Identifying and Quantifying Thin-Bedded Pay (Part B): The Use of Dynamic Data to Evaluate Productivity Potential in Gas Reservoirs

摘要

Intervals of thinly bedded sands have been identified above or below conventional 'thickly bedded' gas reservoirs currently under production. The level of contribution to flow from thin bedded pay however is uncertain and difficult to distinguish from that of the thick, conventional pay intervals. Production data solely from these intervals is extremely limited, so confirming production and ultimate recovery from these resources is challenging. Thinly bedded intervals have historically not been targeted for completion, but may still be contributing to gas rates over a long term production time scale. Producing reservoirs in the bpTT portfolio may already provide evidence for the potential productivity of thin bed pay. Static pressure data from several wells in reservoirs with thin bed pay above or below completed conventional pay intervals have suggested pressure support from a lower rate source when wells are shut in for an extended period of time. Pressure transient analyses in other wells have interpreted heterogeneities in reservoirs where traditionally only conventional thick bedded intervals were considered. In lieu of direct evidence of production such as Production Logs and costly dedicated Thin Bedded Pay well tests, existing data has been used to confirm contribution to flow from thin bed pay and add to recoverable volumes. Formation pressures for a reservoir in the Amherstia field were used to prove depletion and increase the recoverable volumes from time bed pay in 2009. This interval was consequently identified as a future recompletion opportunity. Thin bed pay intervals were also targeted and completed in two newly drilled wells in the Cashima field. Though still early in their production lives, these wells are already showing signs of contribution from thin bed pay. The Amherstia and Cashima success stories demonstrate the potential for thin bed pay as an important resource for the future of bpTT.