Unconventional Gas Resources Research Articles

Fractal analysis of CT images of tight sandstone with anisotropy and permeability prediction

For developing unconventional oil and gas resources, it is necessary to quantify the heterogeneity embodied in both pore-size distribution (PSD) and pore spatial distribution, on the basis of which the relationship between the seepage characteristics and the microstructure of heterogeneous porous media could then be clarified. In this work, micro computed tomography (μCT) and image processing technology were applied to characterise matrix pore structure in tight sandstone. Fractal theory was used to investigate the image-based heterogeneity of tight porous media. On the basis of the verification that the PSD of the tight rock is statistically self-similar at a certain scale, we investigated the relationships between porosity and fractal dimension, and between 2D and 3D fractal dimensions, respectively. The results showed that the pore structure characteristic parameters with anisotropy, i.e., the ratio of the minimum pore size to the maximum pore size λ max /λ min and a proportionality constant C KT , could be obtained by liner fitting fractal dimension and porosity. Moreover, the 2D PSD characteristics of the ‘standard cross section’ were consistent with the 3D PSD characteristics of pore network. A fractal permeability model was established by treating the connected pores in the matrix as a bundle of conical micropipes. The permeability values predicted by the proposed model agreed well with those predicted by finite volume method simulation under the condition where irreducible pores were removed. A sensitivity analysis indicated that increasing the heterogeneity of the PSD and pore spatial distribution reduced the flow capacity of the matrix, particularly for low-porosity porous media. • A method to verify the fractal self-similarity of pore size distribution in CT images. • D f-2 vs D f-3 of microstructure in heterogeneous porous media was explored. • Fractal anisotropic model for permeability prediction in heterogeneous porous media.

Study on the Influence of Shale Storage Space Types on Shale Gas Transport.

Shale gas is an important unconventional natural gas resource. Studying the microstructure of shale and the gas transport law is of great significance for the development of shale gas. This paper uses the field emission scanning electron microscope to observe shale samples of the BC shale gas reservoirs in southern China. It is found that there are three types of storage spaces on the micro–nano-scale of shale samples. The storage space can be distributed either in pure organic matter or pure inorganic matter or in both organic matter and inorganic matter. They are called organic storage space, inorganic storage space, and mixed storage space of organic matter and inorganic matter, respectively. According to these types of storage spaces, an ideal conceptual model that reflects various types of storage spaces has been researched and established on the micro–nano-scale. At the same time, the transport mechanisms of slip, diffusion, adsorption, and coupling have been considered, and shale mixed storage space has also been considered in particular. On this basis, a comprehensive equation that can simulate the transport of shale gas in various types of storage spaces is derived. The equation also introduces the proportional parameters of the organic part, fractal characteristics, and water film of the inorganic part in the mixed storage space. Researchers can adjust this parameter to simulate shale gas transportation in different types of storage spaces and then use the finite element method to solve it numerically. This paper analyzes the influence of shale reservoir space types on shale gas transport. The larger the proportion of organic components in the mixed pores, the better the gas transport. The rough fractal dimension of the pores also affects the gas transport. However, when the pore diameter is less than 300 nm, the rough fractal dimension of the pores has a negligible influence on gas transport. For the water film on the inorganic wall surface of mixed pores, the gas transport of the macropore is more sensitive to the change in water film thickness.

Correlative nano-spectroscopic imaging of heterogeneity in migrated petroleum in unconventional reservoir pores

Low permeability unconventional oil and gas resources may experience formation damage due to the emplacement of viscous petroleum in narrow pore throats during petroleum migration and production. The composition of such pore-clogging molecules remains under-characterized, as standard analytical techniques in organic geochemistry either lack the desired nano-scale spatial resolution with simultaneous chemical specificity, or require extraction and therefore averaging of the suite of compounds that make up bulk crude oil. A new correlative imaging technique with high spatial resolution is demonstrated for migrated residual petroleum in nanopores of Niobrara chalk samples. Imaging combines Infrared scattering-Scanning Near-field Optical Microscopy (IR s-SNOM) with nano-mechanical atomic force microscopy to map both chemical and mechanical properties at ~30 nm spatial resolution. These correlative images demonstrate that heterogeneity exists within emplaced petroleum in situ on the scale of hundreds of nanometers, visualized as clusters of petroleum having distinct adhesive forces. The chemical composition of these clusters remains ambiguous, but their geometry and mechanical properties may imply that they are phase-separated asphaltene preferentially associated with petroleum-attractive nano-domains on calcite pore walls. Despite outstanding challenges, correlative IR s-SNOM and nano-mechanical imaging offer a promising and novel analytical approach to understanding fluid behavior in nanoporous reservoir rocks.

