METHOD FOR PREDICTING DRILLING MUD ABSORPTION ZONES WHEN DRILLING WELLS BASED ON THREE-DIMENSIONAL GEOMECHANICAL MODEL AND TECTONIC MODEL OF DEPOSIT Russian patent published in 2020 - IPC E21B49/00 G06F17/00 

FIELD: soil or rock drilling; mining.

SUBSTANCE: invention relates to methods of investigation of rock massif and can be used for forecast of drilling mud absorption zones during drilling of wells in terrigenous and carbonate reservoirs. Summary: performing complex of geophysical surveys, including seismic exploration operations. Support wells are drilled. Logging data is recorded, coring is selected and analysed for mechanical properties. On the basis of seismic exploration, a cube of seismic attribute Ant-tracking is constructed, which indicates changes in the wave pattern for detection of fractures, cracks and other linear anomalies inside the seismic cube. Exciting disorders are identified. Then one-dimensional geomechanical model and well stability model for support wells is calculated. Resilient-strength properties and main stresses in support wells are calculated. Resilient-strength properties are transferred and propagated in the inter-well space using geostatistics. Three-dimensional geomechanical model is loaded with boundary conditions obtained based on a one-dimensional geomechanical model. Stresses are calculated by finite element method. Result of calculation is full stress tensor in modelling sector, cubes of resilient-strength properties and cubes of main voltages. For isolated surfaces of breaking disruptions Mohr-Coulomb destruction criterion is used, data for calculation of which is taken from calculated cubes of main stresses. For each point on the fracture surface, its state is determined, whether active or inactive. Tectonic model of the deposit is constructed. Discrete network of cracks is built on the basis of tectonic model driver. Conclusion is made on the probability of absorption of drilling fluid based on the intersection of a large number of cracks with the well trajectory, without crossing the trajectory with the fracture. Model of stability of the wellbore of the design well is constructed, and zones of auto-hydraulic fracturing are identified by way of application of the washing program on the model of stability of the design well. Conclusion is made on necessity to correct program of well flushing.

EFFECT: technical result is ensuring trouble-free construction of well, reducing time for construction of well.

1 cl, 5 dwg