Fishbones, Wishbones and Birch-Leaves, Multilateral Well Design on the Srednebotuobinskoye Field in Eastern Siberia

The TAAS-Yurakh Neftegazodobycha Company (TYNGD) have been ramping up the drilling activity in the Srednebotuobinskoye oil field in Eastern Siberia, beating new records and delivering audacious targets in multilateral well designs. Drilling activity has ramped-up from 2 to 10 drilling rigs since formation of the JV business in Early 2015. As development drilling has progressed, a number of existing and newly identified challenges have arisen. Development of the Srednebotuobinskoye oil field is from the Bt. formation which is a thin oil rim with a massive gas cap. As the horizontal permeability is more than 350 mD this leads to severe challenges in increasing the oil production while restricting the production of associated gas and in order to deal with these challenges, a multilateral project was established to apply the best that this technology can offer. The multilateral well concept was a key approach to successfully develop the field, based on the in-situ risks and required well economics. Many of these issues have been addressed, in a stepwise and logical fashion, and this paper describes how this has been achieved and the progress that has been made to date. Economic challenges required that the well construction process be improved in efficiency, increased the individual well productivity and enhanced economic delivery. In order to deliver these efficiencies, the TYNGD Team prioritised a number of initiatives, such as a reduction in the Non-Productive Time (NPT) that is associated with the drilling and well construction process. From vuggy-losses in the overburden, to managing increasing losses and differential sticking within the reservoir; a number of key challenges have been identified; many have been addressed, others are in action and a few remain opportunities. In order to manage limited resources as efficiently as possible, and while building a meaningful and sufficiently populated drilling wells database; a simplistic roadmap of the wellbore construction process was created from best practice. This approach allowed TYNGD to prioritize targeting of trials, pilots and techniques to those areas that were most impactful to the overall field development at this stage. Close integration between the drilling and sub-surface teams allowed such ranking/prioritisation to be highly effective. This began with ensuring that the cement integrity was being achieved through the gas-cap region, to ensure that productivity, in the open-hole was assured. Major losses in the overburden were also targeted and prioritised, and a range of options were developed and deployed in order to help minimise issues. In parallel with this, formation damage and well productivity behaviour was also addressed, which has led to the planning and implementation of a number of multilateral field trials. Development of the Srednebotuobinskoye oilfield is underway and in order to deliver the most efficient development, drilling optimisation and continuous improvement are the key themes. To date a number of initiatives have been identified and implemented that have improved overall performance and resulted in significant economic enhancement. This paper will summarise the approaches taken in developing the field and multilateral well design; the results of implementation to date, as well as identifying and outlining potential further opportunities that are either currently in execution, consideration or planning.