Benchmarking study of coal seam gas production from Brownfield to Greenfield wells in the Surat basin, Australia.

Benchmarking coal seam gas (CSG) production from Brownfield to Greenfield is an important step for assessing the development plan for Greenfield. However, the observed Brownfield production data is impacted by many factors besides reservoir properties, e.g., well spacing, well efficiency factor (WEFAC), surface pipeline network. This paper presents a case study in the Surat Basin to discuss how to benchmark CSG production from Brownfield to Greenfield. The selected Brownfield study area includes 143 wells and the Greenfield 450 proposed wells. Various tools for static modelling, decline curve analysis, and dynamic modelling were used in this study. Results show that the peak gas rate decreases quickly and the time to peak gas rate increases quickly when the WEFAC is less than 0.65. The peak gas rate is reached when the cumulative water production is between 39% and 46% of water-in-place for the selected box model. After introducing the wells' online time ratio or WEFAC from the daily production data and the ratio of the observed cumulative water production to the expected cumulative water production, gas production rates can be predicted based on the modified Morse potential energy equation. Artificial neural networks (ANN) can be used to estimate the peak gas rate, the time to peak gas rate and the decline rate based on the reservoir properties; while the ramp-up rate can be calculated from the time to peak gas rate. • 143 wells with seven years of production data were used in this study. • This study integrated static modelling, dynamic modelling and decline curve analysis. • Artificial neural networks can be used to estimate the peak gas rate, the time to peak gas rate and the decline rate based on the reservoir properties. • The well efficiency factor impacts the wells' peak gas rate, the time to peak gas rate, and the decline rate. [ABSTRACT FROM AUTHOR]