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Petroleum Industry Practice: Waste Water Disposal

by PETER KENGEMAR

I have covered Fracking Technology and have stated that; fracking is applied in other parts of the world but is a technology not needed in our PNG reservoirs, and so it has not been used here.

Next point of discussion is on wastewater is disposed and what is the standard industry practice? Should we associate this with the recent catastrophic earthquake?

When oil or gas is brought to surface, there is associated formation water that co-exists with oil gas is also comes to the surface and is referred to as produced water. Other practices around the world (not in PNG) use that water to also use for Fracturing tight reservoirs to increase and enable oil gas to flow to the surface. The used water or produced water is normally (global industry practice) rejected under pressure slightly above the subsurface reservoir pressure back into the producing reservoir (same reservoir where oil gas is coming from). However the water is re-injected in a specific well called water re-injection well, whose bottom is deeper than the oil gas wells, that way water which is heavier than gas oil can stay at the bottom to support and maintain reservoir pressure and water/oil or water/gas contact depth.

Please note that, any Operator company do this water re-injection is very carefully because they do not want to destroy the virgin reservoir parameters. Maintaining the various reservoir parameters such as, pressure, temperature, fluid contacts (contact depth between gas, oil, water) is very important to maintaining gas oil production rate which turns into millions of dollars if the reservoirs are properly managed.

Modern day reservoir management is all automated and computerized, leaving little room for human error. The pumps and facilities are properly calibrated to operate within pre-set conditions.

In an ideal operating environment with highest industry standards and practices, the re-injected produced water or waste water is properly managed to contain environmental impact both on the surface and at sub-surface depths.

In Moran Kutubu Gobe oil fields, when I was working there over 10 years ago. Chevron set the standards of oil production and treatment of waste water (produced water). We followed the exact industry standards as described above.

I am not privy to Hides Gas production, but I do know that a specific well was drilled which targeted the deeper part of the reservoir which contains the water lag of the reservoir. That is where the waste water is I assume to being pumped back to maintain fluid contacts and assist in maintaining reservoir pressure.

Waste water reinjection inducing earthquake?

Now having discussed the basics, the question that everyone is asking now; is the re-injected water back into the formation inducing and influencing the fault planes that may possibly contribute to the tectonics and seismicity of the fold and thrust belts, which is connected deep via the major bounding fault deep into the plate collision boundary, depths at which the recent catastrophic earthquake epicenters are concentrated.

We can understand that only if the Government sets up a pro bono technical expert team to look for the right data and information.

Again I shall volunteer my services should the Government sanction this investigation.

Our thoughts and prayers are forever with our people who are suffering. Let us do the best we can!!