Inclinometric Observations at the Korchagin Deposit

Abstract

The aim of this work is to analyze the results of geodeformation monitoring at the Korchagin oil, gas, and condensate deposit in the Caspian Sea. The inclinations of the base of the offshore platform are registered using Inklin-2 AGS-5 inclinometers. The software for collection and storage of data is elaborated at the Shirshov Institute of Oceanology, Russian Academy of Sciences. The time series of inclinometric observations were processed using the WinABD package designed at the Shmidt Institute of Physics of the Earth, Russian Academy of Sciences. The tidal and seiche impacts are estimated and the dynamics of time change of the position of the exploitation platform is described. The periodic oscillations of the heel and difference with periods of 24 and 12 h and mean annual amplitude of 0.005° and 0.001°, respectively, are probably related to breeze impacts. It is shown that gravitation tidal effects (lunar–solar static and marine tides) have a minor effect on platform inclination. The results of mathematic modeling of seafloor deformations induced by the exploitation of the deposit show a maximum settling amplitude of ~3 mm. A model of a deformed reservoir–reservoir with Neocomian and Volgian oil-saturated reservoirs is considered. The assessment of the heel and difference in the platform area showed that exploitation-related heel can reach 6 × 10–8 (16 angular ms), whereas the difference is 8 × 10–8 (12 angular ms). Both values are much lower than the resolution of inclinometers and observing deformations caused by other reasons. The absence of critical heel and difference of the exploitation platform is substantiated. Numerical procedures allow a detailed analysis of present-day geodynamic processes, which are caused by the exploitation of the Korchagin deposit under constant monitoring regime.