Identification of low-amplitude tectonic faults in the process of drilling horizontal wellbores in the interval of the Lower Berezovskaya subformation of the Medvezhye field (Western Siberia)

Rodivilov D.B. Branch “Gazprom nedra STC” “Gazprom nedra” LLC Tyumen
Nezhdanov A.A. Branch “Gazprom nedra STC” “Gazprom nedra” LLC Tyumen
Shtol A.V. “Gazprom nedra” LLC Tyumen
DOI: 10.24412/2076-6785-2021-2-17-20

The Senonian exploration project at the Мedvezhy field (Western Siberia) will allow the study of a complex of silicite rocks of the lower Berezovskaya subformation containing hard-to-recover gas reserves. A feature of these deposits is the developed system of tectonic faults. However, the results of interpretation of seismic data are not able to provide the required accuracy in determining the boundaries and amplitudes of dislocations. As a result, the drilling of directional wells carried out in conditions of increased risks. The paper presents a real production experience of drilling a horizontal wellbore 6C in conditions of low-amplitude tectonic faults. A methodological technique is described, the use of which made it possible to identify the tectonic block boundary in real time according to telemetry data of the downhole LWD-system.

Material and methods
The method for identifying the boundaries of tectonic faults in the process of drilling horizontal wells based on the operational involvement of telemetry data from the downhole LWD system (gamma-ray logging data) to build a correlation with the pilot borehole. Correlation performed by means of an algorithm for identifying a set of sequential correlation layers and reference shale strata. The results shown as a detailed correlation graphical diagram. Based on the shift of the reference boundaries relative to the data of the pilot shaft and the geological model, conclusions drawn about the location and amplitude of the tectonic disturbance.

lower Berezovskaya subformation, horizontal wells, hard-to-recover gas reserves, correlation of well sections, low-amplitude tectonic faults
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