India Shale Gas: Environmental Concerns

Shale gas is natural gas trapped in very fined grained sedimentary rocks like shales. These rocks are not very permeable. To release the gas trapped in the tiny pore spaces, the rock is fractured by injecting water, sand and various chemicals into it at very high pressure. Several million gallons of fresh water is needed for such ' fracking' activity at any one site. 

Shashikant Yadav, Gopal K Sarangi and M P Ram Mohan in an essay in the Economic and Political Weekly explain the environmental concerns that shale gas production poses in India.

Regarding the guidelines for environmental management released by the government -

Further, the guidelines mention that water management is one of the key concerns. They state that the major and prime difference being in the hydraulic fracturing technologies requiring a large volume of water; the activities are likely to deplete water sources and cause pollution due to the disposal of produced water. However, instead of dealing with the water-specific issues, the guidelines (apart from explaining existing provisions) stated that the generic environment clearance process adopted by the Ministry of Environment, Forest and Climate Change (MoEFCC) will suffice to ascertain water-related issues posed by fracking. But, MoEFCC has not laid down any specific guidelines, policies, or manuals differentiating between conventional and unconventional gases to grant environment clearance.  More recently, despite the gaps, on 1 August, 2018, the cabinet approved a policy allowing companies to exploit shale gas in contract areas that were primarily allocated to exploit conventional gas.

..and this in the context of the ambiguous legal framework surrounding groundwater -

Considering the limited water legislation in India, the implementation of fracking may result in geopolitical and legislative complexities. For instance, shale rocks are usually adjacent to rocks containing useable/drinking water known as “aquifers.” While implementing the hydraulic fracking, the shale fluid can easily penetrate to aquifers leading to groundwater contamination. This contamination may result in methane-poisoning of water used for drinking and irrigational purposes. To avoid such contamination, as per industry standards, a project proponent must maintain a distance of 600 metres between aquifers and fracture zones (Davies et al 2012).

The Indian water legal regime is far away to make such specific observations, as aquifers are not defined in any of the Indian environmental regulatory or legal regime leading to a free pass for unregulated mixing of shale fluid and aquifers. Moreover, the landless have no right to groundwater, and accordingly peasants and tribal communities who have no ownership rights over land have no right on groundwater. Also, a project proponent may easily exploit groundwater while implementing the hydraulic fracking process with none or limited accountability of their actions.  In such a situation, the intent of “Public Trust Doctrine” is defeated, and the precautionary principle will be non-implementable.

Open Access.

Grand Theft Geology- Report Indicts Reliance Of Pilfering Gas From ONGC Reservoir

Paranjoy Guha Thakurta explains in a detailed article the shenanigans and the disputes over the exploitation of natural gas in the Krishna Godavari basin.

The Krishna-Godavari basin offshore Bay of Bengal composed of Late Mesozoic to Cenozoic deltaic-marine sequences has rich natural gas reservoirs  . Reliance Industries as well as the public sector ONGC are exploring and producing natural gas from adjoining areas. Turns out that in one area the underlying reservoirs are continuous, and ONGC suspected a couple of years ago that Reliance Industries realizing this geological situation drilled wells very close to the common boundary of the blocks. As a result of producing these wells as much as 11 billion cubic meters (bcm) of gas has flowed from the reservoir under ONGC controlled areas into Reliance control. Out of that, Reliance in an unauthorized manner, has sucked out 8.9 bcm of gas worth about Rs 11,000 crore  (~ $1.7 billion).

If fact, the large migration of gas from ONGC controlled reservoir into Reliance controlled reservoir means that it would no longer be economically viable for ONGC  to develop this particular field.

That is the finding of an independent consultant DeGolyer and MacNaughton (D&M) based out of Dallas, Texas, in the US, which was hired to submit a technical report on the ONGC claim which Reliance had disputed.

ONGC has also taken the Government of India to court, naming the Ministry of Petroleum and Natural Gas (MoPNG) and the Directorate-General of Hydrocarbons (DGH) as respondents accusing these agencies of failing to be vigilant in taking precautionary measures.

ONGC claimed in its writ petition:

Pertinently, four wells have been drilled by Respondent No 3 (RIL) within distances ranging within 50 m (metres) to about 350 m from the blocks of (the) petitioner (ONGC) and wells have been so drilled and constructed that there is a pre-planned and calculated slant/angular incline towards the gas reserves of (the) petitioner with a clear idea to tap the same.

According to ONGC, its nomination block, Godavari PML (G4) and discovery block, KG-D5 under the New Exploration Licensing Policy (NELP)-1 are contiguous to the RIL-operated NELP-1 block KG-D6. The public sector undertaking (PSU) had said that it wanted a “truly independent” agency to examine its contention that the Mukesh Ambani-led RIL may have drawn natural gas worth up to Rs 30,000 crore from ONGC’s fields adjacent to the ones in the KG-D6 block where the contracting company controlled by RIL operates.

all this does not reflect well on a government eager to invite foreign investments and collaboration-

Sarma is correctly of the view that management and enforcement of contracts are crucial to good governance in any sector, including the oil and gas exploration industry where the natural resources extracted are not just high in value and also critical to the country’s energy security. A flawed and inadequate PSC between RIL and the MoPNG has been greatly responsible for many of the problems that have been encountered during the exploration and extraction of gas from the KG basin. In the case of alleged theft, the management committee, which included representatives of the ministry, apparently acquiesced in whatever RIL did, and the contractual provisions for joint-management of the gas fields and imposition of penalties were never invoked. This, Sarma points out, does not augur well for a country that is aggressive inviting foreign investments, including investments in the oil and gas industry.

It should also be noted that government-owned companies like ONGC are expected to function independently and safeguard the interests of the shareholders, which include the people of India. The two really “independent” former directors of ONGC persuaded the corporation to approach the Delhi High Court but the ministry under Moily tried to prevent this from happening—it is truly ironic that the government as the major shareholder of ONGC should actively work against its interests and try and cause harm to itself.

