Gazprom Neft has completed testing of four directional wells (drilled to investigate reserves within the Bazhenov formation) at its concession within the southern area of the Priobskoye field (Khanty Mansiysk Autonomous Region). The results obtained have allowed the resolution of the key issue underpinning the first stage of this project: confirming the existence of live oil within the Bazhenov formation. Completion of hydro-cracking operations at all wells resulted in hydrocarbon inflow at varying degrees of intensity. The next stage of this project will involve the drilling of four horizontal wells and the identification of the most effective strategy for the commercial development of unconventional (“tight”) reserves at the Bazhenov formation.
Wide-ranging geophysical investigations were undertaken in the course of drilling to confirm current geological suppositions, including the extraction of a 190-metre core sample: something of significant and immediate interest to geologists.
The strata of the Bazhenov formation in the Southern Priobskoye field lie at a depth of 3,000–3,200 metres. The resources contained therein are categorised as “unconventional reserves”, analogous to shale oil. Analysis of geophysical data, specialist analysis of the well core, and repeated analysis of 3D seismic data was undertaken before drilling commenced at the Bazhenov—Abalaksky field.
Seismic investigations are set to continue, with the company planning to commence horizontal drilling in 2016. The second phase of the project will be dedicated to resolving technological issues: selecting the optimum construction of wells and technologies for the implementation of multi-stage fracking, adapted to the specific conditions of the Bazhenov reserves.
Gazprom Neft First Deputy CEO Vadim Yakovlev commented: “Gazprom Neft continues to actively advance its independent investigation of the Bazhenov formation. Thus far, these resources have been considered ‘unconventional’, but their development is a key strategic objective in our development, and we will soon begin new projects in this area. The development of tight reserves has long been a speciality of Gazprom Neft, insofar as this category constitutes a major part of the company’s resource base. And we have proved our effectiveness in working with these: the proportion of high-technology wells in our portfolio is now in excess of 30 percent — a record within the Russian oil sector.”
The “Bazhenov formation” refers to a specific geological stratum identified in the centre of Western Siberia, running to depths of 2,000–3,000 metres. While the stratum covers an area of approximately one million square kilometres, it is comparatively thin, with a thickness of only 10–40 metres. Estimates suggest that oil reserves at the Bazhenov reservoir could amount to as much as 100–170 billion tonnes in Western Siberia alone.
The Abalak formation consists of offshore maritime geology and coastal sedimentary deposits, lying beneath the Bazhenov formation and, in some instances, abutting it. The full extent of the Abalak formation covers the Krasnoleninsky deposit, the Surgut oil and gas region, and the Uvatsky deposits, with a thickness of 20 metres up to 90, in sedimentary folds.
Gazprom Neft’s second project in the independent prospecting of shale deposits involves work at the Palyanovsky deposit at the Krasnoleninsky field, Khanty-Mansiysk Autonomous Region. This project is now in its second phase, with the drilling of four horizontal wells now begun, consistently increasing the length of the horizontal sections and the frequency of multi-stage fracking. Drilling of the first well (with a horizontal shaft of more than 200 metres in depth) has been completed.
