Modeling the gravitational field fault systems and fracture zones

Abstract

Relevance. The development of new and improvement of existing methods for interpreting geophysical data in order to predict non-structural oil and gas traps caused by fault-block tectonics is a very urgent task for many oil and gas regions, including Ciscaucasia. Aim. Solution of the direct problem of gravimetry for geological and gravimetric models, which are a system of differently oriented linear blocks and zones of increased fracturing. Determination of optimal methods for transforming the initial gravimetric field and morphometric analysis of the relief to identify fault systems and linear zones of increased fracturing for the geological conditions of Ciscaucasia. Methods. Creation of geological and gravimetric models of the fault-block environment, corresponding to the fault-block structure of the Terek-Sunzha anticline zone. Development of algorithms and programs for calculating the gravity field and its derivatives, based on V. Strakhovmethods for solving direct problems of gravimetry for field elements from typical approximating bodies. Testing of computer programs and approbation on model examples. Processing of real gravimetric data using computer programs for the transformation of the gravity field based on the F-approximation method. Building maps of the horizontal gradient vector and the third vertical derivative of gravity, comparing the results of modeling and actual geological and gravimetric data, determining signs of tracing fault boundaries and zones of increased fracturing on maps of the gravity field transforms and the slope of the day surface topography. Results. Typical geological and density models have been created for the characteristic structures of the fault-block nature of the Terek-Sunzhensky anticline zone. An algorithm and a computer program for calculating the elements of an anomalous gravitational field for a system of faults of various orientations of linear zones of fracture, based on the ideas of solving direct problems of gravimetry and magnetometry for elements of fields from typical approximating bodies V. Strakhov. The anomalous gravitational field was calculated for various types of models. The criteria for identifying faults and fracture zones on morphometric maps and maps of higher derivatives of the gravitational field are determined.