Анализ динамики давления и температуры на забое нагнетательной скважины при закачке воды и водогазовой смеси

Analysis of the dynamics of pressure and temperature at the bottom of an injection well during injection of water and water-gas mixture

This paper discusses certain aspects of implementing a simultaneous water and gas injection (SWAG) technology at a pilot site within a terrigenous reservoir of the Romashkino oilfield in the Republic of Tatarstan. The injection was carried out using a pump–ejector system (PES). Operating parameters were monitored by wellhead pressure sensors, along with gas and water flowmeters. Fresh water from the reservoir pressure-maintenance system and associated petroleum gas collected from the annular space of 11 producing wells were used as injection agents. The gas was delivered to the ejector mixing chamber through a dedicated gas-gathering system. Three injection wells were selected as recipient wells, one of which operated under a simultaneous–separate injection. The initial pilot tests of SWAG injection revealed a gradual increase in discharge pressure of the booster pump during PES operation, due to a decline in injectivity of the well. To obtain additional downhole data, a high-resolution downhole logging tool was deployed in one of the injection wells. The analysis of the acquired data suggested the formation of gas hydrates and subsequent near-wellbore plugging. To test this hypothesis, associated gas and mineralized water with a density of 1180 kg/m³ were injected. The discharge pressure of the pump remained stable over a two-day period, confirming that hydrate formation can be prevented when mineralized saline water is used. Due to a reduction in annular pressure in one of the gas donor wells, its operating mode changed from intermittent to stable continuous production, thereby demonstrating the efficiency of the PES. © 2025, Neftyanoe Khozyaistvo. All rights reserved.