Dmitri Polyakov * , Ayupova Diana
The limited scope of geological exploration of offshore fields is the reason for the high structural uncertainty in any traps. The lack of a complete set of initial information for well construction requires an innovative approach to planning, drilling and well support. Geosteering can significantly improve the quality of the horizontal section borehole drilling and is an opportunity to obtain actual data from the bottomhole. Drilling support allows to quickly make adjustments to the well trajectory due to changes in the geological conditions. Based on the geological drilling support experience at the analyzed offshore field, in general the reasons classification for operational adjustments taken during drilling was created. The most common reasons for changing the planned trajectory and the results of decisions are noted. The analyzed field is complicated by faults, has lateral variability of both reservoir properties and lithological composition. This is the reason for the high percentage of possible risks and uncertainties limiting the quality of well placement. Based on this, the specialists of the geological drilling support issue erroneous corrections. This article analyzes the cases of erroneous changes in the well trajectory; the logic of the decisions made based on the interpretation of data from the bottomhole and considers their consequences.