A newly-developed 3 ½-in. coiled tubing telemetry (CTT) system has been used for the real-time operational optimization of such coiled tubing (CT) applications as milling, cleanout, logging, and perforation, in an offshore multi-well campaign in Norway.

The CTT system consists of surface hardware and software, a dual-purpose wire inside the carrying CT, and the multi-function bottom hole assembly (BHA). The wire transmits electrical power from surface to the downhole sensors located in the BHA and the downhole data from these sensors to surface. The BHA, designed in one of three sizes (i.e., 2 ⅛-, 2 ⅞-, and 3 ½-in.), contains a casing collar locator (CCL) and two pressure and temperature transducers that are capable to measure downhole data inside and outside the BHA. One of the main advantages of the CTT system is its versatility. For instance, switching between applications is as simple as only changing a certain part of the BHA. This reduces the need to rig-up and rig-down and leads to operational time and cost savings to operators. Another main advantage stems from its real-time downhole data certainty, as the CT field crew can immediately make decisions based on dynamic downhole events.

A few papers have been published recently regarding a similar 2 ⅛ and 2 ⅞-in. CTT systems (SPE-174850, IPTC-18294, SPE-179101, and SPE-183026). In this paper, several case studies are presented for the 3 ½-in. CTT system for the first time. For instance, in the first well, the CTT system helped remove approximately 26,500 lb of scale through a complex wiper trip schedule, effectively preparing the well for re-completion by the main rig. In the second well, the CTT system helped pull all shallow and deep plugs and perforate three intervals in one run. In the third well, the CTT system helped clean out the well, set a plug, and re-perforate it. In addition to successfully performing all these operations, several other benefits resulted due to the real-time downhole data monitoring provided by the CTT system. For instance, the fluid friction reducer (used for reducing the fluid frictional pressure drop) was effectively used at volumes of 70-75% lower than those recommended when the CTT system is not used. Also, all these operations were performed without the need to mobilize most of the wireline and tractor equipment and crew, saving an estimated time per well of six days of wireline logistics and work.

The paper briefly describes the 3 ½-in. CTT system and discusses the data acquired during these field operations. The system performance and operational benefits confirmed are presented. These findings outline the versatility of the 3 ½-in. CTT system, the predictability of successful operations resulting from using this system, and the cost and time savings to operators.

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