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.
Initial selection and further optimization of drill bits is one of the key factors of an effective drilling process, which is particularly important in high-cost projects. This article presents the incremental changes made to increase the ROP and mechanical efficiency of drill bits while drilling offshore extended-reach drilling (ERD) wells. With the implementation of the tasks based on a well-by-well analysis of bits, recommendations were developed for optimizing the design of drill bits. These recommendations were based on results of bit simulations in specialized software with correlation of proposed models and actual results. Simultaneous bit optimization was performed in conjunction with other elements of the BHA with the help of an integrated engineering analysis system. The result was the development of new bit designs and sizes designed for drilling specific rock in specific fields. In addition to the optimization of the drill bits themselves, a refined technological component was introduced: a real-time drillbit optimization system to enhance ROP, decrease bit wear while drilling, and ensure maximum run length via the optimization of drilling parameters. Application of the proposed technical and technological changes has increased ROP up to two times, and enabled a bit to drill a 4,900-m section in one run with minimum bit wear, leading to a reduction in the cost of the well. As a result, bits for ERD were optimized for each size, and a drilling parameters map was created. This map was updated based on the result of the construction of each well to ensure maximum efficiency with minimal bit wear during subsequent drilling. Additionally, one of the most important results was a 6-year record of no NPT associated with the drill bits. Experience gathered during the development of the bits using advanced modeling applications, together with real-time drilling optimization, will be applied on a nearby offshore field to minimize the time required to reach the optimal ROP. This article describes the selection, optimization, and continuous improvement of drill bits using the latest techniques and technologies, the use of which occurred gradually during development over several years. The above approaches can be applied to ERD and standard horizontal wells worldwide.
To extend areal coverage for maximum reservoir contact from a single offshore platform, Korchagina oil field is developed with Extended Reach (ER) wells with MD up to 8km, TVD 1.5km. The main target of Korchagina field is Neokomian sandstone formation with large gas cap that necessitates field development with horizontal ICD sand screen completions to minimize early gas breakthrough.In 2011 a task was set to work out set of solutions that would convey ICD sand screens to TD in Korchagina ER environment, with openhole coverage up to 5000m, and to design completion elements around these solutions.At planning phase industry expertise -completion practices in projects operating in similar ER environment was reviewed, and existing to date technologies to complete ER wells were analyzed.Existing technologies and practices did not provide sufficiently robust and flexible solutions for Korchagina ER environment. Hence, innovative solution was proposed -Rotating sand screens to TD, with contingency to run in stages if rotation limit is expected to be exceeded based on drilling results.Further, design of completion equipment was reviewed to accommodate high torque and rotation capability: direct wrap sand screen media with proven sand retention performance in high torque; integral centralizers, to transfer rotational motion at contact points to reduce drag; high torque connections. Paper discusses in details the solutions proposed and design of completion equipment.In 2 years 11 ERD wells were completed with TD reaching 7996m MD at 1565m TVD and openhole coverage up to 4700m. Of these 11 wells, in 3 wells actual friction factors came low enough to allow completion run conventionally, in 8 wells rotation was required at 800m-3000m off TD. The results are presented in the paper.Based on successful results of application, rotation is set as requirement for completion design for all the wells of current Korchagina field.
The success of the drilling campaign including drilling efficiency, service quality, personnel safety and cost is critically dependent on robust solutions developed during the design phase of the overall well construction process. One of the most critical stages of the overall well construction process is the well design phase. The drilling project service quality, personnel safety, drilling efficiency and cost directly depend on the robust solutions elaborated at the design phase. This paper describes the advanced technical engagement between an operator and an integrated services company to generate a basis of design for drilling and completing development wells in the Filanovskogo offshore field, in the north of Caspian Sea. The basis of design is a document that describes well design principles, engineering solutions and technologies required to drill and complete the wells. The paper explains the design approach selected by the project team, project design stages, foreseen challenges and technical solutions to deliver efficient well designs that could meet operator requirements and comply with Russian regulatory rules. The key technical challenges of the Filanovskogo field are that the reservoir zone is located at shallow true vertical depth (TVD); the high formation collapse gradients and low mud loss gradients create a narrow mud weight window environment, along with complicated well profiles involving – multilateral horizontals and extended reach (ER) wells. This paper illustrates the development of a basis of design to ensure cost-effective access to reserves. It covers the operator and the service company experience in the drilling of ERD wells, applying advanced technologies for windows milling, completion options screening process and designing a multilateral junction. It also provides an understanding of the importance of operator and service company departments integration processes in order to achieve well objectives. To support the basis of design development, a comprehensive risk register was generated to minimize drilling risks. The process of technical integration between the operator and the service company in the early stages of operational planning by developing drilling and completion design is unique for Russian O&G operators and was done by assuming that it would be very efficient through providing technical integrity and minimizing the project risks. The drilling and completion design consideration processes described in this paper can be used to provide valuable insight for future projects where up-front complex technical study is key to success.
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