Hydrocarbon potential and prospects for exploration of Eastern Arctic oil and gas deposits

Conditions for the formation of hydrocarbon systems and prospects for searching for accumulations of oil and gas in the waters of the Eastern Arctic are considered. Significant hydrocarbon potential is predicted in the sedimentary basins of this region. All known manifestations of oil hydrocarbons are installed on land adjacent to the south, as well as on the east of the shelf. The East Arctic waters are included in a single model in order to perform an adequate comparative analysis of the evolution of hydrocarbon systems. The purpose of the research was to build space-time digital models of sedimentary basins and hydrocarbon systems, and to quantify the volume of generation, migration, and accumulation of hydrocarbons for the main horizons of source rocks. To achieve this goal, a spatiotemporal numerical basin simulation was carried out, based on which the distribution of probable hydrocarbon systems was determined and further analyzed. Following to the data obtained the most probable HC accumulation zones and types of fluids contained in potential traps were predicted. Keywords: numerical space-time basin modeling; modeling of hydrocarbon systems; evidence of oil and gas presence; Eastern Arctic; elements of hydrocarbon systems; oil and gas reservoirs; migration; accumulation; perspective objects

Basin and petroleum system analysis in the southeastern Persian Gulf basin: a 2D basin modeling approach

A regional 2D conceptual model was constructed to study the hydrocarbon systems associated with the Middle Sarvak source rock (Cenomanian) in the southeastern Persian Gulf basin. The 2D cross section used for this purpose was 135 km long and encompassed a total of 17 depositional units with the Late Jurassic Surmeh Formation at the base and the Aghajari/Mishan sequences at the top. Compositional type II-S kinetics was considered for the Middle Sarvak source rock, and the model predictions were calibrated against observe data (corrected bottom hole temperatures and vitrinite reflectance data) coming from 4 wells located on the studied cross section. Our results indicate that hydrocarbons predominantly migrate laterally from east to the west of the study area, thereby sequentially charging potential traps en-route. The interaction between facies patterns and geodynamic evolution controls both the distribution and quality of hydrocarbon accumulations in the study area. The calibrated 2D model reliably predicts most of the present-day hydrocarbon occurrences in the study area and explains the present-day variations in their bulk properties. Our findings provide new insights about the unconventional plays associate with the Middle Sarvak source rock especially in the central parts of the southeastern Persian Gulf basin.

Fading opportunities for mitigating agriculture-environment trade-offs in a South American deforestation hotspot

Strong trade-offs between agriculture and the environment occur in deforestation frontiers, particularly in the world’s rapidly disappearing tropical and subtropical dry forests. Pathways to mitigate these trade-offs are often unclear, as well as how deforestation or different policies alter the option space of available pathways. Using a spatial optimization framework based on linear programming, we developed a landscape-scale possibility frontier describing trade-offs between agricultural profit, biodiversity, and carbon stock for the Argentinean Dry Chaco, a global deforestation hotspot. We use this framework to assess how current land-use zoning, as well as past and future land-use-trajectories, alter the option space to minimize trade-offs between biodiversity, carbon, and agriculture. Our analyses yield four major insights. First, we found substantial co-benefits between biodiversity and carbon, yet strong trade-offs of both with agriculture. Second, development according to the current zoning could lead to highly suboptimal socio-ecological outcomes, and our analysis pinpoints how this zoning could be improved. Third, high landscape-scale multifunctionality can be achieved using different land-use strategies, but maintaining >40% of forest is essential in all of them, and silvopastoral systems appear to be central for achieving high overall multifunctionality. Finally, our results suggest the window of opportunity is closing rapidly: recent land-use changes since 2000 have rapidly moved the Chaco within the options space, with forest extent declining towards critical thresholds for maintaining balanced, multifunctional landscapes. Our results emphasize that the time for sustainability planning in the Chaco is now. More broadly, we show how multi-criteria optimization can describe dynamic trade-offs between agriculture and the environment at landscape and regional scales. This can help to identify land-system tipping points that, once crossed, would inhibit more sustainable futures, and policies to avoid such potential traps.

Seismic Sequence Stratigraphic Sub-Division Using Well Logs and Seismic Data of Taranaki Basin, New Zealand

This study focuses on the sequence stratigraphy and the dominated seismic facies in the Central Taranaki basin. Four regional seismic sequences namely SEQ4 to SEQ1 from bottom to top and four boundaries representing unconformities namely H4 to H1 from bottom to top have been traced based on the reflection terminations. This was validated using well logs information. An onlapping feature on the seismic section indicates a new perspective surface separated between the upper and lower Giant formation, which indicates a period of seawater encroachment. This study focused extensively on deposition units from SEQ4 to SEQ1. The seismic facies, isochron map, and depositional environment were determined, and the system tract was established. This study was also able to propose a new perspective sequence stratigraphy framework of the basin and probable hydrocarbon accumulations and from the general geological aspect, SA-Middle Giant Formation (SEQ3) could act as potential traps.

