Charaterization of the Harmon Lignite for Underground Coal Gasification

Peng Pei, Zhengwen Zeng;Jun He;


The Harmon lignite bed of the Fort Union Formation (Tertiary Age) beneath western North Dakota presents opportunities for applying underground coal gasification (UCG) technology to recover the unmineable coal resources. However, some characteristics of the formation also present barriers. First, the local aquifers coincide with the lignite bed; second, the lithology of surrounding rocks changes greatly within a short distance. These factors set challenges in site screening, feasibility study and assessment of environmental risks. Although extensive investigation work about the Harmon lignite has been conducted, no work has been done for UCG application. In this paper, we review the site selection criteria of UCG, and apply the experience and tools of reservoir characterization in petroleum exploration to investigate the structure and properties of a target site in western North Dakota. Information and data from state and federal geological surveys, water resource commission and oil companies are collected. A 3-dimensional model is built to simulate the Harmon lignite bed, surrounding rocks and aquifers. This “coal reservoir characterization” work provides a clear view of the structure and composition of the lignite-bearing formation, as well as a better understanding of its in situ geology and hydrogeology. Results of this work greatly facilitate the UCG site selection process. Suitability of the potential site for UCG projects is discussed.


Harmon Lignite; Underground Coal Gasification; Site Selection; Characterization

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