Khebab,

Your final graph is interesting. Are you estimating annual decline as the percentage increase of [this year] over [previous year]? Would you care to speculate about the reasons for the change in character of the curve after 1960? Before then it seems almost uncorrelated year on year, whereas after 1960 it gets much smoother and remains so for the next four decades, apart from the last hurrah (Prudhoe Bay?) in 1978-ish. What changed in 1960?

RE: Are you estimating annual decline as the percentage increase of [this year] over [previous year]?

Yes.

RE: Would you care to speculate about the reasons for the change in character of the curve after 1960?

Noise is a lot stronger before 1960 but I really don't know why. Maybe it has to do with the way the data was collected.

I will suggest and answer as to the "why" the US curve smooths out after 1960.

First, if you run a time series analysis on the variance(on the monthly data) you will see there is a periodicity in production of ~2.5 years. Even though they are much smaller in amplitude now, they persist to this day. What it looks like (and models out) is a damped sinusoid.

As the base magnitude of production increases (and "spare capacity" becomes challenged and decreases in both real and relative magnitude), the variance decreases.

Part of this change in amplitude may have been a policy change (and remember OPEC formed in 1960, though they didn't really flex their muscles until 1973). US imports grew significantly during the late 1940's and 1950's from 9% to over 20%, while oil exports fell essentially to "zero."

But in the period of the 1960's, oil imports also stabilized, as a percentage of the total, at around 20%. So, in a growing consumption modality, US production (or imports) could still act as the swing supplier though the degree of "spare capacity." was quickly being "consumed." And remember, the Texas Railroad Commission was also the 800 pound gorilla in the room with regard to US production.

A similar situation can be seen in the global data. If there is a great deal of "spare capacity" in oil production (and you have the storage capacity for what is produced), then you can see a great deal of variability both on the growth side and the downturn side of the production curves that are underpinned by economic conditions. This high degree of variability is seen in data all the way up to 1991.

But in the upturn in production that began in June 1993, the monthly variation became noticeably smaller (almost non-existent) as global oil production increased from about 60 million barrels per day in 1993 to about 67 million barrels per day just 5 years later in 1998. A short sputter between 1998 and 1999 and much monthly variation before resuming a runup into early 2001. Another short sputter into 2002 and then the last runup from 2002 into 2005 with somewhat larger monthly variation than seen in the late 90's run.

But since 1993, the variability (other than economic downturns) has become much smaller than in all previous data.

This diminishing variability looks like what happens when you have strong growth colliding with capacity issues and, in the case of the US in the 1960's, the coming peak. I suggest the same is likely to be true on the global scale, though we have many more "types of oil sources" than we had when the US peak occurred in 1970.

This is not to say we cannot have large spikes in production, but it seems less and less likely. Anyone know of any new Ghawar's planning to come on-line?

As an aside; in a class I teach, I start the class out on corn and wheat production with a progressive reveal of the curves and actually tell them what they are looking at. Then, I show this US oil production data and tell them "Here's 110 years worth of production data, and obviously we've gotten good at this. So, based on what we've done and been able to do so far, where do you think we will be in 40 years?" I also show them the growth variance curve that shows that while percentage growth is getting smaller, growth is still occurring. Then I give them the finer detail (monthly) from 1920 through 1970 so they can see the seasonal effect and the diminishing variability "for the past 50 years" prior to the 1970 peak.

Well, nearly all of the 40 students in the classroom just mentally extend the production out into the future and come up with an answer of "about 6" (representing the billions of barrels produced for a year, though they don't know that).

And then I put the graphs up with all the data since 1970 included and reveal what they are looking at. "Past performance does not guarantee future performance." Knowing what underpins the data, however, is useful.

Great story about your class!

Can you show us the examples you show in your class, or share the data if you have it in a xls format?

I could use that in the class I teach :)

plucky underdog:

In the late 1950's the world began to really use a lot more oil and gas. The oil finding rate was just about at its maximum, and nationalisation was a storm cloud over the horizon. OPEC hadn't been started It was the good old days of the "free market capitalism" approach to the oil business.

As the world changed from coal to oil for its fossil fuel BTUs, the amount in export trade went up a huge amount. At the beginning of the Second World War, Texas produced 60% of the oil and petrochemicals in world trade, although Texas was producing about 5 million barrels a day.
The rest of the oil in world trade came from Iran and the beginnings of the mid east fields from Shell and Anglo-Iranian Oil, now BP.

When the market was smaller and thinly traded, the decline rate was more closely tied to the performance of individual fields or groups of fields. But as the markets grew, the decline rate had a much larger group of producing field to average it over, so the curve got flattened. At any rate, thats my hypothesis and Im stticking to it. Bob Ebersole

Bob, Rembrandt: your explanations sound coherent... anyone know when the US became a net importer? (the readily-available data series on the Web don't go back as far as 1960, let alone before). I'm going to look at the data for the UK, which recently became an importer as well.

Khebab, westexas: if it (production rate volatility) really is affected by the switchover to export, does this analysis have any interesting implications for the predictive power of ELM? Not trying to muscle in on your zetetic bailiwick, just interested.

It appears that the US became a net importer right around 1949, 21 years before we peaked. Because of a rapid increase in consumption, the US actually showed a pretty rapid collapse in net exports.