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This article provides the results of the first experience of running a wear resistant "push-the-bit" RSS (rotary-steerable system) for kicking-off at shallow depth in poorly consolidated sand formations. According to the contractor's best practices, a shallow kick-off in sections with large diameters is performed using PDM (positive displacement motors) with a bent housing angle set up to at least 1.83 degrees. However, for wells in Odoptu field, which is located in the north of Sakhalin island, several specific features pose issues for the effective application of conventional directional drilling equipment to reach the geological targets. A standard approach for drilling the 17 ½-in. section in Odoptu wells requires two runs: Run1: A PDM with roller-cone bit are used to build the inclination from zero to 70-degrees in poorly consolidated sand formations Run2: A conventional RSS with PDC (polycrystalline diamond composite) bit are used for drilling the tangent section. The project team was challenged to reduce the well construction time by drilling this section in one run, however, there were technical concerns. Drilling with a PDM and roller-cone bit would not provide a high penetration rate in tangent section. Drilling with a conventional push-the-bit RSS might not provide the necessary DLS (dogleg severity) in the sandstone due to formation washouts. In addition, drilling in the sands exposes the drilling equipment to excessive erosion because of the high sand content in the drilling mud. Considering the average section length of 2000 to 3000 m of MD (measured depth), this wear could lead to damaging the costly drilling equipment breakdown and causing unplanned tripping operations. The project team alongside the field operator decided to test a wear-resistant RSS for one typical well of the Odoptu-Sea field. As a result, the section was drilled in one run, achieving the planned DLS without any equipment erosive wear. In addition, the 17 ½-in. section of this well recorded the highest penetration rate of 58 m/h in the field. The implementation of a wear-resistant RSS saved 6 days of the total section time.

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Historically most of horizontal wells in Western Siberia have 3 casing string design with liner in horizontal section. Production casing normally was set at the top of productive formation to provide its isolation. Production casing seat selection was affected by unstable shales above productive formation. That was called conventional casing design. Well cycle optimization process almost reach technical limit with current technologies and under current conditions. In order to allow further optimization new approach was required. JSC Rosneft Oil Company found that extensive field data from wells drilled in the formation demonstrates possibility to optimize some operations by combining production section with horizontal one. The concept was named Dual-casing design. Combined interval should be drilled in one run. Once reaching TD tapered casing string should be run. Horizontal well cycle with conventional casing design includes following stages: Drilling section for conductorRun and cement 324mm conductorDrilling section for surface casingRun and cement 245mm surface casingDrilling section for production casingReaming trip before running casingRun and cement 178mm production casingLoggingDrilling of horizontal sectionReaming trip before running linerRun 114mm liner Implementation of dual-casing design will allow to exclude following stages (see Figure 1): Reaming trip before running casingRun and cement 178mm production casingLoggingAdditional trips for BHA changes As a results of preliminary well time estimation well cycle could be reduced by 40% due to dual-casing design. In order to achieve this ambitious plan Rosneft implemented project management approach that includes following: Proper planning and risk assessmentIntegrated managementOptimization based on lessons learnt