Waterjetting 22b - Steep seams and shrouds

It was not until we started to move the auger that I described last time, that I realized how heavy and cumbersome it remained. It is true that we could lighten it considerably (and we did in the UK version), but it was still largely a platform mounted device that was relatively easy to move on the surface, but which would be much more difficult to move around in the confined spaces underground.

In this regard it is worth comparing two photographs.

Figure 1. Coal being transported in the pipes at the Hansa hydraulic mine in Germany.

Notice in this first one how the coal is confined, there is no dust, and the tunnel is relatively clean and clear. Contrast this with the typical mining operation where the coal is carried from the working face to at least the main haulage drifts, and often all the way out of the mine using conveyor belts. (The method of transport that would also likely be used in a typical underground auger section).

Figure 2. Conventional belt conveyor carrying coal underground. (Famur )

Note that in the second photo the belt occupies most of the space in the roadway making passage more difficult, and that the coal is openly exposed. The problem that this occasionally generates is that the coal transfers from one belt to another as it moves through the mine by falling off the end of one belt onto the next. This puts dust into the air, and if not properly maintained coal dust can accumulate under the belt and around the support rollers and drives. If not cleaned this can create heat through friction, and can lead to disastrous fires.

Figure 3. Studying a belt fire underground (Office of Mine Safety and Health Research )

Confining the coal, and using the water that mined it as a transport fluid – or at least part of such – has many advantages.

The Russians were aware of this as they developed some of their different mining machines. One of these was a small monitor that could be pushed up a seam, from a lower drift (without the need of a higher one), by adding segments as the unit was jacked forward.

Figure 4. Russian GVD monitor

The monitor could be advanced up the seam, cutting a channel about 3-ft wide, and to the height of the coal. This relatively narrow channel confined the water and the coal produced, so that both ran back down to the drift, where they could be either enclosed in a pipe, or run into an open flume, that would carry the coal away. Once the drive had reached the end of the section, then the two hydraulic cylinders that sat under the monitor could be turned, so that, from a protected section down-slope, the monitor could successively ream out strips on either side of the entry, until the roof collapsed, or the operation holed through to the previous panel.

Figure 5. Schematic showing the sequence of extraction in a) a coal seam with a relatively strong roof b) a seam with a weak roof, where a pillar of coal is left between successive lifts, typically around 30 ft, so as to provide additional support to the roof as the coal is mined out.

Production from these machines averaged about 76 tons/hour from seams that were in the range from 2 to 4 ft thick, this was more than double the production output achieved by more conventional means, with significantly less manpower.

However while there are some conditions where gravity helps to bring the coal and water back together, there are many cases where this is not possible due to other constraints. This is where it becomes necessary to use a shroud to confine the jets, debris and water so that they can be extracted together, often using a vacuum to assist in the process.

Figure 6. Rendition of the combination of three cutting jets rotating around a vacuum tube to slice into material and remove it.

The particular device shown in Figure 6 was developed as a way of remotely slicing into high-level radioactive waste for the Pacific Northwest National Laboratory. The waste is held in underground storage tanks, where the levels are too high for human access. As a result the waste had to be broken into pieces and removed remotely.

The initial problem was that the tanks, though holding perhaps half-a-million gallons of waste, had only small (18-inches or less) ports through which they could be accessed. Thus a relatively small tool was required, yet the mining rate had to exceed 4-cu. ft/minute. The situation required an excavation system on the end of a robotically controlled arm. But the arm would have to be more than 60-ft long (in the end a cousin of the arm used on the Space Shuttle was used). Any mechanical force applied at the end of such an arm would have tremendous leverage on the holding fixture, and a relatively low overall force would have to be found, yet one capable of cutting material perhaps as strong as a weak cement.

The answer came in the form of the device shown in Figure 6. By placing three cutting jets to rotate around a central tube, connected to a vacuum line, one could cut into the material and break out relatively small pieces, which could be aspirated away with the cutting water. (The requirements were that there would be no water left in the tank for any significant amount of time). Because the bottom of the tank was some 40 or 50 ft below ground level a small, high-pressure (10,000 psi) jet pump was developed by Michael Mann, capable of drawing particles of up to an inch in size into the line, and then projecting them up with sufficient energy to carry them out of the tank.

