GRI Advanced Stimulation Technologies Improve Production in Rose Run Formation
Authors: Fairchild N.R. , Mills J.A. , Wood D.D. 
Published: December 2007

Over the past several years, Belden & Blake Corporation has been working in cooperation with the Gas Research Institute (GRI) on the application of Advanced Stimulation Technologies (AST) to the Rose Run Formation in Randolph Township, Ohio. The objective of the project was to use AST to design and implement a more effective hydraulic fracture treatment which would in turn improve production. Several AST technologies were used to develop a reservoir description and design an improved hydraulic fracture treatment. The newly designed treatment used crosslinked fluids to place more sand at higher concentrations with less total fluid volume. Real-time fracture diagnostics and modeling were used to help place proppant and refine the reservoir description. After the treatments, production data was collected and compared to offset wells that had been stimulated with a variety of treatments (linear gel, CO2 foam). The production comparison showed that the treatment developed through the use of AST, which used more proppant at higher concentrations, out performed past treatments in both oil and gas production.

Background

Belden & Blake's study was located in Randolph Township, Portage County, Ohio near the city of Canton. The wells were completed in the Rose Run Sandstone, a low permeability sandstone which extends north and south throughout much of eastern and central Ohio. The Rose Run appears as several uniquely identifiable sand stringers which are interspersed between Dolomites. It is typically found at a depth of approximately 7,100 feet in this area. Reservoir pressures are approximately 3,000 psia, permeabilities range between 0.05 and 3 md, and typical production varies between 5 to 600 Mscf/D and 1 to 200 bpd of oil. Because of the structural nature of the play, seismic data is used as the major exploration tool. Porosity is primary in nature, but its productivity may be greatly enhanced by natural fracturing.

Previously, acid breakdowns, CO2 foam, and linear gel treatments had been performed on the Rose Run. An analysis of their production data indicated that in many cases, these wells, even after stimulation, acted as natural producers with little or no wellbore.

Frequently, the lower members of this sequence are thought to have higher water saturations and are not stimulated to avoid potential water production problems.

Coring

To develop a better reservoir description, 28 ft of whole core and 10 sidewalls were obtained on the R. Ward Comm. No. 1 Well. Analyses performed on the cores included conventional core analysis, SEM, x-ray diffraction, electrical properties, capillary pressure, relative permeability and fracture fluid compatibility. Cores were also tested using static (tri-axial compression) and dynamic (ultrasonic velocity) tests to determine mechanical rock properties such as Young's Modulus and Poisson's Ratio.

An improved reservoir description was needed to evaluate the production mechanisms of the Rose Run sandstone. Because the Rose Run may appear as several thin lenses, it is probably not possible to control fracture height growth between the individual members. If any of the zones are wet, water production may become a problem due to their interconnection through fracturing. Therefore, it is important to be able to identify under what circumstances water production might be a problem before the well is completed.

As a result of the core analyses, a cementation factor (m) of 1.91 and a saturation exponent (n) of 1.19 were calculated in the electrical properties analysis. As values of 2.0 have typically been used for both m and n, this indicated that the true water saturations are actually lower than previously calculated.

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