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The Well of the Future - Downhole Pressure!
Innovation Challenge: Determine the pressure or level in a well without a gauge.
When operating coal seam gas wells, it is desirable to know pressure and/or water level at the bottom of the well. This “bottom hole flowing pressure” or “fluid level” is useful in operationally maximising the performance from the well in its operating life and production. This challenge is to utilise all the live “production data” and knowledge of the installed equipment on a well to determine the bottom hole flowing pressure or water level without the use of a downhole gauge. The advantage of reducing the bottom hole pressure (or fluid level) is that it has a direct impact/increase on the gas production from each well.
Bottom hole flowing pressure is traditionally measured using manual sonic pings down the well or downhole pressure gauges. These gauges are costly (~$25k each) and are complex to install as the gauges and cables are run the full depth of a well (400m to 1000m). Further, it is not uncommon for these gauges to stop working mid well life, which requires an expensive and complex well intervention to replace the gauge or to run on without the gauge active and thus lose the optimisation opportunity.
The bottom hole flowing pressure is informative as it provides information on the status of the reservoir and the water level in the well (noting that water level can be calculated from bottom hole pressure).
Particularly for lower pressure wells, gas production is strongly impacted by backpressure at the coal. This backpressure is a combination of flowing pressure and water level in the well. A pump is used to extract water from wells. By knowing the water level, the pump rate can be controlled to minimise the water level and thus maximise production. If pumps go too slowly, they will hinder gas production (high water level = more back pressure) and too fast risk damage or degradation of the pump (~$200k ) caused by pumping gas instead of water.
The current case is that we have installed gauges on 7% of wells however the water level within the well is not controlled directly from the gauges. Pumps are controlled by inferring whether the pump intake is water filled by comparing changes in flow to changes in pump speed.
Potential areas to consider:
- Is there a way to use live data to calculate the bottom hole flowing pressure of coal seam gas wells with no gauge?
- Alternatively, is there a way to measure or calculate fluid level in the well?
- Secondary consideration, if there is a gauge, based on production data for that well, is it possible to use data to infer bottom hole pressure after gauge failure? For how long? (run on with well specific knowledge)
- Are there other ways to maximise well production?
- Example production data of wells with down hole gauges for period of 12mths
- Well design information