The Sea Route Planning for Survey Vessel Intelligently Navigating to the Survey Lines

Marine surveying is an important part of marine environment monitoring systems. In order to improve the accuracy of marine surveying and reduce investment in artificial stations, it is necessary to use high-precision GNSS for shipborne navigation measurements. The basic measurement is based on the survey lines that are already planned by surveyors. In response to the needs of survey vessels sailing to the survey line, a method framework for the shortest route planning is proposed. Then an intelligent navigation system for survey vessels is established, which can be applied to online navigation of survey vessels. The essence of the framework is that the vessel can travel along the shortest route to the designated survey line under the limitation of its own minimum turning radius. Comparison and analysis of experiments show that the framework achieves better optimization. The experimental results show that our proposed method can enable the vessel to sail along a shorter path and reach the starting point of the survey line at the specified angle.

Using reflection seismic method to estimate the fluid dynamics parameters related to wakes

<p>In this study, when using reflection seismic data to study the wakes of the Batan Islands, a method for estimating the fluid dynamics parameters such as the relative vorticity (relative Rossby number) and the relative potential vorticity is proposed. Although the relative Rossby number estimation method proposed in this study cannot guarantee absolute accuracy in the calculation value, this method is more accurate in describing the positive and negative vorticity distribution for the wakes, and the resolution of the positive and negative vorticity distribution described by this method is higher than the result of the reanalysis data. For the wakes developed in the Batan Islands, the reflection events in the wake development area have the larger inclination than the reflection events in the western Pacific water distribution area. It is also found that the negative vorticity wakes are mainly distributed on the west side of the island/ridge, and the positive vorticity wakes are mainly distributed on the east side of the island/ridge. This is consistent with the understanding of previous wakes simulations. The strong vorticity values in the study area are mainly distributed at depths above 300m, and the maximum impact depth of wakes can reach 600m. At the downstream position of the wake on the survey line 7, it can be seen that the bottom boundary layer has separated, and there is the negative vorticity wakes on the west side intruding into the positive vorticity wakes on the east side , which is presumed to be caused by the disturbance of the small anticyclone existing near the Batan Islands. For the survey line 7, the negative potential vorticity is mainly distributed on the west side of the island/ridge, and the influence range can reach the sea depth of 600m. In the negative potential vorticity region, there is strong energy dissipation and vertical shear. In this study, we don’t find the existence of submesoscale coherent vortices on the survey line 7, but find the reflection structure similar to filaments on the seismic section. Combined with the analysis of the balanced Richardson number angle of survey line 7, we speculate that the wake in the negative potential vorticity distribution area has the characteristics of symmetrical instability, and the symmetrical instability may destroy the process of filaments forming submesoscale coherent vortices.</p>

Optimal Transponder Array and Survey Line Configurations for GNSS-A Observation Evaluated by Numerical Simulation

The Global Navigation Satellite System-Acoustic ranging combination technique (GNSS-A) has enabled us to measure seafloor crustal deformation in the precision of centimeters, leading to numerous discoveries of subseafloor tectonic phenomena. The moving observation conducted by our research group allows us to measure both the horizontal and vertical absolute positions of a reference point on the seafloor. However, the observation frequency of our GNSS-A observation system is still insufficient to observe short-term phenomena. This paper focused on the possibility to reduce the observation time per a seafloor site by shrinking the seafloor transponder array size and the survey line radius, which were empirically defined to be equal to the seafloor site depth in the early research. We evaluated the effects of changing these sizes on the GNSS-A positioning accuracy by conducting a series of numerical experiments. The results of the numerical experiments indicated that for a seafloor site with a depth of 3,000 m, the positioning accuracy is rapidly degraded as the transponder array size and the survey line radius are reduced to less than 3,000 m. Additional experiments done for transponder array sizes and survey line radii around 2,000–4,000 m revealed that shrinking the survey line radius has a dominant effect on the decrease in positioning accuracy. Thus, shrinking the transponder array size and the survey line radius is not a suitable option for reducing observation time, and the empirically defined observation configurations are concluded to be quite optimal when regarding both the positioning accuracy and the observation time.

GEOCHEMICAL CHARACTERISTICS OF NOVOKOSTIANTYNIVKA URANIUM DEPOSIT

Paper research aim is to identify characteristics of spacious distribution of radioactive- and associated elements in albitites according to depth and ore-level attribution: case study of 35th survey line of Novokostiantynivka deposit. Geochemical characteristics of Novokostiantynivka deposit are defined by presence of upper and lower ore-bearing levels. Geochemical anomalies related to upper ore-bearing level have complex character (uranium, thorium, lanthanum, yttrium, ytterbium, vanadium, and zirconium). At apical part of the deposit (Eastern fault) the albitites of blended type (chlorite, rybekite, aegerine) are dominant. La, Th, Y, and U define geochemical trend. These elements are likely to be related to rare-earth mineralization (monazite, apatite, xenotime), to a lesser extent to thorium and uranium mineralization with subordinate zircon. At deeper levels (Western fault) albitites’ mineral composition becomes more monotonous of rybekite-aegerine, and aegerine. The lead elements are Zr, Y, V, U, Th; Zr and Y noticeably dominate over other elements. Both elements and, maybe, part of U are related to zircon (malacon) which is predominant over rare-earth and thorium mineralization. Geochemical anomalies related to lower ore-bearing level are distinctive with monometallic (uranium) trend. The albitites of large column-like body have rybekite-aegerine, or aegerine mineral composition; phlogopite occurs often. Associated elements like Th, La, Y, Yb, V, Zr specific to albitites of upper ore level are not characteristic to deeper one. Based on seldom minor Th, La, and Y content spikes, rare-earth and thorium mineralization is immaterial. Regarding Zr and V, their contents are not over but most of the time less than background values. Apparently, zircon is not formed in albitites of lower ore-level; vanadium content in darkcolored minerals becomes insignificant, and single lead element is uranium. The most essential feature of Novokostiantynivka deposit is a succession of complex mineralization with monometallic one with depth.

