Benchmarking of Various Types of Completions and MS Technologies for Horizontal Wells at the Priobskoe Field Southern License Topic

Abstract

With each year drilling of new wells is performed in worse and worse reservoir properties conditioned by low permeability and undersaturated reservoir. At the same time, percentage of hi-tech horizontal wells (HW) with multistage hydraulic fracturing (MSHF) is increased, advanced technologies and engineering solutions are deployed; all this allows to maintain and even increase levels of oil production in new wells. As at beginning of 2017, over 200 MSHF HWs have been drilled in the unique Priobskoe field (South Concession Area) with use of the most advanced technologies. Various completion types and MSHF technologies have been deployed and tried in 50 areas in search of the best technologies and engineering solutions. Wells in such areas were producing for more than 1year and at this stage there is adequate amount of data on cumulative production, liquid and oil decline rates for efficiency benchmarking. Number of commissioned MSHF HWs is increased each year and there will be over 600 MSHF HWs by 2019 (+300% to current number) and results of this paper is a determining vector of development for further decisions applicable to improvement of efficiency of MSHF horizontal wells. The following main points for increasing efficiency of MSHF HWs were identified by results of the benchmarking: Increase of HW length to max. 1500 m allows to increase productivity, obtain incremental cumulative production over 20% vs. offset wells with HW length ~ 1000 m.Depending on the distance between ports, an optimal number of MSHF stages is ~ 125 m; in some cases, this distance is increased to ~150 m for large volumes of proppant > 90 tons per stage.Increased mass of proppant > 90 tons per stage (maximum 122 tons, up to 10 tons per 1 meter of formation) allowed to obtain incremental cumulative production from 20 to 48% during the first year as compared to offset wells with proppant mass <50 tons per stage.An optimal range of proppant mass identified for the undersaturated reservoir is 50-60 tons per stage depending on the TVDSS. Success of cluster MSHF was reported for some wells.Use of internal-flush cemented liners with targeted initiation of fractures shows good results in some areas. Subject to the quality cementing, this is the most strategically promising and anticipated approach for the repeated targeted MSHF. History of decline rates, operational experience of fraced directional wells show that over 200 re-MSHFs shall be performed in the next 10 years.