Concentric Coiled Tubing Application for Sand Cleanouts in Horizontal Wells

Abstract

Abstract The evolution of coiled tubing technology has brought many unique wellservice solutions to the oil and gas industry. Concentric Coiled Tubing (CCT)is a recent development which has opened the door to a whole range of new wellservicing capabilities. One of these techniques incorporates concentric coiledtubing equipment with a patented jet pump tool (SandVacSM, US patentnumber 5,033,545) specifically for the purpose of cleaning sand out of lowpressure horizontal wells. This paper will discuss cleanout issues and how the SandVacSM process provides an improved solution to cleaning in lowpressure, horizontal wells. To summarize, a review and discussion of the firstfive Sand-VacSM field applications will be given. Introduction Sand production is often a serious problem for heavy oil producers. Whensuspended in the produced flow, sand can cause destructive abrasion of pumpingequipment. On surface, the operator must deal with separation, handling andfinally, disposal of potentially large quantities of contaminated fines. Themost serious consequence of sand production however, is when deposition occursin the completion. Settled quantities of sand in the completion will impedefluid flow and therefore impede production. This problem is compounded by thefact that heavy oil producers are turning to horizontal well technology tomaximize production. Compared with vertical wells, horizontal wells have thefollowing characteristics:A longer interface for sand-inflowPerpendicular orientation of fluid flow and settling velocity vectorsSlight horizontal trajectory undulations-resulting in "troughing" Each of these conditions has a significant effect on the amount of sandaccumulation in the completion. Sand Control A number of methods have been used to try to prevent sand inflow. Totalexclusion techniques employ a formation barrier designed to prevent any solidsfrom entering the completion. This technique is often very expensive and canresult in severe skin effects at the barrier(l). A more cost effectiveinstallation uses a "partial exclusion" approach. Usually, this takes the formof a liner in which specifically sized slots have been cut. The liner thenpreserves the hole integrity while the slots allow oil inflow.