The entire article is worth reading.

.. and more on the troubled involvement of Reliance Industries with natural gas exploitation in the Krishna Godavari basin .

Rigged: The Slow Decline Of India's National Oil Company

This article came out last year but I came across it today via twitter. In Caravan magazine Krishn Kaushik  writes about India's flagship oil  company the Oil and Natural Gas Corporation Limited and its failure over the years to live up to its mission of finding and producing fuel for the country.

This failure has many causes as Kaushik explores- institutional inertia is one important one, government interference in company functioning is another. But there are also a host of private interests trying to exploit the company's wealth. Reliance comes under particular criticism for its alleged manipulation of the bidding process.

Here is one example:

Things only got better for Reliance with the introduction of the New Exploration Licensing Policy. The former ONGC director told me that during his tenure under the NELP regime, both the Directorate General of Hydrocarbons and the petroleum ministry—then headed by VK Sibal and the Congressman Murli Deora, respectively—made at least three unconventional decisions that disadvantaged ONGC and awarded contracts to Mukesh Ambani.

Bids for oil and gas blocks are given points according to various criteria, he explained. One of these is meterage, the depth of the wells a company offers to drill. In principle, the deeper the better—but every hydrocarbon field has a natural “basement,” based on its geological ability to retain hydrocarbon fuels, beyond which it doesn’t make sense to go. In the Cambay Basin, the director said, “everybody knows that the depth cannot be more than 3,500 metres.” But Reliance “bid 5,000 metres stroke basement”—whichever came first. “They got marks for 5,000, whereas ONGC couldn’t write more than 3,500 because we knew we would hit the basement below that.”

There are also points for how much territory a contractor will explore with three-dimensional seismic surveys. In another NELP round, Reliance offered to survey more than the total area of the block on offer, the director claimed. “So they got marks on that.”

There are also allegations that Reliance is  sucking out natural gas from adjacent blocks under ONGC control in the Krishna Godavari offshore basin. ONGC has taken the government to court over this! .. and the list goes on..

Between all these shenanigans is a bizarre episode of how Russian geologists helped discover Mumbai High,  India's biggest off shore oil field-

Discussing its aleatory nature, Sunjoy Joshi, the director of the Observer Research Foundation, a Reliance-funded think tank, told me a story he heard from Subir Raha, a former chairman and managing director of ONGC. “I don’t know if there is any record of this story,” Joshi said, before relating how Raha, who died in 2010, used to say that the Russians had been engaged to do the surveys far out to sea, “where geologists thought there was better possibility of finding oil and gas. But they had to justify coming to the shore more and more often, to screw all the girls in Kamathipura,” Mumbai’s oldest and largest red-light district. Moving their operations closer to land, they eventually found India’s most prolific oil field to date. “The discovery of Mumbai High,” Joshi continued, chuckling, “owes a lot to those poor women.”

Its a long read but well worth it.

Report: Global Shale Gas Development And Water Availability

This is something that I have written about before in the context of shale gas development from Indian sedimentary basins. The availability of fresh water might set up conflicts with agriculture demands and limit exploitation of shale gas.

A report by the World Resources Institute on the global situation points out the same problem elsewhere in many areas of the world.

38 percent of shale resources are in areas that are either arid or under high to extremely high levels of water stress

19 percent are in areas of high or extremely high seasonal variability; and

15 percent are in locations exposed to high or extremely high drought severity.

Furthermore, 386 million people live on the land over these shale plays, and in 40 percent of the shale plays, irrigated agriculture is the largest water user. Thus drilling and hydraulic fracturing often compete with other demands for freshwater, which can result in conflicts with other water users. This is particularly true in areas of high baseline water stress, where over 40 percent of the available water supplies are already being withdrawn for agricultural, municipal, or industrial purposes.

China, Mexico, South Africa and India all have sedimentary basins with shale gas potential located in areas of high water stress i.e. extraction of either surface water and/or groundwater exceeds natural replenishment.

WRI Full Report On Shale Gas and Water Availability
WRI Executive Summary On Shale Gas and Water Availability

The report relies on EIA estimates of technically recoverable shale gas and tight oil. These numbers may be subject to revision as more detailed studies are taken up in sedimentary basins in India and other countries as well.

India is still some way away from exploitation of shale gas. It faces many other problems besides availability of water. This earlier post summarizes these issues.

How Are Diagenetic Studies Useful In Understanding Sedimentary Basin History

I dusted of my PhD dissertation last week for two reasons. A friend insisted that she wanted to see my research.. and then this paper in the Journal of Sedimentary Research (behind paywall):

Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan by J. A. D. Dickson and J. A. M. Kenter

The work is eerily similar to what I did for my PhD which was carrying out a detailed study of cementation patterns in Middle and Late Ordovician carbonate parasequences from the southern Appalachians.

Dickson and Kenter use petrographic techniques along with cathodoluminescence to tease apart the cementation sequence and pore space modification of the carbonate rocks. Hydrocarbon reservoir quality depends in part on how reaction of sediment with water either dissolves material to create pore space or precipitates cements to modify pore space. So, understanding the timing of these events in the context of the burial history of the sediment pile on a basin wide scale can help geologists predict reservoir quality.

Ok, so what are Parasequences?

Reliance Cites Geological Surprises In Krishna Godavari Basin

My friend S.C.N Jatar, former CMD Oil India and ONGC Videsh writes about the suspicion that Reliance overstated reservoir potential in the KG -D6 field of the Krishna Godavari basin.

