Targeted steam injection using horizontal wells with limited entry perforations

Limited-entry perforations have been used in vertical wells in both Califor nia and at Imperial Oil Resources' Cold Lake field as a method for distribu ting steam to different zones. The technology relies simply upon designing the number, size, and placement of the perforations so that critical or cho ked flow occurs across the perforations during steam injection, and steam e xits the well with the desired distribution. This paper describes an experi mental horizontal well where this same technology was used to replace ten v ertical injection wells with a single horizontal well. The well was located between rows of vertical wells in a reservoir that had been subjected to m ore than ten years of operations under cyclic steam stimulation. The Limite d-entry perforations enabled steam to be targeted at the cold regions of th e reservoir. A more typical completion such as a screened or slotted liner would not have provided any control over the placement of steam in the rese rvoir. The 1,000 m long liner was cemented in place with a completion desig n consisting of only 28, 9.5 mm diameter, perforations which were drilled t hrough the casing and cement. The design injection rate for the well was 2, 000 to 3,000 m(3)/day of 70% quality steam. This paper presents an assessme nt of the performance of the well based on theoretical calculations, measur ed injection pressures and rates, and 3D seismic imaging.