Concentric Coiled Tubing Vacuum Technology (CCTVT) was developed in the mid 1990s in Canada, and since then has spread worldwide. The technology was initially focused on sand cleanouts in heavy-oil, low-pressure, deviated wells, where other cleanout methods, including conventional CT interventions, were inefficient. Under such conditions, CCTVT provided a simple but very effective solution.In general terms, the technology comprises a downhole jet pump run on a concentric coiled tubing (CCT), which is a coiled tubing string inside another coiled tubing string. A single-phase fluid is pumped through the inner string to power the downhole jet pump, creating a localized drawdown that vacuums well fill (fluids and/or solids), increases the return pressure, and circulates fluids and solids back to surface via the CCT annulus.Since the introduction of this technology, it has gone through several updates in order to face new challenges. The latest BHA versions include multiple operational modes to improve cleanout efficiency, minimize runs, function with supplementary tools and most recently, to accommodate a specialized electric conductor to run a real-time logging tool in conjunction with the jet pump.Currently, the application of the system has extended beyond solids removal on heavy oil, onshore wells. The current work scope ranges from very simple operations such as drilling fluid and filter cake removal, liquid unloading, inflow profiling, evaluating completion integrity, matrix stimulation, pressure and temperature logging, etc.; to more complex and challenging operations such as memory production logging, H 2 S inhibition, multilateral wells, chemical sand consolidation, hydrate removal and realtime production logging. These operations are occurring in the full range of oilfield locations: onshore and offshore wells, from fixed installations to mobile rigs, in jungle to arctic conditions. This paper will summarize the new techniques that are being applied in many global locations with CCTVT. Each technique will be illustrated with case histories detailing time and cost savings and, where relevant, production improvements.

The Orinoco Oil Belt (OOB) is located in the southern strip of the eastern Orinoco River basin in Venezuela, with a total area of 55,314 km2. This formation represents the largest heavy-oil reserves from unconsolidated sandstones in the world. Unfortunately, sand production is a common problem associated with this type of formation. In addition, it is very challenging to successfully remove solids and stimulate large, highly deviated wells with low bottomhole pressures. Since 1999, a technology combining concentric coiled tubing (CCT) with a jet pump has been used in the OOB to remove solids and fluids (stimulation treatments, drilling fluids, etc.) from the wellbore. Due to the characteristics of these heavy-oil wells, with their unconsolidated sands and highly deviated well paths, sand/well vacuuming technology (SWVT) has become the main alternative for intervention operations such as sand cleanouts, stimulations, drilling fluid removal, and any kind of job requiring the use of coiled tubing. Conventional SWVT permits changing the configuration of the tool into two modes: sand vacuuming for solids removal, and well vacuuming for fluids recovery. During SWVT operations, two main scenarios exists where it is necessary to change the bottomhole assembly (BHA) used with SWVT for a regular BHA with enhanced jetting, thereby requiring extra runs to finish the jobs.Breaking through hard bridges formed by sand and oil or by solid materials as elastomers from progressive cavity pumps.Pumping down chemical stimulations treatments. To overcome the issues resulting from cleaning and increasing efficiency with stimulations jobs in a single run (avoiding extra running of different BHAs), an improved SWVT with a jetting switch has been developed, incorporating a third mode: high jetting. In this mode the SWVT BHA can handle higher fluid rates and achieve the necessary impact pressure to break solids bridges or to perform stimulations jobs efficiently. This paper discusses the implementation of this tool in the OOB and explains the results in terms of efficiency increase and best practices for this type of intervention.