“Geological surprise” is cited as the cause of Reliance’s production shortfall. KG-D6 block commenced production in September 2008 with 0.58 million standard cubic meters per day (mmscmd) reaching a peak of 69.43 in March 2010 and then declined to 13 mmscmd currently. Reliance attributed the decline to substantial variance from prediction in reservoir behaviour, higher than envisaged pressure decline and unpredicted early water production in some wells. Was there a geological surprise? In an article published 10 years ago in Business Standard on January 13, 2003, I wrote, “Producing even 40 mmscmd for 10 years will need an unusually large number of wells....” The latest thinking on such reservoirs is that one can expect unpleasant surprises even after 3D surveys confirm the ‘structure’ because it cannot confirm the ‘reservoir’. I had then stressed: “There is a big question mark over the projected recoverable reserves of the Dhirubhai fields.”

Rest of the article here. 

India Energy Report- Some Rambling Thoughts

The latest from the U.S. Energy Information Administration. For those who follow the energy sector, nothing terribly new here, but it is a useful document to keep bookmarked for quick reference.

Meanwhile, Swaminathan Aiyar takes an optimistic look at the future of methane hydrate deposits which he thinks can provide significantly to India's energy needs. These deposits are formed when methane is trapped within a crystalline cage of water molecules. They occur in cold deep sea sediments and also onshore in permafrost settings.There are estimates that resources in sediments in India offshore basins on both the west and east coast may be around 1800-1900 trillion cubic meters.

My take is that whatever the estimates, we may be decades away from successfully exploiting them. Of more relevance over the short to medium term is onshore shale gas. Estimates for those vary wildly from an earlier EIA estimate of about 63 trillion cubic feet to a revised USGS estimate of only 6-7 trillion cubic feet to a figure often quoted in the India media of about 500 trillion cubic feet to 300-1200 trillion cubic meters! These disparate estimates only underscores the need for a more detailed exploration of Indian sedimentary basins.

Some Good Readings About U.S. Oil In Shale Resources

I go over to the Oil Drum often to catch up on news and analysis on oil and natural gas. A few that caught my eye over the holiday period:

1) Does the U.S. Really Have More Oil than Saudi Arabia? - some fundamentals about the difference between shale oil and tight oil, and resources and reserves cleared up.

2) Bill O'Reilly Is Misinforming Americans About Oil Supplies - U.S oil exports and imports and the link to gasoline prices and jobs.

3) Shale Oil: The Latest Insights -  Development of "shale oil" resources and impacts on the shale gas production.

4) Gas Boom Goes Bust: On the future of the shale gas industry.

The Oil Drum has generally been giving a more cautious and conservative long term perspectives on the recent elation over shale gas and new discoveries of "shale oil".

Geophysicst Mark Zoback On Fracking

Another terrific geology related talk on Generation Anthropocene. Geophysicist and shale gas expert Mark Zoback attempts to clear up the many misconceptions about fracking. He doesn't minimize or take lightly the negative impact of shale gas drilling, but rather puts it in a broader context. The greater risk of contaminating overlying aquifers is not from the act of hydraulic fracturing itself but from improper well construction and from leaky ponds which are constructed to store waste water that flows back out of the formation. This water may contain metals like iron or arsenic flushed by reaction with the shale. So actually according to him, there is nothing in the fracking fluid that is dangerous. But that fluid after reacting with the rock may become toxic.

Shale gas drilling companies don't have to disclose the exact composition of the fracking fluid as they have an exemption under the Clean Water Act. But perception does matter. As Mark Zobeck points out, there was growing support for nuclear power in the U.S. until the accident at Fukushima occurred. Public perception about risk can reverse major energy policy decisions regardless of the actual risk. If that is so, then why slow down or kill the shale gas goose? Perhaps it will be wiser to change policy and to come clean about fracking fluids.

Meanwhile, on the topic of shale gas in India,  a reader wrote in a comment on an earlier post I had written about Indian shale gas prospects:

US geological survey says the total shale gas reserves to be 6.1 Tcf, contrary to 63 Tcf by EIA. What are your views on this?

That is a major downgrade for Indian shale gas prospects. I could only suggest this possibility:

thanks Dakshina.. yeah.. i saw those figures.. hard to say but downward revisions are going on in many other basins around the world.. perhaps the actual recovery rates observed from shale gas wells i.e. their performance over a longer term have not been as good as initially projected..leading to downward revision of technically recoverable resources in other areas as well.. or maybe it has to do with the reassessment of the basic geological data.. can't say for sure without reading more details.. ///

Also worth reading is another article by Mark Zoback on the seismic risk posed by shale gas drilling and waste water disposal.

ExxonMobil Were Playing Both Ways On Global Warming All Along

Fresh Air has an absolutely fascinating interview with journalist Steve Coll who has written a new book on ExxonMobil.

For many years ExxonMobil engaged in a campaign to downplay the human role in global warming and tried to discredit the science of recent climate change.

And yet:

GROSS: Just one more thing about climate change. During the period when ExxonMobil was trying to defeat global warming science, at the same time scientists within Exxon were trying to figure out, well, if the planet is warming, how can we profit from that? So they work in both fronts at the same time.

COLL: Well, that's right. They're a science-based organization. They employ a lot of geologists, and the mission of those geologists is to understand the Earth's structure and how changes in temperatures, geology, technology, could intersect to create opportunities to find oil. And as the book reports, geologists in some of their most important kind of discovery departments were looking at how warming might unlock oil reserves and positioning ExxonMobil with advice about how to think about that.

GROSS: So in other words, Exxon wanted to defeat global science because that says that fossil fuels, burning fossil fuels is warming the climate and creating weather changes and climate change, and that would mean problems for Exxon because it's the fossil fuel industry.

But at the same time, its own scientists were saying, well, it looks like the Earth is warming, so let's see what new oil reserves that might open up to us.

Those new reserves that might open up were under the Arctic sea bed, made more accessible as increased summer melting of the Arctic sea ice makes it easier to explore and eventually exploit those resources.

There are a lot more interesting tidbits in this long interview including ExxonMobil's tussle with the U.S. government over human rights issues in oil rich countries like Chad and the company's increasing interest in unconventional oil and gas resources.

