Kvitebjoern is a Statoil operated gas and condensate field that lies in block 34/11 in the Norwegian North Sea. The reservoir lies about 4,000 meters down, and features high pressure and temperature conditions (770 bar and 160 deg C). 34/11-A-9 T2 well was drilled as a gas producer by end of October 2009 and completed in February 2010. During the final completion phase, it was not possible to open the High Pressure/High Temperature (HP/HT) isolation ball valve set in the 9 7/8" liner at 6245.7 m MD / 3795.8 m TVD through pressure cycling.After several failed attempts to open the isolation ball valve with wireline using mechanical override tools, it was decided to punch above it to allow well production passing the outside of the valve through the annulus between 9 7/8" liner and the 5 ½" tail pipe. However, the production performance was poor. A feasibility study was carried out to evaluate available methods for opening or milling out the valve with the objective to improve the production characteristics. The well is an exploration well and an important objective for the operation was also to allow access for future production logging tools.The decision was then taken to mill the stuck-closed isolation ball valve using Coiled Tubing (CT).The operation presented several critical challenges. Statoil had not performed any HP/HT CT operations and the available experience was limited.To minimize uncertainty relating to depth determination during the milling operation, it was decided to use a telemetry system run at its operational pressure and temperature limits to provide real time Casing Collar Locator (CCL) reading in addition to downhole pressure and temperature data.

Summary Available footprint on offshore platforms (Fig. 1) can be a significant challenge for coiled-tubing (CT) operations. Many times, platform limitations require that a smaller CT unit be deployed for work that would be faster and easier operationally with CT of a larger diameter. Often the platform's crane capacity dictates the size of CT used, which in turn reduces the working envelope of the CT. Some wells offshore India are completed horizontally and require intervention using larger sizes of CT in order to gain horizontal reach and manipulate sliding sleeves. When CT is used for these operations, the weight of the CT reel itself is critical to the effectiveness of the overall operation and requires proper management. Traditional methods of managing/reducing CT-reel weight involve spooling the CT string from a boat to the platform or joining CT sections by butt welding on the platform. Bringing the required length of CT onboard in two or more sections and joining them with a spoolable connector provides significant benefits over the traditional methods. The use of just one spoolable connector can reduce the maximum CT-reel lifting weight by typically 30 to 40% while increasing the CT size by one or two gauge sizes. This paper describes the results of a feasibility study performed to address typical challenges and presents actual case histories in which a spoolable connector was used to connect two CT strings. Required equipment was built and mobilized so that two separate strings could be joined on the platform with the aid of a connecting jig. Several trips were performed safely without the need to change the spoolable connector. Specific benefits of the spoolable connector over the traditional methods are explained. Methods to monitor the usable life of the spoolable connector while tripping in and out of the well (Fig. 2) will also be discussed, as well as new developments currently under way.

Available footprint on offshore platforms can be a significant challenge for Coiled Tubing (CT) operations. Many times a smaller CT unit is deployed for work that would be faster and operationally easier with CT of larger diameter. Often the platform’s crane capacity dictates the size of CT to be used, which in turn reduces the working envelope of the CT. Some wells offshore India are completed horizontally and require intervention utilizing larger sizes of CT in order to gain horizontal reach and manipulate sliding sleeves. When CT is used for these operations, the weight of the CT reel itself is critical to the effectiveness of the overall operation and requires proper management. Traditional methods of managing / reducing CT reel weight involve spooling the CT string from a boat to the platform or joining CT sections by butt welding them together on the platform. Bringing the required length of CT onboard in two or more sections and joining them together utilizing the spoolable connector provides significant benefits over the traditional methods. The use of just one spoolable connector can reduce the maximum CT reel lifting weight by typically 30-40%, while increasing the CT size easily by one or two gauge sizes. This paper describes the results of a feasibility study performed to address typical challenges and presents actual case histories in which a spoolable connector was used to connect two CT strings. Required equipment was built and mobilized so that two separate strings could be joined on the platform with the aid of a connecting jig. Several trips were safely performed without the need to change the spoolable connector. Specific benefits of the spoolable connector over the traditional methods are explained. Methods to monitor the usable life of the spoolable connector while tripping in and out of the well will also be discussed, as well as new developments currently underway.