Gazpromneft-Yamal, a subsidiary of Gazprom Neft, has begun pilot oil production from the Achimov deposits at its Severo-Samburgskoye oil field (in the Purovsky District, Yamalo-Nenets Autonomous Okrug). A well drilled by the previous license holder, Gazprom Dobycha Urengoy, has been recommissioned and tested at the block. Flow production at the well is far in excess of planned performance, standing at 120 tonnes per day.
Seismic investigations will also be undertaken as part of pilot works at the Severo-Samburgskoye licence block, the results of which should allow total oil reserves to be clarified by the end of 2017, and priority areas for drilling determined. Re-testing of a further exploratory well is planned for winter 2017 — 2018, allowing more detailed information on the field’s potential to be obtained, as well as drilling of several horizontal wells for multi-stage fracking of the strata, allowing the optimum development strategy for this asset to be identified.
Initial reserves in place at the Severo-Samburgskoye field’s Achimov deposits are estimated to be in the order of 426 million tonnes of oil, with recoverable reserves during the first stage of development, moreover, estimated at 72 million.
The decision to designate the Achimov deposits an independent exploration prospect, and to commence implementation of the “Bolshaya Achimovka” project was taken by Gazrom Neft in 2016. Since that time, work has been undertaken on developing a local geological model of the Achimov deposits as part of a dedicated programme to fine-tune drilling technologies and improve inflows in geologically complex strata; opportunities for expanding the company’s resource base are also under consideration.
The Severo-Samburgskoye field occupies a key location in the northern cluster of Gazprom Neft’s project on development of the Achimov deposits. The potential of this cluster is estimated at four billion tonnes of hydrocarbons, in terms of initial reserves in place. Development of the Achimov deposits is complicated by poor reservoir quality i.e., low permeability and porosity, with high reservoir compmentalisation, abnormally pressured zones, and high gas content. Gazprom Neft is in the process of selecting technologies for the effective development of these reserves as part of its Bolshaya Achimovka project.
First Deputy CEO, Gazprom Neft, Vadim Yakovlev, commented: “In commencing pilot development at the Severo-Samburgskoye field Gazprom Neft has taken another step forward in developing a key production region for the company — the Yamalo-Nenets Autonomous Okrug. Pilot testing of technologies for accessing the Achimov deposits will allow us to continue our research into non-traditional reserves, as well as fine-tune drilling methodologies and well finishing. Detailed investigations into the Achimov deposits will further expand Gazprom Neft’s opportunities for improving efficiencies in working with hard-to-recover deposits.”
The Severo-Samburgskoye oilfield, classified as a major field, and located in the Purovsky District, 100 kilometres north of Novy Urengoy, was discovered in 1998. The licence for exploration and development of the field was transferred to Gazprom Neft from Gazprom Dobichye Urengoy in April 2017.
The Achimov formation consists, both horizontally and vertically, of poorly continuous lenticular sandy-aleuritic strata, located in the lower part of Cretaceous (chalk) deposits almost directly above the oil-bearing Bazhenov formation. The Achimov strata occur throughout the central zone of the West Siberian basin, with the thickest strata found in the Urengoy District of the Yamal-Nenets Autonomous Okrug. The Achimov strata are characterised by a complex geological structure, with low permeability and porosity, together with poor reservoir connectivity, necessitating the use of technologically complex inflow-stimulation techniques in developing these reserves.