The example of the Beluga oil field on the southern shelf of Vietnam shows the possibility of complex geological modeling of Miocene and Oligocene deposits with limited data, using a conceptual model. In studying the field, a number of features have been identified, concerning an allocation of new productive sediments, a large oil-saturated level, a complex fault system, and high heterogeneity of the section within the key beds. The main problems and uncertainty in the field are the low confirmability of the structural plan according to the seismic data, low study of the full-sized core, fragmentary testing of the pay zone, uncertainty of the well logging interpretation, ambiguous level of the oil-water contact.
The experience of neighboring fields demonstrated that high expectations for reserves and productivity in conditions of insufficient knowledge led to the failure to fulfill the production plan. Thus, within the framework of geological and hydrodynamic modeling on a new feature, attention is focused on sources of geological uncertainty. To this end, a conceptual model of the geological structure was created, an approach to modeling under conditions of significant uncertainties was developed and a probabilistic estimate of the reserves was made. The history of the development of the Cuulong basin has been studied and applied in modeling; the sweep direction of the material has been taken into account. Due to the limited volume of core material during the drilling of exploratory wells, an electrofacial analysis was performed. The performed analysis of the distribution of the reservoir porosity and permeability and the results of PLT on the isolated electrofacies was used in further modeling. The risks associated with the allocation of reservoirs and the non-confirmation of the structural plan, performed on the basis of a probabilistic model are also taken into account. A variant of object modeling based on the conceptual model of sedimentation of pay beds is implemented, in which variations in the sizes, shapes and orientations of features are determined.
As a result, a detailed, volumetric representation of the geological structure of the field was created. In the framework of insufficient knowledge of the offshore field, the creation of a conceptual geological-facial model served as the basis for constructing probabilistic geological and hydrodynamic models and their analysis, the results of which allowed planning the economically efficient development of the feature.
References
1. Obobshchenie i analiz geologo-geofizicheskikh materialov severnoy i severo-vostochnoy chastey mestorozhdeniya Belyy Tigr s tsel'yu vyyavleniya nestrukturnykh lovushek UV (Generalization and analysis of geological and geophysical materials of the northern and northeastern parts of the White Tiger field in order to identify non-structural hydrocarbon traps), Hanoi: Publ. of VPI, 2014.
2. Shoup R.C., Morley R.J., Swiecicki T., Clark S., Tectono-stratigraphic framework and tertiary paleogeography of Southeast Asia: Gulf of Thailand to South Vietnam shelf, URL: http://www.searchanddiscovery.com/pdfz/documents/2012/30246shoup/ndx_shoup.pdf.html.
3. Podschet zapasov nefti i rastvorennogo gaza mestorozhdeniya Beluga bloka 09-/12 Kyulongskogo basseyna (Calculation of oil reserves and dissolved gas of the Beluga field of Block 09-/12 of the Kyulong Basin), Vung Tau: Publ. of NIPImorneftegaz, 2016.
4. Pereschet zapasov nefti i rastvorennogo gaza mestorozhdeniya Belyy Tigr bloka 09-/12 Kyulongskogo basseyna (Recalculation of oil and dissolved gas reserves of the White Tiger field of Block 09-/12 of the Kyulong Basin), Vung Tau: Publ. of NIPImorneftegaz, 2016.
5. Muromtsev V.S., Elektrometricheskaya geologiya peschanykh tel – litologicheskikh lovushek nefti i gaza (Electrometric geology of sand bodies - lithological traps of oil and gas), Leningrad: Nedra Publ., 1984, 260 p.
