Managed Pressure Drilling technology became popular and widespread in Western countries in the early 2000s and has long been successfully used for drilling complex wells onshore and offshore projects (for example in the North Sea, Gulf of Mexico and etc.) In Russia this technology has found its application relatively recently and still has never been used for offshore drilling. This article describes the results of the first MPD offshore application in Russia for drilling an HTHP exploration well in the Caspian Sea. A fully automated MPD set with early kick detection system (EKD) and back pressure pump (BPP) was applied, allowing to control pressure and drilling fluid outflow besides drilling, during connections. The drilling conducted using reduced mud weight in «near balanced» conditions, which compared to conventional strategy sufficiently reduced formation overbalance and losses risk as well. Specialized MPD tests used to determine formation and fracturing pressure limit in uncertainty geological conditions, optimizing core sampling drilling and mud roll-over strategy.

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Yurubcheno – Tokhomskoe oilfield is located in Eastern Siberia, Krasnoyarsk region, where the most part of oil and gas reserves are contained in Riphean high fractured carbonate reservoir. This reservoir contained a lot of secondary interstices and caverns, that are tend to enlarge due to excessive pressure exerted, that leads to loss circulation, differential sticking and associated NPT [1]. In case of conventional drilling on Yurubcheno – Tokhomskoe oilfield, such problems don't allow to reach the project depth in horizontal sections 152.5 mm (6in) – 1 000 m. The most popular method of struggling loss circulation is using loss circulation materials (LCM), which dramatically affects reservoir production properties. Furthermore, effectiveness of LCM wasn't enough, because volume of lost drilling fluid, which is oil based mud, remained too high. Managed Pressure Drilling technique was applied for resolving problems while drilling horizontal section in Yurubcheno – Tokhomskoe oilfield that allowed to reach the TD. Compare to conventionally drilled wells, using of MPD in Yurubcheno – Tokhomskoe oilfield resulted in reducing mud losses up to 3 – 5 times, reducing 152.4 mm section drilling time by 20% and increasing well production by 65 – 180%.

The utilization of managed pressure drilling (MPD) techniques has grown significantly over the past three years in the Russian Federation. This paper describes the application of MPD surface back pressure technique using both single and multiphase drilling fluid systems in several oil and gas fields located in Russia. The Komi Republic is one of the biggest oil and gas producing areas in the European part of Russia and among Russia's top ten producers. Although the Yurkharovskoye oil and gas condensate field in Western Siberia is in the Tazov Peninsula, most of the field is situated offshore. That part of the field is developed from onshore locations using horizontal and extended reach development wells. In Eastern Siberia, the Yurubcheno-Tokhomskoye field is one of the biggest oilfields and presents highly fractured carbonates. Each field presents a different challenge and requires a specific approach. The application of MPD technology improved drilling performance and helped avoiding non-productive time. Utilization of reduced mud weight with MPD procedures using a semi-automated system helped reduce lost circulation and safely control background gas, thus avoiding well control events in the Lambeyshorkoye, Komandirshorkoye, and Alabushina fields. In the Yurkharovskoye field, a high-pressure, high-temperature well was successfully drilled to TD with application of a fully-automated MPD system, which facilitated precise control of bottomhole pressure during drilling, pumps-off events, and tripping operations. A multiphase MPD technique helped achieve planned TD in horizontal sections in Riphean formations of the Yurubcheno-Tokhomskoye field without catastrophic fluid losses. By injecting oil-base mud with nitrogen, the equivalent circulating density (ECD) was drastically reduced, lowering the volume of losses up to 5 times. In addition, near balance conditions increased the ROP while drilling. The first ever multi-lateral well drilled with multiphase MPD was successfully completed on Yurubcheno-Tokhomskoye field with minimal mud losses and no well control events. This paper will present details about how MPD technology makes it possible to drill formations with narrow mud weight windows where traditional approach was ineffective. The application of MPD technology helped successfully drill wells while reducing non-productive time, improving performance, and increasing the safety for personnel.

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