METHOD FOR LOCALIZING PROMISING ZONES IN OIL SOURCE STRATA Russian patent published in 2021 - IPC G01V1/28 G01V1/30 G01V11/00 E21B47/06 E21B47/07 

FIELD: oil industry.

SUBSTANCE: invention relates to the oil industry and can be used in the development of oil deposits of unconventional reservoirs of oil source strata of the Bazhenov formation. A method for localizing promising zones in oil source strata is claimed, which includes conducting well surveys, comprehensive analysis and interpretation of core test results, verification of parameters, construction of maps and their joint analysis. According to the proposed method, the values of Poisson's ratio and Young's modulus are obtained in the oil source formation, the overlying and underlying fluid seals, the Poisson's ratio values are averaged over the thickness within the intervals of the oil source formation, the overlying and underlying fluid seals, and its effective values are found for each interval of the Poisson's ratio and plotted source formation, overlying and underlying seals. The brittleness index is calculated in the interval of the oil source formation, the intervals of brittle zones with a brittleness index of ≥0.5 are identified, they are summed up, the total thicknesses of the brittle zones for each well are found, and a map of the thicknesses of the brittle zones of the source formation is built. As a study of the core, its laboratory pyrolysis is carried out, on the basis of which the type of kerogen is established, its kinetic spectrum, the thermal history of the oil source reservoir and the history of submersion of its top from the moment of its formation to the present state are determined. Based on the data of 3D seismic exploration and geophysical studies, a map of the current depths of the top of the oil source formation and maps of the total thicknesses of the oil source formation, the overlying and underlying fluid seals are built. Based on the data of production geophysical studies, maps of the density of the rock of the oil source formation, the overlying and underlying fluid seals and a map of the current formation temperatures of the oil source formation, a map of the concentration of kerogen in the source formation in paleo conditions based on laboratory core pyrolysis data are built. The correspondence of the kinetic spectrum of kerogen to the thermal history of the oil source formation is verified on the basis of numerical modeling of the kinetics of thermal decomposition of kerogen according to the previously determined thermal history of the oil source formation; kerogen and similar values calculated from laboratory core pyrolysis data for specific wells. Numerical modeling of the change in pore pressure in the source formation is carried out and a map of the potential pore pressure in the source formation is built. Based on the map of the current depths of the top of the oil source formation and the map of potential pore pressure in the source formation, a map of the calculated coefficients of anomalous pore pressure in the source formation is built, it is jointly processed with the map of the thicknesses of the fragile zones of the source formation by ranking the intervals of the values of the calculated coefficients of anomalous pore pressure not less than more than 3 ranges and thicknesses of fragile zones not less than 3 ranges. The maps of the calculated anomalousness coefficients of the pore pressure in the source formation and the thicknesses of the fragile zones of the source formation are recalculated into the corresponding maps of discrete indices by replacing the actual values of the parameters with the values of the discrete index for the corresponding intervals in ascending order of their values; conditions for reaching the maximum values of anomalous pore pressure and thicknesses of brittle zones in the oil source formation, with a further decrease in the discrete index of prospects as the values of the ranges of anomalous pore pressure and thicknesses of brittle zones decrease, intersecting on the maps of the calculated anomalousness coefficients of pore pressure in the source formation and the thicknesses of the fragile zones of the source formation, and on the basis of this condition, a discrete map of promising zones, ranked according to the priority of prospects, is constructed, where the maximum discrete index of prospects corresponds to the most promising zones.

EFFECT: improving the accuracy of localization of promising zones from the point of view of development in oil source strata, taking into account the degree of maturity of the oil source rock and the processes of primary migration of mobile hydrocarbons.

1 cl, 13 dwg