Australia is the world''s second largest producer of coalbed methane (Faiz, 2008). Characterized as a marginal tectonic setting, the Bowen Basin of Queensland displays a thick succession of numerous thin bituminous rank coal seams. The area''s heterogeneous production is particularly perplexing; it is not unusual for production to change as much as 50-75% between neighboring wells within a few kilometers of one another. A myriad of factors can affect coalbed methane production to include coal thickness, coal cleat architecture, local maximum horizontal stress direction, and the in situ stress magnitude. We show how seismic curvature attributes illustrate lineaments that correlate to production. We use a technique to generate 3D rose diagrams from curvature attributes and show that the diagrams depict the face and butt cleat architecture.
Unconventional reservoirs continue to contribute an increasing percentage of the total amount of oil and gas production in the world. Shale and coal are examples of low-permeability unconventional reservoirs that often act as both the primary source rock and the reservoir. The application of seismic attributes and multiattribute transforms are incrementally pushing the limits to seismic resolution and facilitating different data analysis perspectives to use during reservoir characterization. Geologic Background The Bowen Basin is a Permian-Triassic age major economic coal basin that extends approximately 900 km in a generally north to south direction in the eastern portion of Queensland, Australia. The Bowen Basin is one portion of the Bowen-Gunnedah-Sydney foreland system that formed as a result of the collision of the paleo-Pacific and paleo- Australian plates beginning as early as 294 Ma in the Early Permian. This orogenic belt is often referred to as the New England fold belt. Figure 1 is a map of Australia which outlines the approximate geographical limits of the Bowen Basin in Queensland. Toward the end of the Permian, the coal measures formed in environments described as fluvio-deltaic. Structurally, this reservoir lies within a large anticlinal structure that Korsch (2004) has labeled a fault-propagation fold. Figure 2 is a seismic inline view of the fault propagation fold from the 3D seismic data for this study with interpreted faults. Figure 3 shows the seismic line (A-A'') from Figure 2 and well production data for this 3D seismic survey. Seismic Data Quality The company''s primary goal for this 3D seismic survey was the improved mapping of the upper coal horizons within the basin. The survey size is 31.56 km2 of rolling farmlands. The data were recorded using 45 source lines with a 200 m interval and 23 receiver lines with a 200 m interval, resulting in a natural bin spacing of 25 m x 12.5 m. Four Mertz M26 vibrators vibrated with a sweep length of four seconds and a sweep frequency range from 6-130 Hz. Group arrays consisted of twelve sensor SM4, 10 Hz geophones in a linear array with the source in the middle of each line, resulting in a multiplicity of 36 fold. The sampling rate of the data is 2 ms.
