Yudin, A. (Schlumberger) | Tarakanov, I. (Schlumberger) | Klyubin, A. (Schlumberger) | Ablaev, A. (Schlumberger) | Zharikov, M. (Gazprom Dobycha Urengoy) | Vashkevich, A. (Gazprom Dobycha Urengoy) | Yaskin, I. (Gazprom Dobycha Urengoy) | Sabirov, L. (Gazprom Dobycha Urengoy)
This paper was prepared for presentation at the Young Professional Session of the SPE Russian Oil and Gas Exploration and Production Technical Conference and Exhibition held in Moscow, Russia, 14–16 October 2014.
In the Urengoyskoe field, Russia, the Achimov deposits are found at depths of nearly 4000 m and feature a more complex geological structure when compared to the Cenomanian and the Valanginian deposits. Furthermore, the Achimov deposits feature abnormally high formation pressure (over 600 bar) and are characterized by a multiphase state of hydrocarbons. To achieve economic well production, performing stimulation treatments in the Achimov formation of Urengoyskoe gas condensate field is required.
Hydraulic fracturing proved to be a reliable method for increasing well productivity from the Achimov formation by a factor of 2.5; however, well completion restrictions allow for placing only small-size proppant mesh. Proppant fracturing treatments are conducted with high-polymer loading to ensure fluid stability at high formation temperatures, which leads to further reduction of fracture cleanup efficiency. These effects reduce the effective half-length and compromise the full production potential.
New channel fracturing technology that creates open-flow channels inside the proppant pack was selected to improve production. Channels are created by pulsating proppant at surface. Pulses with proppant are separated by pulses of clean fluid, which creates proppant clusters inside the fracture, holding the walls of the fracture open. Fracture cleanup is conducted through channels without restrictions to fluid and polymer flowback. Thus, the channels improve effective fracture half-length and, consequently, gas condensate rates. The increased drainage area also improves hydrocarbon recovery.
Previously in Russia, channel fracturing was used primarily in oil fields. The largest gas operator in Russia has initiated an extensive pilot campaign for channel fracturing in new areas of the Urengoyskoe field. To date, seven wells have been successfully completed with channel fracturing, leading to a significantly higher productivity of 30% versus offset conventionally stimulated wells and lower drawdown.