Innovative Hybrid Rotary Steerable System Allowed Drilling a 6 in. Horizontal Hole Through a Carbonate Reservoir With a Record Dog Leg Severity of 13°/30m

摘要

This paper describes the successful field test of an innovative hybrid Rotary Steerable System(RSS) developed for high Dog Leg Severity(DLS)applications.This novel technology has been applied for the first time in Continental Europe to drill a sidetrack well in a sensitive area where the application of new technologies is strictly related to the commitment to minimize the environmental impact of well operations activities. The sidetrack was drilled to optimize the oil recovery from a carbonate reservoir.A solution was needed to drill the 6 in.sidetrack horizontal well starting from a 7 in.casing window,which must be opened just below the top of the reservoir due to operational constrains. The challenge was to reach the targets,identified by the reservoir geologists to increase the reservoir exposure and maximize the oil production,while ensuring an optimum borehole quality.This required an optimal trajectory design and an accurate directional drilling control to land the well in the shallower part of the reservoir,far away from the Oil-Water Contact(OWC).A 3D well plan was engineered,with DLS up to 10°/30m.In the past,similar wells were drilled with a Positive Displacement Motor(PDM),which often produced poor hole quality.The novel hybrid RSS used to drill the sidetrack well has internal pads that push against an articulated sleeve pivoted on a universal joint to point the bit in the desired direction, enabling high build-up rates and a smooth wellbore. The field test demonstrated the reliability of the system which successfully drilled the 6 in.curve section with a maximum DLS of 13°/30m,yet with an optimum wellbore quality.The performance was further enhanced by using a Polycrystalline Diamond Compact(PDC)bit specifically designed for compatibility with such innovative hybrid RSS. This paper describes the field test and the well engineering process that led to the successful application.