Gazprom Neft obtains first shale oil inflows at Southern Priobskoye field, Khanty-Mansiysk Autonomous Region

Gazpromneft Khantos has completed testing of an initial two wells, drilled to allow analysis of deposits in the Bazhenov formation, in the south of the Priobskoye oilfield. Hydraulic fracturing (fracking) was undertaken at both (directionally drilled) wells, and an inflow of hydrocarbons obtained; testing of a further two similar wells is to be undertaken in the nearest future.

Gazpromneft Khantos has, for many years, undertaken development of traditional oil reserves at the Southern Priobskoye field, before obtaining a licence for geological prospecting at promising deep oil-saturated strata (the Bazhenov and Tyumen formations) in March 2014. The strata lie at a depth of 2,000–3,000 metres, and the low filtration properties (flow capacity) of the underlying geology mean the reserves contained therein are hard-to-recover. The Bazhenov and Abalaksky formations are also categorised as unconventional (“tight”) reserves, or “shale oil”.*

Priobskoye field, Khanty-Mansiysk Autonomous Region, March 2014

Analysis of geophysical data, specialist research of well-core data, and repeated analysis of 3D seismic data was undertaken at the Bazhenov-Abalaksky Southern Priobskoye field in 2014. The first stage in the prospecting programme for this category of reserves envisages the directional drilling of four prospecting and appraisal wells.

The key objective of the current phase of the prospecting programme at the Bazhenov strata will be the clarification of the nature of the geology, and the confirmation of the existence of mobile original oil in place (MOOIP). The next step will then be lateral extended-reach drilling, together with multi-stage hydraulic fracturing, in order to determine initial and subsequent changes in flow rates at individual wells and, subsequently, to evaluate volumes of recoverable reserves. Plans for 2016 include the continuation of 3D seismic and the drilling of horizontal wells.

Gazprom Neft’s second project in the independent prospecting of shale deposits involves work at the Palyanovsky reserves at the Krasnoleninsky field, Khanty-Mansiysk Autonomous Region. A new prospecting programme, initiated in autumn 2014, envisages the drilling of four horizontal wells, 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, with multi-stage fracking expected to begin as soon as possible.

Reference

Shale oil deposits can be found in the Bazhenov, Abalak, and Frovolov formations, Western Siberia — deposits of ultra-low permeability, but also high oil saturation.

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 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. The deposit thickness in sedimentary folds is from 20 to 90 meters.
 

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