Figure 7. Basic system conceived to mine high-level radioactive waste and remove it from a storage tank.

While this description of the system makes the tool seem to be relatively simple to build and operate there are a number of features to the design that are fairly critical in order for it to work well, and I will cover some of those next time.

Tech Talk - Optimism is becoming harder to sustain

For some time the nations of OPEC have been suggesting that demand for their oil will remain relatively stable in the near future, as increased production from the non-OPEC nations is expected to more than meet demand increases. Thus, for example, in the May Monthly Oil Market Report OPEC anticipates that global oil demand will increase by 1.14 mbd this year, while non-OPEC production will increase by 1.38 mbd, allowing a slight reduction in the volumes OPEC market, which continues to fluctuate around 30 mbd. In the longer term, however, as previous annual oil company prognostications of future supply have emphasized, the MENA countries are going to be pulling an increased weight in supply. For example ExxonMobil has noted:

The Middle East is expected to have the largest absolute growth in liquids production over the Outlook period — an increase of more than 35 percent. This increase will be due to conventional oil developments in Iraq, as well as growth in NGLs and rising production of tight oil toward the latter half of the Outlook period.

At the same time BP pointed out that in just a couple of years demand for OPEC oil is likely to start to steadily increase.

Figure 1. BP view of the increased demands to be made on OPEC oil with time. (BP Energy Outlook 2035)

A large part of that increase has been expected to come from Iraq. With the end of the Iraq war, and the government encouraging development there were some claims that production might eventually rise to over 13 mbd (ahead of both Russia and Saudi Arabia). But those optimistic views had to be measured against the reality that the country has taken a long time to recover back to the 3 mbd levels of exports that it had achieved before conflict.

Figure 2. The fall and recovery of Iraq’s oil production. (EIA)

At present OPEC reports that Iraq was producing at 3.298 mbd in April, making it second only to Saudi Arabia (at 9.579 mbd) among the OPEC nations. There still seemed to be some chance that the country might be able to reach some lower target figures, such as those suggested in the OGJ.

Figure 3. Anticipated Iraqi exports and their market region (OGJ)

Regrettably violence is now significantly increasing in the country, with Mosul being over-run by Sunni militants. This puts them in charge of the main pipeline to Turkey, as well as giving them potential control of some of the adjacent oilfields.

Figure 3. Known Iraqi oilfields in 2010.

Euan Mearns has written of the potential for oil from the Kurdish regions and Turkey has just allowed a second tanker to sail from Ceyhan carrying oil from that region to the market, without Bagdad’s permission. The oil is being delivered through a new pipeline capable of carrying 100 kbd from Kurdistan into Turkey. The main pipeline (shown in Figure 3) can carry as much as 600 kbd and runs from Kirkuk and perilously close to Mosul. The new pipeline runs through Kurdish territory until it reaches Turkey.

The declining influence of the central government over the northern territories of Iraq does not bode well for future production gains. Conflicts are getting worse, and the country is approaching the point where it could well be partitioned, since the government forces seem unwilling to take on the insurgency. Violence has already spread to the Al-Bayji refinery some 130 miles north of the capital. This is the largest refinery in the country, and currently produces below its 300 kbd capacity, all of which is used for domestic consumption.

The problems that this reveals are unlikely to be resolved soon, it is much more likely that they will continue to escalate over the next months, if not years. The impact on Iraqi oil production should not be underestimated. While the oil in the Kurdish region can make its way through the smaller pipeline that is under Kurdish control, the greater flow rates needed to sustain future growth in supply cannot be met by that pipe.

In the South developments in the Mesopotamian region around Basra from the fields of Rumaila and Majnoon will likely continue, with production being shipped out from the new facility offshore, although this is already quite significantly behind schedule.

Figure 4. Oil fields of Southern Iraq (IEA )

One has only to look at the degrading situation in Libya, where production has fallen from 1.6 mbd to a current level of less than 200 kbd, with no path forward now evident for production levels to be restored. Those familiar with the region doubt that there will be much improvement in the situation this year, and if the country follows the Iraqi path (figure 1) then it is unlikely that the world will see significant Libyan production for this decade.

