DEVELOPMENT OF A THREE-DIMENSIONAL HYDRODYNAMIC MODEL OF THE UPPER CONTROL HORIZONS AND NEAR-SURFACE SEDIMENTS FOR INVESTIGATION OF THE MONITORING SYSTEM OF THE NORTH-STAVROPOLSK UNDERGROUND GAS FACILITY TIGHTNESS

Abstract

Relevance. Underground gas storage is a type of geohydrodynamic systems that require constant control and monitoring of ongoing processes in an underground reservoir and well, since the formation of an artificial gas deposit in depleted hydrocarbon fields is the main and most complex technological object in the gas infrastructure. Monitoring of technological processes in gas storages is carried out by GIS in production and observation wells. To ensure the tightness and safety of operation of a gas storage facility, it is necessary to develop a three-dimensional geological model that makes it possible to implement monitoring systems for ongoing processes in the upper control horizons and near-surface deposits within the mining allotment, to assess the current technogenic gas reserves and their distribution along the section. Purpose: development of a three-dimensional geological model of the upper control horizons and near-surface deposits for monitoring the tightness and safety of operation of an underground natural gas storage. Objects: system for monitoring the tightness of an underground gas storage: the upper control horizons and near-surface deposits of an underground gas storage within the boundaries of a mining allotment. Methods. To build a three-dimensional geological model of the upper control horizons and near-surface deposits, the following were used: data from the geological study of the area and sediment stratigraphy; the contour of the stratigraphic surface of the top of the sedimentary sequence; digitized information from reserves calculation maps; coordinates of wells and reservoir intersections. Geological-physical, field and analytical data were used to create a digital filtration model. Stratigraphic referencing of target reflectors was made on the basis of well data. Models of the software «tNavigator» were used, for geological modeling – «Designer of Geology» and for gas-dynamic modeling – «Designer of Models». On this basis, objects (points) were selected for modeling in the database structure based on the results of field, geological, geophysical information. The well location data was loaded in the Welltracks model format. To construct the structural surfaces of the horizons, files in the txt format are loaded into the programs, which are referred to as «Markers» within the software product. Results. A structure was developed and an information field and geological database was created for the upper part of the section of the underground storage, taking into account the available geological, field and research information and data obtained during the drilling of production wells on the Khadum deposits and observation wells on the Khadum horizon and the green suite; a permanent geological and technological model of the upper control horizons and near-surface deposits of the underground storage facility (geological and gas-dynamic models) was developed; on the basis of the conducted geological constructions, an assessment of the technogenic volume of gas in the upper control horizons was carried out; a system was developed for monitoring the underground storage tightness by existing and planned wells to the upper control horizons and near-surface deposits.

Keywords

• mining allotment
• gas
• well
• underground gas storage
• drilling
• control horizons
• deposits
• monitoring
• tightness
• three-dimensional geological model