Highly accurate random DNA sequencing using inherent interlayer potential traps of bilayer MoS2 nanopores

Solid-state MoS2 nanopores are emerging as potential real-time DNA sequencers due to their ultra-thinness and pore stability. One of the major challenges in determining random nucleotide sequence (unlike polynucleotide strands) is the non-homogeneity of the charge interaction and velocity during DNA translocation. This results in varying blockade current for the same nucleotide, reducing the sequencing confidence. In this work, we studied the inherent impedance-tunability (due to vertical interlayer potential gradient and ion accumulation) of multilayered MoS2 nanopores along with its effect on improving analyte capture and charge interaction, for more sensitive and confident sensing. Experimentally we demonstrate that 2-3 nm diameter bilayer MoS2 pores are best suited for high accuracy (~90%) sequencing of mixed nucleotides with signal-to-noise-ratio greater than 11 in picomolar concentration solutions. High temporal resolution demonstrated by bilayer MoS2 nanopores can help detect neutral proteins in future. The high accuracy detection in low concentration analyte can hence be applied for control and prevention of hereditary diseases and understanding health effects of rare microbial strains.

THE MODEL OF FOLDING PROCESS AND BREACHES FORMATION IN BORISLAV-POKUTTIA ZONE OF THE PRECARPATHIAN DEFLECTION

The topicality of the research is determined by the detailed study of the peculiarities of the geological structure of Boryslav-Pokuttia zone of the Precarpathian deflection, in particular of local structural forms as probable traps for oil and gas, for reliable prediction of the oil and gas potential of the subsoil. Boryslav-Pokuttia zone of the Precarpathian deflection refers to one of the oldest oil and gas producing regions in Ukraine. Its hydrocarbon potential is far from being exhausted. The complex block structure of Boryslav-Pokuttia zone requires the development of specific methods for conducting oil and gas prospecting. In this regard, determining the distribution nature of the local structures and specifying the peculiarities of their morphological forms in the area under investigation are of great importance. The issue of tracing tectonic disturbances and determining their screening ability which determines the possible existence of hydrocarbon deposits remains to be an urgent matter. Solving these issues will significantly improve the geological efficiency of prospecting and exploration in the areas of Boryslav-Pokuttia zone. At the modern stage of the Earth sciences development computer processing of geological data is widely used.Therefore, along with the traditional approach to describing structures as potential traps for oil and gas, it isnecessary to analyze their quantitative (numerical) parameters. It gives a possibility to confirm the stablished regularities more reasonably. Handling large array of quantitative indicators of local structures and the dependencies established among them makes it possible to simulate the processes that formed them and to determine the regularities of their distribution. The most important scientific and practical results include: the quantitative indicators ranking of the local structures of Boryslav-Pokuttia zone (the ranking contains four groups of structures classified according to their morphological texture); the investigated conditions for the formation of morphological varieties of local structures and the character of the distribution of tectonic deformations in them. The results of geological and mathematical simulation according to a complex of quantitative indicators help to state that local structures with certain morphological features, which are revealed to various extent in their deformations, are formed by tectonic movements of different magnitude and direction and are described by the numerical parameters peculiar only to them. Investigating the distribution of tectonic stresses and deformations, which can be estimated in quantitative indicators, will contribute to a more reliable prediction of the oil and gas potential of the subsoil. In its turn, it will improve significantly the geological performance of oil and gas prospecting in the areas of BoryslavPokuttia zone of the Precarpathian deflection.

Some problems in the statistical processing of astronomic data

The problems that could arise with a correct statistical processing of astronomical data and a search for linear statistical dependences are analyzed. It has been shown that the use of standard statistical software can yield incorrect results. The iterative procedure of processing based on multi-year experience is proposed. It covers all stages: creation of sampling, discarding of outliers, search for statistically significant regressors, excluding insignificant regressors, finding out multiparametric dependencies and their analysis, etc. This paper is a methodological one and is it describes some potential traps in the statistical processing of observational data. We forewarn against some actions that may lead to data selection or to incorrect conclusions about the influence of some factors on the quantity being studied. Some examples of problems associated with data selection, correlation between regressors, Malmquist bias and correction are given.

Petroleum system of Srikail gas field using sequence stratigraphy

A sequence stratigraphic analysis was carried out on the sedimentary packages of parts of the Bengal Basin hydrocarbon province. This paper focuses on the identification of petroleum system of Srikail Gas Field within eastern folded belt of Bengal basin using sequence stratigraphic concept. Three strike and five dip seismic lines are used in this work and data analysis is done using Petrel 2015 software. Seismic line-2 (SK-2) of Srikail is good in resolution and is used here only for identifying potential petroleum system. Seven sequence boundaries were identified on the basis of onlap and reflection truncation. The result of the interpreted sequence boundary has revealed that all the elements which are required to generate a potential prospect are present in the study area. Fine grained sediments deposited during the rising and lowering of sea level might act as a potential source rock. Time contour maps of the study area have revealed that the NWSE trending anticlinal Srikail structure is largely affected by shale filled channel in the crestal and western flank. The channel filled shale is later acting as a seal on north and western part of the structure. Erosional remnants truncated against shale fill canyon is acting as prospective reservoirs in the Srikail gas field. The NW-SE trending anticlinal structure and shale fill canyon help this sand as potential traps for hydrocarbon accumulation. Hence the petroleum system of the study area become very prospective in terms of hydrocarbon accumulation.Bangladesh J. Sci. Res. 30(1&2): 1-9, December-2017