As part of its ongoing “Technology Strategy”, Gazprom Neft has established a programme directed at developing technologies to exploit oil reserves located below a gas cap.* Implementation of the projects within this programme will, in the long term, allow some 215 million tonnes of oil reserves to be brought into development.
Total recoverable oil and gas condensate reserves at Gazprom Neft’s gas cap drive reservoirs exceed 500 million tonnes, of which only 300 million tonnes can be developed through the use of current technologies: a further 200 million tonnes could be extracted through projects under the company’s new technological programme. Gas cap drive reservoirs require very accurate and precise tools in their development. Work with such reserves demands, in particular, very effective management of gas influx into oil wells, and a greater oil recovery factor where there is significant gas content. The new programme has been developed by employees at the Gazprom Neft Joint Scientific and Research Centre and includes 13 technological initiatives directed at interpreting downhole surveys, forecasting the gas input factor, and developing value engineering tools, equipment and algorithms for the effective operation of wells with significant gas content.
The Novoportovskoye and Messoyakhskoye fields, selected for pilot operations in the implementation of new production technologies, both contain major gas cap drive reservoirs.
The Messoyakhskoye field, specifically, has already seen the implementation of a project for the selection of optimum well construction technologies in gas cap drive reservoirs. Drilling technologies for complex multilateral wells have also been tried out at the field (so-called “fishbone” wells), which are expected to be replicated in line with geo-mechanical modelling currently being actively developed by the Gazprom Neft Joint Scientific and Research Centre. In order to further enhance oil recovery, Gazprom Neft is also developing new hydraulic fracking technologies, since the possible ingress of gas into oil wells means traditional fracking techniques cannot be applied at such reserves.**
* A gas cap drive (or an “oil rim”) reservoir is one that forms part of an oil or gas condensate deposit in which gas constitutes a considerably greater volume than oil. It is, in fact, a thin seam between a significantly larger gas cap and a water-bearing stratum. The main issue in developing oil rim reservoir relates to the ingress of gas and water into oil-producing wells. The effective development of such resources demands the implementation of new technological solutions in the drilling of complex wells, the identification of ways of lifting liquid with a high gas content, and the extreme precision required in integrated design engineering.
** 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 well and the strata. 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.
