We introduce a new method for constructing a structural model of an oil and gas field, focused on the consistent integration of well and seismic data represented in different domains-depth and time. To address the problem of reconciling heterogeneous data, we propose the application of 3D approximation methods such as 3D splines and collocated cokriging. These methods combine well and seismic data in a single variable space. This approach simplifies the workflow for structural model construction by eliminating the need for both explicit generation of average velocity maps and introducing adjustments to regression relationships. We have also compared the quality of structural models obtained by the proposed methods - 3D spline approximation and collocated cokriging with results produced by traditional approaches, including linear regression and methods based on average velocity maps generated in various ways. The comparison is based on error analysis using cross-validation. The 3D spline method, which has not previously been applied to structural mapping problems, provides the best results. The traditional approach based on linear regression with subsequent modification of the structural map using interpolation and adjustments demonstrates a comparable accuracy. We have obtained the results by structural modeling of the upper part of the Bazhenov Formation in the Kazan oil and gas condensate field. High well density allows us to assess the accuracy of different structural modeling methods according to varying levels of well data availability, typical for different stages of field development.
