Over the past several years the coiled tubing industry has seen significant coiled tubing-related technology advancements that have supported new applications for smaller coiled tubing (CT) services, from basic onshore capillary chemical injection installations to more complex offshore CT applications 1-8 . New and older well completion and location challenges continuously redefine the boundaries of conventional CT well intervention methods especially for offshore situations which can often be difficult to economically justify. These challenges require solutions that yield better economics. Small CT technologies have recently been developed and deployed on challenging projects in Asia Pacific to provide operators with cost effective methods to maintain wellbore integrity and enhance production.A lightweight, small-footprint coiled tubing unit (CTU) has been developed in Asia allowing for the use of Small CT technology on a broad spectrum of well service applicationsThis OTC paper will cover the specifics of an application of Small CT technology in Malaysia. Numerous challenges will be reviewed including using small (1-in. OD) CT pipe, small CT motors and working inside a restricted completion with high dogleg severity and a 70 degree hole angle. A total of 23 CT runs, inclusive of 14 CT perforation runs, were performed and the entire job was completed safely, without any major operational issues and delivered a gas rate of 15 MMscfpd.The Small CT equipment package is very comparable to a more conventional, larger CTU spread. A Small CT package can consist of a lightweight and small-footprint CT unit, a small nitrogen unit, reduced-size nitrogen tanks and compact pressure pumping equipment. As an example, for a gaslift type job using Small CT versus conventional CT equipment, the equipment footprint is reduced by 40% and the equipment weight is reduced by 46%. The small footprint and light weight of the Small CTU is especially beneficial where crane or deck space limitations are challenges. Small CT equipment can be customdesigned to suit most land or offshore applications, and the CT pipe can be installed on a semi-permanent basis (such as small capillary installations) or deployed as a work-string for well intervention programs.Application of this technology has the potential to substantially reduce operating costs, logistical support and risk exposure and can be applied to both onshore and offshore environments worldwide. Wells that were once considered plug and abandon candidates due to economic, technical challenges or accessibility may now be candidates for Small CT technology solutions. CT Run 4Perforation #1 The objective for this run was to perform an equalization shot from depth 2225-2235m MD-RKB. Start RIH with an equalizing shot at 15m/min and stop at 2261m MD-RKB (actual TD 2272m MD-RKB). CT Run 5 Perforation #2 The objective for this run was to perforate the interval 2220.7-2229.5m MD-RKB. RIH gun BHA with THP=550psi and stop CT at depth 2259.6m MDRKB to correlate depth. CT picked-up to top of the de...

DescriptionThe development of coiled tubing as we know it today dates back to the early 1960s. It has become an integral component of many well service, workover applications and programs. While well services and workover applications still account for approximately 75% of Coiled Tubing (CT) use, technical advancements have increased the utilization of CT in both drilling and completion applications 1 .

Coiled tubing (CT) is one of the most common and effective methods employed to mill out composite bridge plugs (CBPs) that are used to isolate zones during completion. Typically, the zones are normally pressured or over pressured, i.e., each interval approximately the same pressure. Recently, in a New Zealand field, a plan was set to mill out CBPs that had been set between zones that were tight gas and conventional with as much as 3,780 psi pressure differential between them.One major challenge relates to the CT CBP milling. While milling the plug that isolates the over-pressured zones, the differential pressure can exert significant forces on the milling assembly, raising the potential for buckling/failure of the CT. To reduce this risk it was decided that a bridge plug with an equalizing path would be used to eliminate the large pressure differential and potential upward forces. Another challenge was the issue of cross flow between the zones after milling was completed, and the potential for well control issues due to some under-pressured zones that could not support a full fluid column, causing loss of hydrostatic pressure.For the under-pressured zones, nitrogen was used to equalize the pressure across the plugs prior to milling them. To minimize the risk of getting stuck and potential CT failure, the operation was closely monitored and optimized by using a CT real-time downhole communication system. The real-time downhole pressure captured by the system during plug milling provided the firm evidence that equalization had occurred. This paper reviews the selection of plugs/mills and the milling strategy for safely milling CBPs that have been set across zones with significant differential pressures. The benefits of using a CT real-time downhole communication system is discussed by illustrating the case study of successfully removing 25 CBPs with CT in the three wells within a field.

Fracture stimulating horizontal wells is challenging using traditional workover methods. Running perforating guns in the horizontal well section, performing a fracture treatment, running a bridge plug, and then pulling or milling all the plugs has shown to be an extremely time consuming and expensive operation. An option using coiled tubing was proposed in China to improve on operational efficiencies.Multiple zone completions using coiled tubing has traditionally used a straddle cup tool. This has proven effective for fracturing multiple zones in shallow environments. The drawback to this method is high pumping friction due to the small inside diameter of coiled tubing. With wells reaching ever greater depths and higher deviations, the multiple zone fracturing method using coiled tubing and straddle cup tools becomes unfeasible. A coiled tubing method using the larger area annulus was investigated and subsequently recommended for performing fracture treatments in deeper and/or horizontal wells.The annular fracturing process involves first perforating by utilizing a coiled tubing sand jetting procedure and then pumping the fracture treatment through the coiled tubing by casing annulus. Following the fracture treatment, an ultra light weight proppant plug provides effective zonal isolation from the lower frac. The process is then repeated from the toe to the heel of the horizontal wellbore for the required number of fracture treatments. A sand cleanout at the end of the last fracture treatment removes sand isolation plugs. The method can quickly fracture stimulate a large number of sections in a horizontal wellbore with an easily removable isolation system.Results to date have been improved well productivity and decreased workover time compared with traditional frac and plug methods in horizontal wells. A field wide case study is examined to discuss design criteria, job execution, improvements, procedures and results. As the world moves to deeper and more complex wellbore trajectories, this technique is a viable method for horizontal or deep well stimulation.

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