A seismic structural overview of Liard Basin, Northeast British Columbia, Canada

The Liard Basin is an important subbasin of the Western Canada Sedimentary Basin located in Northeast British Columbia along the eastern margin of the Canadian Cordillera. It contains significant potential unconventional gas resources but is largely underrepresented in public literature. Using available-for-purchase 2D seismic data, a regional structural interpretation of the basin was completed providing the first seismically controlled, high-level overview of the structural features of the basin and its surrounding area. The shape of the Liard Basin largely reflects the orientation of older Paleozoic and Proterozoic extensional structures that localized structures formed during Cretaceous-Tertiary compressive deformation. The eastern boundary of the basin is marked by the well-documented Bovie Structure. The Liard Anticline and the Liard River Anticline found near 60°N latitude are the only large structures located within the Liard Basin proper. Inversion of the herein named Liard Basin Boundary Structure, a west-side-down fault zone of Early Paleozoic age, localized the northwest boundary of the basin with the Liard Fold and Thrust Belt. A triangle zone bounds the Rocky Mountain Foothills and the Liard Basin to the southwest. Reflectors in the Proterozoic strata below the Liard Basin were deformed by compressive and then extensional structures prior to the deposition of Paleozoic strata. Proterozoic strata are involved in all of the major structures of the adjacent Liard Fold and Thrust Belt, the Rocky Mountain Foothills, and the Bovie Structure. These structures controlled the location of the Liard Basin.

Fracturing technology with carbon dioxide: A review

As unconventional oil and gas have increasingly gained considerable attention, the application of water-free fracturing technology represented by carbon dioxide (CO 2 ) fracturing technology in unconventional oil and gas resources development has broad prospects. The CO 2 fracturing technology has several advantages, such as low damage and easy flowback. It is especially suitable for complex rock strata exhibiting low pressure, low permeability, and strong water sensitivity. Moreover, this technology positively affects the reservoir with low water content and experiencing serious pollution. In this paper, the related literature of the different CO 2 fracturing technologies from the aspects of technical principle and technological process, technical characteristics, fracturing fluid system, and field application is analyzed, the fracture initiation and propagation are summarized as well. The results indicate that CO 2 fracturing can stimulate unconventional reservoirs more effectively than the conventional hydraulic fracturing, exhibits high technical feasibility, and can be applied in the reservoir stimulation and reconstruction in the future. In this paper, how to further improve the viscosity of fracturing fluid, enhance the sand-carrying capacity of fracturing fluid, and reduce the pipeline friction is determined. • The latest advancements in CO 2 fracturing technology are reviewed. • The phase change process in CO 2 fracturing is clearly introduced. • CO 2 fracturing is a technically feasible means of reducing CO 2 . • CO 2 fracturing has broad application prospects in unconventional reservoirs.

A new type of low density cement slurry suitable for sandstone formation

Unconsolidated sandstone reservoir is an important unconventional oil and gas resource with the characteristics of porosity, low permeability, strong heterogeneity and many interlayer. The main challenge of unconsolidated sandstone formation is sand production of oil wells, and the more serious situation is high-pressure oil and gas escaping, blowout accidents, environmental pollution and the safety of operators. In order to solve the sensitivity problem of loose sandstone, a low density admixture was developed: 10.5% artificial floating bead + 4.5% power plant floating bead + 35% micro silicon + 30% fly ash + 20% slag. The particle size distribution of single lightweight material is narrow, and the effect of reducing density is not significant. The developed low-density mixing material has wide and uniform particle size distribution, and can reduce the density of cement slurry to the maximum within the minimum dosage. The new low density admixture cement slurry with adjustable density in the range of 1.4 ∼ 1.7 g / cm3 has good rheological property, short thickening time, water loss less than 50 ml, 24 h compressive strength more than 12 MPa, which can meet the needs of site construction. The temperature and pressure test results show that the system has a wide range of temperature and pressure applications and stable performance. Compared with the similar low density cement slurry, it is about 40% lower than the market price and suitable for commercial application.