That loss of a million barrels a day is likely to become increasingly evident as world demand continues to grow at greater than that level each year. When this is combined with the increasingly inability of Iraq to increase production as it moves back into more vicious internal strife, then one has to ask from where can future gains in oil production be anticipated?

The major oil companies have urged complacency having bet on Iraq and OPEC coming through (and in the process assumed that Saudi Arabia would also increase production significantly above 10 mbd, something that they have consistently declined to commit to doing). As Libya and Iraq remove that surplus from the table then the question becomes where else can it come from?

It is increasingly unlikely that US increases in production can be sustained for long, given the very short high-level life of the new wells completed in shale, and as the sweet spots in the current fields are consumed. Thus within a couple of years we are now likely to see an increasingly desperate search for new reserves. But those reserves take years to find and develop (as well as large amounts of money), and if the crisis comes at a faster pace than most now expect, then $100 a barrel oil may seem an absurdly cheap price to have had to pay. It may even have an effect on the next Presidential election.

Waterjetting 22a - Mining horizontal coal

Over the last few posts I have discussed some of the problems that arise in dealing with the use of waterjets in mining coal, when the material mined has to be collected and transported away from the face where the coal is extracted. I thought I would follow on that thread in a few more posts, ending up, hopefully, where I began back in the process of removing thin layers of material (such as rust) from flat surfaces.

But to get there I am first going to go back to coal mining. One of the problems with adapting what we might call conventional hydraulic mining to coal is that many of the coal seams around the world are relatively flat – it is, after all, the way in which the vegetation that became coal was laid down. Thus the gravity that can be used in a steeply dipping seam as a way of carrying away the coal and the water together, is not initially that helpful.

There are several different ways that have been suggested over the years to solve the problem. Initially these were based on existing mining machines, and methods for mining the coal, but with the teeth of a conventional machine replaced with high-pressure waterjets. One such, as I have written earlier was the MS&T Hydrominer, where the cutting teeth along the edge of a coal plow were replaced with oscillating dual-orifice waterjets to cut a kerf around the coal being mined.

Figure 1. Artist’s impression of the initial Hydrominer, with jets cutting a slot one foot deep ahead of the wedge shape of the plow.

The water used was less than that conventionally used on a mining machine to suppress the dust generated as coal is mined from the solid, and the coal loads onto the armored face conveyor on which it rides down the face.

That particular design was based on an earlier mechanical machine, the Meco-Moore, which I had previously seen working on a longwall in the United Kingdom.

Figure 2. Meco-Moore mining machine set up to mine coal. The cutter jibs cut slots and the coal then collapses onto the transverse conveyor.

However this concept required a considerable investment in the supporting longwall equipment both to hold up the roof and to remove the coal. An alternative approach was to continue to conventional roof-and-pillar mining which is the most popular method of underground coal mining in the United States, but again replacing the cutting teeth with waterjets. The first of these was conceived by IIT Research Institute in Chicago, under Dr. Madan Singh.

Figure 3. A high-pressure waterjet continuous miner.

Unfortunately in this configuration the system did not work well. The jet pressures used were too high, and in consequence the volumes of the jets too low to achieve a deep penetration into the coal.

When the jets were replaced with a combination similar to that of the Hydrominer, and in a device we called RAPIERS, a slightly better performance was achieved, but the demand for innovation had, by that time passed for a spell, even though this particular machine was developed with considerable technical input and financial assistance from the Jet Propulsion Laboratory in Pasadena.

Figure 4. Progression of the RAPIERS machine in room-and-pillar mining.

Both of these machines required that a second set of machines sit behind the excavator and carry away the coal that had been mined, again at significant cost, and they also required machines to support the roof.

There is a different type of machine that is often used at the edge of the productive limit of surface mining. As seams near the surface get deeper so the cost of removing the overlying material becomes too expensive to justify continued mining. At that point companies may bring in an auger which can drill long holes into the coal, and remove the material as with conventional smaller augers that might be used for drilling in dirt (or even drilling holes in wood).

Figure 5. Conventional auger mining (Rosamine )

Because the auger drills a hole to the size of the following scroll, it is relatively easy to carry the coal back out of the horizontal hole, which might exceed 300 ft in depth. But there is a problem with the machine, in that the cutting force to push the auger teeth into the coal at the face of the machine has to be carried through the entire string of augers.

