Leveraging Gas Reservoir Data

At a time when budgets are tight, it is increasingly important to maximise the use of gas reservoir information. This paper presents methods for leveraging gas content and permeability data and quantifying uncertainty. The objective is to adequately define the gas reservoir in terms relevant to how the data will be applied - for the least expenditure and risk. In the case of gas content, reduction in data noise reveals underlying trends that can then be mapped across a deposit. Essentially defining gas domains, with equations and uncertainty, it permits more targeted drilling and rationalisation of exploration plans. Permeability data are invariably sparse and yet critical in reservoir assessments. Two methods are presented to extend the range of direct well test data – the first maps inherent fracture development based on residuals of the Initial Desorption Rate (IDR30)/gas content relationship. The second provides a process for utilising observed relationships between permeability, depth and gas saturation to map permeability distribution with quantified uncertainty. The quantified relationships and uncertainty can then be used as inputs to probability modelling for gas emission, gas drainage and life of mine gas production.