Abstract

In the Viking formation in the Redwater Operations area of Alberta, Canada, horizontal wells are typically completed using slotted liners. Earlier wells were usually completed in the vertical and subsequent fracturing of the perforated interval would generally lead to productivity improvements. In a new horizontal well drilled early in 2009 it was decided to cement casing through the productive zone and then perforate several intervals and fracture them in an attempt to improve productivity. Fracturing of horizontal sections in the past has proved problematic with the use of diverters being ineffective and cup packers being unreliable, so a new approach to allow for selective treatment of each set of perforations was researched. As a result a selective “jet pack” straddle system was chosen which allows for setting it across the zone, fracturing, unsetting the straddle, circulating the well clean and providing for the possibility of moving it further uphole to treat the next set of perforations. The well was drilled to a total vertical depth (TVD) of 650 meters (2133 ft.) and a measured depth (MD) of 1481 meters (4859ft.), with a maximum inclination of 91°. A 4-1/2” 11.6lbs/ft casing string was then cemented in place and the well perforated with six sets of perforations each one meter in length with depths ranging from 817-1467 meters (2681- 4813 ft.). A straddle system was then deployed on 2-7/8” coiled tubing with the objective of selectively fracturing each interval with some 45 metric tones (99,180 lbs) of sand at pump rates of 12-16 Bbls/min with breakdown pressures ranging from 20-30 MpA (2900-4350 psi).

In this paper the authors will briefly discuss the history of the field and the evolution of the completion methods employed. They will go on to review the features of the straddle assembly and to describe in detail the selective fracturing operation which was performed in which the straddle was set and unset twelve times in six runs into the well. Productivity over the first 4 months was 50Bbls/Day, which is the longest & highest initial production rate in the field to date.

You can access this article if you purchase or spend a download.