Because of the string of segments this becomes more difficult to control with longer depths, and in addition there is a friction loss due to the continual rubbing of the scrolls against the floor and sides of the hole. Together these act to limit the machine range, since there is little to steer the machine other than the direction of the hole, as it deepens.

Figure 6. Picks on the face of the auger, with early jets mounted in the center of the head to cut a central hole.

If, however, the picks on the face of the auger are largely replaced with waterjet nozzles, particularly at the outer edge of the auger, and with the flow directed there, rather than, as shown in Figure 6, towards the center, then an outer free face – up to a foot deep, can be cut ahead of the cutting head. With larger auger heads the nozzles can be placed across the face, to break the rib of coal, should it start to get too large – especially since the coal needs to be fragmented somewhat to feed down the auger.

Figure 7. Waterjets across the face of an auger (courtesy W.A. Summers)

The reduction in the amount of force that this allows on moving the auger into the coal can be illustrated by example. In developing a version of the machine we built an artificial coal face, made up of coal pieces and cement. It is a little more resistive than conventional coal, however the student, Chris Cannon, had little difficulty pulling the machine into the face with a come-along, even though he only had one uninjured arm at the time of the test.

Figure 9. Chris pulling the 2-ft diameter auger into the artificial coal seam.

By confining the coal and water it was possible to recover both, so that the water could, if needed be recycled.

I’ll continue the thread next post.

Tech Talk - what the EPA Plan neglects

One of the problems, I suspect, with predictions of future energy use and production is that physical reality can become entangled in the politics of the day. Thus news that tends to negate the optimistic views of future American oil and natural gas production is subsumed by the need to keep the level of those predictions hecause of other political needs.

President Obama has now announced his decisions on a new incentive to combat his perception of the future as it sits threatened by the increased carbon dioxide produced by the burning of fossil fuels, particularly coal. As announced by the EPA, the Clean Power Plan “will maintain an affordable, reliable energy system, while cutting pollution and protecting our health and environment.”

The proposed rule has the intent of lowering carbon dioxide emissions by 30% from the levels of 2005, by 2030. As with many energy-related plans this one will take some time to implement, particularly since individual states have some input to the final program that will be put in place. More to the point, it will influence the thinking of power generators and legislators over the next few years.

Beyond the actual implementation, the real impact will be in the planning departments of the utility companies around the country. There is at least an even chance that, at some time in the future, these will become the regulations that must be followed, and as future power plant construction is planned, so the options that will be considered will now be changed to accommodate these likely regulations.

Realistically the closure of coal-fired plants will likely be followed by the construction of more natural gas plants, since the overall electrical energy needs of the country are unlikely to fall significantly. In the short term this is unlikely to be a problem. However as one moves into the intermediate term (say more than 5 years out) the old plants will have gone, and the country will become increasingly dependent on natural gas, in the same way as Europe is at present. As the old coal plants are demolished, they, and the coal mines that supply them, cannot be resurrected within a five-year period given the amount of permitting, financing and overall planning that is now required for such construction.

Natural gas has advantages over coal, in that it can be supplied by pipeline that makes it less susceptible to weather. But by the same token it is rarely stored on site, but metered along the pipeline as demand rises and falls. As history has shown, this can lead to critical shortages when, at times of high demand, the pipeline cannot keep up with demand.

At present the likelihood of problems seems remote, wells continue to be sunk and production in increasing in fields around the country. But if one goes beyond the picture that is projected as reassurance to those concerned for energy supply in the future the numbers revealed are not that comforting.

Figure 1. The changing picture of natural gas demand (EIA)

One begins with the prediction that the US has about 100 years of natural gas supply with a total extractable volume in reserves and resources of over 2,718 Tcf. It is a reassuring number but, as with the total volumes of either oil or coal in the ground, it does not really give that much information on what will be available as demand continues to rise.

Consider that, increasingly, the volumes of natural gas that are being sought are in shales, where the well must turn and drill along the shale horizon, before being fracked to produce gas and oil within the rock.

Figure 2. Number of rigs defined by type of well (Baker Hughes via EIA and Penn Energy)

The increasing dominance of horizontal well completions brings with it a considerable increase in well costs. You can see this as the technique became of increasing importance after 2005.

