Do Oil Wells Re-Charge Themselves?

There have been numerous reports in recent times, of oil and gas fields not running out at the expected time, but instead showing a higher content of hydrocarbons after they had already produced more than the initially estimated amount. This has been seen in the Middle East, in the deep gas wells of Oklahoma, on the Gulf of Mexico coast, and in other places. It is this apparent refilling during production that has been responsible for the series of gross underestimate of reserves that have been published time and again, the most memorable being the one in the early seventies that firmly predicted the end of oil and gas globally by 1987, a prediction which produced an energy crisis and with that a huge shift in the wealth of nations. Refilling is an item of the greatest economic significance, and also a key to understanding what the sources of all this petroleum had been. It is also of practical engineering importance, since we may be able to exercise some control over the refilling process. _Recharging of Oil & Gas Fields

RigzoneOf course we all understand the concept of "repressurising oil fields" using gas injection and other means.

As the oil or natural gas in a formation is produced, the hydrocarbons remaining in the reservoir may become trapped because the pressure in the formation has lessened, making production either slow dramatically or stop altogether.

...gas injection is used on a well to enhance waning pressure within the formation. Systematically spread throughout the field, gas-injection wells are used to inject gas and effectively sweep the formation for remaining petroleum, boosting production.... gas injection can serve as an economical way to dispose of uneconomical gas production on an oil reservoir. While in the past, low levels of natural gas that were produced from oil fields were flared or burned off, that practice is discouraged in some countries and against the law in others.

...Gas Injection, Gas Lift & Gas Miscible Process
Although the terms are sometimes interchanged, gas injection and gas lift are two separate processes that are used to increase production. While gas injection is a secondary production method, gas lift is a type of artificial lift.

Artificial lift is another way to increase production from a well by increasing pressure within the reservoir. The main types of artificial lift include gas lift and pumping systems, such as beam pumps, hydraulic pumps and electric submersible pumps.

While gas injection is achieved by injecting gas through its own injection well, gas lift occurs through the production wells. In gas lift, compressed gas is injected down the casing tubing annulus of a production well, entering the well at numerous entry points called gas-lift valves. As the gas enters the tubing at these different stages, it forms bubbles, lightens the fluids and lowers the pressure, thus increasing the production rate of the well.

Furthermore, a type of EOR employed on a well in the tertiary production process, a gas miscible process can be used to increase production. The difference in this recovery method is that the gases introduced into the reservoir are not naturally occurring. In a gas miscible process, carbon dioxide, nitrogen and LPG are injected into the reservoir. _Rigzone Gas Injection

Most of the oil in existing wells remains underground, waiting for people to become smart enough to retrieve it. Better enhanced oil recovery techniques will inevitably be developed to extract more and more of the residual hydrocarbon -- until it is no longer economical to do so. Then the remaining oil will wait for further developments.

Thomas Gold argues (here and here for example) that oil wells are charged and re-charged with new oil & gas from below. He claimed that most new hydrocarbons are generated deep in the crust, rising into geological traps at several different depths for particular parts of the crust. That is the abiogenic theory of hydrocarbon production, which is supported by astronomical data and by lab data simulating conditions in the deep crust and upper mantle.

Rapid charging of oil fields -- such as is suggested here -- would require deeper secondary reservoirs under pressure, feeding into the primary reservoirs as they are depleted.

There is another way in which oil & gas fields are re-charged -- via the biogenic production of oil & gas. But biogenic production via geologic heat and pressure is generally a much slower method of re-charging than Gold's abiogenic method. But it inevitably occurs all the same. Biogenic oil is a renewable resource, but it is renewable on a different time scale than humans generally use.

And yet, there is a way in which biogenic oil can "rapidly" recharge a depleted oil field. In the case of multiple communicating oil reservoirs at different depths, heat, and pressure, a deeper biogenic reservoir could re-fill a more superficial reservoir at variable rates, depending upon a number of factors. Oil & gas migrate upwardly, when given the opportunity. In this case, instead of "turtles all the way down," it is "oil & gas reservoirs all the way down." ;-)

Biogenic Oil FormationThis image illustrates the conventional idea of biogenic formation of oil. Imagine it taking place over and over again, during the 3 billion + years that photosynthetic life has been converting CO2 into various biological carbon polymers, layer stacked upon layer etc etc . . . . .

Abiogenic Hydrocarbons Forming in the Mantle

This image illustrates the likely abiogenic formation of hydrocarbons in the upper mantle. These hydrocarbons then can migrate upward into the crust, and become trapped under impermeable minerals. Abiogenic hydrocarbons almost certainly mix with biogenic hydrocarbons.

Abiogenic hydrocarbons are also modified in various ways by deep crust microbial populations. In other words, the predominately short-chain abiogenic hydrocarbons from the mantle can be converted to longer chain hydrocarbons on the way up.

