The End of Oil Part 7
In this post I will attempt to explain in more detail the methodology of the Hills Group in their 65 page paper issued as a second version in March 2015 entitled “Depletion: A Determination for the world’s petroleum reserve An exergy analysis employing the Etp model.
Fair warning: the interpretation and explanations are mine and mine alone and they may be inaccurate, wrong or confusing. I come from a scientific background and took advanced chemistry, physics, biology and calculus level math but I struggled to understand portions of this paper and had to refresh long forgotten concepts in thermodynamics. If I am uncertain of my understanding I will so state.
I will give the abstract to their report……..
Petroleum is a primary energy source; its other uses have only minor commercial value. It therefore follows that to be an energy source petroleum must be capable of providing sufficient energy to support its own production system (extraction, processing and distribution). Thus, the total specific (per unit) energy needed to complete the process cannot exceed its own specific exergy. Entropy production (a Second Law mandate) in the petroleum production system (PPS) requires that a point will to be reached when the production energy required to drive the process forward becomes equal to its specific exergy. It can be shown that this breakeven point for petroleum production occurs when the cumulative production curve approaches its top abscissa. This point represents the maximum theoretical volume of petroleum that can ever be extracted for use as an energy source. The total production energy (ETP) is therefore a function of the cumulative production function (CPF) and the entropy production of the PPS. The entropy production of the PPS is derived through the solution of the Entropy Rate Balance Equation for Control Volumes. The ETP function generated is an accurate predictor of historic and future petroleum prices, production, and the depletion status of the world’s petroleum reserve.
M King Hubbert who first predicted depletion of the world’s reserve made a prescient statement and is taken from a new book “The Oracle of Oil(2016):
“ So long as oil is used as a source of energy, when the energy cost of recovering a barrel of oil becomes greater than the energy content of the oil, production will cease no matter what the monetary price.”
I will attempt to simplify the key methods used by Hill et al and use a few definitions as possible.
I have previously stated in an earlier blog some of the world Resource estimates which are not reserve estimates. A reserve is a known quantity that can be economically extracted. A resource is an estimate based on educated guesses, proximity to active producing fields, perhaps preliminary seismography fields, similar geology and so forth. Both resource and reserve terms have many sub headings which I will not go into here. The USGS in 2000 gave a world resource base of 4300 Gigabarrels(4.3 trillion barrels.) The world to date (2016) has consumed 1.29 trillion barrels. The Hills group decided at the outset that they could use only verifiable data sets and not company or country figures and they chose world production of conventional oil starting in 1900 through 2009 which was obtained from the EIA along with the price history. They attempted to analyze then entire production process such as extraction, processing and distribution. It is not stated in the paper how this was achieved or obtained and what factors were included or omitted. Nevertheless they determined as best as possible how much energy was used per year and called it Etp, total production energy.. Obviously this figure had to be less than the specific Gross Exergy which is given by the unburned virgin energy of a specific variety of crude API 30-45 deg. Which is 140,000 btu/gal. They call this quantity exergy, not energy which I believe is incorrect. Exergy is energy available to do work and no work is available to be performed until oil is burned . After it is burned 29% is given off as waste heat which generally (but not always) is lost as exergy, which leaves 99,400 btu/gal as your exergy, your quantity to do work.
They then modeled oil production in three control volumes which by definition are open systems allowing mass and energy to be transferred. These control volumes differ from some types of thermodynamic analysis which is structured using isolated or closed systems. This open system is assumed to closely represent an oil reservoir/well head environment. I am unable to reproduce their sketch but it shows a simple diagram with at the bottom the black oil reservoir with a drill pipe passing through the ground to the well head exiting in the Environment, that is reservoir, well head and the environment as three control volumes. The next section shows the calculation of Etp(Total production energy) using a daunting equation which again does not reproduce accurately for me. If I can reproduce these pictures and equations later I will include them in this blog. They are available to view on pages 6 and 7 in their paper. The group then endeavor to simplify using the Entropy Rate Balance Equation for control volumes which seems straight forward enough as they calculate the entropy production in the Petroleum production system and in the end they show their calculated value for btu/gallon per 1 billion barrels for premium API 35.7 crude. They determine the flow rate out of an oil reservoir calculating the rate of crude flow and water mass flow which they say is the cumulative distribution function of the production data set. The resulting production function is displayed as a logistic curve. A logistic curve is the familiar sigmoid or s shaped curve which is a type of exponential curve combining the standard exponential increasing at an increasing rate curve combined with with a bonded exponential so called.