Figure 3. Change in the average cost of natural gas wells (EIA )

Well construction prices have continued to rise since that time, with numbers now running up to and beyond $10 million. The rising costs makes it harder to achieve a reasonable return on that investment, particularly as there has been no great increase in the overall price of natural gas to reflect its increased popularity, in large part because of the rush to drill and produce the known reserves.

Figure 4. Recent changes in natural gas prices (EIA )

As a result the number of rigs working in the natural gas fields has fallen, to the lowest levels of the recent past.

Figure 5. Change in the natural gas rig count over the past year. (Baker Hughes )

If you can’t make a profit on the merchandise, then after a while you stop trying to produce it. Despite the optimism that leads folk to anticipate large volumes of low-priced natural gas being able to sustain us into the foreseeable future if the companies cannot make a profit, after a while they stop. Which means that prices will go up, re-opening the cycle, but on a higher step. In time this will bring natural gas prices back up to around $8.00 per tcf, which will make the industry more comfortable.

What it will not do, however, will be to favorably impact the economics of the electricity business, where doubling the cost of fuel has a quite negative effect on prices and overall economics. But concerns over the rising price to be paid has had little impact yet on political decisions on energy in Europe, and one has to presume that a similar blindness to energy price consequences will also prevail in the United States. After all there is lots of natural gas around, it just has to be perceived as remaining a cheap fuel to validate the political plans . . .right ??!!

Waterjetting 21d - confined coal transport

Collecting the material that a high-pressure waterjet has dislodged from a surface can be carried out in a number of ways, depending on the scale and volumes of material that have to be removed. One of the initial problems that arise depends on the energy of the jets that are striking the target, and the part of that energy that remains in the water and dislodged particles after the jet impact.

If a surface is relatively smooth (think for example of a ship hull, or the deck or sides of a bridge) then when a jet has hit the surface and removed the small amount of material (such as rust or paint) it will likely continue in a relatively straight line forward, since the surface roughness of the target, while disrupting and flattening the jet, has not sufficient angle to radically change much of the flow of the jet.

Which might make it time for a little recap. One of the experiments that I would run with an introductory undergraduate class was to give each student a high-pressure lance, and then have them hold the nozzle just above a target surface. The pressure of the water being fed to the gun was then slowly raised, and as this occurred the jet went from striking the surface and then just flowing along it, when there was no penetration or surface material removal, to being reflected back at the lance holder.

The reason for this is that, as soon as the jet started penetrating into the material (usually a rock for the purpose of the demonstration) then the water is entering a hole where the only exit is back the way that it came in. It is a salutary lesson for the lance holder since all of a sudden the jet is coming straight back (which is why all the personal protective equipment is an important part of the lesson).

This only holds true where the jet is hitting a relatively flat surface in an approximately normal or perpendicular axis of attack. In the more general case the cut along the surface will cause the water and debris to scatter in a more general spread, and it becomes a more difficult job to collect both back together in a way that allows both to be contained and removed from the site (an increasingly important part of the environmental parts of the process).

There are places, such as steeply dipping coal seams, where the geometry of the excavation itself helps to confine this ejecta and direct it, under gravity, to fall into a narrow space where the water and coal particles are brought together so that the coal is suspended in enough water that it can then be carried away from the work zone.

Perhaps the best example of this was the Sparwood mine in British Columbia in Canada, where the mine was extracting coal from a seam that was roughly 40 ft thick, and which dipped at around a forty degree angle.

Figure 1. Section showing the Sparwood mining plan

Drifts were first run at a slight angle (this started at six degrees, but after lining the flume with Teflon plates the mine was able to reduce this to just over four degrees) to the strike of the seam. This was a sufficient angle that, when all the coal was caught in the flume it would be carried down without settling by the spent water from the mining process, which was also trapped in the underlying drift, and held by a barrier across that drift. The shallower the angle then the more coal could be recovered above the main haulage ways at the back of the working area.

