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.

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.

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.