Today, an effective application of multistage fracturing (MSF) became an acute problem for the Yamal Peninsula fields. At Novoportovskoe oil and gas condensate field, in order to achieve an effective reservoir coverage with fractures to increase hydrocarbons recovery, it was decided to revise the concept of horizontal wells completion, increasing the number of MSF stages and decreasing the distance between the stages.
In the complex geological conditions of the Novoportovskoye field, a fundamentally new solution was proposed for horizontal well completion – full bore MSF system with sliding sleeves, operated by hydraulic shifting key with coiled tubing (CT). This completion system allows to perform MSF without pulling CT out of the well to the surface and instantly use CT for well clenout in the case of screenout (SO). This decision is aimed to increas production and achive economic efficiency of the field development by increasing the formation coverage by means of larger number of MSF stages per well, and optimizing costs by reducing the time for the entire range of work at the well.
At the moment, 2 wells at Novoportovskoe field were completed with described MSF system, with total 40 stages fractured.
The technology allowed increasing of stages number to 20 in a 1000 m long horizontal section and installing selectively ports in the most effective zones of the formation. The coefficient of formation coverage was increased due to uniform placement of longitudinal fractures, which could not be achieved with standard "ball" MSF technologies.
As a result, by reducing treatment size and increasing number of stages, positive results were achieved: the water cut was 39%, with an average of 60% and the gas factor was 472 m3 / tonne, with an average of 800-1000 m3 / tonne in neighboring wells.
As a result, with use of integrated completion system with shifting ports, fracture control was obtained in real time due to coiled tubing functioning as a dead string during fracture, and, at the same time, data was stored at memory downhole gauges installed in the CT bottomhole assembly (BHA).
Innovative technology and a comprehensive approach to the design and implementation of fracturing operations in complex geological conditions of the Novoportovskoe field is a unique experience for the region. The possibility to increase an oil production of a horizontal well MSF (HWMSF) without breaking fractures into the gas cap was proved. This system has advantages with respect to standard MSF technologies in conditions of oil rim deposits, and is applicable for other projects where an increase of MSF stages and the completion cycle time reduction is required.