Riphean anisotropic cavernous-fissured carbonate reservoirs of oilfield at East Siberia area – one of the most problematic objects of oil and gas production described in this article. Here is discussed geological substantiation and first result of new technology involving in drilling of Riphean carbonate reservoirs with "Controlled pressure technology" by recovery wells with horizontal bottom at the oil-gas condensate field in Evenki Region. Comparison results of conventional drilling and "MPD" (Managed Pressure Drilling) technology. Riphean reservoirs drilling process could be provided in two options. The first one – horizontal conventional drilling. As far as the bit penetrates into the reservoir we are seeing SPP (Stand Pipe Pressure) decrease which means we have total lost circulation. There was only one means for resolving this problem – using LCM (Lost Circulation Material). Due to complicated geology and high parameter of gas factor in Riphean reservoirs (losses while circulation/ gains while static), LCM was insufficient solution. The second is to perform drilling process using MPD (Managed Pressure Drilling) technology. We have the advantage using lower mud weight compared with conventional drilling. MPD technology corresponds with geological conditions of Riphean reservoirs and can be more profitable in future production from these wells. MPD technology with closed loop circulation system showed that we can "manage" BHP (Bottom Hole Pressure) and it really works in temperature conditions of 45 Celsius below zero in Evenki Region (East Siberia). In practice we have seen, that it was possible to achieve more gentle management of BHP than with conventional drilling using LCM. Also with "MPD" system in this oilfield we were able to drill the first ERD (Extended Reach Drilling) well. However, even with such extended horizontal section (1000 meters), a significant reduction of losses was achieved without using LCM. Total results of MPD technology we will see after DST (Drill Stem Test) of drilled wells. New technology showed that it was a right choice to use close loop system and MPD. Also for drilling new wells in this Riphean carbonate reservoirs of this oilfield area we will use this experience. Best way to reduce catastrophic losses in abnormally low pressure reservoir conditions is reduce and control the ECD and details how to achieve it we have considered in this article. The results: Reduced interval construction time. From 31 days to 24 days.Reduced fluid loss during drilling. From 2000 m3 to 1200 m3.Improved the operational safety by closing the loop and real time early kick and loss detection.

As an industry segment, drilling with casing and liner is still very much in its infancy. However, a few "early adopters" have been successfully extending the operational envelope and discovering new applications. The fundamental value of drilling with casing lies in improving drilling efficiency by eliminating flat spots in the drilling curve. It also has the capability of extending open hole sections to reach deeper casing points with smaller diameters, thus eliminating contingency intermediate strings. The implications for exploration and production industry are significant. Currently, there are two basic methods of drilling with casing divided as follows: Rotating the casing at surface to transmit torque to the drilling BHA, or having a retrievable BHA latched inside the casing that incorporates a motor that drives a conventional bit and underreamer. Both systems, though operational and technically sound, still have many technical issues to overcome concerning all aspects of well planning to operations on the rig floor. This paper will focus on drilling with liner by rotating the casing without Top Drive. The paper will highlight the significant lessons learned from these experiences. This emerging technology is considered '"game--changing" and is seen as complementing the expandable and underbalanced technologies which promise to revolutionize well construction. IntroductionOperators have drilled with liner in a number of areas for many years. The recent resurgence of the technology and significant developments in technology have resulted in a renewed industry interest in the technology of drilling with casing. One of the key factors leading operators to this technology is the removal of time from the drilling curve. An industry term, "nonproductive time," currently is used to describe problem time, and time associated with tool failures and inefficiencies. The procedures for rotary drilling with casing are relatively simple, and involve little extra equipment that is not normally present on a typical rig. Compared to a traditional drilling BHA, should be simple, because it is left in the ground. When TD is reached and circulating bottoms--up, cementing can begin immediately, since a float collar is present in the string throughout the drilling operation. To allow drilling with casing, a number of technologies had to be developed to enable safe and efficient and problem free operations.

Oil and gas operators have explored in the Arctic regions of Russia for more than 40 years. Early drilling campaigns encountered significant problems drilling through the shallow permafrost sections due to degradation of drilling conditions as a result of permafrost thaw. Experience from these earlier operations and experiments conducted by Kutasov et al (1988) has highlighted the need to maintain chilled drilling mud to minimize permafrost thaw during the well construction process. After time technologies made step forward and casing drilling is in addition option with Kutasov technology to improve drilling process. This technology is one of the greatest developments in drilling operations. Casing drilling involves drilling and casing a well simultaneously. Casing drilling system has been designed primarily for multi-well offshore platforms, multiwell operations on land, deep-water operations, and for situations requiring operators to drill through and place casing across problem formations quickly. This technology was applied successfully to drill through depleted reservoir (problems: wellbore instability, mud losses into the depleted zones) as an alternative to the underbalanced drilling, which requires special equipment.