A model for nitrogen injection in horizontal wells of tight oil reservoirs

ABSTRACT In the petroleum industry, nitrogen is often used to improve the recovery of unconventional oil and gas resources such as heavy oil, tight oil, and shale oil. When nitrogen is injected into the oil and gas layers along the horizontal section of the wellbore, its pressure and temperature and other physical parameters all change with coordinates and time. These changes of pressure and temperature will have certain impact on the recovery efficiency. Therefore, it is necessary to simulate the non-isothermal variable mass pipe flow process of nitrogen in the horizontal wellbore. Based on the principles of conservation of energy and momentum, this paper establishes a nitrogen flow model in the horizontal wellbore by coupling sub-models such as the reservoir suction model. Results show that: (a) when the number of grids reaches 100, the degree of agreement between the predicted pressure value and the measured value of the model has met the requirements of engineering calculation accuracy. (b) when the injection pressure is lower than 2.7 MPa, the temperature gradient at the heel end and toe end of the wellbore is similar, while when the injection pressure is high (equal to 2.9 MPa), the temperature gradient at the toe end of the wellbore is significantly higher than that at the heel end.

Hydrocarbon generation and expulsion characteristics of the Lower Cambrian Qiongzhusi shale in the Sichuan Basin, Central China: Implications for conventional and unconventional natural gas resource potential

In recent years, significant progress and breakthroughs have been made in the exploration of conventional and unconventional natural gas in the Lower Cambrian petroleum system in the Sichuan Basin in Central China, showing excellent exploration prospects. However, detailed evaluation of the Qiongzhusi shale, the main source rocks in the Lower Cambrian petroleum system, including their hydrocarbon generation and expulsion characteristics, is lacking, even though such evaluation is critical for understanding conventional and unconventional natural gas resource potential. To investigate the geological and geochemical characteristics of the Qiongzhusi shale, experiments including pyrolysis, total organic carbon (TOC), vitrinite reflectance (Ro), gas chromatography (GC) and gas chromatography–mass spectrometry (GC–MS) were conducted. Based on modeling work and fluid inclusion analysis, the hydrocarbon generation and expulsion characteristics of the Qiongzhusi shale and their control on hydrocarbon accumulation was analyzed, and the conventional and unconventional natural gas resource potential of the Lower Cambrian petroleum system was systematically evaluated. The results indicate that the organic matter of the Qiongzhusi shale is mainly derived from bacteria and algae deposited in a saline, reducing marine environment. The shale is predominantly composed of type I kerogen with an average TOC value of 1.85 wt%, and is widely distributed in the basin with an average thickness of 212.7 m. The Qiongzhusi shale is primarily post-mature with an average vitrinite reflectance (Ro) of 2.53%. Modeling work suggests the Qiongzhusi shale reached the hydrocarbon expulsion threshold (HET) at Ro = 0.9%, and the main hydrocarbon expulsion stages are Triassic, Jurassic, and Cretaceous. The maximum hydrocarbon generation and expulsion intensities at present day are 32 × 10 6 t/km 2 and 18 × 10 6 t/km 2 , respectively. The conventional natural gas resource potential of the Longwangmiao Formation derived from the Qiongzhusi shale is estimated to be between 9.51 × 10 12 m 3 and 19.03 × 10 12 m 3 . The unconventional shale gas resource potential of the Qiongzhusi shale is predicted to be 1.4 × 10 12 m 3 , showing significant prospects for natural gas exploration. • Geochemistry characteristics of the Qiongzhusi Formation were systemically evaluated. • Hydrocarbon generation and expulsion characteristics of the Qiongzhusi Formation were first analyzed. • Conventional and unconventional natural gas resource potentials of ancient Lower-Cambrian petroleum system were calculated.

