The calculation of bottomhole pressure is the most important task of monitoring the operation of oil producing wells. When it is impossible to directly measure it, in practice, calculation methods are used, including methods for recalculating wellhead parameters (annular pressure, dynamic level, etc.). For this purpose, LUKOIL-PERM uses two methods for recalculating wellhead parameters into bottomhole pressure: one is fully analytical, and another is analytical with address correlations. The article presents the results of assessing the reliability of determining bottomhole pressure using these methods. The material was used for two fields of the Perm Territory - Magovskoye and Shershnevskoye, including the results of parallel wellhead and deep measurements. Comparison of actual and calculated by existing methods values of downhole pressure showed a low reliability of their application. The main reason for the low reliability of the applied methods should be considered the need to use the characteristics of the gas-liquid mixture in the wellbore and the annulus space, which cannot be determined accurately enough due to the complex nature of multiphase flow. The article proposes a fundamentally different approach, consisting in the construction of multivariate mathematical models based on statistical processing of the accumulated material of parallel wellhead and depth measurements. For this purpose, data from 235 wells surveys from the fields under consideration are involved. As the initial data in the developed method, it is proposed to use well performance indicators, the definition of which is not accompanied by difficulties: oil and liquid flow rate, water content, dynamic level, annular pressure, pump depth and its immersion under dynamic level, distance to water-oil contact. Multidimensional mathematical models are built for both fields under consideration. To assess the reliability of the developed methodology based on the use of multivariate models, the tools of mathematical statistics were used. The developed technique has demonstrated its high accuracy compared to the currently used methods for determining bottomhole pressure when recalculated from wellhead parameters.
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