Finally, there is the ocean crustal tectonic activity which feeds a constant supply of partially processed organic material to the deep crust and mantle via constant subduction of ocean crust beneath continental crust. This is a slow but steady pipeline which supplies feedstock for production of oil & gas on a constant basis. The Earth's huge gas hydrate resource likely owes a great deal to this tectonic process.

Methane Clathrate Exploratory Research in Alaska

One intriguing idea for the simultaneous recovery of energy and sequestration of global warming gas is proposed by the transformation of methane hydrates to carbon dioxide hydrates with the injection of liquid CO2. Here we use molecular dynamics simulations to show that the replacement can take place without melting of the network of hydrogen-bonded water molecules. Depending on the distance to the interface between the liquid CO2 and solid clathrate hydrate, we find that the replacement occurs either via direct swapping of methane and CO2 or via a transient co-occupation of both methane and CO2 in one cavity. Our results suggest that, with a careful design of the operation condition, it is possible to replace methane from methane hydrates with CO2 in the solid phase without much change in the geological stability. _ACS Abstract

ACS
A team of American and Japanese researchers are in Alaska this month to test a new method of extracting methane hydrates from rich Arctic resources. They intend to inject CO2 into the hydrates in hopes that the waste gas will replace the more valuable methane in the ice cage, freeing up the methane for extraction and use.

This month, scientists will test a new way to extract methane from beneath the frozen soil of Alaska: they will use waste carbon dioxide from conventional wells to force out the desired natural gas.

...The test will use the Ignik Sikumi well, which was drilled on an ice platform in Prudhoe Bay last winter. Specialized equipment has been installed, including fibre-optic cables to measure the temperature down the well, and injection pipes for the CO2. “None of this is standard equipment; it had to be built to design,” says Boswell.

...During the test, the researchers will inject nitrogen gas into the hydrate deposit to try to push away any free water in the system, which would otherwise freeze into hydrates on exposure to CO2 and block up the well. The next phase is to pump in isotopically labelled CO2, and let it ‘soak’ for a week before seeing what comes back up. This will help to test whether the injected carbon is really swapping places with the carbon in the hydrates. Finally, the team will depressurize the well and attempt to suck up all the methane and carbon dioxide. This will also give them a chance to test extraction using depressurization — sucking liquids out of the hydrate deposits to reduce pressure in the well and coax the methane out of the water crystals. “We’ll continue to depressurize until we run out of time or money, and see how much methane we can get out that way,” says Boswell. _Nature

Methane, trapped in an icy cage of water molecules, occurs in permafrost and, in even greater quantities, beneath the ocean floor. It forms only under specific pressure and temperature conditions. These conditions are especially prevalent in the ocean along the continental shelves, as well as in the deeper waters of semi-enclosed seas (see graphic).

World reserves of the frozen gas are enormous. Geologists estimate that significantly more hydrocarbons are bound in the form of methane hydrate than in all known reserves of coal, natural gas and oil combined. "There is simply so much of it that it cannot be ignored," says leading expert Gerhard Bohrman of the Research Center for Ocean Margins... _DerSpiegel

As humans devise more and better ways to utilise methane in place of crude oil, it makes sense to learn how to extract the richest reserves of methane in the crust.

We do not yet know how much of the methane resource originates abiotically in the mantle -- and thus can be theoretically seen as "renewable methane." It is likely to be substantial. And thanks to the giant tectonic plate mechanism, with ongoing subduction of organics-rich oceanic crusts under continental crusts, biogenic methane is, to a large extent, renewable as well -- on an extended time scale, and on a continuous basis. Where do you think most of these methane hydrates came from in the first place? No matter. There are a lot more where those came from.

How Humans Cause (and Prevent) Earthquakes

The best-known case is the earthquake caused by the Zipingpu Dam, in China’s Sichuan province, in 2008. Zipingpu held 42.3 billion cubic feet of water, the weight of which precipitated what Klose says is the largest human-triggered earthquake to date: a 7.9-magnitude quake that killed nearly 80,000 people. Klose estimates that Zipingpu, with nearly 320 million tons of water pressing down on a fault line, contributed enough stress to trigger the quake through a process called impoundment. “If you push your finger on top of a paper plate, the plate will bend,” he says. “That same effect works on all the tectonic plates on the Earth’s crust.” The quake occurred two years after the dam’s completion, and its epicenter was a mere three miles from the structure.