Unconventional hydrocarbon resources in Tanzania: insight from geology and previous exploration of conventional resources

Unconventional oil and gas exploration has been developing rapidly in recent decades, while Tanzania has been paid very little consideration. This review aimed to infer these unconventional hydrocarbon resources in some basins, mostly the intracratonic Karoo basins and one coastal basin (Ruvu basin), from a piece of the very limited information available from the previous exploration of conventional resources. The presence of thick dark carbonaceous shales of Makarawe formation at Ruvu basin with TOC% 2.4–4.0% and a thickness between 107 and 698 m capped with non-porous oncolitic limestone and the gas shows encountered at an interval of 107 m of Makarawe shales at Makarawe-1 well makes Ruvu basin as important play for unconventional shale gas. The intracratonic Karoo basins have a thick deposit of Karoo sediments interbedded with coal deposits. Coal bedded methane has been encountered in a deep coal exploration borehole at Songwe-Kiwira coalfield. Geochemical analysis of outcrop samples from Namwele, Mbamba Bay, Njuga, and Mhukuru coalfields shows that the interbeds of coal-carbonaceous shales/mudstone have the rich organic matter of type III or both II and III and trace of oil on samples from Ketewaka and Ngaka coalfield make these sub-basins to be considered as potential plays for shale oil/gas. The presence of probable shale gas resources ranging from 50 to 200 trillion cubic feet at the Selous basin increases Karoo basins’ potentiality in exploring unconventional gas resources. In addition to the discovered conventional gas resource in offshore Tanzania, any unconventional resources will impact the country’s economic growth.

A Novel CO2 Responsive Viscoelastic Surfactant based Clear Fracturing Fluid for High-Temperature Unconventional Reservoir

An unconventional reservoir is a term to describe a hydrocarbon resource that could not be technically or economically recoverable without stimulation. Unconventional oil and gas resources are 4-5 times over conventional oil and gas resources. Currently, there is a limitation for using slick-water volume fracturing and gas (water) injection adding energy for drainage and displacement individually. Also, the efficient hydrocarbons production from the high-temperature unconventional reservoir is the main challenge. In the current study, a CO2 based viscoelastic surfactant fracturing fluid with a specific molar ratio of erucic acid, 2,6,10-trimethyl-2,6,10-triazaundecane, potassium hydroxide, and carbon dioxide (EA-TMTAD-KOH-CO2) was developed as a good candidate for high-temperature and water alternating treatment for high-temperature unconventional reservoirs. The fracturing fluid will play the role of “one with multi-purpose” by proppant-carrying, CO2 energy supplementary displacement, and surfactant imbibition drainage displacement. The fracturing fluid (EA-TMTAD-KOH-CO2) performance evaluation method for determination of shear and heat resistance, viscoelasticity, proppant carrying capacity, gel breaking ability, and salt tolerance is employed as evaluation indices by using HTHP rheometer. The rheological results of steady shear viscosity of the fracturing fluid system confirm that the EA-TMTAD-KOH-CO2 was observed in the properties of a wormlike micelles (WLMs) structure, micelles assembly, and the intermolecular interactions. The steady shear viscosity above 41 mPa.s at a shear rate of 170 s‒1 and temperature 95 °C validates the excellent proppant carrying capacity as per national industry standards of the fracturing process. Further, the gel structure breaking at temperature 135 °C and 170 s‒1 bear the shear viscosity less than 5 mPa.s, which results in a rapid flow back from the well after the fracturing process. Moreover, the fluid system has high salt tolerance against different inorganic salts such as NaCl, KCl, CaCl2, and MgCl2 using different concentrations. By retaining the desirable qualities such as; easy to prepare, environment friendly, commercially available, high in viscoelasticity, and thermally stable; the fracturing fluid system (EA-TMTAD-KOH-CO2) will be an outstanding candidate in industrial applications like water-alternating and high-temperature unconventional reservoirs.

