This paper outlines how modern horizontal well completion designs and stimulation techniques are being further optimized with new assessment techniques and leading to even more efficient operations and evenly stimulated stages along longer laterals in the reservoir. Chevron wanted to improve their completion design and perforating strategies in the Denver-Julesburg (DJ) basin, and utilized high-resolution acoustic imaging in combination with surface treatment data in a three-phase multi-well assessment to improve their stimulation programs. The assessment quantified the impact of perforation orientation, orientation deployment system, and the effectiveness of dissolvable frac plugs compared to composite plugs in three phases. All designs utilized a limited entry completion design to achieve even slurry volume distribution within each stage. Two key performance indicators derived from the acoustic imaging technologies measurements of post-fracture perforations are used in the assessment, namely cluster efficiency (CE) and uniformity index (UI). Based on the results from the assessment, changes to the completions design yielded a 15% increase in the CE, 13% improvement in UI, and an observable increase in early-life production rates when these changes were correlated with production data.
To complete this three-phase assessment, Chevron selected and deployed high-resolution acoustic imaging technology post-frac and plug drill-out on coil tubing in six wells. In each phase, a single variable was manipulated to systematically quantify and evaluate the impact of each variable. In the first phase, three zipper frac’d wells using dissolvable plugs for isolation were imaged to assess the effect orientation design and orientation system have on stimulation performance. Additionally, each plug set depth was analyzed using advanced plug location visualizations generated by the acoustic technology, which revealed that a high percentage of the stages indicated a lack of stage isolation due to plug damage.
Based on these results, a second phase with composite plugs was executed. Composite plugs increased the CE, perforation efficiency (PE), and UI relative to previously deployed dissolvable plugs, with minimal time and cost added to the overall stimulation operations. Finally, a third phase was designed to assess the impact of the perforation orientation on these key performance metrics. In this phase, a single well was completed with a 90° phased non-oriented, 0° (highside) oriented, and 120°/240° orientated perforations that alternated from stage to stage throughout the well using the orientation deployment system discovered in Phase 1.
Chevron iteratively and systematically optimized its stimulation design by analyzing the submillimetric three-dimensional (3D) point cloud of data at each perforation quantified by the acoustic technology, in combination with surface treatment information. The data collected through this assessment quantify the improvements of oriented perforating on perforation size consistency and isolation reliability. The result was a significant improvement in completion performance across key metrics. CE improved from 70% to 85% (+15%), and the UI increased from 67% to 80% (+13%). Therefore, this paper highlights the implementation of a systematic completion design optimization program evaluated using acoustic imaging and surface treatment data.
