Drilling Optimization in Achimov Horizontal Wells by Integrating Geomechanics and Drilling Practices

Abstract

A workflow was developed for effectively handling the development challenges in the Yamal oil and gas province of Western Siberia. The workflow integrates geomechanics with efficient drilling practices and leads to the implementation of an engineered drilling system (EDS). The workflow for development in the Yamal region encompasses phases from modeling to drilling practices, incorporating an understanding of challenges faced and lessons learned from previous drilling. The majority of Achimov operations in the Yamal region have been conducted in the Urengoy gas condensate field, which is divided into different blocks. The Achimov deposits are deep (true vertical depth is about 3,750 m), exhibit abnormally high formation pressure (over 600 atm), and contain multiphase hydrocarbons with the presence of heavy paraffins. Unstable shale formations must be drilled prior to penetrating the Achimov itself. These challenges affect drilling efficiency and interfere with the well construction schedule. The Achimov formations present two main challenges to horizontal drilling: wellbore instability leading to stuck pipe incidents in the build section or inability to run liner/casing to total depth and loss circulation, potentially compromising well delivery and project objectives. Thus, previous drilling has shown that developing and producing from these enigmatic resources requires more than just horizontal wells and hydraulic fracturing. Companies are aggressively pursuing Achimov deposits, hoping to extract additional gas and gas condensate volumes from the declining fields and to implement a strategy to raise natural gas production. Successful operations require an integrated approach, using multiple data sources, to determine the key parameters needed to understand the Achimov formations and extract the hydrocarbons. Among the successes, an operator company for Urengoy field demonstrated how developing a mechanical earth model (MEM) of the reservoir and continually improving processes paid big dividends. By implementing the EDS approach, unique results have been achieved in drilling and completion of Achimov horizontal wells. Outstanding drilling performance in Achimov horizontal wells has led to a revision of the field development plan.