The Significance of the Pinedale Field
Thomas Meyer, Mark Longman, 2014. "The Significance of the Pinedale Field", Pinedale Field: Case Study of a Giant Tight Gas Sandstone Reservoir, Mark W. Longman, Stephen R. Kneller, Thomas S. Meyer, Mark A. Chapin
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Pinedale field is located in the northern part of the Green River Basin in western Wyoming about 90 mi (145 km) southeast of Jackson, Wyoming, near the town of Pinedale (Figure 1). It is one of the largest natural gas fields in the United States with ultimate recoverable reserves estimated to be about 39 trillion cubic feet (tcf) of methane-rich natural gas. Despite the huge gas reserves, the field’s productive areal extent is relatively small as it is only about 30 mi (48 km) long and less than 5 mi (8 km) wide. The field covers an area of about 84 mi2 (220 km2). In this sense, it is a very concentrated gas resource.
Production at Pinedale comes from the Lance Pool, which is nearly 6000 ft (1800 m) thick and consists of multiple stacked discontinuous Upper Cretaceous Lance and upper Mesaverde sandstones and siltstones that were predominantly deposited by fluvial processes and are encased in shales and mudstones. The reservoir rocks in Pinedale field occur at depths of about 8500 to 14,500 ft (2600–4400 m) and are tight with fairly low porosity (mostly 10%) and very low (micro-Darcy) permeability. The tight nature of these reservoir rocks makes it difficult for gas to move laterally and vertically for significant distances. As a result, it is necessary to conduct multistage hydraulic fracturing in all of the field’s wells to create pathways for the gas to enter the wellbores at commercial rates. The tight nature of the reservoir rocks at Pinedale begs the question: “What makes Pinedale such a prolific natural gas field?” The field has some unique geologic characteristics.
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Improved geologic insights combined with advances in technology and innovative thinking, mainly since the laste 1990s, have driven Pinedale field’s development and unlocked a giant natural gas resource in stacked low-permeability fluvial sandstones. Understanding this field can provide a model for developing similar tight sandstone reservoirs around the world. This memoir contains 15 well-illustrated, peer reviewed chapters that describe the history of field development, the deposition and diagenesis of the reservoir rocks, geophysical characteristics of the field, special core analysis techniques used to better quantify the reservoir, petrophysical characteristics and interpretations of the reservoir, the types and abundance of natural fractures, and fluid production characteristics in the field. Finally, static and dynamic models for the field are presented in an attempt to integrate all the pieces of this giant geologic puzzle.