The mining tunnels (drifts) were first driven to the back of the section, using a small road heading machine to extract the coal, while installing a flume along the side of the drift so that the coal could be immediately transported away as it was mined. Full support to the tunnel was also installed using arch girders, with bracing wooden slats between the girders. Once the drift had reached the end of the seam, then a hydraulic monitor was placed in the uppermost drift, and the arch girders and wooden planks removed from the final fifty feet of the tunnel, with the monitor placed under the last few tunnel supports of the remaining tunnel section.

Figure 2. Layour of the monitor within the access drift.

By using a jet of just over an inch in diameter. the jet was able to reach the back of the section of coal that had been exposed when the supports were removed (zone 5 in figure 2) a distance of over 120 ft. the monitor was moved by two sets of hydraulic rams, but if you note where the operator is standing at the back of the machine, this is some 40-ft from the opening and the mining operation itself is not visible.

Figure 3. A monitor in operation at Sparwood. Note the short length of the barrel, which would still produce a high-quality jet, since flow straighteners were used in the barrel, placed directly behind the nozzle.

The operator uses the rams to move the nozzle in an oscillatory path, and listens to the sounds of the jet as it strikes the coal. The sound is quite distinctly different when the jet is hitting coal, as opposed to striking roof rock or shooting into the open space of the drift updip. (I was told this, not having that experience, though I have found similar changes in sound useful in other applications that I will discuss from time to time). It takes, apparently, a couple of days for an operator to be able to consistently detect and use the sound differences to be able to effectively mine with the monitor.

Figure 4. Operator at the Sparwood mine, standing at the back of the machine, and beside the flume.

The way in which the coal broke under the jet attack was only controlled by the operator to a limited extent, so that there can be a significant volume of large coal surviving into the lower entry for collection, and flume transport needed a smaller size distribution. For this reason the coal company installed a coal breaker at the entry to the flume so that the water carried the coal lumps through the breaker, and only then did they enter the flume (Figure 4).

At the time that I visited the site the slurry was higher than shown in the above figure, with coal overlying parts of the back of the breaker. To make it easier to operate the breaker, while keeping the operator safe behind the roof supports, a second small monitor was set by the operator which could be used to clear off the machine from time to time.

The machine was operated by two individuals and over the course of ten years averaged a production of over 3,000 tons a shift. It was also for many years, the safest mine in Canada. To put that production in perspective, in those years an average section in the underground mines in Illinois, running a continuous mining machine, might average about 700 tons a shift, and would need about 14 men to achieve that target. (Production rates have since risen considerably as automation and remote control have reduced the number of folk needed, while higher-powered machines now produce greater coal volumes faster.)

Yet the range of seams where this type of mining can succeed is limited, particularly in the United States, and in coal seams that do not dip as steeply it becomes more difficult to control the particle and water spread as it leaves the impact region.

I’ll talk about a specific way that one can, on occasion, change that, in the next post.

Tech Talk - China, Russia and East Siberian natural gas

The recent agreement between Russia and China for the sale of some 38 billion cu m of natural gas a year for 30 years, at a reported price of $400 billion ends a long-going negotiation between the two countries over the price of that supply. (Which works out at roughly $10 a thousand cubic feet, just over double current US prices). The price apparently includes some $25 billion to help with construction of the pipelines that will start feeding gas into the Chinese networks within four years. It is less than the price of LNG in the Pacific, and thus will likely lead to market adjustments for that product.

Figure 1. Potential interconnections to bring Russian gas into China (Washington Post )

It is equally of interest to see where the other ends of the potential pipelines lie, since this locates the natural gas fields that will be used to provide the supply. Looking at the distribution of pipelines and fields, the current preponderance of connections into Europe is hard to miss, at the same time as is the large gap in development in the Eastern side of the country.

Figure 2. Natural gas basins in Russia (Oil Peak )

Thus while the potential connection from Urumqi to Gorno-Altaisk allows the Chinese pipeline into a feed from the network that supplies Europe, that market is not going to go away. Yet the two towns are just 560 miles apart and the connection has been known as the Altai project, or Western connection, since it was first planned over 10 years ago, extending a new pipe up towards Yamal and the basins that feed Europe.

Figure 3. The Altai pipeline project (Gazprom )

Developments that reach up into Eastern Siberia, above Lake Baykal and Mongolia into the fields of Kovyktinskoe and Chayandinskoye through the “Power of Siberia” pipeline will allow gas from those fields to also feed Western China.

