Integrated modelling approach to oil recovery increase of Achimov formation

Abstract

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.