Well Placement in Carbonates. Success Brought by Multilayer Bed Boundary Detection Technology

In the Volga-Ural region, a significant part of the horizontal drilling is carried out on the carbonate formations. Wells with horizontal sections of 300–400 m are drilled on Bashkirian, Tournaisian and Famennian deposits. In addition to maintain the horizontal section within the reservoir, depending on the formation and the field, the task for vertical coverage of the formation is also set. The purpose of this approach is to maximize coverage of the tight and porous intervals vertically, as well as maximize the zone of reservoir drainage. To perform these tasks, understanding the structure boundaries at a distance from the well is critical and is ensured by Multilayer Bed Boundary Detection Technology.

Standard electromagnetic logging of propagation or induction resistivity in highly resistive interbedded formations such as carbonate deposits can to some extent distort the real resistivity values of reservoir, underestimating the values in tight intervals, which usually have very high resistivity.

Nevertheless, the Multilayer Bed Boundary Detection Technology has been successfully used during the well placement in the carbonate sediments of the Volga-Ural region, it allowed mapping the boundaries in conditions of high formation resistivity and low resistivity contrasts between the interbeds.