Gazprom Neft becomes the first oil company in Russia to utilise full-cycle field development technology in opening up unconventional reserves

Construction of a well with a 1,000-metre horizontal section, to be used for the development of unconventional reserves of Bazhenov formation, has now been completed by Gazpromneft-Khantos (a Gazprom Neft subsidiary) at the Palyanovsky block of the Krasnoleninskoye field.* Nine-stage hydraulic fracturing (fracking) undertaken at a high-technology well has secured a natural flow of dry (pure) crude oil from the productive horizon, located at a depth of 2,300 metres.** Flow rate is running at more than 45 tonnes of oil per day.

Palyanovskoye oilfield Khanty-Mansiysk Autonomous Okrug

Gazprom Neft is the first company in Russia to implement the full-cycle technological solutions used throughout the global oil and gas industry in developing shale oil reserves, as part of project to develop unconventional reserves in the Khanty-Mansiysk Autonomous Okrug. This has involved, in particular, horizontal well sections being reinforced with flexible (elasticized) cement, followed by multi-stage fracking involving the high-speed injection of process (drilling) mud. Distensible cement differs from standard cement in its resistance to sustained exposure to variable loads during multi-stage fracking, meaning the fissures created can be relied upon to be kept apart. The combination of good isolation and high-speed injection in fracking makes possible the formation of a concentrated network of fractures throughout the entire length of the horizontal section, thereby increasing the volume of hydrocarbons made available in development.

It is precisely the use of similar technologies that has made possible the viable development of shale deposits internationally. Results obtained from the application of similar operations at the Bazhenov formation (for which optimum strategies for commercial development have not yet been determined) point to the possibility of the full-scale development of these reserves in the future.

The planning and monitoring of these new technological operations is being undertaken by specialists from the Gazprom Neft Joint Scientific and Technology Centre (Gazpromneft NTC). All technical solutions are supported by geological and geo-mechanical modelling of the strata, constructed on the basis of large volumes of factual data on reservoir properties. Drilling of the well was also undertaken with round-the-clock support from specialists from the Gazprom Neft Drilling Support Centre, as well as departments responsible for implementation of the project.

Two horizontal wells have, thus far, been successfully drilled in the Bazhenov formation at the Palyanovsky block throughout 2015-16. Thanks to the effective work of all departments involved, drivage efficiency (a well’s penetration of a target productive horizon or strata) has reached more than 90 percent. The latest fracking technologies*** have been tested at both wells.

Vadim Yakovlev, First Deputy CEO, Gazprom Neft, commented: “The drilling of a 1,000-metre horizontal well, as well as conducting multi-stage fracking in Bazhenov formation, is, under current macro-economic limitations, unique not just to our company, but the Russian oil and gas industry. The success of works to date can be seen as a major step forward in the development of hard-to-recover reserves.”

Reference

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 and with a thickness of 10 to 100 metres, covering an area of approximately one million square kilometres. Best-case estimates suggest that oil reserves at the Bazhenov formation (categorised as unconventional reserves) could amount to as much as 100–170 billion tonnes in Western Siberia alone. The rock of the Bazhenov formation is believed to be analogous with those of North American shale from which oil shale is extracted in the United States. Technological solutions for the full-scale development of the Bazhenov formation are currently being identified prior to commercial development commencing. Bringing unconventional resources into development is a key element of Gazprom Neft’s Technology Strategy, with the company’s Joint Scientific and Research Centre leading studies into the Bazhenov formation as well as planning pilot activities that involve implementation of advanced techniques in well construction, and in stimulating in-flows into these.

Gazprom Neft is implementing pilot projects, directed at investigating the Bazhenov formation, at the Yuzhno-Priobskoye and Krasnoleninskoye fields in the Khanty-Mansi Autonomous Okrug, as well as at the Vyngayakhinskoye field in the Yamalo-Nenets Autonomous Okrug. Twelve directional and low-angle wells have been drilled at these fields in order to assess the potential of unconventional reserves, and hydraulic fracturing (fracking) of the strata undertaken, with oil inflow obtained. These operations have allowed the potential for the commercial development of the Bazhenov formation to be confirmed and the potential for isolated fracturing to be evaluated, allowing progression to an assessment of the effectiveness of basic production technologies — the drilling of horizontal wells with multi-stage fracking. Two wells (with horizontal sections running to 1,000 metres), have been drilled at the Palyanovskoye project, and drilling and finishing technologies put in place. Improvements to the technologies applied have included liner cementing and various fracking techniques. Gazprom Neft began its first investigations into the Bazhenov formation in the Yamalo-Nenets Autonomous Okrug in 2015. Fracking operations have been undertaken at the Vyngayakhinskoye field through a new prospecting well and two directionally-drilled wells, with all wells obtaining oil inflows.

** Hydraulic fracking is a means of increasing oil production. It involves the high-pressure injection of a mixture of fluids and a special proppant agent (proppant) into strata. The process of injecting the mixture creates highly conductive channels (“hydraulic fractures”) connecting the bore hole and the strata which are subsequently strengthened with a proppant. These fractures allow oil to flow that would not, under other circumstances, reach the well. Under multi-stage fracking, multiple fracking operations can be undertaken from a single horizontal well, allowing a manifold increase in the catchment area covered from that well.

*** These operations have involved the use of technologies including Slick Water hybrid hydraulic fracking — both of which are proven technologies in shale production. Their main difference from standard fracking operations lies in the high-speed injection of fluid into the strata, which — instead of a single crack or fracture at each stage of fracking — allows the formation of a fracture network, significantly increasing the extent of the strata that can be stimulated.

Slick Water — a fracking fluid made up of ordinary water to which special additives have been added, allowing losses caused through friction of the propping agent (proppant) against the walls of the well to be reduced. Hybrid fracking is a technology involving the use of various combinations of process fluids (with different properties) to ensure maximum efficiency on injection. In this context, standard reservoir (stratal) water with a friction reducer was used in the initial stage, with a viscous gelling agent then applied to ensure optimum strengthening of the fractures.

Separation of each fracking stage was facilitated through the use of Plug&Perf drill-out plugs.

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