For the first time Russian oil company has applied a new generation intelligent completion system in the Caspian offshore; the system can measure zonal phasic flow rates, fractional composition of the flow, zonal water cuts, pressures and temperatures. This equipment allowed to perform well cleanup with the new strategy, making optimization in the real time. This article describes experiences of running these operations, which are unique both for the Russian and for the world industry.
Since the technical resources in offshore field development are limited, it used to be impossible to run a thorough cleanup and assure the production of ERD wells at optimal level of performance. It states question about the practicability of long wells drilling. Three ERD wells in the Caspian offshore were the first ones where the Russian oil company used a unique all-electrical intelligent completion system. The system includes the flow control valve with infinite number of positions and the set of downhole sensors that provide a unique composition of measurements – pressure, temperature, phasic flow rates, fractional composition of the flow for each zone individually. Novel technology opened an opportunity to optimize the cleanup process by cleaning every zone separately. Meanwhile, it became possible to understand the extent to which every zone is cleaned and in real-time optimize the process by increasing the drawdown in the undercleaned zones.
New methodology to speed up cleanup process, test and commission the well was designed. It is a crucial aspect for the wells that are drilled from an offshore drilling rig. Currently there are 5 wells in Russia and 9 of them in the world where the cleanup operations were performed with the use of described completion technology.
Methodology and technology that are described in the article are innovative for the world industry. Interpretation of the expanded dataset that was obtained from the downhole sensors used to be unavailable for general use during the cleanup and it is described for the first time using an example from several wells.
Practices, experiences and technology described in the article will be useful for the field engineers, reservoir engineers and specialists who make decisions related to planning and organizing the operations both for the offshore and onshore fields.
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.
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