Vietsovpetro JV conducts exploration and development of hydrocarbon fields on the continental shelf of Vietnam. The following fields were put into development at block 09-1: White Tiger, Dragon, White Bear, White Hare and Southern Dragon-Sea Turtle. During production a detailed study of the geological structure of productive rocks and deposits is carried out and a large amount of data has been obtained in productive deposits which characterizes the properties of reservoir and their distribution in rocks. The article discusses methods for studying the heterogeneity of reservoir rocks properties of productive deposits of the Lower Miocene deposits located on block 09-1, in the Vietnamese offshore. Based on the sediments, 8 productive units and 48 productive layers were identified. Their distribution over the area of the block and the section of deposits was studied. The average values of the distribution of porosity and oil saturation, characterizing geological heterogeneity, were determined and analyzed using statistical methods. Algorithms for the distribution of calculation parameters for the probabilistic-stochastic volumetric method of for calculating oil and gas reserves are proposed. The Monte Carlo method was used to quantify the parameters of deposits. According to the results of reservoir properties study at the White Tiger and Dragon fields during the recalculation of reserves in 2023–2024 years new productive deposits were identified that had not previously been identified during the study of the geological structure. The results of reserve volumetric recalculation were approved and tested during the development of deposits. The obtained data from studying the heterogeneity of reservoir properties and the geological structure of the White Tiger and Dragon fields are of practical interest when using the results of work in similar geological conditions in poorly studied areas and marginal deposits of the continental shelf of Vietnam. According to geological survey data, development and additional study of existing fields of block 09-1, using the example of productive deposits of the Lower Miocene, characteristics of the distribution of porosity and oil saturation of were obtained. Methods for assessing reservoir properties and volumetric reserves, prospects and marginal hydrocarbon plays of Vietnam continental shelf are considered. Conclusions are drawn about the application of methods for studying physical properties for similar conditions. Using this method, reserves of the White Tiger and Dragon fields were recalculated in 2023–2024 and approved in Vietnam.
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