Fracture Height Containment in the Stimulation of Oriskany Formation

Abstract

The Oriskany sandstone formation has been a prolific producer of natural gas in the Appalachian basin since 1930s. Lot of production wells have been converted to gas storage wells for the ease of operation. Natural gas storage industry is a vital part of North American energy driven economy because of the fluctuation in seasonal demand and in maintaining the reliability of supply needed to meet the demands of the consumer. However, the storage wells suffer from an annual deliverability loss of 5% owing to the various damage mechanisms. A lot of work pertaining to the issue of identification of damage mechanisms and subsequent development of stimulation technology in order to mitigate the damage and restore the wells deliverability have been done in a joint effort between The Gas Research Institute, Department of Energy, American Gas Association and the various other operator companies involved in the storage industry. Operators mostly rely on traditional methods such as blowing, washing, reperforating, acidizing, infill drilling to restore wells deliverability. These traditional methods do provide short term benefits, but the longevity is not sustained and the overall situation remains same. Hydraulic fracturing is not preferred in terms of legitimate concerns over excessive vertical height growth, long fracture fluid cleanup times, lack of expertise and cost. This research study was carried out to understand the various damage mechanisms affecting the Oriskany wells, with a focus on gas storage wells. We then developed a dataset of reservoir properties, rock properties and fracture treatment data for Oriskany based on a complete literature review and calculations from a sonic log. Parametrical studies were carried out to investigate the effect of type of fracture fluids, injection rate, types of proppant, treatment volume, reservoir pressure and treatment schedule on fracture geometries in the Oriskany formation. Based on the results, we developed new stimulation methods that lead to increased well deliverability, fracture height containment, and higher average fracture conductivity. This new understanding and knowledge help in practicing engineers design better treatments in stimulating Oriskany wells.