Background. Tight sand deposits development has always been a challenging process that frequently requires application of innovative approaches. Horizontal drilling in non-uniform lithology is frequently accompanied by circulation, wellbore stability losses and other complications. Hydraulic fracturing stimulation does not always result in productivity increase, which reduces profitability of development. Due to the incomplete understanding of geological and geomechanical specifics of Achimov deposits, — formations with complex heterogenous structure, low permeability, presence of low-amplitude structural dislocations, — the controlled use of features of formation is hindered and, in turn, makes it necessary to develop an innovative strategy of their surveillance and stimulation. Aim. In purpose to optimize an existing development strategy of Achimov deposits in Vingayakhinskoe oilfield, we have developed and applied an approach involving complex cross-segment modelling. At the same time, verification of hypothesis on possibility to identify and activate naturally fractured zones. Materials and methods. To form criteria for verification of hypothesis of fracture network generation in Achimov deposits, a 1D and 3D geomechanical models have been built in view of the applied approach, along with a model of natural fractures. Development of hydraulic fracturing designs, efficiency of which has been evaluated with respect to such reservoir modeling results as predicted production rate and cumulative production, have been the next step, performed for different geological and geomechanical conditions. Thus, the principal feature of applied approach is coupling between geomechanical modeling, complex multivariant hydraulic fracturing modeling and reservoir modeling with the target to maximize production. Results. The well stimulation strategy, selected based on the results of multivariate integrated modeling, was successfully implemented as part of the pilot high-flow hydraulic fracturing operation, which led to an almost twofold increase in the initial production rates of project wells versus off set wells. Conclusions. The obtained results of the work confirm that the developed integrated modeling approach can serve as a reliable basis for optimizing the development of heterogeneous and low-permeability formations such as Achimov deposits.

Work is devoted to construction 3D Geomechanics model for Achimov Formation for one of the West Siberia oilfield. The model is performed for monitoring and control field throughout the cycle of its life – start from drilling process (recommendation for optimization well trajectory and well design to exclude drilling risks) and during oilfield development (monitoring the development process to take account of changes in the stress state of the oilfield, its influence on the hydraulic fracture growth and hydrocarbon production processes). Oilfield, which are currently introduced in the development, characterize by increasingly complex geology and, consequently, require more sophisticated technological solutions for both the construction of wells and the development process, which involves the need to build complex 3D geological and geomechanical models. As a result of the work was calculated current stress state on the field, taking into account the effects of faults. Special attention was paid to the process of mapping of faults and low-amplitude tectonic dislocation. For this purpose used inversion stress model, including simulation of deformations and displacements arising under the action of tectonic driver. This model allows to select the tectonic dislocation, the scale of which is significantly smaller than the resolution of seismic. Based on the results of the verification of geomechanical model and sensitivity analysis to the source data, formulated the basic methodological approaches for building and testing models of geomechanical properties was done. During the work was made a forecast borehole stability for horizontal wells, create a map of faults, found the relationship between the faults parameters and their impact on the stress changes in the area of interest, assessed the impact of changes in reservoir pressure during field development on the stress orientation, predicted direction of hydraulic fracture and formed recommendations on hydraulic fracturing design taking into account possible variations in the stress state of the sector of modeling.