Map Of Potential Carbon Dioxide Storage Sites In U.S. Sedimentary Basins

via Nobel Intent:

Potential carbon dioxide sequestration sites are shown in blue.

Carbon capture and sequestration (CCS) is a climate change mitigation measure. Carbon dioxide emitted by power plants is compressed into a supercritical fluid and injected in deep saline aquifers with an impermeable geological capping layer that prevents the liquid CO2 from escaping.

Does U.S. sedimentary basins have enough storage capacity to make a difference in emissions? From the abstract published in PNAS:

We show that in the United States, if CO2 production from power generation continues to rise at recent rates, then CCS can store enough CO2 to stabilize emissions at current levels for at least 100 y.  This result suggests that the large-scale implementation of CCS is a geologically viable climate-change mitigation option in the United States over the next century.

Will it be economically viable though? There seems to be no hurry in the climate change policy environment in making CO2 emissions expensive enough for companies to turn to CCS.

A Buried Devonian Manhattan Made Of Calcium Carbonate

I'm continuing with the theme of carbonate reservoir rocks - and for good reason. I found this gem of a story about coral reef oil reservoirs from the Devonian carbonate depositional basins of Alberta, Canada in the comments thread of a post on the Oil Drum -

RockyMtnGuy writes:

Well, yes, carbonate reservoirs do test your wits. The ones in Alberta are particularly difficult to deal with. They are just like the girl with the curl right, in the middle of her forehead: when they are good, they are very good, but when they are bad, they are horrid.

A classic was the Rumsey Reef, which they found not too far from where I grew up.

In 1982, Gulf Canada Resources discovered a small pinnacle, called the Rumsey Reef, just to leeward of the Stettler-Fenn-Big Valley reefs. It produced over 3.7 million barrels of high gravity oil from one well; 90% was recovered during the first three years. During that period it flowed 3,000-4,000 bbls/day. A decade later, Gulf explorers, Lemon and Taylor (1993) presented a paper with the wistful title, “The Rumsey Leduc Pinnacle Reef: Where are the Rest?”

The Rumsey Reef is an oil field about the size and shape of a New York skyscraper, just full of oil waiting to be sucked out. Based on the geological history of the area, there must be thousands of similar reefs out there, but they just don't show up on seismic.

Probably most of the remaining Leduc pinnacle reefs in central Alberta, and we have measured many of them, are physically too small to be adequately resolved by reconnaissance seismic exploration, whether 2D or 3D. Our measurements suggest pinnacle reefs, similar to Rumsey in size, are pillars of coral growing between 550' to 700' high from the Cooking Lake carbonate platform. They appear to range from 70' to 225' in diameter.

Wow! .. where does one start?

The Rumsey Reef is an oil field about the size and shape of a New York skyscraper, just full of oil waiting to be sucked out. 

Today most of the Devonian strata of Alberta is in the subsurface, buried underneath younger sediment.

But imagine a sea floor 400 million years ago, where thousands of self assembled towers were being built by organisms scavenging calcium and carbonate ions from sea water to form skeletons made up of the mineral aragonite or calcite. A  living breathing city of underwater skyscrapers hundreds of feet tall, extending in narrow zones tens of kilometers in length, along the edges of depositional basins, where the shallow sea bed suddenly slope into an abyss. The Devonian Alberta basin was a flat shallow water area that gave way along steeper slopes possibly due to faulting activity to deeper waters. These are classic settings for a pinnacle reef to form.

The schematic figure below shows the different settings where reefs form. The patch reefs shaped like towers are the pinnacle reefs. They are called patch reefs because they occur as isolated communities.

Source

A Pinnacle reef is a type of reef wherein the structure is a shape of a pinnacle or tower.  Reefs are biologically constructed structures that rise from the sea floor to form mounds. They are made up of the skeletons of organisms that prefer sunlight depths. Ordinarily, in shallow seas, the upward growth of reefs stop when the reef organisms start getting exposed to the atmosphere at low tides. The reef then grows laterally forming a broad structure.

In certain settings though, a rapidly subsiding sea floor creates space, maintaining a certain water depth, and the reef grows upwards maintaining its colonies in the optimal sunlight zone. Such conditions are present around volcanic islands. As volcanoes become dormant and erode and subside, reefs nucleate along their flanks and grow upwards as pinnacles. This situation is observed today along many tropical volcanic chains in the Pacific ocean.

Another environment for the formation of pinnacle reefs occurs when rapid sea level rise creates sufficient water depth. Pioneer colonies of reef building organisms tolerant of greater water depths may initiate the building of a bio-structure. As the reef grows into shallower water, a different species assemblage may become more common. The communities that build pinnacle reefs may change as the towers grow through different water depths.

The image below is of the coast of Belize. You can see a long north south trending white barrier reef in the center of the image. To the right is the open Caribbean sea. To the left are relatively deeper and quieter lagoons, environments where pinnacle reefs would likely grow. Some of the white isolated patches you see may be pinnacle reefs. This is just to give you an idea of the setting for pinnacle reefs, but I can't say for sure whether those patches are pinnacle reefs from this particular image.

Many of these Holocene reefs in Belize and the West Indies islands have grown on a Pleistocene limestone substrate (figure to the left, SEPM strata.org), which during the last sea level fall was weathered into an undulating topography known as karst. In early Holocene, sea level rose and flooded this limestone substrate. Reefs that took root in the depressions i.e. greater water depths, grew upwards to form pinnacles. In Alberta, the situation was different. The basin was an extensive shallow sea and the sea bed was broken into deeper and shallower areas by faults. My guess is that the Alberta basin experienced many episodes of sea level rise in the Devonian, and reef communities growing along the edges and flanks of fault blocks repeatedly grew upwards to form pinnacles.