Authorities in Basel, Switzerland, shut down the city’s geothermal plant after a 3.4 quake in 2006. Tapping geothermal energy involves boring into rock miles beneath the Earth’s crust in search of steam as a source of energy. Engineers in areas without much water, such as Basel, sometimes create boreholes by way of hydraulic fracturing, or “fracking,” which involves forcefully injecting water to create fissures. Fracking can generate small tremors, but the real damage may happen as excess liquid pools in the cracks between rocks, making them less stable. Although dams have caused some 76 earthquakes, mining is responsible for at least 137 earthquakes, over half the number of man-made quakes to date.

In 1989 a 5.6-magnitude earthquake hit Newcastle, Australia, the direct result of coal mining. Extracting millions of tons of coal added stress to the fault lines, but the real danger resulted from the water that was extracted during mining. For each ton of coal produced, Klose estimates, 4.3 times as much water was pumped out of the ground, a necessary step to prevent flooding inside the mine. But removing so much water dramatically altered the stability of the earth surrounding the mine. Klose says the earthquake caused $3.5 billion in damage—an amount that nearly equaled the profit of all the coal produced by the mine over its 200-year history. _PopSci

More here

Other human-caused micro-quakes have occurred via deep well injection of fluids, and by experimental deep hydraulic fracturing into crystalline rock (such as granite) near faults. It should be noted that shale fracturing -- such as is done for oil & gas production -- has not produced a causal link to earthquakes.

The recent small quakes in the Youngstown, Ohio area are associated with deep well injection of waste fluids -- a completely different process from shale fracturing.

Unfortunately, a large part of the news media has reported the quakes as having been caused by shale fracturing -- which is not the case. This type of skanky behaviour by news media is nothing new, but one has to wonder whether it is caused by ignorance or by willful deception.

We expect the faux environmental and green sites to misreport such events -- out of both ignorance and willful deception, depending upon the outlet. But in the case of the Ohio micro-quakes, normally careful sites such as oilprice.com, slate.com, and other mainstream outlets produced news copy that was not fit for a third grade newsletter, due to the inaccuracies. This is a troubling trend that should be watched very carefully.

It has been shown for decades that deep fluid injection into the crust can induce micro-quakes, if it takes place near known and discovered faults. And of all energy-related drilling, the type most closely associated with inducing micro-quakes is geothermal -- both enhanced and the geyser type. Deep CO2 injection is likewise liable to induce micro-quakes. Shale fracturing is probably the least likely cause of micro-quakes due to the more shallow nature and due to the type of rock involved.

But if one wishes to be absolutely sure that one is not performing shale fracturing near a fault zone, a thorough seismic survey (for about $10 million) can be done prior to any drilling. Clearly a less expensive method of reassuring the panicky public, skankstream media, and less than honest environmental media is needed.

Scientific research is the best antidote to the type of superstitions being purveyed by the modern skankstream.

Some European experience:

The data generally support the view that injection in sedimentary rocks tends to be less seismogenic than in crystalline rocks. In both cases, the presence of faults near the wells that allow pressures to penetrate significant distances vertically and laterally can be expected to increase the risk of producing felt events. All cases of injection into crystalline rocks produce seismic events, albeit usually of non-damaging magnitudes, and all crystalline rock masses were found to be critically stressed, regardless of the strength of their seismogenic responses to injection. Thus, these data suggest that criticality of stress, whilst a necessary condition for producing earthquakes that would disturb (or be felt by) the local population, is not a sufficient condition. The data considered here are not fully consistent with the concept that injection into deeper crystalline formations tends to produce larger magnitude events. The data are too few to evaluate the combined effect of depth and injected fluid volume on the size of the largest events. Injection at sites with low natural seismicity, defined by the expectation that the local peak ground acceleration has less than a 10% chance of exceeding 0.07 g in 50 years, has not produced felt events. _Geothermics

Enhanced geothermal drilling is a far greater micro-earthquake hazard than is any drilling or fracturing in porous shale for oil & gas. But even so, it is best to avoid overreacting to the risk, but rather to plan deep drilling and hydraulic fracturing of crystalline rock very carefully, to minimise risks.

The risk of overreaction to the risks inherent in deep geothermal projects is very real. The establishment of an overly harsh regulatory framework would penalize the geothermal industry in comparison to other energy sectors that carry a recognized risk of inducing seismicity, such as gas extraction or coal mining.

From their outset, EGS projects need to be thought of both as pilot projects with scientific unknowns and as commercial ventures with technological and financial risks. Companies need to have allocated enough of their budget to scientific investigations not directly related to the exploitation of heat. Local authorities need to avoid being enticed by the promises of alternative energy, and to remember to ask the right questions. Risk evaluations need to be done before — not after — these projects begin. _Nature

In such cases where the risks are small but clear, appropriate care must be used in conjunction with any deep geothermal drilling, or deep well injections -- particularly near fault zones.

