The Surat Basin Coal Seam Gas (CSG) play requires a vast number of wells to develop, and reservoir productivity changes quickly over small distances. Well testing provides a means to evaluate these changes. But, the high cost of conventional testing precludes sufficient tests to ensure areal and statistical coverage across a large well stock. This paper discusses a new approach whose reduced cost allows five times more wells to be tested than conventional methods. By testing more wells, there is more data for subsurface model calibration and productivity fairways can be better mapped and developed.In the Surat Basin CSG play there is an industry-wide completion technique that uses air to lift every well to size the initial downhole pump for dewatering. This paper describes an enhancement to this standard pump sizing test which facilitates the provision of key reservoir information: full well permeability, skin and productivity. This novel well test is termed an Air Assisted Flow Test (AAFT).During the AAFT the well is produced at a predictable drawdown for up to an hour whilst accurate rate measurements are made at surface. A downhole shut-in is then performed and a pressure gauge measures the build-up pressure response. The additional equipment and rig time have been designed to add a minimal cost to the standard completion operation and test cost is 20% of a traditional Drill Stem Test (DST).Field tests using the AAFT and multiple dual packer DST's in the same well clearly demonstrate that both testing methodologies deliver the same results. It is therefore valid to incorporate the AAFT into the extensive permeability database for the Surat Basin. Additionally drawdown dependent skin has been observed in data from the new AAFT. This phenomenon is interpreted to be the result of stress dependent coal fracture permeability in the near well bore region.This new testing method is only directly relevant to CSG developments. However the awareness to gather additional data, from enhancing a standard operation, is applicable to all unconventional and conventional reservoirs.

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This paper discusses the use of distributed temperature sensing (DTS) in QGC's Surat Basin wells, and how this new technology has been used to improve reservoir characterisation through enhanced resolution of zonal productivity and flowing contributions.In stacked reservoirs with zones of varying quality, it is vitally important to allocate production volumes to flowing zones in order to adequately characterise the reservoir and create a representative dynamic simulation model that can accurately match reservoir productivity and depletion.For conventional oil and gas production, subsurface allocation of flowing contributions can be achieved through the use of production logging tools, which provide a measurement of volumetric flow rate and fluid density along the completed well length. The nature of Coal Seam Gas (CSG) well completions reduces the options available for allocation of flow to zones. Also, the producing characteristics of a CSG well can make this zonal allocation more complicated. Firstly, the lower zones of QGC's Surat wells are subject to higher back-pressure due to the column of water sat in the annulus, rising above the pump location. Secondly, the de-watering and subsequent de-sorption periods complicate matters, where initially 100% water flows from a zone followed by a gradually increasing gas-water-ratio: the rate of transition from water to gas production is expected to be different for each producing zone. Additionally, due to the stress dependency of coal fracture permeability during the de-watering phase, and later the impact of gas de-sorption on fracture permeability, different zones might be expected to show larger or smaller changes in productivity with time: to understand this would require repeatable measurements through the production life of wells.In this work, DTS technology has been proven, for the first time in QGC's Surat CSG wells, as a means of achieving subsurface allocation of well test kh. This is important for the justification of permanent installations that will allow ongoing zonal allocation of produced volumes. The impact of this methodology on history match quality and reservoir characterisation accuracy is discussed. It is suggested that these new workflows could prove very beneficial in the characterisation of CSG reservoirs.