Losses risk minimization while predrill stage and realtime drilling geomechanics support on the north part of Caspian sea

Summary Oil field development in the northern Caspian Sea involves the drilling of horizontal wells in terrigenous Lower Cretaceous sediments with low hydraulic fracture pressure, where both geological and technical conditions increase the risk of fluid loss. The main geological factors that cause losses on the Filanovsky and Korchagin fields are wells with direction to maximum horizontal stress azimuth, fractures and faults, and depletion of producing formations. Technical reasons include high mud density, use of standard (without increased diameter) casing, poor borehole cleaning, which leads to unacceptable growth of equivalent circulating mud density during drilling. Separately, the high probability of losses during the cementing phase of the well is considered. One of the proactive tools for managing drilling fluid loss risk is building a geomechanical model that includes calculation of losses and hydraulic fracturing gradients, which allows determining safe limits of equivalent circulating density during drilling and performing trajectory optimization at the initial planning stage to expand the safe drilling fluid density window.