Challenge The operator of a deep high-pressure low-permeability gas field wanted to assess the feasibility and effectiveness of completing a horizontal well with an uncemented liner that had 10 sliding sleeve valves/ports but, unusually, no isolation packers.   Completed in the standard way, this well would require 10 packers, adding significant cost and complexity to the completion. A successful strategy for packer removal would lower completion costs, increase installation efficiency, and reduce future maintenance challenges. These savings and efficiencies would multiply substantially for field-wide application.   The chief concerns about the new strategy were that lack of isolation during fracturing might prevent sufficient fracture force being focused on each target zone and whether the result would be one large fracture rather than multiple distributed fractures. Another challenge was to evaluate the success of the strategy by identifying and locating the fractures to establish their extent along the wellbore and assess the performance of each fracture group.   Conventional production diagnostics could only assess flow entering the wellbore at each port and would, therefore, not reveal fracture location or distribution or even distinguish reservoir flow from port flow. A sophisticated post-fracture assessment was needed to determine whether the technique had been successful and to fine-tune future operations. New ChorusX answers transform the professional workflow, enabling analysts to diagnose well systems flows with greater ease and confidence. In this complex scenario, the Phase Map and Radial Map reveal the location of active fractures directly behind the frac ports. Conventional diagnostics would be unable to deliver this level of clarity and certainty. Solution TGT’s Fracture Flow diagnostics product is used to evaluate the effectiveness of hydraulic fracturing operations. In this well, the new ChorusX acoustic array platform was included in the survey programme to bring a wide range of additional benefits and fracture performance insights.   Using ChorusX, analysts located the precise depth and distribution of induced fractures and evaluated the relative contribution from each fracture along the entire reservoir section. ChorusX can distinguish between flow from fractures and flow through the sliding sleeve valves, even when the fractures are located at the same depth interval as the valves. This breakthrough enables the operator to distinguish between port flow and fracture flow, thus giving greater clarity and certainty to evaluations. Analysts can call on new ChorusX answers to resolve even the most complex flow scenarios. The Phase Map and Radial Map bring valuable insights that complement other measurements, leading to a more confident diagnosis. The top section of this ChorusX answer product identifies and locates active fractures, whereas the lower section confirms that no active fractures are present. Result TGT analysts used ChorusX data to identify and precisely locate fractures right along the reservoir section. The survey also provided an accurate flow geometry that displays the relative contribution that each fracture makes to production.   The Acoustic Radial Map serves as a highresolution, near–far indicator for flow and can distinguish between port flow and reservoir fractures in the immediate vicinity of the ports. These innovative features are unavailable in even the most advanced single-sensor acoustics systems.   The Fracture Flow product with ChorusX technology proved the effectiveness and viability of the new, ultra-efficient completion technique in this geological setting. The results provided the operator with valuable insights that will enable them to optimise the fracturing parameters and the completion design for field-wide roll out. This will deliver enormous savings in time, cost and resources, thereby helping operators access ‘hard to recover’ reserves in a more efficient and economic way.

Challenge Leaks observed in an active well in the Netherlands forced the operator to suspend the well. An initial examination indicated that the integrity breach could be located in the tubing, casing or any of the completion elements within or beyond the A-annulus envelope. A pressure test confirmed that the leak rate was small, just 0.25 bar per day, but this was sufficient to pose a health, safety and environmental risk and trigger the suspension of the well.   Leaks in the well system are a serious issue, and well integrity engineers want to understand precisely how and where the leaks originate so they can be repaired. The combination of many potential leak points spanning the length of the completion coupled with a small leak rate made this a challenge to investigate. The operator needed diagnostics technology that had a large radial reach and was both sensitive and accurate enough to scan for leak points and help steer a repair programme. Multi Seal Integrity example well. Multi Seal Integrity evaluates the seal performance of multiple barriers, locating leaks and flowpaths throughout the well system, from the wellbore to the outer annuli. Delivered by our True Integrity system with Chorus, Indigo and Maxim technology, Multi Seal provides a clear diagnosis of leaks and rogue flow paths so the right corrective action can be taken. Multi Seal is used in a targeted fashion to investigate a known integrity breach anywhere in the well system. Barriers can also be validated proactively to confirm integrity. Either way, Multi Seal provides the insights needed to restore or maintain a secure well. Solution The operator selected TGT’s Multi Seal Integrity answer product, upgraded with the new ChorusX acoustic array platform to meet the three-part challenge of sensitivity, accuracy and reach. ChorusX combines an array of eight nano-synchronised acoustic sensors with advanced processing to deliver a dynamic recording range that is ten times wider than in previous Chorus technology, specifically at the ‘quiet’ low-amplitude end of the Acoustic Power Spectrum.   The higher-resolution measurements from the ChorusX array reveal flow activity with increased definition and clarity, and TGT’s unique ‘near–far’ phase shift processing helps analysts distinguish between flow events near the wellbore, in the completion, and far from the wellbore, in the reservoir. This enables operators to target remedial actions with greater precision and implement them with higher confidence. The operator also chose to include Chorus9 technology in the survey programme to make a technical comparison between the two platforms. Multi Seal Integrity answer product using ChorusX. The Chorus9 acoustic power spectrum (left) indicates the approximate depth of the leak, but multiple indicators from ChorusX (right) combine to indicate the type, depth, radial proximity and extent of the integrity breach with much greater precision and clarity. Result The Multi Seal Integrity survey was performed while applying pressure in the A-annulus and observing a pressure drop of 0.25 bar per day, confirming the very low leak-rate. The Chorus9 and ChorusX platforms both recorded acoustic signals at X378 m, but the Acoustic Power Spectrum (APS) of ChorusX was far more detailed and informative (Figure 1).   The sharp change in polarity of the phase shift data, as seen in the Acoustic Phase Map, indicated a localised ‘singular’ leak point and its precise depth. The location and character of the data signature in the ‘near’ panel of the Acoustic Radial Map indicated that the source of flow was near the wellbore within the completion, and not in the reservoir. The precise nature of the radial map data signature further confirmed the exact depth of the leak source.   The combination of independent acoustic indicators enabled analysts and the operator to isolate the integrity breach to a single location in terms of depth, extent and radial distance from the wellbore. This enabled a highly targeted approach to remediation planning and implementation.