There are now practically no unexplored areas of the world left likely to hold significant oil reserves. Exploration targets these days are likely to be complex geological structures, located in remote areas, with challenging climatic conditions. Gazprom Neft is developing its resource base by deploying cutting-edge technologies in acquiring and analysing data on the structure of oil and gas basins and specific deposits.
Prospecting for new oil reserves is a complex and high-cost endeavour, even when it involves traditional resources. The cost of geological prospecting operations, and the cost of mistakes, are still higher when investigating previously un-researched, inaccessible regions. Much of this uncertainty can be eliminated prior to commencing field work through the process of basin modelling.
Basin modelling means taking a journey millions of years back into the past — recreating the formation of (and changes to) geological strata in order to determine when they first appeared, how they were built up, and how hydrocarbons are distributed within them.
Using this technology, and based on all information available on a region’s geology, mathematical and analytical methodologies can be used to recreate those processes involved in strata being formed or changed. Which means that areas containing hydrocarbon accumulations can be revealed.
Once a basin model has been built and calibrated, the most promising blocks are chosen, and models of those fields constructed. Risk assessments are then undertaken, meaning the case for developing certain deposits can be completely justified.
Genuinely effective and fully inclusive basin modelling tools for complex formations do not yet exist — for which reason, their development has become a key priority under Gazprom Neft’s Technology Strategy.
High-density UniQ seismic
Seismic refraction in subsurface investigations is a key technique in geological prospecting today. It involves causing acoustic waves to be created (using an artificial source): these waves are then registered by seismic receiversA seismic receiver
for converting mechanical oscillations into an electronic signal. The seismograms produced this way then undergo mathematical analysis and geological interpretation.
The accuracy and reliability of such investigations depends, to a large extent, on the number of acoustic transmitters and receivers involved. Until recently, however, increasing the availability of transmission and receiving points was constrained by the limitations of cable connections for transmitting high volumes of data: a situation made resolvable through the advent of fibre-optic technology, however.
Using UniQ technology (developed by Schlumberger and introduced into Russia by Gazprom Neft at its Vakunaisky block at the Chonsky project, Eastern Siberia), the volume of active data-transmission channels can be as much as several hundred thousand — significantly greater than under traditional methodologies.
The very significant impact of higher-density seismic acquisition at the company’s Eastern Siberian fields has been made possible by combining UniQ data with information sourced through cutting-edge geoelectrical-prospecting technologies.
High-density geoelectrical prospecting
Various electromagnetic methods are widely used in all stages of prospecting, exploration, and field development, due to their high efficiency and relatively low cost.
The high density of data points involved means modern geoelectrical prospecting is practically a 3D technology. Investigations undertaken by Gazprom Neft at fields on its Chonsky project in 2014, moreover, have proved to be the most extensive in the world in terms of the number of physical data points involved (more than 7,600), and the record time in which the project was completed.
Gazprom Neft was the first company in Russia to test aerial geochemical prospecting — an innovative molecular-level hydrocarbon prospecting technology. This high-tech methodology is based on recording hydrocarbon gas molecules at ground level, reflecting the geographical location of oil-bearing areas (“pay zones”). Special materials (absorbing agents) have been developed to capture hydrocarbon molecules exclusively. Based on analysis of these samples specialists can then identify those areas where molecules are most heavily concentrated. This helps determine the most promising blocks for subsequent geological prospecting.
In order to increase efficiency in geological prospecting, and to optimise costs in the initial stages of developing assets, the company will be integrating its use of both traditional seismic and non-seismic prospecting techniques, including geochemical prospecting.
“Green (wireless) seismic” is based on the RT System 2 wireless radio-telemetry datalogging system. Gazprom Neft’s first usage of such seismic investigations took place at the Shakal block, Iraq, where wireless sensors were used to simplify the process of installing equipment in such mountainous terrain.
Being able to use this kind of technology in inaccessible areas has led to Gazprom Neft specialists coming round to the view that using it in Siberia could make it possible to manage seismic operations in a way that is not only more effective, but also more environmentally friendly.
Compact wireless recording equipment can be delivered to an installation site without the need for special heavy vehicles, which typically require forestry clearance to a width of at least four metres in order for them to get through. Green seismic technology only needs
This technology was successfully tested at Gazpromneft-Noyabrskneftegaz’s Zapadno-Chatylkinsky block in the Yamalo-Nenets Autonomous Okrug in 2014, and is now being successfully used at other Gazprom Neft assets in the Yamalo-Nenets and Khanty-Mansi Autonomous Okrugs, as well as the Tomsk Oblast.
An information system for analysing geological and field data — GeoMate — has been commissioned at Gazprom Neft, bringing together geological information on all of the company’s fields. The GeoMate system covers approximately 80 percent of the geophysical and field-data analysis that would typically be undertaken by a geologist. Access to a single, cohesive IT environment gives employees across all Gazprom Neft subsidiaries direct and immediate access to all data in building field models and identifying and detailing promising zones and formations.
A “Digital Core” project is planned for implementation as part of the development of the GeoMate system. Supported by machine learning, this will allow the construction of 3D-drill-core models on which mathematical experiments can be undertaken, reducing the need for lengthy laboratory research.