Today, the dominant reef building organism are species of scleractinian corals, a group of coral organisms which have a symbiotic live in relationship with algae. In the Devonian, the community structure of reefs was different. There were corals present, but they predominantly belonged to two now extinct groups known as tabulate corals and rugose corals. Along with corals were stromatoporoids, an important coral like colonial organism, also now extinct. And there was a supporting cast of algae and molluscs.

The reef building activity in the Alberta basin lasted hundreds of thousands of years. It was not a continuous process. Sea level falls would have interrupted reef formation. A subsequent sea level rise would have allowed reef builders like stromatoporoids to colonize older reef substrates and resume the construction of these enormous towers. Each reef building episode may have lasted a few tens of thousands of years.

Eventually, water depths become considerably deeper, stopping reef growth. Sedimentary conditions changed and buried the reef under layers of mud or fine grained sediment. The reef itself, because it is built by organisms having branching structures is quite porous. Besides this primary porosity, the Alberta basin reefs underwent extensive alteration during burial. The minerals aragonite and calcite were replaced in patches by dolomite. This created more porosity as the replacement dissolved the original minerals and a denser dolomite occupied the space. Oil then migrated into the open pores and got trapped because the reef is capped by fine impervious material. Many of these living towers got transformed over time into a reservoir rock,  a buried skyscraper full of oil.

Regarding the Alberta basin, all these reefs are in the subsurface, and although they are invisible to seismic surveys, new exploration methods using  telluric currents have successfully identified more pinnacle reefs. Many of them will turn out to be prolific oil reservoirs.

But I can't get that 400 million year old underwater Manhattan of calcium carbonate out of my mind!

Reservoir Rock In World's Biggest Oil Field Is Made Of Shit

From Ken Deffeyes book “Hubbert’s Peak”, via the Oil Drum:

Most massive and nonporous limestones contain textures made by invertebrate animals that ingest sediment and turn out fecal pellets. Usually, the pellets get squished into the mud. Rarely do the fecal pellets themselves form a porous sedimentary rock. In the 1970s, the first native-born Saudi to earn a doctorate in petroleum geology arrived for a year of work at Princeton. I used the occasion to twist Aramco’s collective arm for samples from the super-giant Ghawar field. As soon as the samples were ready, I made an appointment with our Saudi visitor to examine together the samples using petrographic microscopes. That morning, I was really excited. Examining the reservoir rock of the world’s biggest oil field was for me a thrill bigger than climbing Mount Everest. A small part of the reservoir was dolomite, but most of it turned out to be a fecal-pellet limestone. I had to go home that evening and explain to my family that the reservoir rock in the world’s biggest oil field was made of shit.

A bewildering variety of particle types get bound together to form limestones. Post Cambrian times, the calcium carbonate shells of marine organisms have been the most common particle type, the primary building blocks of limestones. But other particle types like fecal pellets are also common.

For carbonate sedimentologists involved in oil exploration, the most important task , is understanding the origin and distribution of porosity and permeability i.e. the open spaces in which oil migrates and is naturally stored. Sedimentologists recognize two broad categories of porosity. Primary porosity and secondary porosity.  Primary porosity is the open space between the grains and forms as grains settle down during deposition into different packing configurations depending on their shape and size.  Sediments that are deposited in environments where wave and tidal movements are vigorous will have high primary porosity because in such settings finer mud that can clog up interstices between coarser grains is winnowed away, leaving behind a lag of clean sand.

The image below is a photomicrograph of a fecal pellet sand from the Jurassic of England. The shining white material between the dark pellets is calcium carbonate cement which has filled up the primary porosity. Occasionally, there may be no precipitation of cement as the sand gets buried. In such situations the primary porosity is preserved and the deposit may become a reservoir rock.

 

Source:  SEPM Strata

And here is a picture of the Bahama Banks of the coast of Florida.

Arrows and labels show environments facing open ocean where currents and waves are vigorous and where primary porosity in sediment will be high. In the interior of the Bahamas, wave energy is much lower, resulting in sediment with less primary porosity. Fecal pellets may originate in the interior of platforms, in low energy settings. They often harden in these settings due to precipitation of cement in micro-pores within the grains. Often due to storms, these hardened pellets are then transported to high energy settings. Due to this early hardening, pellets resist getting squished against each other as the sediment is buried. Open spaces are thus preserved in such early hardened fecal pellet deposits.

Although the paleo-geographic setting would have been different than the Bahamas, the sediments of the Jurassic Ghawar reservoir limestone would have been deposited in high energy settings resulting in substantial primary porosity.

 Another category of porosity is secondary porosity that forms due to the reaction of the sediment with water during burial. It results in open spaces being created by the dissolution and leaching away of mud and grains and also due to volume changes as calcite gets replaced by the denser dolomite. This type of porosity is also present in the Ghawar limestone.

Since 1950's the Ghawar field has produced over 65 billion barrels of oil. Daily production is about 5 million barrels, about 6% of global production.

And.. what do  you know?  Glenn Morton has found another use for those famous fecal pellets..refuting young earth creationism:

One of the interesting things about Ghawar is the nature of its reservoir which provides an argument against an ideology I fight all the time, Young-earth Creationism. Ghawar is largely made of dung, which would be hard pressed to be concentrated during a global flood and thus contradicts the young-earth creationist claims.

A chaotic flood would have dispersed and broken up fecal pellets in to mud. Only long periods of  wave action and winnowing and early cementation on a sea floor would have produce the well sorted fecal pellet sands of the Ghawar reservoir deposit.

Natural Gas: Expectations Fulfilled?

Couple of articles on the expectations surrounding natural gas -

Over at the Barrel, John Kingston points to an article by Mriganka Jaipuriyar on the delays and production problems at India's giant natural gas field KG-D6 in the east coast Krishna Godavari basin.

Across the continents, Ian Urbina of the New York Times dives into industry memos and internal emails expressing skepticism about the potential of shale gas in the U.S to remain a vast and profitable source of energy in the future. 

