Abstract

Over the years geologists and economists have grappled about the unconventional gas reserves across the world. If they gas can be extracted it can lead to drastic changes in the gas market and make tremendous impacts on the economic growth. However, the methods of extracting the gas have remained controversial for decades with stakeholders questioning its economic benefits due to the high costs of production. Although incredible extractions methods have been adapted for the last hundred years hence making it cheaper to extract convectional gas when it comes to unconventional gas it remains problematic. Most of the unconventional gas remains rooted in the ground around the globe as scientists continue to introduce slow but sure methods of gas exploration and extraction. In recent years, increase in prices of convectional gas coupled by diminishing gas has raised the stakes of unconventional gas as the only realistic alternative to our immediate problems. This is due to the fact that even if green gas is better it is not viable in the foreseeable future due to logistics of production and subsequent use. However, some places like North America and United States exploration and subsequent extraction of unconventional gas is on the high gear with considerable success.

Introduction

Unconventional gas is simply the natural gas that cannot be extracted using the normal methods. The most common gas includes the following: gas shale’s, tight sands, liquids from chemicals and coal bed methane. These oils cannot be extracted, refined or simply transported like the convectional oil due to their compositions. Some of the compositions that inhibit these processes include high levels of vanadium and nickel metals in addition to substantial concentrations of sulfur. The implications is that it becomes hard to pump from them ground especially through pipes due tom their mere density. In fact some solidifies at room temperatures and are highly viscous even in liquid form. The product of these oil always have adverse effects on the environment hence it is very unpopular among green movements. One of the biggest unconventional oil reserves is situated in Venezuela at Orinoco belt with over a trillion barrels in capacity. This belt is also very rich in terms of oil sands and heavy oils meaning that if exploited fully it can produce significant oil compared to convectional oils they possess.

However, oil sands and heavy oils are generally found across the globe but Orinoco and Athabasca in Canada are the only two places that have significant deposits. In fact the two places have over a half of the world non convectional oil reserves’ which has been scientifically ascertained. However, exploration in to other countries such as Russia and Middle East is still minimal. In fact experts believe these places contain considerable amount of gas. This can be attribute to the fact that both place still have considerable convectional gas which is still been extracted coupled by the fact extraction  cost has gone done while e the prices of gas have risen leading to high profits hence they are experiencing a comfort zone. In the near future, experts claim that the extraction may pick up across the world especially in the countries like China where energy demands have skyrocketed in the last two decades. Although united states are extracting a considerable amount and national debate of dependence on the foreign oil taking a centre stage in recent times it seems exploration and extraction will continue tom increase in coming years.

On the other hand,  the  two areas in Canada and Venezuela have some slight differences in terms of composition of the gas for example in Venezuela belt extra oil is different from sand oil in that it readily flows hence it could be easily be produced with cold flow method. Though this method could be effective,its recovery rates are minimal compared to other methods. Conversely, exploiting these oil field pose a great challenge due to various production constraints. Some of the challenges include enormous capital required in terms of machinery, human resource, land and energy to power the extractions. However, recent strides have been made in dealing with those challenges and others are being debated like building of nuclear plant to power the production. This is due to the fact that the production of this gas strip mining techniques or in situation method which requires more energy than convectional mining techniques.

The Canadian belt has also raised other concerns about the gas especially the coal bed with debates about if it is renewable or not. Recent studies have shown methane is constantly made by the bacteria’s in the underground hence concluding that it is a natural resource. On the other hand, the pumping of water which is associated with extracting process interferes with the bacteria hence affecting the production of the gas. The production is also hindered by environmental activists who claim on the long run it will not be economical because of extraction methods. The debate about sustainable development has overshadowed the extraction of the gas coupled by technology constrains.

Methods of Estimating Unconventional Gas Resources

Although unconventional gas exists across the globe, the methods of estimations differ depending on the natural gas in question.  In case of shale gas estimations four techniques have been widely used to determine the amount of the gas. These methods are mainly: geographical parameters analyses, extrapolation experience of production, judgments by the experts and review of existing literature. In most cases these techniques are usually combined in order to boost accuracy levels hence they compliment each other. However, is good to note that problems exist in these methods and most have their loopholes. This can be attributed to the fact that this type of gas extraction is still new and a lot is yet to be studied and analyzed. This simply means that with technology still in its early stages with little progress in North America better methods are likely to be incorporated in the future.

The geographical parameters approach is based entirely in analyzing the characteristics of a rock in a particular area and then estimations are made about the gas which can be found and recovery rate is then assumed. These estimates are then used to tabulate the probable amount of gas available in a particular place. Unfortunately, the results are based on the assumed recovery rate hence it lacks uniformity because different experts can assume different recovery rate. This has generally led to minimal success has been recorded despite wide geological knowledge. There is also a challenge in selecting recovery factor due to subjectivity in making the decision. Secondly, this can lead to some recoveries being so low whereas the gas in that particular area is so high.

