Brisbane

Here in beautiful Brisbane, Australia this week.

Brisbane Skyline

I'm here to review a development plans for a coal seam gas field.  CSG and coal-bed methane (CBM) require well de-watering in order to reduce the pressure on the coal to very low values.  Once this is done the  coal gives up methane that has adsorbed onto the surface.  There is substantial amounts of gas in this unconventional hydrocarbon reservoir type.  The gas produces at decent rates depending on the permeability for a while and then declines.  Keeping the pressure low allows gas to flow at low rates for many years. 

The de-watering is normally done with Progressing Cavity Pumps.  These are suitable because they generate the low pressure and generally tolerate the well conditions and the fines production.  Still, the run lives for these (rod-driven) pumps is on the order of 1-3 years.  That means a fair number of workovers on a well.  Some of these fields have more than 4000 wells, so that is a lot of rigs and rig workers. Sounds like the areas around these fields have become boom areas like the Eagleford, Bakken and Marcellus shale areas in the US.  Low unemployment, lots of opportunities to become an entrepreneur, but also lots of change to the rural communities as thousands of rig workers move in. 

A more capital-intensive option is gas lift.  Normal gas lift cannot reach the low pressures required, however placing the end of a gas lift string in a water-filled sump allows the pressure at the top of the water to be close to atmospheric.  The primary advantage is that there will be very few workovers on the gas lift wells.  The system can be designed with sufficient pressure to have a single point of injection so this artificial lift technique has no moving parts and may last 15 years or more without a workover.  Makes a big difference when the alternative is 40 rigs running full time for those 15 years.

We came up with ways to improve the gas lift system concept substantially and to get the risks under control, and even a few ways to improve the PCP concept.  Now they are ready to run the numbers and make a recommendation.

Anyway, Brisbane looks like a fun town, but I didn't see too much of it this trip.  Work, work, work...