Angeles, Renzo (ExxonMobil) | Cole, Stephen Wayne (XTO Energy Inc.) | Benish, Tim George (ExxonMobil Production Co.) | Tolman, Randy C. (RC Tolman LLC) | Gupta, Jugal (Exxon Mobil Corporation) | Ross, Kirk B. (XTO Energy Inc.)
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 over-stimulation 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.
Recent advances in multi-stage stimulation technologies, including open- and cased-hole types, have largely overlooked the advantages of single-zone stimulation due to hardware and cost limitations. In most conventional methods, multiple perf clusters are treated at once using one single frac stage with the expectation that equally-stimulated fractures will be created at each perf cluster within tens and hundreds of feet. This creates over-stimulation in some perf clusters and under-stimulation in others, which unveils the current economic and practical limits of effectively creating fractures where needed, not where it is possible to place them. Other methods use a large number of frac plugs which require additional wireline trips and later need to be drilled out, increasing the total cost and mechanical risk of the completion. As lateral length increases, many operators also face the challenge of not being able to remove all frac plugs due to coiled-tubing depth limitations.
This paper introduces the recent implementation of Just-In-Time Perforating (JITP) in shale gas, unconventional plays. JITP is one of the Multi-Zone Stimulation Technologies (MZST) developed and patented by ExxonMobil over a decade ago and extensively used in vertical and S-shaped wells in the Piceance basin, Colorado, and recently implemented in the XTO Fayetteville Shale, Arkansas. JITP creates multiple single-zone fracture stimulations on a single wireline run using ball-sealer diversion and perforating guns that remain downhole during fracturing. Other key features of this method are the use of less horse power, significant reduction in the number of frac plugs, fewer wireline runs, and added flexibility in water management. This paper describes the technical advantages and business justification for applying JITP in unconventional resources and also provides preliminary results from the performance of the JITP field trials in horizontal wells.
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.
Technology Focus - No abstract available.