compared to the mechanical compaction domain. Velocity inversion with depth due to the presence of source rocks, effect of pore fluid and pore pressure has been demonstrated for different wells. AVO modeling for different fluid saturation scenarios indicates that the synthetic seismic is sensitive only to the initial 10% gas saturation in oil – gas system, with the saturated bulk modulus being the main controlling parameter. The insitu AVO response for the Tubåen reservoir is class IV, meanwhile the Kobbe reservoir gives a class III signature. The corresponding gas models indicate that, ∆Vs and Poisson’s ratio are key parameters increasing the reflectivity with offset (angle), meanwhile the impedance contrast in the half space single layer models ... |
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