METHOD FOR PREDICTING THE PRESENCE OF MOVABLE OIL DEPOSITS IN BAZHENOV DEPOSITS BASED ON THE DETECTION OF CATAGENETIC ALTERATIONS Russian patent published in 2023 - IPC E21B49/00 

FIELD: oil geological research.

SUBSTANCE: detection of movable oil deposits in high-carbon oil source Bazhenov deposits (VNBO). In particular, a method is claimed for detecting positive catagenetic features associated with hydrothermal development of rocks in high-carbon oil source Bazhenov deposits, including a sequence of actions in accordance with which a reference well is selected in which gamma ray logging is performed, as a result of which Bazhenov deposits are isolated with subsequent selection core from an interval including Bazhenov deposits, as well as underlying and overlying deposits at a distance of at least 5 m intervals. In the core column, a layer is isolated with the radioactivity of the rocks, more than 2 times higher than the radioactivity of the clays underlying the Bazhenov deposits, from which samples are taken in the amount of at least 3 pieces per 1 m of core without the content of mussel residues, followed by measurement of pyrolytic parameters in these samples, including the amount of hydrocarbons that can be formed when the oil source potential of the rock is realized and the total amount of organic carbon in the rock, which determine the index of organic matter transformation (TR_support). In the core column, cores and fissures filled with carbonate minerals are distinguished. At the same time, at least one sample of calcite and/or dolomite is taken from the central part of the cores and from the walls of fissures, the oxygen isotope composition is measured for all selected samples with the determination of the ratio of stable oxygen isotopes δ¹⁸O and select the minimum value of the specified parameter. Next, samples of quartz crystal are taken from the core column with subsequent measurement of the homogenization temperature (T_homogen) of gas-liquid inclusions for each selected sample and the maximum value of the specified parameter is selected. Then, pieces of rock in its natural state are chipped from the core column in the amount of at least one chip per meter of core, excluding limestones and dolomites, with subsequent determination of minerals-indicators of the process of hydrothermal carbonation on the surface of the chip. The conclusion about the presence of positive catagenetic alterations in the reference well is made when the following conditions are met: TR_support> 30%, δ¹⁸O<(-18), T_homogen>(H*30+10), H is the depth of the sample and the amount of minerals-indicators of hydrothermal processes≥1.

EFFECT: development of a simple and reliable method for predicting the distribution of promising oil and gas areas through the use of a set of significant parameters that make it possible to predict the spread of increased catagenetic alteration of Bazhenov rocks while reducing the volume of core studies, areal seismic, gravity and magnetic exploration.

6 cl, 7 dwg