Mitigating Application-Specific Challenges Through a Total System Approach

Abstract

Abstract Economical demands within the oil and gas industry are the driving force to exact significant advances in Drilling and Formation Evaluation Technology. This has been exemplified by the application of new technology to address the complex challenges of the Troll Field Reservoir in the Norwegian North Sea. Exploiting the Troll reservoir requires horizontal geosteering through relatively unconsolidated sandstones with localized zones of hard calcite-cementation. Optimum well placement is of the utmost importance and demands reduced tolerance for any inaccuracy within the thin oil reservoir column throughout the progressively increasing drained hole section. Consequent to the advancement in drilling technology, the horizontal reach has been extended from some 500 meters to more than 5000 meters in a single reservoir section including horizontal turns of up to 360°. In 2001 an innovative service was introduced to the Troll field, being founded on a new multi-sensor data acquisition and processing Measurement-While-Drilling (MWD) tool. The downhole tool contains various dynamics and mechanical sensors, and a high-speed data processing system to continuously provide an accurate picture of the downhole conditions and the energy transfer train. The service was deployed to optimize the mechanical efficiency of the drilling process by facilitating the immediate response to differing situations encountered while drilling complex heterogeneous formations. This real-time service, but also the intrinsic detailed studies on BHA and bit design with ensuing in-depth knowledge capture have lead to a comprehensive understanding of the Troll drilling challenges and thereby facilitated the design and utilization of application specific bottom hole assemblies with associated relevant drilling procedures and practices. This paper will discuss how this technology is used and how this total drilling system deployment concept has been applied to successfully surmount the specific challenges of the Troll Field.