India Basin-Wise Shale Gas Estimates

Sometime back I had posted a graphic of Indian sedimentary basins and the potential of shale gas from these basins. Currently India has reserves of about 38 trillion cubic feet (Tcf) of conventional natural gas i.e. gas stored in pore spaces of coarser permeable sedimentary rocks like sandstones.

I had mentioned that shale gas i.e. natural gas trapped in very fine grained, impermeable shales might add substantially to the existing conventional natural gas reserves. I did not have any numbers to put out at that time.

Now the U.S Energy Information Administration (EIA) has come out with a report (51 mb) on global shale gas potential that includes some Indian sedimentary basins as well. The report has been prepared for the EIA by Advanced Resources International, a company based in Virginia, U.S.

About 70 shale formations from 48 basins in 32 countries were studied. Here is the global summary in terms of shale gas potential. The report only partially estimates shale gas resources since it excludes Russia and the Middle East. It also excludes offshore basins and many other onshore basins for which data is not available:

Although the shale gas resource estimates will likely change over time as additional information becomes available, the report shows that the international shale gas resource base is vast. The initial estimate of technically recoverable shale gas resources in the 32 countries examined is 5,760 trillion, cubic feet, as shown in Table 1. Adding the U.S. estimate of the shale gas technically recoverable resources of 862 trillion cubic feet results in a total shale resource base estimate of 6,622 trillion cubic feet for the United States and the other 32 countries assessed. To put this shale gas resource estimate in some perspective, world proven reserves of natural gas as of January 1, 2010 are about 6,609 trillion cubic feet, and world technically recoverable gas resources are roughly 16,000 trillion cubic feet, largely excluding shale gas. Thus, adding the identified shale gas resources to other gas resources increases total world technically recoverable gas resources by over 40 percent to 22,600 trillion cubic feet.

Global consumption of natural gas was estimated to be about 100 Tcf in 2009 and is projected to increase to about 156 Tcf by 2035.

Do read the summary and the report (51 mb) to get an idea about the methodology for estimating shale gas resources. 

For India, data adequate enough to generate estimates of shale gas was available from 4 sedimentary basins. These were from the Cambay Basin, the Krishna Godavari Basin, the Cauvery Basin and the Damodar Valley Basin. These basins are estimated to contain about 63 Tcf of recoverable shale gas.

There are many other sedimentary basins which remain relatively unexplored for their shale gas potential.

Image below shows the assessed sedimentary basins along with other basins which are though to contain shale gas but for which adequate data is not yet available.

Below is a basin-wise breakdown of the shale gas estimates along with graphics of the basin structure and prospective blocks within the basins.

Cambay Basin:

This is an elongate intra-cratonic rift basin of late Cretaceous-Cenozoic age situated in western Indian state of Gujarat. The formation of interest is the Palaeocene-Eocene Cambay black shale. Technically recoverable shale gas is estimated to be about 20 Tcf.

Krishna Godavari Basin:

A Late Permian to Tertiary age basin in eastern India consisting of a series of horst and graben. The prospective formation is the Permian age Kommugudem shale. Technically recoverable resources are estimated to be about 27 Tcf.

Cauvery Basin:

The Cretaceous-Cenozoic Cauvery basin in south eastern India is another basin with horst and graben structures and prospective shales. The formations of interest are the early Cretaceous Andimadam Formation and the Sattapadi shale. Technically recoverable resources are about 9 Tcf.

Damodar Valley Basin:

This basin is part of the "Gondwana" basins of India characterized by their mostly non-marine sedimentary fill and narrow graben structures. Although filled with mostly Late Permian to Triassic terrestrial sediment, there is a significant thickness of a marine shale known as the Barren measures, so called as it is barren of coal. The technically recoverable resources from this shale are estimated to be 7 Tcf.

Below is a table summarizing the geological and shale gas attributes of the basins of interest.

As the report makes clear, these are initial estimates (not proven reserves) based on available data on shale formations from basins that already have seen substantial exploration for oil and conventional natural gas. As more focused exploration for shale gas continues from these basins and as more basins are explored these estimates of shale gas resources will likely change.

Update [ May 17 ]: [ Just a quick clarification on terminology. In the table above three estimates of gas are given. GIP is Gas in Place and it refers to the total gas content of the shale formation as estimated from geological attributes. Risked GIP is a fraction of GIP after applying certain success factors i.e. using information available of the productivity of the formation and other factors that might limit its development. Finally, Risked Recoverable is the fraction of Risked GIP that can be technically recovered. That is the amount - 63 Tcf- I have used in this post.

There are reports in the media claiming for example that shale gas in India has been estimated to be about 600 - 2000 Tcf. These refer to Gas in Place estimates and are comparable to the GIP estimates in the EIA report. They are sometimes improperly referred to as reserves (amount of resource that can be exploited economically at any given time). These large amounts mentioned in some media reports are not proven reserves but an estimate of the total gas content stored in the formation. Out of that only a fraction will be technically recoverable.]

India produced about 1.4 Tcf in 2009 and consumed about 1.8 Tcf.  These shale gas resources as they are realized will add significantly to India's hydrocarbon reserves.

Some broad issues to think about:

1) Will a shale gas policy allowing for exploration and exploitation be put in place quickly?

2) Will concerns about leakage of fracking fluids and methane into groundwater be addressed thoroughly and transparently.

3) Besides contamination of groundwater, there is also a concern of water usage. Wells drilled into shale require large amounts of water to be pumped in during the process of fracking i.e hydraulic fracturing of the rock.  How will conflicts of water use with farmers and affected communities be resolved?

