Coiled-Tubing-Deployed Shutoffs in Alaska With a Polymer Gel and Microfine Cement

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 173655, “Coiled-Tubing-Deployed Gas and Water Shutoffs in Alaska With a Polymer Gel and Microfine Cement,” by D.B. Robertson, SPE, BP; M.A. Brown, Petrotechnical Resources of Alaska; L.H. Duong, SPE, BP; O.V. Ivanova, Schlumberger; and A. Tambe, SPE, BP, prepared for the 2015 SPE Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 24–25 March. The paper has not been peer reviewed. A common problem in oil and gas wells is excess free gas or water production from only certain portions of the completed interval. A coiled-tubing-deployed profile-modification technique was developed primarily to shut off excess free-gas production from the heel of cased-and-perforated horizontal oil wells. The technique has also been used for water and gas shutoff in both vertical and horizontal wells in a variety of lower-completion types. Introduction Coiled-tubing work has a well- established track record in North Slope of Alaska oil fields involving several thousand interventions of various types. Fig. 1 is a photograph of a typical Arctic-winter coiled-tubing operation. Most of the approximately 1,700 wells in the Prudhoe Bay field penetrate either an extensive gas cap or the aquifer in the sandstone reservoir. Mechanisms for excess free-gas or water production can be related to poor primary-cement jobs of production liners, fluid-contact movements over time, coning, or corroded or damaged liners. In general, any through-tubing-profile modification that can be performed to reduce excess free-gas and water rates and increase oil rate or time on production is beneficial to overall field production. With many candidate wells, there has been a continuous evolution in job design and execution techniques over the years.