The Appalachian Basin has long been known for its relatively shallow and associatively economical wells. However, in the fairly recent past the Marcellus Shale has caused a buzz in the industry reaching from the small independents of West Virginia to the established majors of Texas and beyond. This creates a two-fold problem for those parties interested in exploring this play. Firstly, how can the independents justify breaking into a tier of spending not typical of Appalachian Basin operations, and secondly, how can the majors create economical situations in an unfamiliar and challenging environment.
Although uniquely different, the path to each solution is similar, both attempting to create an economical and successful project. This begins with careful planning, and a realistic approach. For those familiar with the terrain and environmental challenges, a focus upon fiscal planning and careful economic research is necessary to walk the fine line between feasibility and cutting yourself short. Others may be familiar to large-scale projects, but inexperienced in the challenge that is Appalachia terrain.
All of this plays a direct impact on what may arguably be the most crucial aspect of the entire project - the stimulation design. Without proper planning and execution of site and approach construction, the majority of designs are moot. The facts are that Marcellus Shale wells demand large volumes of materials, delivered at a high rate.
This paper will explore the logistic challenges that any operator could expect to encounter in the Marcellus Shale, and will discuss stimulation design options shown by field experience in over 150 stimulations.
There have long been successful projects completed in the Appalachian Basin within the realm of oil and gas productivity. With few exceptions (ala Trenton Black River), these completions have been the majority of 5000 feet and under. Casing programs of two to three strings of pipe with a 4.5" long sting for production have become commonplace within the northeast and as compared to the total AFE cost, are quite economical. Although some TBR and oriskany projects remain productive with the basin, it's safe to say the majority of work up to the Marcellus Shale has been geared towards minimal horsepower, simple fluids, and energized stimulations. Foamed water, guar gels, and crosslinks make up the bulk of completions with proppant usage limited to a few hundred to a couple thousand sacks of typically white sand spread across several isolated zones of interest. These types of treatments and the associated equipment necessary for drilling and completion go hand-in-hand with the challenge of Appalachian terrain, and the hardships of moving heavy equipment in sometimes the most isolated areas of our country. Whether the terrain dictated the equipment which in turn dictated the design of fracturing or opposite is analogous to the chicken and the egg. The mostly independent pool of E&P's had figured out the low-hanging apples of gas acquisition in the basin, and the service companies conformed their services and equipment to match.