Figure 4. The connecting fields and pipelines for natural gas from Eastern Siberia (Gazprom )

The gas fields will feed into gas production facilities in Irkutsk and Yakutsk with oil production scheduled to start from Chayandinskoye this year, and natural gas production to follow by 2017. The field is expected to yield 25 billion cu m of natural gas and 1.5 million tons of oil a year at full production, and is estimated to hold 1.2 trillion cu m of natural gas. Kovyktinskoe was licensed to Gazprom in 2011 for exploration and production and is estimated to hold natural gas reserves of 1.5 trillion cu m. Smaller local fields at Bratsk and Chikanskoye have been developed since 2007, with the gas being used locally to supply the region.

Figure 5. Developing natural gas fields in Eastern Siberia (Gazprom )

These two fields alone therefore seem capable of meeting the current sales volume that is to be needed for China, given that the time to delivery is some four years, and both fields are anticipated to be on line, with the gas production facilities, within three years.

Pipeline construction is already underway. The “Power of Siberia” will initially connect into Vladivostock, taking the natural gas to the higher demand industrial Eastern China, but likely the additional funding that China is now providing will also help the Westward expansion to the Western gateway.

Figure 6. The Power of Siberia natural gas pipeline as planned. (Gazprom )

The natural gas pipeline is being routed along with the East Siberia – Pacific Ocean (ESPO) oil pipeline to simplify logistics, the second section of which was opened by President Putin at the end of 2012, a year ahead of schedule. The two sections will have a capacity of handling 80 million tons of oil a year (roughly 1.6 mbd) as supplies increase from the different fields to achieve that target. (The largest current contributor is the Vankor field producing slightly more than 500 kbd).

Yorubcheno-Tokhomskoye is expected to come on line in 2017, reaching full production of around 100 kbd by 2019, as the field develops the natural gas associated with the field will also be brought into the network.

There is anticipated to somewhere around 60 trillion cu. m of natural gas in Eastern Siberia (about 23% of the Russian reserve in 2009) and as this is only now being developed and the infrastructure put in place, it can be expected to last for some considerable time.

So far I have not mentioned the reserves that are now on line at Sakhalin Island. Gazprom built the Sakhalin–Khabarovsk–Vladivostok pipeline in 2011and this carries the natural gas down to Vladivostok, and thence largely into China and other Asian markets. The island also has an LNG facility which supplies that fuel to Japan and North Korea.

Figure 7. Natural gas pipeline from Sakhalin Island (Gazprom )

The pipeline is intended to carry up to 30 bcm per year of natural gas from Sakhalin fields, particularly those offshore.

Given the size of the fields that are thus available to Russia and that will feed into pipelines that will be in place at the time called for in the new agreement it is clear that the new market will not likely require any input from the fields that are currently supplying Europe and other markets.

As industries switch out of coal and into natural gas, however, a change driven partly by environmental and partly by cost considerations, so the demand for natural gas may potentially increase significantly. (As a minor indication of this the primary fossil fuel at the university in town is now natural gas and the coal fired plant just closed). There is less capacity to store natural gas than other fuels, which can raise some concerns over available supply in particularly cold days of the year. Such factors may change the situation somewhat, but realistically I would suspect that natural gas will play an increasing role in global fuel supplies for at least another decade.

Waterjetting 21c - collection in Gilsonite and steep seams

Picking up the debris from a waterjetting operation can be a more expensive part of the process than actually removing the material in the first place. This is particularly true where the material no longer has any inherent value, but is sufficiently toxic that it has to be collected and then properly disposed of. On the other hand, in most aspects of mining, it is the inherent value that is contained in that debris that makes the whole process worthwhile, and in this latter case requires that as much of the material be initially collected as possible. This can be difficult where, for example, gold particles are being produced, since these are heavy and naturally rapidly sink through the water to settle onto the floor where, if this is rough, they can then lie is natural traps that make it hard to re-elevate them and move them to a desired collector.

If one is to continue to move the particles there must be some mechanism that will continue to move the particles to the point that they can be collected. The very condition that makes it difficult to manually mine coal from steeply dipping beds also serves to carry coal and other minerals from those veins, once the material is broken free from the solid.

