Conventional and Unconventional Systems in Petroleum Geology

Introduction

A system is defined to be a set of interacting parts that are made to function as a whole unit. The systems view involves a methodical study of the linkage that is present between the parts of the components and how each of them work together (Christiansen and Hamblin, 2014). It has helped geologists, engineers and researchers to better understand how the Earth operates and how each of the things interrelate with one another (Christiansen and Hamblin, 2014). Most of the systems are open, i.e., they can exchange the matter and energy across their boundaries and share it across the area. Such types of systems are often considered to be dynamic in nature as they generally do not have any boundaries inside of them. Naturally occurring systems, however, have a predefine boundary present in them. These systems boundaries can either be that they are covered by a flowing stream of water or covered in rocks or the boundaries are considered to be arbitrary in nature as they are defined for the purposes of the research. Everything that is outside the system is considered to be its surroundings and these are not considered to be part of the system (Christiansen and Hamblin, 2014). Systems are considered to be an integral part of the science as it encompasses all components of the Earth such as air, fire, water and rocks which allows the engineers and geologists to gain a more comprehensive understanding of the world (Butz, 2008).

Of the systems that are present in the Earth, the two main ones that are found are the conventional systems and unconventional system. The purpose of this assessment is to explain and assess the differences that are found between conventional system and unconventional systems. It would allow us to understand what can be obtained from them with respect to the hydrocarbon resources that are collected from them. In addition, examples would be provided as well in order to clearly illustrate the differences present in the two systems as well as the hydrocarbon resources that are found from them as well. These would help in understanding what kind of gas and oils can be produced from them which can be used as fuel or petroleum.

Main assessment

Conventional and unconventional hydrocarbon resources are generally formed during the thermal progression of rocks or fossils. Both of these are typically used to refer some quantity of fuels that can be used to contribute to a reserve if the resources are economically extracted. The difference that is found, however, between them is that both of these are a different set of resources that can be removed as well as the ease with which fuels can be obtained from it.

Conventional resources such as oil and gas are made from traditional resources are generally formed by using standard or straightforward methods to extract the products from them (Everett et al., 2012). The extraction of the fossil fuels from these is generally done using standard processes which are used to remove these from the deposits. In general, conventional resources are considered to be more comfortable and less expensive to produce as these do not require any specialized technologies to extract it, and accepted methods can be leveraged in order to collect them (Everett et al., 2012). Due to the simplicity that it possesses and how cost-effective it is to produce one, it can be seen that conventional resources are generally some of the first resources that are used in the industry activities.

In addition, conventional oils are hydrogen-filled compounds that are made of short hydrocarbon chains and made of hydrogen and carbon atoms which range from C1 to C60. Due to these, it can be seen that these have lower molecular weights compared to unconventional oils (Gordon, 2012). Since most of the energy from these comes from hydrogen while carbon is just there to carry the hydrogen atoms, it can be seen that conventional oils produce more power with less waste compared to their unconventional counterparts.

In contrast, unconventional oils are considered to be harder to extract as it is seen that some of the resources are trapped in the reservoirs that are surrounded by reduced permeability and porosity. This leads to an increase in the difficulty, or it is generally impossible for oil or gas to flow through the pores and exit out into the standard wells. In order to extract from these resources, specialized techniques and tools are generally used that can be expensive to produce. For the extraction of oils such as shale oil, a hydraulic fracturing step is used to form several cracks in the resources so that the oil and gas can flow through it. In the case of oil sands, a situ deposit should utilize steam-assisted gravity drainage that is able to form a thick bitumen from the underground deposits. All of these methods are considered to be costly compared to the ways that are generally used for the extraction of conventional oils (Everett et al., 2012). However, it can be seen that these allow for the production of hydrocarbon products from the places that are not accessible before or were unable to extract from. These resources can generally be turned into reserves which could then be economically utilized.

