Accounting for productive deposits heterogeneity in geological modeliling in order to improve an efficiency of water-alternated-gas injection

The article is devoted to forecasting heterogeneity of sediment permeability in the process of geological modelling. The correctness of this operation largely determines the effectiveness of water-alternated-gas injection on hydrocarbon deposits. The presence of fractured zones and significant variability of the parameter under modelling within a single cell significantly complicates the design of water and gas exposure. It is proposed to abandon the generally accepted method of predicting the filtration properties of productive deposits based on the empirical dependence of permeability on core porosity. The paper considers the possibility of using probabilistic methods that have been successfully tested in the construction of geological models of gas reservoirs associated with terrigenous deposits of the Yamalo-Nenets autonomous district to evaluate filtration properties. For this purpose, based on the results of laboratory core studies, the empirical dependence of the probability of permeability for each excess of the standard class values (according A.A. Khanin classification) on porosity is calculated. Subsequently we have carried out the adaptation of patterns to the scale of cells of the geological model. For this purpose, the cells were represented as a set of conditional rocks, the size of which is comparable to laboratory samples. Using a random number generator, virtual differences were assigned porosity values with the condition that their average value was equal to the porosity determined from logging. Then, for each conditional sample, the probability of exceeding the standard values of the corresponding classes was calculated. After averaging the obtained values, the dependences of the probabilities of the existence of certain groups of reservoirs are calculated. This allows to calculate the permeability histograms for each cell of the geological model. © 2021, Neftyanoe Khozyaistvo. All rights reserved.