Mudstone diagenesis: Research advances and prospects

Driven by the shale oil and gas revolution，important advances have been made in mudstone diagenesis， which is a frontier in sedimentology and petroleum geology. Mudstone diagenesis of not only controls the generation and migration of oil and gas， but also has important influence on the composition， microstructure， reservoir physical and mechanical properties. The research status and prospects of the study were documented. At present， the research advances of mudstone diagenesis is mainly reflected in 4 aspects： （1）diagenetic evolution of inorganic minerals； （2）diagenetic evolution of organic matter and the development of organic matter-hosted pores； （3）driving mechanism and physical response of mudstone diagenesis； （4）effects of diagenesis on mechanical properties of mudstone. The study of mudstone diagenesis will continue to complement and improve the basin diagenesis system， and provide theoretical support for the exploration and development of unconventional oil and gas resources. The study of mudstone diagenesis system at different scales under the control of multi-field coupling indicates a profound and extensive development prospect.

Coal mine gas separation of methane via clathrate hydrate process aided by tetrahydrofuran and amino acids

Coal bed methane (CBM) is an unconventional natural gas resource generated and stored in coal seams. It is currently not commercially viable in many regions due to the high concentration of non-flammable gases such as nitrogen. The CBM separation is crucial for both economic benefit and methane emission reduction. The biggest challenge lies in the separation of low-concentration CBM. Gas separation via gas hydrate is gaining great attraction due to its safe, clean, and economically efficient features. We examined the effects of two environmentally benign amino acids L-tryptophan and L-leucine on hydrate formation from 30% CH4/70% N2 mixture in the presence of tetrahydrofuran (THF, 5.56 mol%). Experiments were carried out at 283.2 K and 3.0 MPa with different solution volumes to study the impact of gas/liquid volume ratio (calculated at standard pressure and temperature conditions). The lower gas/liquid volume ratio improved the CH4 recovery ratio and separation factor but lowered the kinetics. The effect of amino acid is concentration-dependent. In synergy with 5.56 mol% THF solution (gas/liquid volume ratio of 67/1), L-tryptophan (5000 ppm) enhanced the CH4 recovery ratio from 58.3% to 71.4% and boosted the initial hydrate growth rate by 130%. On the other hand, L-leucine (5000 ppm) showed no obvious impact on the kinetics but achieved the highest CH4 enrichment in the hydrate phase (from 30.0 mol% in the feed gas to 56.8 mol% in the hydrates). The high CH4 recovery ratio, enhanced kinetics, and simplicity of this process demonstrate the potential of developing an efficient and economical recovery method for low-concentration CBM.

Experimental investigation on the breakdown behaviours of sandstone due to liquid nitrogen fracturing

Liquid nitrogen (LN) fracturing is an efficient technology for the development of unconventional gas resources. Due to continuous injection of cryogenic LN, the reservoir temperature decreases and then cooled rock regions are gradually generated during fracturing process. To investigate the breakdown behaviours of sandstone induced by LN fracturing, laboratory simulation experiments were performed with a self-designed setup. The experimental results showed that rising initial rock temperature greatly reduced the breakdown pressure of sandstone, whereas hardly affected the fracture complexity. Under cryogenic conditions, both the compaction and cracking effects exerted influence on the pore structure of sandstone. Thus, the change in breakdown pressure depended on which effect played a domain role. Although the cryogenic conditions probably made the breakdown pressure of sandstone increase, the fracture complexity was expected to be significantly improved. In addition, the initial rock temperature increasing played a positive role in improving the fracture complexity under cryogenic conditions. For initial or heating sandstone samples, the fracture pattern mainly presented in the form of bi-wing fractures. However, for cryogenic samples, the fracture patterns contained both local fractures and complex fractures. The former was generated with lower breakdown pressure while the latter was generated with higher breakdown pressure. Additionally, the gas leak regions were observed in cryogenic samples during LN fracturing. Under cryogenic conditions, the sandstone used was favourable to generate more complex fractures and the permeability of rock matrix in unbroken region was proved to be improved due to LN fracturing. Collectively, fracturing with LN could improve the fracture complexity and the permeability of rock, which was very beneficial for well production.

