The reason was stated this way:

“The fact that oil can still spurt out of the earth under tremendous pressure suggests that either oil is still forming and/or that it has not been there for the supposed millions of years. When a fire extinguisher’s pressure gauge is in the red, this indicates that the pressure has been spent over some limited time-span. Oil pressure in rocks challenges the many millions of years concept. How could the indicator stay “green” for so long?”  (Humber 2013)

Humber’s conclusion:

Oil found in reservoirs at high pressure demonstrates that they did not form millions of years ago.   He says that they must have either

1) be still forming

or

2) not have been there for “the supposed millions of years”  

His claim doesn’t really seem to be that the pressured reservoirs prove that the Earth is young but that they do not prove that the Earth is ancient, just as was the case for his point 18 on oil formation.  In support of this, he offers the analogy of modern fire extinguishers. We all know that they do lose some pressure over time.  Does this mean that hydrocarbon reservoirs cannot have formed over deep time?

In this case, petroleum explorationists (geologists, geophysicists and geochemists, etc.) agree with Humber – in part.  We certainly believe that many, perhaps most oil reservoirs are being charged today.  As described in my oil formation responses:  Generating Oil and Deep Time – Part 1;  Generating Oil over Deep Time – Part 2, geologists looking for oil find that when oil source rock is currently at the right temperature and pressure to be generating today (in exploration vernacular, it is in the “oil window”), this  reduces the risk that oil will not be found in any particular trap that is being assessed. If the source rock is too shallow, it will not have been heated enough to generate oil and gas. If the source rock is too deeply buried, then oil generation will have stopped and instead of oil, gas will be generated and then eventually, the source rock is tapped out. However, we would certainly not want to assume that oil reservoirs can be charged in a few thousand years. We do recognize that they are often filling today, albeit more slowly. Charge might have been episodic, but big oil reservoirs indicate charge over a longer period than since the date typically given by YEC for Noah’s flood or the period after the flood.

Humber claims that if oil and gas reservoirs were filled over millions of years, then the oil and gas would have leaked away. Here again, there is some agreement. Petroleum geologists recognize that oil and gas reservoirs leak. Many geochemists believe that all gas fields are being charged today because gas leaks more readily than oil and they don’t believe that it would stay trapped over millions of years. In any major hydrocarbon basin, there are oil and gas seeps. Many, perhaps most, large fields have seeps directly associated with them.  In such cases, we simply recognize that the reservoirs are filling at least as fast as they are leaking. In some cases, viable traps existed at one time, but just residues of oil are found today.  I can remember some expensive wildcat exploration wells in frontier basins (basins with no oil or gas production from them) where the trap was apparently breached and only staining and residues remain in what once were viable traps. One famous example was the Mukluk 1, the most expensive dry hole in oil exploration history. (Bailey 2011)

Humber proposes that it is unreasonable to assume that oil or gas would remain in a trap for millions of years. It would be difficult to actually measure how fast oil migrated into a particular trap.  When we explore in a new basin that does not have established oil or gas production, the risk that there will not be an adequate seal over the top of a trap is a significant risk. If unsuccessful wells have been drilled and samples of the rock drilled through are available, we may try to use these samples to measure the capillary seal capacity of shale units that overlie a potential hydrocarbon trap that we want to target.  Thus, we can, for instance, test shales to see how much of a column of oil that they might be expected to hold over a long period of time. Not all shales are equal. In an exploration context, one would prefer to have 10 meters of a good very clay-rich shale than thousands of feet of silty or sandy shale. As this quote reflects, “a few inches of ordinary clay shale are theoretically adequate to trap very large column heights of hydrocarbons.” (Downey 1984)  The most effective seals are composed of continuous salt or beds of evaporites like gypsum. In general, because oil is often more economically attractive, the best seal often is one that can hold a good oil column but leaks gas. 

Downey, 1984 reports, “If the reservoired hydrocarbon is oil, little or no diffusive leakage through a seal is likely. If the reservoired hydrocarbon is methane, and is sealed by rock layers lacking connected pore water (salt, anhydrite, or gas hydrates), no diffusive loss should be expected. However, if methane is sealed by a porous, water-bearing shale, substantial diffusive losses can occur over significant geologic time”

All this is to say that we recognize that oil and gas traps leak.  We do find cases where oil apparently migrated into some reservoirs and the source rock that fed them is beyond the oil window today, though they are the exception. The fact that such are found is evidence that their oil migrated in the past over deep time.

Could seals really be effective for millions of years? In some cases, we have data that demonstrates exactly that. Holes between sand grains, known as pores become partially filled with minerals called cements, that reduce the pore space that can hold oil and gas.  As the cements form, tiny pockets form that are filled with the fluid that was in the units at the time, known as fluid inclusions. If oil was present, it was trapped as well. When cuttings and core from wells are examined in exploration areas, these inclusions are often studied.  These can show the temperature and pressure present at the time (McLimans 1987).  McLimans reports as examples that the oil migration in the Wealden Basin in England took place during the Cretaceous period. In Dubai, oil migration into a giant field there took place in the Oligocene to Middle Miocene. Other data shows that the cementation took place as the rocks were heated from burial. These reservoirs have held their oil for a long time.

For this claim to be a problem for an old Earth, it would be necessary for YEC advocates to 1) demonstrate that large reservoirs filled or at least could have been filled in a very short time (such as since Noah’s flood) and 2) demonstrate with some sort of data that reservoirs could not hold hydrocarbons for thousands or millions of years. There doesn’t seem to be any data given that supports these points. It is hard to document how fast fields fill, but given the time that it took to bury the source rock through the oil window it is reasonable to conclude that the reservoirs filled over that time.  The calculations of seal capacity support that oil can be held for millions of years.  The analogy to a metal fire extinguisher is interesting, but without some data to support its applicability, it is just inadequate.