The result is a nice s- shaped curve which describes biological systems like population growth and finite resources of certain types.. The logistic curve is the shape of the Etp curve of the Hills Group. Hubbert’s curve(remember Hubbert’s curve?
is the so called first derivative of Hill’s cumulative production/Time curve.
Hubbert’s curve is a Gaussian or bell shaped curve depiction of oil depletion derived from entirely different ways of predicting oil field depletion than BH Hills work employing thermodynamics but the results are strikingly similar, particularly the above grey curve which is the NET Hubbert curve. Both curves show in plain sight as plain as the nose on your face that we may be reaching a crucial point that M King Hubbert said in a quote I listed in an earlier blog. When all the oil energy used to extract, process and distribute oil is being consumed by the petroleum industry then it is game, set, match for society as none of that energy is being returned to society as energy or as wealth. Our industrial society is entirely dependent upon that received energy and matter to advance an energy dependent technology and maintenance of its complex institutions and remove that crutch, that support and all growth and expansion of societal growth and wealth will cease. If you follow Hills curve to when that point will occur, you will see the year as 2031. No one, No One! is acknowledging or mentioning this possibility although there have been plenty of hints within and without the Oil Industry for many decades. Here a a few quotes gleaned from books I have on hand and the net: “We’ve embarked on the beginning of the last days of the age of oil”—-Mike Bowlin, CEO ARCO, 1999.
“By early in the 21st century, the era of pumping black gold out of the ground to fuel industrial societies will be coming to an end”—Paul Ehrlich(1974)
Is BH Hill’s model of oil depletion correct and is it really possible that the end of oil could be happening as soon as 13 or 14 years hence? I don’t know but I cannot find any substantive flaw in his work. If oil exergy cannot support its extraction then it’s my guess that other energy sources will need to be utilized as subsidy but what can we use ? Coal or gas energy? Electricity?
Coal and gas are poor substitutes for petroleum and electricity of course is not an energy source anyway. It is just a convenient carrier of energy, which would have to be supplied from gas or coal or nuclear and none of those sources can compete with oil’s utility to make things move! Remove oil and most motion of goods in trade, in transportation will grind to a halt. Will every car and truck and plane stop flying in 2031? Of course not. Hill’s work is directed at field and reservoir depletion and at extraction, production and distribution of the so called marginal barrel, the next barrel. There will still be oil in those legacy fields being drawn to the surface and distributed but in ever diminishing amounts. If society could wake up and go on a crash program to conserve what oil exergy remains to smooth out the transition to a carbon constrained future, we could find as a society a way to safely ride the backside of Hubbert’s curve and stretch out what is left but I see no reason to be optimistic that the United states with 5 % of the world’s population who consume 25% of the world’s oil is showing any inclination to even consider changing its energy wasteful lifestyle of suburban sprawl and happy motoring. The leaders of the new administration are embarking on a clueless pursuit of trying to recapture a period in US history that was fostered by almost unlimited cheap fossil energy to make America great again? The clock is running down on the oil age and whether it happens as soon as 2031 or a decade or so later, is irrelevant. This fossil energy that has provided vast wealth, enormous exponential population growth, exponential food production, easy cheap mobility and wasteful extravagance and complexity is starting to run down but our business model at least in the US and developed economies with its dependence upon oil energy is kaput or soon to be. We will simply have to switch to non oil energy sources and use far less energy to boot, and very soon if BH Hill is right.