These kinds of resources are generally identified by their distinct characteristics. The heavier the oil is, the more carbon it contains along with being high in sulphur and is filled with impurities. These are generally heavier compared to conventional oils (Gordon, 2012). Due to the contaminants that are found inside of it, impure oils require typically substantial energy input to upgrade and process in order to turn into synthetic crude oil which could then be used to make petroleum-based products or fuels (Gordon, 2012). Generally, it can be seen that some of the newer oils are in solid form and must be extracted through mining or heating until they are able to flow (Gordon, 2012). These new forms of fats are generally considered to be less valuable compared to the traditional or conventional oils as these require more time to transform and produce, which makes them less marketable as well.

Unconventional systems have generally played an essential part in the increasing demand in the global production of petroleum and gas, which have been demonstrated by the creation of the oil sands, CBM (coalbed methane), and gas along with the rapid increase in the shale gas and tight oil production that is present in countries such as the United States. (Jia, 2017). In addition, Venezuela and Canada are two major countries that produce oil sand and heavy oil. These are generally more utilized as decades of oil, and natural gas productions have led to extensive use of conventional resources. Due to these, new technologies are being made that could allow one to extract unconventional oils through the use of economic methods that were considered to be impossible in the past. The formation of these have a significant commercial potential as large section of hydrocarbon reserves are estimated to be found in unconventional resources

Meanwhile, the largest production areas for conventional oils are the Middle East and the Central Asia-Russia (Zou et al., 2014). About two-thirds of the remaining recoverable reserves and undiscovered recoverable resources of conventional hydrocarbons are mostly found in these two regions, with the oil and gas accounts for 66% and 67% respectively. The output of the oil and gas proportions of these two areas has been rising continually (Zou et al., 2014). Unconventional resources have become an essential resource for fossil fuels in the world. It can be seen that tight oil has been crucial for researchers and engineers due to its abundant reserves, wide distribution and high reliability of the recoverable resources as well. Unlike conventional resources, conventional resources like tight oil reservoirs are dominated by extremely heterogeneous reservoirs that are constructed with nanoscale pore systems with small pore throat size and complex pole structure that are made to control oil accumulation and percolation in it.

Conventional hydrocarbons generally focus on studying whether the hydrocarbon is accumulated in a trap or not and assessing the six elements along with their matching relations (Zou et al., 2013). The items that are found inside these are the source, reservoir, caprock, trap, migration and preservation. Meanwhile, unconventional oil and gas concentrate on the study of whether the oil and gas are contained in the reservoir and assessing the six elements. Unlike conventional resources, however, the six factors that are being evaluated in it are hydrocarbon source properties, lithology, physical properties, brittleness, hydrocarbon-bearing property and stress anisotropy along with their matching relationships (Zou et al., 2014). Each of the assessment is done in order to determine the quality of the hydrocarbon found from it as well as to understand the difficulty with which hydrocarbons can be converted into fuels or petroleum-based products.

Based on these, it can be observed that conventional resources mainly deal with hydrocarbon generation, reservoir beds, hydrocarbon distribution and recovery. The critical theories usually consist of anticline and trap, hydrocarbon generation by organic matter and petroleum system. In addition to these, other methods such as continental petroleum geology and marine and deep-water petroleum geology are also considered to be important in these regards as well. Meanwhile, unconventional resources are characterized by their continuous distribution, tight reservoir properties, multi-phase coexistence, proximal or intra-source accumulation and the unique mechanism that is made to accumulate them which cannot be explained by classical petroleum geologies. These are part of the economic significance that is made to increase the global petroleum reserves and of the scientific importance that can help scientists to innovate in the petroleum geology.

Conclusion

From the above assessments, a clear distinction between unconventional and conventional resources has been defined. This would help in understanding what kinds of hydrocarbon products can be obtained from them and how we can obtain it from them, which can be useful in the future when working on extracting petroleum or fuels from either of the resources as it would help in understanding what methods or techniques should one use in order to accomplish it. Additionally, it provided an insight on what makes them different and what each of them are made of as well.