Solid Paraffin Inhibitors Pumped in Hydraulic Fractures Increase Oil Recovery in Viking Wells

Abstract

The Viking formation in southern Saskatchewan Canada represents an active area where steep production declines in the first year of production are common and are often attributed to wellbore or near-wellbore precipitation of paraffin. Excessive decline rates within the first year on production have been observed.A producer was experiencing paraffin deposition in the wellbore and suspected it to be the reason for production declines. Conventional treatments targeted at wellbore deposition were carried out with little effect on production rates. In an effort to improve production rates horizontal treatments were attempted. These treatments resulted in brief increases in production (up to 6 weeks). Horizontal treatment success led to investigation into other treatment options. Precipitation in the formation may contribute to reduced conductivity and, therefore, lower oil production rates. Solid paraffin inhibitors delivered via hydraulic fracturing offered the best potential for success in new wells.The chemical additive treatment was designed through product selection testing using cold finger deposition tests, compatibility testing with the hydraulic fracturing fluid system, and proppant crush prediction models. A baseline of the untreated oil characteristics was determined using offset wells. Pour point, carbon number distribution and wax percentage were analyzed in offset untreated wells and each treated well. Production trends were used to track the performance of the treatments. The solid inhibitor application effectively prevented conductivity restrictions due to paraffin precipitation issues in the proppant pack.Placement of solid paraffin inhibitors into the Viking formation with the proppant during hydraulic fracturing increased cumulative production by approximately forty percent in the first 350 days on production and reduced decline rates. Comparing 150 untreated wells with the 90 wells treated with the solid paraffin inhibitor in 2012 has increased revenue by about 15.8 million USD over the 350-day period. Wells drilled in the same area, with similar frac treatments, depths, horizontal lengths and stages were compared.