Efficiency Analysis of Massive Fracturing with Linear Gel Pad on the Achimov Formation of the Urengoyskoe Field

摘要

The primary objective of large fracturing treatments(from 150 to 300 tons of proppant)in the Urengoyskoe(Urengoy)field is to increase the drained volume of the producing zone of the target reservoir by increasing the fracture length and placing a larger mass of proppant while maintaining similar fracture widths and heights.The basic goal of fracturing is to increase production from the target reservoir.In this study,to increase the fracture length and propped fracture length in the target zone,linear gel fluid was used for the main fracture pad stage instead of the traditional cross-linked fluid pad.Because of the high filtration rate of linear fluids and their reduced efficiency,pads of larger volumes were used and were pumped at a higher rate.An additional goal of this strategy was to increase the formation coverage.The fracturing treatment proppant stages were pumped using crosslinked fracturing fluid,which helped to reduce the risk of screenout.Large fracturing treatments using linear fluid pads increase risk because of the high possibility of screening out and because of undetermined economic efficiency.The initial strategy of the Achimov formation development for the given section of the field planned to complete wells using standard large fracturing treatments on S-type wells with crosslinked fracturing fluid throughout all of the main stages.Because of similar geological conditions across the field,the significant number of previous well stimulation operations performed,and the use of extensive logging by the operating company(including bottomhole pressure and temperature online monitoring during fracturing job,and production logging),it was possible to evaluate and compare the economic efficiency of large fracturing treatments using linear fluid pads and large fracturing treatments using crosslinked pads.The comparison of the results from geophysical studies after the fracturing and the subsequent well productivity analysis have been performed.The described operations enabled fracturing risks and economic efficiency to be understood,both in the Achimov formations of the Urengoy field and in similar gas reservoirs with low permeability.Well productivity after fracturing with a linear pad increased in comparison with offset wells treated with crosslinked fracturing pad fluid.