Update Jan 5 2012: In a recent assessment (USGS Fact Sheet India Shale Gas 2011) of the Cambay, Krishna Godavari and Cauvery provinces of India, the United States Geological Survey has downgraded shale gas resources from 63 tcf estimated by the Energy Information Agency to 6.1 tcf. Downgrading shale gas resource estimates is not unique to India. Revisions are going on all over the world and is probably due to the observation that production from shale gas wells falls significantly after the first year or so of extraction. So their performance over the long term may not be able to match up the initial surge.  For example, the prolific Marcellus Shale from eastern U.S initially estimated to contain 410 tcf of gas again estimated by the EIA has been downgraded to contain about 84 tcf of technically recoverable gas by the USGS.

The India revision is analogue data and was developed using estimates of ultimate well recovery and success ratios from various U.S. data. This figure might itself be open for revision as more focused exploration is undertaken in these various basins.

A Long View Of The Age Of Oil

I took this from Ursula Goodenough's post on NPR's Cosmos and Culture blog.

Source: Steve Mayfield

Indian Natural Gas: Policy And Governance Issue

I wrote a post a couple of weeks ago on the geological context of Indian shale gas potential. Indian sedimentary basins have considerable potential in both conventional natural gas as well as shale gas. These resources are being hailed as critical to India's future energy needs.

But geological presence has to be translated into effective use of this resource and how the produced natural gas is to be most efficiently allocated to various sectors is a question that has not been satisfactorily fleshed out at the policy level. The big users of natural gas are 1) Feed stock for fertilizer 2) Power generation 3) Transportation.

Here is an example of the kind of thinking and debate going on within policy and energy expert community regarding best utilization of the gas resources keeping in mind India's food security, need to reduce oil imports, and achieving a cleaner emissions profile. These have been written by energy experts of Prayas Energy Group based in Pune.

Towards a rational, objective natural gas utilization policy, Ashok Shreenivas and Girish Sant, June 2009

Shortcomings in governance of natural gas sector, Ashok Sreenivas, Girish Sant, July 2009

Worth a read to get a flavor of the debates concerning policy and governance issues regarding these resources.

Indian Sedimentary Basins And Shale Gas

Over the last few months, several articles and papers have emphasized the potential role shale gas will play in India's hunt for energy. Shale gas is natural gas trapped in fine grained sediment.

Update May 18 2011: [ See post India Basin-Wise Shale Gas Estimates for estimates of shale gas from various Indian sedimentary basins.] 

These articles did not have any graphics so I am putting up a map of Indian sedimentary basins and a graphic depicting shale gas geological reservoirs.

Indian Sedimentary Basins

 Source: Geotimes

The basins of interest in terms of shale gas potential are the mostly marine Mesozoic and Cenozoic basins in Rajasthan and Gujarath and the Cenozoic basins of Assam. The Gondwana basins of central and eastern India are continental interior rift basins and are coal rich and have associated coal bed methane which if tapped could also play an important role in India's energy mix.

Shale Gas Geological Reservoirs

Unlike gas reservoirs in coarser materials like sands, natural gas in shale is trapped in micro pores which may not be connected to each other i.e. they have low permeability and the gas is quite difficult to extract.

India's conventional natural gas reserves are growing with new discoveries mostly along the east coast Krishna Godavari offshore basins. Early estimates of these gas resources if proved correct may more than double in terms of energy equivalence India's proven reserves of about 5.6 billion barrels of oil. Unconventional resources like shale gas have the potential of adding substantially  more to these resources. Currently natural gas makes up a small portion of India's energy consumption pie (see fig on left) and the chance to move towards a cleaner emissions profile by substantially displacing coal in power generation (coal makes up about 70% of electricity generation) and eventually as fuel for transport makes these unconventional sources a critical energy resource of the future.

I don't know how much shale gas resources India has because there has not been a systematic evaluation of shale gas. India's current energy policy prohibits exploitation of shale gas and coal-bed methane. The sooner that policy changes the better for energy starved India.  

[Update Sept 3:] As a reader pointed out in the comments there is recent movement from the government on the exploitation of shale gas and coal bed methane. See this article. A policy on shale gas is likely to be out by next year, while the government has already auctioned of several blocks for exploration of CBM from various basins.

Still, there is one aspect of exploiting these resources that has not been touched upon by any of the articles I have come across and that is the environmental costs of extracting shale gas. Since this gas is locked up in impermeable layers one of the common methods of extracting it is by hydraulic fracturing of the rock. This involves injecting the shale with fluids and gels mixed with particulates like sand to keep the induced fractures open and enable migration of the gas along open fractures.

A new film "Gasland" discussed on Science Friday last month looks at some of the problems of hydraulic fracturing or "fracking" of the Marcellus shale that underlies large parts of Pennsylvania, New York and Ohio and West Virginia.  Chemicals used in the injecting fluid has been reported to contaminate groundwater in Pennsylvania. At least according to the film, the energy companies have been less than forthright about the chemical composition of the injecting fluids which the film claims includes carcinogens and neurotoxins.

All this should send warning signals about the way and means by which India goes about exploiting these shale gas resources.  Groundwater is as important a resource for India's economic development as is natural gas. Almost all drinking water needs in rural areas are met by groundwater. A significant majority, about 2/3, of arable area in India is irrigated by groundwater.  Contamination of large portions of the overlying aquifer will be nothing short of a catastrophe for farmers who have no other water supply but groundwater.

The exploitation of coal bed methane offers another avenue for social conflict. The Gondwana basins which are coal rich are forested regions and home to many tribal communities. There has been a long history in India of the government and private mineral companies riding roughshod over tribal rights. The current violent insurgency that is taking place along tribal regions of Chattisgarh, Maharashtra and Jharkhand has its roots in the rampant exploitation and callous indifference shown by the state and private companies towards tribal communities.

So, shale gas and coal bed methane offer a significantly large energy source but also open up the possibility of more environmental and social disruption.

Update May 18 2011: For latest estimates of shale gas see - India Basin-Wise Shale Gas Estimates.