Thirdly, other issues arise when deciding on which geographical valuables to adapt.  This can pose a problem when you consider that the fact it is hard to estimate gas saturation in a particular place which is a factor in determining recovery rate. Fourthly, this method dependence on drilled wells means shows some serious loopholes. For example, in the United States well have been drilled have shown different amount especially those that are outside the sweet pot. This means that sometimes estimations can be determined until the actual drilling has taken place. Finally, the issue of uncertainty runs supreme in this method which raises serious questions about this technique effectiveness. Until to date , experts are yet to formulate mechanism of eliminating uncertainties that are usually associated with this technique.

Secondly, extrapolation method uses production data from a particular area and compares it with the same area where production has not been done. It can also be applied in different areas which have the same geographical characteristics. The results are therefore sensitive on the productions which have been happening. The actual estimates are usually based on assumed recovered gas from the wells. This is done by drawing a curve from the previous productions data and then it is extrapolated to the future. The behavior of the curve is that it decrease which has raised controversies among the experts about the rationale behind these method. It is not known if the decrease is continuous or it stop at a certain level. Some scholars have argued that decline has been underestimated hence consequently overestimating the ultimate recovery. One of the advantages is the fact  it eliminates some of the problems that are experienced when dealing with geographical approach.

However, lack of enough proof on the contrary has made the method to stand and this can been attributed to minimal production activities hence it is hard to discredit the method. Another loophole of the method is due to the fact that productions have happened with high yields. The implication is that recovery rate might have been overestimated considering there are areas with low yields.  The analogous that is used becomes problematic when choosing which to use because there are always difference in the outcome depending on which to use. The field is still new which raise the issues of successful predictions due to the fact that only a small area has been extracted hence lack of adequate data.

The process of delineating into high and low yield area may not genuinely show their homogeneity and this can create huge discrepancies on the final results.  However, with continuous production it will be easier to have a clearer picture in future due to availability of adequate data to compare. A good example of the short coming of this method was manifested when INTEK consultancy and USGS came up with two different estimates of shale gas of Marcellus. This happened despite of the two organizations using the same techniques to estimate the amount of tight gas in the region. The discrepancies were mainly caused by factors which are based on the subjectivity. 

Judgments by the experts are simply opinion by professions based on their personal observations. The professions just observe the area and analyze previous data ad finally and ten they finally come with their own conclusion about the return rate of the gas. One of the short coming of this method is simply because of the subjectivity of the person in question. It is hard to predict because we cannot actually predict the behavior of a rational person. This means that the method can give conflicting data based on different experts. This method can only be used in context of other methods in order to come up with conclusive data. When combined with other methods like geographical approach it can help to diminish the effects of subjectivity. In fact this method cannot on it own give any conclusive or viable information Finally, literature reviews entails analyzes of the past experiences and conclusions and how it turned up. It therefore simply compares the past information concerning the gas resource and the actual findings. The logic behind this method is simply to relate between the past in order to predict the future. The method still have the same short coming of expert methods because it is human beings who simply determine what to use and what not to use. However, it is applicable in the following ways:

It therefore draws information from a variety of sources which also means they have to incorporate different procedures that were used. This is usually done in order to eliminate the uncertainties that arise from different methods that were used in history in determining the resource quantity in an area. Unfortunately, this method does not offer much in regard to other countries which are outside North America.  Another potential problem is the fact that it is prone to subjectivity of the experts doing the analysis. This is simply because it depends on them to make methods from the past and they might be biased on their choice or simply over use one method. It cannot work independently and requires a lot of comparison with other methods. It is clear that the best method of estimating the shale gas in a particular area cannot be based on one method. It is therefore paramount to use at least to or more techniques in order to get considerable results.

Another technique that is used is Rate Time Decline Curve which is basically based on the assumption that the output trend of the past can be put in a mathematical sequence to predict how the future production will behave. However, this technique can only be used in a mono layer instance since multilayered brings out challenges o, fluids composition, permeability variations and volume. This means that when using this technique the following assumptions have to be made about the well: that is pressure is constant at the bottom, constant drainage area and the production is done at the near capacity. Some of the above assumptions apply when dealing with tight gas wells especially production in most cases is usually at the capacity. However, initial decline in parameters is usually accompanied by high permeability. Another challenge is the logistics problems in considering if the well is experiencing constant drainage area. A good drainage is the one that decrease the parameters of the well.

Despite great strides being undertaken in geophysics for the last one hundred years, we still have some major loopholes. In all the techniques discussed above they have their short comings and we cannot comfortably apply any single method successfully. Some people blamed these problems on the fact that the field of extracting tight gas is relatively new. The implication is that technology is yet to develop to the extent of making exploration or extraction cheaper. However, there is great optimism that with increased technology the productions cost will generally go down coupled by high production rate. In fact the same trend was not in the early twentieth century when the production of convectional gas was taken place.

In summary, we can argue that at the moment we still have a lot to do in order to formulate viable estimation techniques of the tight gas. This does not mean progress has not been made as some countries like United States are using more non-convectional energy. However, investment in research is paramount if we will ever successfully exploit the full potential of the tight gas across the globe. In the meantime tight gas estimation should involves systematic analyses of available date and at the same time apply all the available techniques. When these techniques act in a complimenting manner it generally leads to accuracy to some extent.

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