Abstract

The paper summarizes application experience and optimization of oil-based drilling fluids for the development of oil and gas condensate fields in the north part of YaNAO area. Key requirements, application criteria, design decisions, advantages and limitations, main features and field application results are analyzed based on Yurkharovskoe oil/condensate field. Extensive computer modeling and hydraulic simulations were performed to take into account temperature and pressure conditions. Actual results are compared to that achieved in the field. The main features of proposed OBM formulation are discussed with respect to local field and reservoir specifics, including wellbore stability, ECD management, reservoir damage, drilling waste management. ERD specific features and benefits are highlighted.

Article demonstrates how extensive planning and preparation work has allowed to overcome many obstacles, typically associated with OBM application in remote areas with harsh climate conditions. Environmental regulations were thoroughly evaluated and proactive waste management was implemented to mitigate environmental risks.

Reservoir conditions and wettability were evaluated to ensure minimum OBM formation damage. Production data is included to demonstrate OBM applicability as reservoir drill-in fluid for oil-wet Yamal reservoirs.

The large scale implementation of oil-based drilling fluids in YaNAO is an ongoing unique project with the massive amount of lessons learned and “know how” technologies involved from all parties. The OBM application experience provided in the paper can assist other companies working in YaNAO with planning and execution of ERD projects and simplify OBM implementation. The experience gained on Yurkharovskoye oil/condensate field can also be applicable to other North Russia projects onshore and offshore.

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