Just-In-Time-Perforating (JITP) was developed by ExxonMobil over a decade ago to improve multi-zone stimulation in vertical and S-shaped wells in the Piceance basin, Colorado. With this technology, multiple single-zone fracture stimulations are performed on a single wireline run using ball sealers and perforating guns that remain downhole during the fracturing treatment. This results in substantial cost reduction and productivity uplift because perforation intervals are individually and effectively treated one at a time with less horse power, smaller number of frac plugs, and fewer wireline runs. The method has been successfully implemented by ExxonMobil in more than 350 wells and over 10,000 treatments and is licensed to a number of service companies.There is substantial business incentive to implement the JITP technique in horizontal wells, extensively used in unconventional gas developments. With XTO Energy joining ExxonMobil, the global gas portfolio incremented by 45 trillion cubic feet. This includes conventional gas, shale gas as well as other unconventional resources, such as tight gas, coal bed methane, and shale oil. This paper presents the first application of JITP in horizontal wells. Operations were conducted in the Fayetteville Shale, Arkansas. The paper discusses advantages and disadvantages of the method as well as lessons learned from pre-field trials and full-well implementations. Critical to the success of the initial technology application was the enforcement of a structured approach which included technical feasibility studies, contractor qualification, pre-field trials, well candidate selection, and a deployment plan to capture learnings and best practices. Pre-field trials were executed in several wells to test potential technical/operational concerns, such as sand build-up around perforating guns, fluid diversion with buoyant and non-buoyant ball sealers, and the ability to move guns through the lateral. Preliminary field costs and production performance in horizontal wells are promising and support continued deployment of the technology.
This paper demonstrates how a single permanent fiber installation allowed the development of improved completions designs in real time in order to improve well economics. Design changes were adjusted during the completion of the well to determine stage length and completion execution. Improvements were applied to the subsequent wells in the program. In 2018, an eight-well pad was completed with the intention of immediately drilling and completing a second directly offset eight-well pad. Further options for additional wells would be evaluated based on the performance of these sixteen wells. The laterals of the project wells were arranged in a wine-rack configuration targeting zones in the Upper and Lower Eagle Ford Formation. Initial designs were based on analytics from the area resulting in an initial design for cluster spacing, stages per cluster, injection rates and volumes, and fluid volumes. The primary goal of the diagnostics expenditure was to improve the dollars per barrel relationship, specifically by increasing stage lengths that could be effectively completed along the lateral wellbore. The project included a casing-installed fiber optic cable to record the distributed acoustics and distributed temperature along the wellbore for, respectively, stimulation flow profiles and production flow profiles. Acoustic-based flow profiles were generated during the project and evaluated to influence the next set of stage designs. These design changes involved among other variables adding clusters to the stage, sand staging, and rate adjustments, At the end of the project, completions changes resulted in a reduced individual well cost of 11%. Production profiling began to compare stage designs along the lateral and to confirm baseline well performance versus its peers. In both cases, those results confirmed that the design changes lowered the overall cost while maintaining well performance.
In order to reduce stimulation costs, most conventional methods incorporate hydraulic fracturing of multiple perf clusters over multiple stages to treat large segments of shale rock in horizontally completed laterals. Under ideal situations, this technique would create equally-stimulated fractures at each perf cluster. However, in practice, such treatments can create overstimulation in some perf clusters and under-stimulation in others with unknown stimulated lengths and volumes. As operators move towards increased number of stages, increasingly larger number of plugs cause additional wireline trips and associated plug drilling time, which increases the total cost and mechanical risk of the completion. In some fields, operators use combinations of ball actuated sleeves and plug-and-perf methods due to technical limitations in drilling out of all the frac plugs. In response to these practical issues, ExxonMobil has implemented its proprietary Just-In-Time Perforating (JITP) technique in multiple horizontal wells over the last year. Prior to this deployment effort, JITP had been extensively used in vertical and S-shaped wells in the Piceance basin, Colorado. This paper discusses the learnings obtained after one year of multi-stage fracturing using horizontal JITP in unconventional plays. JITP creates multiple single-zone fracture stimulations on a single wireline run using ball-sealer diversion and perforating guns that remain downhole during fracturing. With the unique granularity of single-zone fracturing, much has been learned about the shale and treatment design. Better placement control can be useful in avoiding fracturing into offset wellbores. Field applications have confirmed the use of less horsepower, fewer frac plugs, improved fracture placement control, and added flexibility in water management. This paper also reviews technical considerations for other completion designs and fluid systems as well as opportunities for enhanced operations based on recent field learnings.
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