Prediction of S-wave velocity by a hybrid model based on the Greenberg-Castagna equation
| Autor: | José J. S. de Figueiredo, Carolina B. da Silva, Murillo J.S. Nascimento, Matias C. de Sousa |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Lithology
Petrophysics Well logging 02 engineering and technology Geophysics 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology 01 natural sciences Physics::Geophysics Fuel Technology 020401 chemical engineering Shear (geology) Regularization (physics) S-wave 0204 chemical engineering Slowness Saturation (chemistry) 0105 earth and related environmental sciences |
| Zdroj: | Journal of Petroleum Science and Engineering. 172:303-313 |
| ISSN: | 0920-4105 |
| DOI: | 10.1016/j.petrol.2018.09.014 |
| Popis: | In geophysics, more specifically in rock physics and petrophysics, empirical equations play an important role in data regularization, especially in datasets that are difficult to acquire in situ. In terms of well logging, a common scenario is the absence of shear wave slowness data, which can be handled by different methods that aim filling data gaps (regularization). This work consists of the application of a hybrid approach (based on Greenberg-Castagna method) to estimate S-wave velocity in brine-saturated lithologies on well-log datasets. The combination of local polynomial regressions with a fluid substitution analysis (Gassmann's equation) leads to an effective method of estimating shear wave velocity ( V S ) from compressional wave velocity ( V P ) when information about lithology and saturation are available. Well-log datasets (from the Norwegian Sea region) are used to demonstrate the feasibility of our methodology and show its usefulness for dataset regularization based on the local information. We selected learning and test wells from the Norne Field, where Lower to Middle Jurassic sandstones behave as hydrocarbon reservoirs. Our results show that the best fitting between the measured and predicted S-wave velocities were obtained from the modified Greenberg-Castagna method (in this work, named calibrated relation), also verified on a well from the North Viking Graben (validation dataset). |
| Databáze: | OpenAIRE |
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