Today, when most reservoirs have low productivity, the question of whether hydraulic fracturing can be applied to the oil rims becomes very important. In such environment, the challenge of this widespread method of production intensification is significantly increased risk of gas breakthrough. Another challenge that is faced primarily during development of oil-rim (sub-gas) reservoirs is the selection of the most suitable completion designs. An outstanding example of oil rim stimulation was a project in Novoportovskoye field where an operator faced with a complex geological model of the reservoir characterized by an absence of strong clay bridges and minor contrasts in stress between interlayers associated with high risks of breakthrough into the gas zone.
In 2016, the Novoportovskoe field operator successfully performed a 20-stage fracturing job. An innovative optimized multistage fracturing (MSF) solution was used that employed shifted closable fullbore sliding sleeves operated by coiled tubing (CT) intermittently with fracturing operations. This method was used for the first time in the development of the hydrocarbon deposits of the Yamal Peninsula and is based on the use of sliding sleeves that allow opening and closing of separate hydraulic fracturing ports. Such a design allows, in the course of further operation of the well, to cutting off or separating ports to prevent the inflow of water and gas, or, at the same time, to conduct refracturing of certain parts of the formation if required. This technology, which optimizes the fracturing process by utilizing shifted closable fullbore sliding sleeves/ports consists of the following: Reclosable CT fracturing sleeve (fullbore cemented sleeve that could be opened/closed an unlimited number of times)Openhole hydraulic packers to isolate zones in case of uncemented completionCT shifting tool (CT/tubing conveyed)Multistage mechanical packer (optional, could be used in case of inability to close one of ports). The resettable packer could be activated in any part of liner with axial CT movements; 10 000-psi rated.
The main risk for hydraulic fracturing, in the absence of barriers is the proximity of the gas and water layers. Breakthrough of a hydraulic fracture into a gas- or water-bearing zone leads to a significant reduction in oil production rates. Stimulation operations in such difficult geographic and geological conditions have shown opportunities for the oil industry in the Arctic.
Главная цель Научно-Технического Центра «Газпром нефти» («Газпромнефть НТЦ»)повышение нефтедобычи и ее эффективности за счет внедрения новых технологий и проектных решений на месторождениях «Газпром нефти». НТЦ обеспечивает аналитическую, методическую и научно-техническую поддержку процессов разведки и добычи нефти.
Today, when most reservoirs have low productivity, the question of whether hydraulic fracturing can be applied to the oil rims becomes very important. It was revealed that the efficient way to compensate the fractures and formation contact area under conditions of a necessary hydraulic fracturing reduction was the implementation of a special well completion technology, during which renewable frac sleeves were installed in the fullbore diameter of a liner, with sleeve density being increased for a reliable coverage of the well horizontal spacing with longitudinal fractures (Ishangaliev et al., 2017).
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, that was detailed described by Kazakov et al., 2017.
An outstanding example of oil rim stimulation and application of new technology was a project in Novoportovskoye field where 30- and 27- stage mulstistage fracturing operations were successfully performed with shifting ports comopletion operated by coiled tubing.
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