Consistency evaluation technology for automatic well-log correlation using well logging data

UDK: 550.832:681.518
DOI: 10.24887/0028-2448-2021-8-22-26
Key words: automatic well-log correlation, pair-wise correlation methods, estimation of correlation reliability, verification of correlation results, triangulation network, pathways of paired correlations
Authors: K.E. Zakrevskiy (Rosneft Oil Company, RF, Moscow), R.K. Gazizov (RN-BashNIPIneft LLC, RF, Ufa), E.A. Ryzhikov (RN-BashNIPIneft LLC, RF, Ufa), K.V. Freydin (RN-BashNIPIneft LLC, RF, Ufa)

Geological well section correlation is one of the most important geological problems, since its results are used for further construction of geological models. The results of manual correlation are subjective and depend on the specialist's qualifications performing it. The correlation process is a routine and time-consuming work which requires processing big data sets, therefore automatic well correlation methods are necessary for better performance. In practice, as a rule, the boundaries of the layers in neighboring wells are found by paired correlation method of the corresponding well logging data based on a well with known reservoir boundaries. The sequential correlation on a large number of wells leads to the fact that the result significantly depends on the order of their bypass. This is the main problem with automatic correlation methods. Usually the triangulation networks method is used as a verification method of well correlation results. This approach is implemented in a number of domestic software products. It should be noted that this method also depends on the order of well bypass in which they are correlated.

In this paper, we propose a verification method of well logging correlation results for a given pair of wells, based on the statistical evaluation along different wells pathways. We assume that each pathways starts and ends at the specified wells and passes through various intermediate wells. The Dynamic Time Warping (DTW) method and the method based on the wavelet analysis are used as pair correlation algorithms. One part of the developed method is an algorithm for generating a set of paths connecting the wells under consideration and passing in some limited area. Also we propose correctness verification procedure for the developed method. Examples are given to demonstrate the developed approach and its comparison with the well-known verification algorithm based on triangulation networks.

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