Predicting Flow Distribution for SAGD Producing Wells By Use of Permanently Installed Fiber Optics

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 102159, "Predicting the Flow Distribution on Total E&P Canada's Joslyn Project Horizontal SAGD Producing Wells Using Permanently Installed Fiber-Optic Monitoring," by P. Krawchuk, SPE, and M.A. Beshry, Total E&P Canada, and G.A. Brown, SPE, and B. Brough, SPE, Schlumberger, prepared for the 2006 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24-27 September. During the startup and early operation of horizontal steam-assisted gravity-drainage (SAGD) wells, it is important to understand the flow distribution of bitumen and water along the horizontal reservoir interval so steam distribution can be adjusted to optimize the startup and early operation of the SAGD pair. The injector/producer interval between SAGD wells was modeled with a thermal reservoir model. The results highlight the need for distributed temperature measurements in SAGD wells to understand the temperature response over time. Introduction The Joslyn field is west of the Athabasca River in Alberta, Canada. The McMurray formation is a 50-m-thick high-permeability sand at 60 to 100 m below the surface and contains high-viscosity bitumen. On the western part of the lease, the recovery method is SAGD, which requires injection of steam into an upper horizontal well, creating a steam chamber and reducing the viscosity of the bitumen. The bitumen and condensed steam flow by gravity down into the producer well 5 m below the injector, and from there they are pumped to the surface. A pilot horizontal injector/producer pair was installed in the Joslyn field in 2004 as Phase I of reservoir development. During completion of the SAGD pair in Phase I, a fiber-optic distributed temperature system (DTS) was installed in the producer well, and data from this were monitored as the well was put on production. In January 2005, a workover was performed. Temperature monitoring along the wellbore with the DTS system continued through 2005. Joslyn Completion The upper and lower horizontal wells were completed with slotted liners along the reservoir interval. The upper steam-injection well had injection tubing to the toe of the well, allowing steam to be injected at the heel, toe, or a combination of both. The production well initially was completed with no tailpipe along the reservoir interval. The downhole instrumentation string consisting of bubble tube and optic fiber in its 1/4-in. control line was deployed inside 1 1/2-in. coiled tubing (CT), which was inserted along the reservoir interval. In addition to the optic fiber, three vertical observation wells intersected the horizontal well trajectory between 1 and 2 m from the SAGD wells. These were at the heel, midway, and at the toe of the horizontal wells. Temperature measurements in these wells were provided by a string of 30 thermocouples that were monitored regularly.