3.1.2. Program Design and Overview of Major Projects

Early EGSP efforts were directed at determining the geologic character and magnitude of the Devonian shale gas resource and toward increasing production of natural gas from the resource base. Formation characterization required to update the resource knowledge base and geological evaluations to ascertain basin limits and stratigraphic targets as potential gas sources were the first tasks to be completed. With this understanding, researchers identified large areas of the Devonian shale that exhibited certain characteristics that required particular technological developments for extraction.

Figure 3.1.1: Extent of Eastern Gas Shales Distribution. (Click to enlarge)

Accordingly, EGSP activities were planned for each of a number of gas shale provinces (Figure 3.1.1), namely:

1. Then-productive areas of Kentucky and West Virginia.
2. Ohio and related areas in New York, Western Pennsylvania, and Northern West Virginia.
3. Appalachian Front in Pennsylvania, Maryland, West Virginia, and Virginia.
4. Deep Appalachian Basin in Pennsylvania and West Virginia.
5. Illinois and Michigan Basins.
6. Speculative areas in all Eastern states.
EGSP research identified the nature of producible gas containment to be the microfractures and macro-factures of the shale formation.

Knowledge of these fractures, their directionality, and density enabled the development and testing of effective techniques to connect the gas-bearing natural fractures to the borehole.

Pilot tests of stimulation techniques in light of the geologic environment in the respective gas provinces then permitted the development of a rationale for stimulation strategy.

The EGSP was structured into the following functional categories or program activities:


• Evaluation.
• Resource and Site Characterization.
• Research, Instrumentation, and Modeling.
• Production Technology Development.


The first three activities provided for resource data acquisition and the development and testing of techniques for locating probable areas of gas-bearing natural fracture systems and for predicting the probable production from a particular stimulation method in a certain geologic province.

The fourth activity was directed at the development and testing of cost-effective methods for extracting gas from the various geologic provinces in the shale.

Each of these program activities are briefly described below.

Evaluation -- The Evaluation activity was designed to integrate facts as they developed, to assess recent technological developments and related industry activities, to ensure compliance with environmental regulations and address site-specific environmental problems, to develop a systems model for updating estimates of the potential resource, and to develop and monitor program plans that reflected the integration of the technical, geologic, economic, and other types of data.

Resource and Site Characterization -- This activity of the project was structured to develop the necessary resource data base for characterizing the Devonian shale provinces and to develop exploration rationales. Core information was used to assess the potential of various resource areas, to guide modeling efforts, and to design stimulation tests.

Types of data collected included stratigraphic, structural, sedimentological, physical, and chemical data for identification of gas-bearing fracture systems. Field work consisted of coring and logging to provide data for lab work. Laboratory research included chemical, physical, elemental, and mineralogical studies to determine the stratigraphic sources of gas and the degree of fracturing in the reservoir. The data was developed through contracts with universities and state geological surveys and the results were compiled and synthesized by the USGS for the various geologic provinces. Shale characterization studies were carried out through contracts with universities, research institutes, and private industry to develop and improve methods of locating gas-bearing naturally fractured reservoirs.

Research, Instrumentation, and Model Development -- This activity in the project was directed at the development of new diagnostic tools, stimulation approaches, and predictive capability to accurately forecast reservoir performance whenever extraction methods are applied to particular geologic provinces in the Devonian shale. Meeting these objectives required basic and applied R&D in the laboratory and the field and the development of models. The models served to describe the current understanding of the stimulation processes, gas flow from the reservoirs, and economic parameters related to fracturing and production.

Production Technology Development -- This activity in the project was directed at the development of effective stimulation methods for various geologic environments and the testing of these designs in field applications. The designs tested were conceptual models that evolved from sequential laboratory and simulation studies. Detailed documentation of field tests under controlled conditions complemented with systematic well testing were conducted through cost-sharing contracts with private industry.

Field tests (16) and demonstration projects showed that advanced stimulation technology (foam, cryogenic, MHF, and chemical explosive fracturing) could result in wells that produced considerably more than those stimulated with conventional wellbore explosive fracturing, at least in the gas province associated with historical shale production. Particular emphasis was placed on the use of energy assisted fracturing fluid in low-pressure fractured shale reservoirs.

Directional deviated well technology was also investigated, as well as the relationship of frac length and reservoir permeability to productivity. Location of regions of increased fracture intensity was found to be required to assure the likelihood of a commercial well, and the stress ratio concept (minimum horizontal-vertical) was investigated as an estimator of fracture intensity.

The objectives of the EGSP that emphasized the definition and characterization of the Eastern Gas Shales as a resource were completed as planned and provided an important knowledge base and framework for exploration activity within three basins.

The objective of developing methods for extraction employed geologic and reservoirengineering tests to understand/predict production performance in established areas of potential. This was necessary to separate the effects of the stimulation method employed from that of the reservoir itself.

While the milestones for comparing stimulation methods in new areas of potential were completed as planned, the validation of a strategy for the matching of a specific technology to a given geology was not. This required a shift in project strategy from an R&D testing mode that produced gas to one that emphasized reservoir science.

Accordingly, a three well, highly instrumented field laboratory was established to determine in situ gas storage, release mechanism and production rate, in situ natural fracture system spacing and distribution, response to stimulation, and well spacing required for development. This was successfully completed in one geologic province having production potential.

The original EGSP plans to extrapolate this knowledge to new areas of potential was subsequently terminated and thus it was left to industry (motivated by tax credits) to assume this higher risk activity.

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