The Latest Numbers On Arctic Oil and Gas Potential

Some interesting readings I came across on hydrocarbon resources and challenges over the last few days.

Geology.com has published a report by the Energy Information Administration on the latest estimates of undiscovered technically recoverable oil and gas resources of the Arctic basins.

And the number is large - about 400 billion barrels of oil equivalent or about 20 odd percent of the world's undiscovered resources. This is an estimate based on occurrence of geologically favorable conditions in various Arctic basins. These are resources or potential. They will be or rather a fraction of these will be added to reserves only when someone drills and more directly estimates the amount of hydrocarbons that can be economically recovered.

We won't be running out of oil and gas or other fossil fuels like coal soon,  geologically, and BP's chief executive officer Tony Hayward thinks that in 2030 fossil fuels will still be meeting 80% of the world's energy needs.  He explains his position in a speech given at the Oil and Money conference, London. The title of the conference conjures up images of greedy petro-oligarchs doing everything to maintain a vice-like grip on the supremacy of fossil fuels, but the changeover to renewables won't be easy given the enormous gap that exists between the contributions from fossil fuels and renewables to our energy mix. India for example generates 70% of its electricity from coal and has plans to build plenty of coal fired power plants in the near future. The contribution of solar and wind to power generation in India is currently negligible. The U.S generates about 46% of power from coal and the contribution of non-hydro renewables to power generation is just 3%.

If fossil fuels are going to be an important if slowly declining part of our energy mix for some time to come then Geoffrey Styles of Energy Outlook argues that we rethink our reluctance to pursue low emissions strategies like carbon capture and sequestration (CCS). He writes on not just the technological and economic challenges facing CCS but also a public backlash against it based on  - he thinks - a lack of education among the public about geological principles and the efficacy and safety of CCS.

Plenty to think about as the Copenhagen climate change summit nears.

How Much Oil Underneath?

A friend asked me a few days ago why the Karnataka government were giving two different estimates for iron ore potential in the state. One file says that the iron ore reserves are about 3,447 million tonnes, while another department file says that the state has about 9,000 million tonnes of iron ore resources.

I replied that assuming the Karnataka government is using the words as they are commonly used in industry, reserves are the fraction of resources that can be economically exploited at any given time. Neither is a static quantity. Both will change given new finds, technological breakthroughs that enable recovery of previously out of bound deposits and the economic and political climate.

Coincidentally Scientific American has an article in their recent issue on the current reserves of oil and how that quantity is changing with new finds and new technology. They give one example:

When Kern River Oil Field was discovered in 1899, analysts thought that only 10 percent of its unusually viscous crude could be recovered. In 1942, after more than four decades of modest production, the field was estimated to still hold 54 million barrels of recoverable oil, a fraction of the 278 million barrels already recovered. “In the next 44 years, it produced not 54 [million barrels] but 736 million barrels, and it had another 970 million barrels remaining,” energy guru Morris Adelman noted in 1995. But even this estimate proved wrong. In November 2007 U.S. oil giant Chevron, by then the field’s operator, announced that cumulative production had reached two billion barrels. Today Kern River still puts out nearly 80,000 barrels per day, and the state of California estimates its remaining reserves to be about 627 million barrels.

This story will apply to a wide range of mineral/oil deposits all over the world.  Famously the United States has produced a cumulative 200 billion barrels of oil from reserves that never at any one time exceeded 40 billion barrels.

In the many responses to the Scientific American article I thought this one from JR Wakefield stood out as it explains what peak oil means from different perspectives:

Its not about how much oil is in the ground, it's how fast you can get it out and at what net energy.  This thus article is highly misleading.   Here are the Five Horsemen of Peak Oil:

1) Geological Peak. That is the point where we have consumed half the oil in the ground. So far we have consumed a trillion barrels. Estimates of remaining oil range, but the number appears to be 3 trillion barrels remaining in the ground. So we are not at geological peak. Hence skeptics of peak oil use this for their arguments, like this SA article does.

2) Flow Rate Peak. That's the point at which you cannot extract the oil fast enough to meet demand. This is especially so with old fields in decline (which is a fact) and new fields which have difficult geology (like this one).  The flow rate from them does not keep up with decline, nor keep up with growing demand. The article failed to mention that North Sea is all in terminal decline and the UK has to now import oil. Indonesia peaked years ago and has to import oil forcing them out of OPEC.  The Cantarell field in Mexico, the third largest in the world, and the US's 3rd import source, was producing 2.3mb/day at it's height.  Today it's 560kb/day with a 41% drop from last year.  WE ARE AT FLOW RATE PEAK NOW.

3) Geopolitical Peak. That's when exporting countries, due to their own growing demand, decide not to sell their oil abroad any longer but decide to keep what's in the ground for their own future domestic needs. So far only the US does this, but expect other countries to soon follow that.

4) ERoEI peak. This is the point at which it takes as many joules to extract the oil than you get from the oil extracted. That is, one barrel in to get 1 barrel out. Conventional wells in the 1960s were 100:1. That has dropped to about 25:1 today. Aging fields and new unconventional fields have very low ERoEI. The tar sands in Alberta for example is less than 6:1. Our entire society is based on the NET energy, not what's extractable. Calculations show that we will reach over all break even in oil extraction between 2020 and 2030. Once that is reached it basically means we have completely run out of oil.

5) economic peak.  This is the point where the economy cannot tollerate high oil prices and plunges the world into a recession, like this one which was caused by $140.barrel oil.

The challenge before us in terms of combating global warming is to ensure a transition from hydrocarbon energy to low emissions renewable energy much much before we start running out of the stuff not just in geological terms - which is not going to occur anytime soon - but by the other measures like Flow Rate and ERoEI as well. Likely even the Flow Rate Peak and the ERoEI peak are not constant but will keep shifting as more efficient ways of extracting oil and other hydrocarbon resources are discovered.