Dubai

I'm in Dubai,just finishing up a 'Producing the Limit' workshop for an asset in a nearby country that has some 'security issues'.  I decided I'm not a fan of Dubai.  Most of what I could see is a large construction site covering the whole city.

Dubai the construction zone

Most of the asset team is based here in Dubai now.  Unfortunately, no field trip was possible (or safe).  

The team noted several times in the opening presentations that they had 'back out' of low pressure wells with high pressure wells.  As you may know, this is a common statement that is imprecise at best and misleading/wrong at worst. The truth is that there were high rate wells that when producing increased the overall system pressure so that some weaker wells could produce.  This happens only in one circumstance: when there is a common section of the system that these wells produce through, AND it has significant pressure drop in this section, AND there are some wells which have low or zero rate at the new higher wellhead pressure.

So, when we looked, we managed to find a section of piping between the manifold and the separator with a high pressure drop. According to fluid mechanics (e.g. Darcy Weisbach) if the rate doubles, the pressure drop in a  section of pipe increases four times.  Since a few of their wells make 70% of the production, if one of these wells is turned on, the pressure drop, and consequently the wellhead pressure on all the other wells connected to this pipe, increase significantly.  Since they are drilling new wells this problem will get much worse at the overall rates increase.  That was the bad news.  The good news is that pipe was only 30m long!  So, it should be fairly easy to fix.  Failing to fix it would have cost thousands of barrels of oil per day from their new wells as the friction caused high back pressures.  There is also a mystery element:  30m of 6" pipe should have about 3 psi of pressure drop at these rates.  The measured pressure drop was 150 psi.  There was a globe valve in that piping and my bet is that it is either under-sized or plugged.

The reservoir in this field was also very interesting, a naturally-fractured, metamorphic rock with just about zero porosity.  The recovery factor expected from this reservoir is only a few percent, but the oil in place is huge, so we suggested they look seriously at massive hydraulic fracturing.  If they can get equipment with enough frac pressure/rate, it might just work and improve the economics of the field dramatically.  

The team has suffered from losses of critical people as the security issues have come and gone, consequently the whole team was more fragmented in their thinking than some other teams I work with.  However, during the workshop the disciplines started working together and at the end they highly recommended to their management to have quarterly and annual integreated workshops to keep things more integrated.