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The drilling of the hundredth well of the project intended for the production of Turonian gas has begun at the Yuzhno-Russkoye field
Back to newsOn September 19, 2021, drilling of the last of 88 wells of the full development stage began at the Yuzhno-Russkoye oil and gas condensate field. Together with 12 wells of the first start-up complex, it will be 100 wells intended for the production of hard-to-recover Turonian gas. A beautiful figure, but what is behind it that will help to better represent the full scale of this project?
It all began on October 27, 2018, when the construction of 12 pilot wells was started to produce gas lying under abnormally high reservoir pressure at depths of 810-840 meters in a heterogeneous and lithologically variable, low-permeability reservoir of the Turonian formation. Nine of them are U-shaped and three are horizontal.
The U-shape well design is an inverted semicircle and covers the pay zone both in the descending part and in the ascending part of the trajectory, where the zenith angle reaches 116º. This is done in order to increase the length of the well in the most productive part of the formation. Geosteering is used to drive a well along a given trajectory. This is a special service, thanks to which specialists remotely in real time make adjustments to the well trajectory. In the interval of the Turonian formation, the production string of U-shape wells is equipped with a slotted filter, which is designed to prevent the ingress of sand and solid particles from the formation into the well, while minimizing pressure reduction.
Horizontal wells have a slightly simpler trajectory and run along the reservoir at an angle of 87º. But the complexity of these wells lies in the use of high-tech completions to carry out four stages of hydraulic fracturing. A feature of the hydraulic fracturing itself is that diesel fuel is used as a fluid in order to create highly conductive fractures inside the formation and deliver propane to them. In total, up to 900 m³ of diesel fuel is used for the four stages of hydraulic fracturing carried out in the well. At the same time, 150 tons of propane, injected into the created highly conductive fracture at one of the stages of hydraulic fracturing, became a record for the Yuzhno-Russkoye field.
After the start-up complex, drilling of Turonian wells began to rapidly gain momentum and, starting from November 2019, another drilling rig was put into operation every month. In March, their total number reached six, and a year later, in March 2021, when the seventh drilling rig was put into operation, a record was set for the number of drilling rigs simultaneously involved in production drilling at the Yuzhno-Russkoye field. The number of coiled tubing installations involved in well development was also a record one. At the same time, four rigs were used to handle high-tech horizontal well completion, as well as gas dynamic studies and logging tests.
During the construction of such complex wells, it was necessary to organize the work of a large number of people and equipment. This demanded complete dedication and real professionalism from the employees of the Company. The schedules of equipment delivery, equipment arrival were optimized, the optimal rock cutting tool and well drilling modes were selected, aimed at maximizing the mechanical speed while observing the well construction technology. With the planned duration of construction of one U-shape well of 30 days, its average duration was 25 days. And the best indicator is 20 days per well, and it has been achieved more than once.
Not without difficulties. Here was the cold winter of 2020/2021, when in total 16 days the temperature did not rise above the maximum permissible for the safe operation of drilling rigs -42°C, and several geological complications, which were simply impossible to predict, and of course, a pandemic, which had a significant impact on the organization of work. But, in spite of everything, work on the construction of 100 Turonian wells is being completed well ahead of schedule. If it has been originally planned to complete drilling in mid-2022, then in fact the operations is to be completed in 2021.
Ahead of the specialists of the Company is the summing up of the results of the drilling company and the building of so-called base of «lessons learned». For all the experience gained to be successfully applied in the future, including in other fields, where there are Turonian strata, it is necessary to carry out «work on mistakes». Today, no one in the world has such a rich experience in the construction of Turonian production wells as the specialists of OJSC Severneftegazprom.
Service for the organization of construction and workover of wells of OJSC Severneftegazprom