Control of Lithofacies and Geomechanical Characteristics on Natural Fracture Systems in Qusaiba Shale, Rub’ Al-Khali Basin, Saudi Arabia

The lower Silurian Qusaiba Shale is one of the major source rocks for Paleozoic oil/gas reservoirs in Saudi Arabia and recently considered a potential unconventional shale gas resource. The study aims to evaluate the reservoir heterogeneity and production potential of Qusaiba Shale through the integration of geological, geomechanical and fractures characteristics. Three lithofacies were identified in Qusaiba shale. Mineralogical composition resulted in variable amounts of quartz ranging from 39 to 40, 45–55 and 60–78% for Lithofacies-I, II and III, respectively. Inter-granular porosity of these lithofacies is very low; however, fractures along laminations, at angle with laminations, and few micro-faults enhance porosity up to 5–6, 2–3, and < 1% in Lithofacies-I, II and III, respectively. The Lithofacies-I hosts the lowest fracture density (1.2 fractures/foot), likely due to the relatively lower quartz content (39%) as compared to other lithofacies. The fracture densities in Lithofacies-II and III are 2.1 and 3.2 fractures/foot, respectively. Lithofacies-I exhibits low stiffness in terms of low Young’s modulus (average 26 GPa) and high Poisson’s ratio (average 0.34). Mineralogy- and elastic parameters-based brittleness indices exhibited ductile behavior of this lithofacies. The brittleness index exhibited brittle behavior for silica-rich Lithofacies-III and has highest intensity of natural fractures. Hence, it is concluded that mineralogy and geological characteristics are the main controlling factors on shale brittleness, mechanical properties and fractures characteristics. The integration of geology, mineralogy and geomechanics plays the key role to better evaluate the prospectivity of shale reservoirs.

BiVO&amp;lt;sub&amp;gt;4&amp;lt;/sub&amp;gt;/MnO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Composite Photocatalytic Material for the Shale Gas Flowback Wastewater Treatment

The management and disposal of the shale gas flowback wastewater is one of the greatest challenges associated with the exploration and extraction of unconventional natural gas resources. High salinity and complex chemical composition of fracturing fluids are the main limiting factors for beneficial reuse of the shale gas flowback wastewater, which has become a tough problem in the global environmental field. In this study, a composite photocatalytic oxidant of MnO2 modified BiVO4 was successfully synthesized with one-step hydrothermal method, and used to treat the shale gas flowback wastewater. The synergistic effect of photocatalysis and oxidation has made a great contribution to the removal of COD value in wastewater. When catalyst dosage was 0.6 g, the pH value was controlled to 3, and visible light exposure was 4 h, the prepared BiVO4/MnO2 exhibited the optimum photocatalytic oxidation activity, and the removal efficiency of COD could reach 65.5%, which is better than that of pure BiVO4 or MnO2. Furthermore, in this case, the COD value could be decreased from 188 mg/L to 64.9 mg/L, complying with the first-level standard limit requirements in the integrated wastewater discharge standard (GB8978-1996). Moreover, in the viewpoint of dynamics, Langmuir isothermal-like equation can better describe the relationship between COD removal efficiency and illumination time.

Coordinated Development Mode of Oil and Gas Resources and Water Resources in Western China

Western China is an important area for increasing oil and gas reserves and production in China, and it is also the most arid and water-deficient area in the country; there is a complex linkage between energy and water resources in this region. Hence, it is important to promote the coordinated management of energy and water resources. In this article, we review the prospects and deployment of oil and gas production in Western China, investigate the development mode and water utilization status of different oil and gas fields from seven companies of China National Petroleum Corporation in Western China, and analyze the guarantee risks of water resource and water environment during gas and oil development. The research shows that oil and gas production has steadily increased in Western China in recent years, and the consumption of fresh water in oil and gas fields has changed little, owing to the continuous improvement in sewage treatment and recycling efficiency. However, considering the progressive development of unconventional oil and gas resources, future oil and gas development in Western China is likely to significantly affect the surface and underground water systems. It is suggested to develop precise water injection and waterless fracturing technology to stabilize oil production and control water use, increase the recycling of produced water to strengthen scientific water management, and improve the comprehensive allocation guarantee system of water resources, so as to reduce the impact of oil and gas development on water system while ensuring water use security for energy industry, thereby realizing the coordinated development of energy and water resources in Western China.