Consider, for example, the early mining of Gilsonite, which is a naturally occurring hydrocarbon found in thin vertical veins in places such as Utah. It is named after one of its first developers, Samuel H. Gilson.

Figure 1. Pieces of Gilsonite (Metroexpand )

The problem with mining this material is that the dust is very explosive, and remote, safer methods were needed to get men away from the mining process. In 1957 the major American company, American Gilsonite, turned to the use of hydraulic mining. At first the seam was mined using a series of horizontal lifts, with the washed out material and water being collected in drifts that carried it to a pumping station. However, because of the vertical seam, it was easier to used a drill, with lateral jets so that the rotating waterjets mined and flushed the material down into underlying drifts, where it could be collected.

Figure 2. Method for Mining Gilsonite.

By moving the mining tool along the vein the material could be mined out, without miners at the working face, and without the risks of explosion from the conventional mechanical mining methods.

A recent blimp trip over the Bonanza mine shows the results from years of the mining process, as the seam has been removed.

Figure 3. Mined out seam of Gilsonite at Bonanza, Utah. (J.S. and S.W. Aber)

More recently the mine has returned to a mechanical method for mining the material since the customer wanted a dry, rather than a wet product, and, with demand for the material rising, hopefully they will continue to operate safely – the material is now airlifted to the surface. Mining has been restricted to the top 500-ft of the vein.

The hydraulic mining process demonstrated here shows some of the advantages of the use of waterjets in that there are no workers in the mining area, and that the tool is able to remove the mineral without generating the sparks and explosive dust clouds that can be a danger otherwise.

Figure 4. German coal seam side view, showing thickness and angle of slope. (Benedum, W., Harzer, H., and Maurer, H., "The Development and Performance of two Hydromechanical Large Scale workings in the West German Coal Mining Industry," paper J2, Proc. 2nd Int. Symp. Jet Cutting Tech., BHRA.)

Coal mining has some of the same problems, and in Germany the idea was tried (in a slightly modified version) as a way of mining coal. Rather than operate from a drilling rig at the surface, holes were drilled along a very steeply dipping seam. The process was in two parts, evaluating whether it was better to start at the bottom and drill up, or to start at the top and drill down.

Figure 5. Methods tested for bore and mine coal recovery. (Benedum, W., Harzer, H., and Maurer, H., ibid.)

The method where the drill goes down, and then reams back up turns out to be the better approach. The reason for this is that the coal breaks out along natural planes, and these can produce coal pieces that are large enough to block the drilled hole through which all the material must pass, when drilling upwards. This is not a problem when drilling down, since the coal is falling through a much larger space (the mined out volume). This makes it a little more difficult to recover, since it is not confined where it falls into the lower drift. But, by adding a small monitor in the second drift, the broken coal can be lifted back into a slurry that can then be channeled into a flume, and carried away from the working area.

The process was effective, in that it showed that the coal could be mined from one drift to the next, using the method, but it was difficult, because of the varying conditions of the seam over its length, to make the connecting drill holes at an economic speed, and thus to mine the coal at an economic rate.

Figure 6. Looking down to the lower drift from the upper, after mining, with all the coal removed. (Benedum et al ibid)

Note that in the above picture there is little roof collapse into the mined out cavity. This is either beneficial (since it allows all the coal to be removed) or it can be a disadvantage. Other than the safety factor of having a roof hang up until a very large area collapses at one time (where the air blast can do considerable damage), a continual roof collapse as the coal is mined can provide confinement for the water and, hopefully, enough restriction that the water will carry the coal to a collection point.

This was the idea behind the JPL coal mining worm that they proposed some years ago:

Figure 7. The JPL concept for a horizontal jet mining system (Miller, C.G., and Stephens, J.B., Coal Worm: A Remote Coal Extraction Concept, JPL Report 5010-7, December, 22, 1976, Jet Propulsion Laboratory, Pasadena, CA.)

Unfortunately when a coal mine roof collapse occurs the rock breaks into relatively large pieces so that the water can flow away through the pile, without being confined sufficiently to provide the needed motive force to move the coal to the collection point. For that, the system would still need a steeply dipping bed, and I’ll talk more of this and debris collection in future posts.