When drilling horizontal wells, geological uncertainties have a much greater effect on the fulfillment of geological tasks than when drilling vertical wells. The combination of the classic geosteering methodology, complemented using logging while drilling (LWD) technologies, and rotary steerable systems, allows you to quickly make decisions on changing the well trajectory to optimize the entry into the target formation. During subsequent drilling within the target formation, the use of multilayer mapping technology in conjunction with an extended LWD and RSS system - helps to more accurately adjust the position of the horizontal section in the reservoir, thereby increasing the rate of reservoir penetration

This article describes the effectiveness of the geosteering service to reduce structural uncertainties of landing of the transport section and while placing a horizontal section in the productive part of the S. Nurzhanov field. Structural uncertainties were mainly caused by the proximity of the regional fault to the horizontal section and the variability in the thickness of the target intervals in the offset wells.

The provided geosteering service made it possible to complete all the tasks set for drilling the horizontal section, preventing the exit from going beyond the target zone and avoiding the unwanted approach of the wellbore to the unproductive rocks lying within its boundaries.

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