Distribution and estimates of Australia's identified energy commodity resources

Australia is endowed with abundant, high-quality energy commodity resources, which provide reliable energy for domestic use and underpin our status as a major global energy provider. Australia has the world’s largest economic uranium resources, the third largest coal resources and substantial conventional and unconventional natural gas resources. Since 2015, Australia’s gas production has grown rapidly. This growth has been driven by a series of new liquefied natural gas (LNG) projects on the North West Shelf, together with established coal seam gas projects in Queensland. Results from Geoscience Australia’s 2021 edition of Australia’s energy commodity resources assessment highlight Australia’s endowment with abundant and widely distributed energy commodity resources. Knowledge of Australia’s existing and untapped energy resource potential provides industry and policy makers with a trusted source of data to compare and understand the value of these key energy commodities to domestic and world markets. A key component of Australia’s low emissions future will be the development of a hydrogen industry, with hydrogen being produced either through electrolysis of water using renewable energy resources (‘green’ hydrogen), or manufactured from natural gas or coal gasification, with carbon capture and storage of the co-produced carbon dioxide (‘blue’ hydrogen). Australia’s endowment with abundant natural gas resources will be a key enabler for our transition to a low emissions future through providing economically competitive feedstock for ‘blue’ hydrogen.

Geological and Bioregional Assessments: a tale of two basins

The Australian Government’s $35.4 million Geological and Bioregional Assessment (GBA) Program is assessing the potential impacts of shale, tight and deep coal gas development on water and the environment in the Beetaloo, Isa and Cooper GBA regions. This paper compares the outcomes of impact assessments for the Beetaloo and Cooper GBA regions, highlighting the role that local geology, hydrogeology, ecology and regulatory regimes play when assessing potential impacts of unconventional gas development. Unconventional gas development activities between basins are broadly consistent, involving drilling, stimulation of the reservoir (typically through hydraulic fracturing), production and processing of hydrocarbons, export to market and decommissioning and rehabilitation. The characteristics of these activities and their potential impacts are strongly influenced by local factors including the geology, environment, industry practices and regulatory regimes. While subsurface impacts associated with hydraulic fracturing and well integrity are considered unlikely in both regions, regional geology means there is greater stratigraphic separation between target resources and overlying aquifers in the Beetaloo Sub-basin than in the Cooper Basin. Local ecological conditions and species influence the nature of potential impacts on protected matters in the two basins, which are mostly associated with surface disturbance and spills or accidental release of fluids. A key similarity between the two regions is the broadly consistent regulation and management of potential impacts in the two basins. Preliminary results of the causal network analysis indicate that mitigation measures are available for all pathways in which unconventional gas resource development activities may have the potential to impact on endpoints.

Geological and Bioregional Assessments: assessing direct and indirect impacts using causal networks

The Geological and Bioregional Assessment (GBA) Program assesses the potential impacts of shale, tight and deep coal gas development on water and the environment. The cause-and-effect relationships that allow unconventional gas resource development activities to lead to an impact on environmental values are often interrelated, leading to both direct and indirect impacts. The GBA Program developed an impact assessment methodology based on causal networks that explicitly map out these cause-and-effect relationships, including all direct and indirect impacts. This network approach is coupled with a spatially explicit, systematic evaluation of the likelihood, consequence, control and mitigation strategy for each cause-and-effect relationship. Combining these evaluations based on the network structures identifies which activities could lead to potential impacts. The assessment identifies where more detailed local-scale assessments, management and monitoring should focus, as well as where impacts are unlikely to occur.

Technological revolution in the US energy sector, understanding the implications for the US dependency on fossil energy imports

AbstractDuring various periods, the United States (the US) has adopted diverse policies for achieving self‐sufficiency in supplying its required energy. Technological revolution that has begun from a decade ago pursues the goal of energy independency. Using new technologies for developing its unconventional oil and gas resources, the United States has taken steps in line with the accomplishment of its objective of energy independence. Numerous articles have examined the various technical, economic and political aspects and consequences of the US technological revolution. This paper, in a new and innovative approach based on theoretical framework of neorealism, aims to show the implications of technological revolution in energy sector on the US dependency on fossil energy imports. Efforts will be made to find an answer to this main question as to what effects have the technological revolution occurrence in energy sector had on the US dependency on the fossil energy imports? In response, the study's main hypothesis is that, the US policy to exploit the unconventional oil and gas resources through technological revolution can be elaborated within the framework of the self‐sufficiency strategy for energy production in line with the reduction of the threats stemming from dependency on the oil and gas imports.