IMPROVING EFFICIENCY OF HYDRAULIC FRACTURING UNDER HIGH WATERCUT RESERVOIR CONDITIONS OF БВ-8 FORMATION, POVKHOVSKOE FIELD

摘要

Its first large-scale hydraulic fracturing operation was performed at Povkhovskoe field with up to 200 tons of proppant agent injected. The technology has been developed to improve the efficiency of fracking, tapping hard-to-recover and bypassed oil reserves in water-flooded zones of the reservoir. The introduction of large-scale fracking lead to the significant increase in the recovery factor on the pilot area due to extra contact with the reservoir, i.e. higher sweep efficiency. Based on the analysis of the oil reserves recovery and their vertical distribution it has been noted that the application of a large-scale frac job is guided by the presence of zones with uneven residual oil distribution, layers with high residual oil saturation, abundance of blind or dead-end zones, lenses and hemi-lenses at a certain distance from the wellbore which have not been developed yet. As possible candidates wells with over 95% watercut (9 wells) have been studied and analyzed from the idling well stock: piezometric, suspended, not producing in the previous years due to their unprofitability. This approach addresses one of the top challenges of an oil company – how to lessen the number of idling wells. Large volumes of the proppant agent injected create rather long hydraulic fractures up to 120-200 m which extend far into the formation thus draining the interwell reservoir space which is poorly developed. The reach or the step-out of the second boreholes at Povkhovskoe field is in the range of 150-350 m. Field trials of large-scale fracking at БВ8 development target of Povkhovskoe field resulted in high average efficiency with increased oil rate and specific technological efficiency of 10.8 tons per day. The economic calculations showed that hydrofrac with 200 tons of proppant injected is cost-effective at the minimum incremental oil achieved of 9.8 tons per day. Large-scale fracking operations may be considered as an alternative to expensive and high-cost sidetracks.