But the risks of shale drilling and fracturing are completely different -- and orders of magnitude smaller -- than the risks of drilling and fracturing crystalline rock such as granite. If regulatory agencies rush in to ban economically important procedures which have been demonstrated to be safe over decades of experience and geological testing, they will be doing a grave disservice to their constituents.

Can Humans Get Over Their Fears of Small Earthquakes?

Scientists are continuously thinking of ways to try and reduce earthquake power. Some are trying to lessen the friction between colliding plates. They poured water down a fault where two plates were grinding together. The water “lubricated” the fault, letting one piece jerk free with a number of little earthquakes and preventing a large tremor. _EarthquakePrevention

If humans can get over their fears of small earthquakes, they could reap the bounty of huge amounts of energy beneath their feet, of multiple types.

Geothermal energy from EGS represents a large, indigenous resource that can provide base-load electric power and heat at a level that can have a major impact on the United States, while incurring minimal environmental impacts. With a reasonable investment in R&D, EGS could provide 100 GWe or more of cost-competitive generating capacity in the next 50 years. Further, EGS provides a secure source of power for the long term that would help protect America against economic instabilities resulting from fuel price fluctuations or supply disruptions. Most of the key technical requirements to make EGS work economically over a wide area of the country are in effect, with remaining goals easily within reach. _MIT Report 14 MB PDF

100 GWe is roughly the amount of power generated by 100 large nuclear reactors -- or several hundred small modular reactors. Geothermal power is available 24 hours a day, as baseload ... load following ... or peaking power. It is the ultimate non-nuclear, non-carbon power source -- if humans could only get over their fears of small earthquakes.

Small earthquakes can be frightening to children and those who have not grown accustomed to them. But the right succession of small earthquakes can relieve enough stress on crustal faults to prevent, delay, or mitigate the effect, of larger quakes that were destined to occur. Earthquake prevention is a difficult science due to the multiple interlocking crustal faults at varying depth -- many of which have not yet been discovered.

The fear of triggering small earthquakes has become a tremendous obstacle -- both to the development of rich new energy resources, and to the exciting new field of seismic exploratory activity aimed at eventually preventing large quakes. Energy starvationists of the green lefty-luddite dieoff.orgiast persuasion in particular, have been quick to seize on the common primal fear of small earthquakes, in order to shut down promising, reliable new sources of energy.

Geothermal energy can be tapped in multiple ways:

The Geysers Field north of San Francisco is home to more than a dozen large power plants that have been tapping naturally occurring steam reservoirs to produce electricity for more than 40 years.

However, newer technologies and drilling methods can now be used to develop resources in a wider range of geologic conditions, allowing reliable production of clean energy at temperatures as low as 100C (212F) - and in regions not previously considered suitable for geothermal energy production.

Preliminary data released from the SMU study in October 2010 revealed the existence of a geothermal resource under the state of West Virginia equivalent to the state's existing (primarily coal-based) power supply.

...Three recent technological developments already have sparked geothermal development in areas with little or no tectonic activity or volcanism:

1. Low Temperature Hydrothermal - Energy is produced from areas with naturally occurring high fluid volumes at temperatures ranging from less than boiling to 150C (300F). This application is currently producing energy in Alaska, Oregon, Idaho and Utah.

2. Geopressure and Coproduced Fluids Geothermal - Oil and/or natural gas are produced together with electricity generated from hot geothermal fluids drawn from the same well. Systems are installed or being installed in Wyoming, North Dakota, Utah, Louisiana, Mississippi and Texas.

3. Enhanced Geothermal Systems (EGS) - Areas with low fluid content, but high temperatures of more than 150C (300F), are "enhanced" with injection of fluid and other reservoir engineering techniques. EGS resources are typically deeper than hydrothermal and represent the largest share of total geothermal resources capable of supporting larger capacity power plants. _Geothermal Promise

More information at this helpful Google enhanced geothermal website, including videos and links to information on some of the latest research and technologies.

Geothermal power at the Geysers in Lake County, California, has been associated with thousands of tiny earthquakes above magnitude 1 since 1975 when the resource was tapped. But earthquakes are triggered by a number of different things, including the construction of hydroelectric dams.

Depth of the reservoir is the most important factor, but the volume of water also plays a significant role in triggering earthquakes.
RIS [Reservoir Induced Seismicity] can be immediately noticed during filling periods of reservoirs.
RIS can happen immediately after the filling of a reservoir or after a certain time lag.

It would be best for humans to invest in the best accelerated research possible to clearly and unequivocally define the risks and benefits of small scale induced seismicity. One of the best ways of doing this would be for seismic scientists to work closely with deep drilling enterprises which also involve the deep injection of fluids into the earth's crust. By piggy-backing onto economic activity which is already being done, seismologists can increase the detail of their seismic maps, and can also collect abundant data on the impact of deep crustal fluid injection into different fault configurations.