Coiled-Tubing Telemetry Intervention in Shut-In Conditions

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 189910, “Operational Improvements Using a Coiled-Tubing-Telemetry System for a Complex Milling Operation in Shut-In Conditions,” by P. Correa, D.  Parra, S. Craig, SPE, S. Livescu, SPE, A. Yeginbayev, and Z. Nadirov, Baker Hughes, a GE Company, prepared for the 2018 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, USA, 27–28 March. The paper has not been peer reviewed. When a new horizontal well in Asia was incapable of unassisted flow, coiled tubing (CT) was selected for the perforation and stimulation intervention. Mechanical isolation was required to ensure that the stimulation fluids entered only the new zones. Accurate depth control was required for three runs: setting two composite bridge plugs (CBPs), deploying CT-conveyed perforating guns for opening two intervals, and milling out the two CBPs without taking returns to surface. For the first time, a tension, compression, and torque (TCT) subassembly was used to improve the milling operation. Introduction CT telemetry (CTT) systems have proved to be effective in enhancing operations by providing real-time monitoring of downhole data including depth, pressure, temperature, force, and torque. For data transmission from downhole sensors to surface, these telemetry systems can use either insulated wire or optical fiber. With insulated wire, power can be transferred from surface to the downhole sensors. With optical fiber, downhole batteries are required in the bottomhole assemblies (BHAs) to power the downhole sensors. When compared with braided systems using the 0.125-in. insulated electrical cable (Fig. 1), the main advantages of the CTT system are its low weight and the fact that balls can be pumped through the CT. A small wire has a minimal effect on the CT cross-sectional area. Balls up to 7/8 in. in diameter do not become stuck, and there is a minimal effect on the CT fluid pressure drop. Description of the Wire CTT System The 0.125-in.-wire CTT system has several components, such as surface hardware and software; the ⅛-in. insulated electrical conductor inside the CT string; and a BHA with different sizes, including 2.125, 2.875, and 3.5 in. The 2.875-in. BHA with three subassemblies is shown in Fig. 2. The 2.875-in. sensor assembly has the following components: Tubing end connector Head that secures the wire downhole, seals the exterior of the wire, and provides downhole electrical connection 0.875-in. ball-operated wire-release mechanism Double-flapper check-valve housing Electronic module with a casing collar locator (CCL) and pressure/temperature sensors (internal/external) Motorhead section, where a ¾-in. ball-release mechanism is located followed by a circulating port activated with 0.625-in. balls Burst-disk section enabling 0.5-in. balls to pass through to activate downhole tools