NIS (Naftna Indusrija Srbije), a subsidiary company of Gazprom Neft, supported by specialists at its research and development (R&D) centres (the Gazprom Neft Scientific and Research Centre, and the NIS-Naftagaz Scientific and Research Centre) has undertaken a series of hydraulic fracturing (fracking) operations in high-temperature horizons at the Kikinda Istok, Crna Bara jug and Vojvoda Stepa fields in northern Serbia. Fulfilment of these operations saw the company utilising a new special gel, making possible hydraulic fracking of the deposit at temperatures of 150°С to 180°С. Using this unique technology will allow NIS to increase production by opening up reserves not currently in development.
Hydrocarbon reserves in Serbia are distinguished by specific temperature characteristics: at a depth of just 3.5 kilometres oil-bearing horizon can reach a heat of up to 190°С. Such characteristics are more typical of ultra-deep strata, found at depths of more than five kilometres. Strata temperatures at Gazprom Neft fields in Western Siberia do not exceed 70—100°С, so gels traditionally used for proppant injection will not demonstrate the necessary reliability and effectiveness under Serbian conditions.
The special gel used on the high-temperature fields in Serbia has sufficient viscosity to retain heavy proppant particles during injection into the strata, and can withstand reservoir conditions; it can be applied under various fracking technologies, including multi-stage fracking, and is suitable for both oil and gas deposits.
Vadim Yakovlev, President of the NIS Board of Directors, commented: „The application of high-technology operations in field development opens up a new stage in NIS’ activities, with the company increasing its efficiency in opening up mineral resources, and will ensure production growth, bringing new reserves into development. Gazprom Neft’s extensive experience in field development will allow international best practice to be used in Serbia, making operations as safe and as effective as possible.”
* Hydraulic fracturing (fracking) is a means of intensifying output at a field, through the high-pressure injection of a mixture of fluids and a special proppant agent (proppant) into oil-bearing strata. The process of injecting the mixture creates highly conductive channels („hydraulic fractures ”) connecting the well (bore hole) and the strata. These fractures allow oil to flow that would not, under other circumstances, reach the well. Hydraulic fracking is undertaken through horizontal wells. Under multistage fracking, multiple fracking operations can be undertaken from a single horizontal well, allowing a manifold increase in the catchment area covered from that well.