Dynamic Behavior of a Multi-Layered Coal Seams Gas Reservoir in the Bowen Basin

Abstract

Fairview field is located in the Bowen Basin in South East Queensland and covers an area of approximately 1600 km2. It has been in production since 1994, from the 6 main coal seams of the Bandanna Formation. Presently, about 150 wells are on-stream feeding the domestic gas market. Further development is in progress to supply the Gladstone LNG plants on Curtis Island in 2015. This paper focuses on a developed zone in the North of the field where extensive production and pressure data; more than 15 years, are available. The majority of the wells in the area are commingled and target the sweet spots with permeability ranging from tens to a few hundreds mDs. Material balance analysis observed a typical layered reservoir behavior which is consistent with permeability discrepancies measured between seams. It also provided a comprehensive large scale calibration of the gas accumulation split between well connected and poorly connected areas. This split tightly controlled the gas production performance and recovery. A strong permeability increase over reservoir pressure depletion was also identified after the two-phase flow production period. The magnitude was a 10 fold increase over 300 psi of depletion which is likely related to the well known coal shrinkage effect. This observation is consistent with previously published data from the San Juan Basin in the US. Within the high quality seams, this phenomenon had limited impact on long-term production recovery; however the impact on expected-ultimate-recovery (EUR) was more significant in the poorer seams. These two phenomena show that permeability characterization, including its relationship with reservoir pressure depletion, is a key element for better production forecast.

History, Geology, In Situ Stress Pattern, Gas Content and Permeability of Coal Seam Gas Basins in Australia: A Review

“…Burgoyne and Shrivastava [158] Scotia Field, Bowen Basin Characterization of stress-dependent behaviour of coal from changes in well productivity Belushko, Herwin [159] Fairview Field, Bowen Basin Production data analysis Yarmohammadtooski, Salmachi [65] Clarkson and Salmachi [160] Fairview Field, Bowen Basin Production data analysis Salmachi and Barkla [155] Fairview Field, Bowen Basin Time-lapse pressure transient analysis Palmer and Mansoori [149] San Juan Basin, the United States Production history matching Gierhart, Clarkson [156] Time-lapse PTA of 28 infill wells Production data analysis works well when there are strong constraints on flowing bottom-hole pressures and reservoir pressures with the latter being more important. When such constraints exist, trends of permeability change with reservoir pressures are very comparable to pressure transient analysis methods.…”

Controlling factors towards co-production performance of coalbed methane and tight sandstone gas reservoirs

“…For coal seam and tight sandstone layer with small thickness, single-layer development has low productivity and difficult production problems. In order to improve the productivity and efficiency of gas wells connecting multiple layers, many novel fracturing technologies and theoretic models have been developed (Lefkovits et al 1961;Larsen 1981;Gouth and Belushko 2014;Du et al 2014;Wu et al 2021;Miao et al 2020;Wei et al 2019;Fu et al 2013;Xiong et al 2013;Li and Li 2012;Xiong et al 2010), including layered fracturing and combined layer drainage, combined layer fracturing, and combined layer drainage. Multi-layer co-production can not only improve the productivity of single well, reduce oil pressure, and improve the development benefit of the whole gas field, but also extend the stable production period of gas well, and reduce the total cost of gas well.…”