Subsurface Imaging of 2D Seismic Data of Balad-Samarra (BS-92) Survey Line, Ajeel Anticline Oilfield, Central Iraq, Using Kirchhoff Time Migration Method

Kirchhoff Time Migration method was applied in pre-and post-Stack Time Migration for post-processing of images collected from Balad-Samarra (BS-92) survey line that is sited across Ajeel anticline oilfield. The results showed that Ajeel anticline structure was relocated at the correct position in the migrated stacked section. The two methods (Pre and Post) of migration processing showed enhanced subsurface images and increased horizontal resolution, which was clear after the broadening the syncline and narrowing or compressing the anticline. However, each of these methods was associated with migration noise. Thus, a Post-Stack process was applied using Dip-Removal (DDMED) and Band-Pass filters to eliminate the artifact noise. The time-frequency and signal to noise spectrum analyses as well as the ISO-velocity distribution analysis confirmed that the Pre-Stack Time Migration method outperformed the Post-Stack method as a result of structural complexity.

Evaluation the freshwater-saltwater interface using geophysical and geochemical investigations within the single borehole

<p>The Korean peninsula has three sides facing the sea, and many monitoring wells for seawater intrusion observation installed along these coasts. The electrical conductivity (EC) profiles of these monitoring wells are found to vary greatly depending on the hydrogeological characteristics of the coast. The research area is located in Seocheon, Chungnam, where two wells are about 1.5 km away, one borehole is freshwater and the other boreholes have high electrical conductivity. In the well where the high electrical conductivity is measured, the electrical conductivity increases rapidly at a depth of about 90m. The well is located about 50 meters from the coast, and the change in water level reflects tidal changes well. We conducted a variety of field surveys and laboratory tests to clarify whether seawater intrusion occurred in the freshwater-saltwater boundary at the depth of about 90 m and whether the freshwater-saltwater boundary was affected by tides. Applied methods are electrical resistivity survey, geophysical well logging and geochemistry. The geophysical survey line was located along the coast centered on the well and measured every six hours. As a result of the survey, it was difficult to identify the change of electrical resistivity due to tidal changes in the lower alluvial zone, that is, the rock formation. These result indicates that the permeable fracture zones are rarely distributed in the rock below the survey line, so the change of the formation resistivity of according to the tidal change is very small. Geophysical well logs such as optical televiewer, spectral gamma log, and water quality logs (i.e., temperature, EC, pH, DO, and ORP) were measured, and groundwater samples were collected according to depth and analyzed for T, EC, pH, DO, ORP, and 222Rn. We found it difficult to identify permeability fracture zones in the temperature gradient and optical televiewer logs. The electrical conductivity is generally around 4,000 uS/cm and increase rapidly from about 90m to 48,000 uS/cm. The water quality logs and the analysis of groundwater samples showed pH range of about 7 to 7.5, DO of 7 to 14 mg/L, and OPR of -80 to 180 mV. pH does not change with depth, DO decreases slightly, and ORP decreases rapidly around the fresh-saltwater interface. The analysis of 222Rn shows that, to the median depth of the borehole, it is similar to the intensity of natural gamma rays and decreases rapidly across the lower freshwater-saltwater interface. Finally, we measured the electrical conductivity logs repeatedly at the interval of 30 minutes in the lower borehole where the freshwater-saltwater boundary was formed, and identified that the profiles of electrical conductivity change with tides.</p>

Estimation of hydraulic parameter from geoelectrical measurements : A case study of the western Pingtung Plain in Taiwan

<p>In Taiwan, most of the rivers in the Pingtung Plain are ephemeral stream. In the dry season, the water source is unstable and cannot be used all the year round. Due to the uneven distribution of time and space, the supply and demand of water resources are often imbalanced. In order to provide a stable groundwater source strategy, it is necessary to understand the geologic characteristics of groundwater.</p><p>Electrical resistivity surveying methods have been widely used to determine the thickness and resistivity of layered media for the purpose of assessing groundwater potential and siting boreholes in fractured unconfined aquifers. In this study, we used CP configuration on the Electrical Resistivity Tomography (ERT) monitoring system at two study sites. One is the surface-borehole survey line at the Dashu, Kaohsiung City, Taiwan, and the other is the surface survey line at the Daliao, Kaohsiung City, Taiwan. Both of sites located on Quaternary alluvium of Pingtung Plain which composed of coarse sand and gravel.</p><p>The resistivity difference might be caused by the dynamic of the groundwater. We analyzed the change in the electrical properties of the gravel layer during the rainfall season at the Dashu site and analyzed the groundwater level change by ERT method during the pumping event at the Daliao site which is the pumping station to understand the groundwater replenishment situation. The ERT result can be calculated Relative Water Saturation (RWS) of the shallow formation fluid, and it reveal the permeability of the gravel layer and the hydrogeological characteristics of the sites. Furthermore, we assumed the different particle size and porosity to estimate the resistivity and the hydraulic conductivity coefficient theoretical trend line, compare the observation well data is used to estimate the actual porosity and the actual hydraulic conductivity range. Finally, for the groundwater conditions in the large area of the Pingtung Plain, we use the theoretical trend line to analyze the data of WRG’s 34 wells in western Pingtung Plain. The results show (i) the well logging resistivity is positively correlated with the hydraulic conductivity. (ii) the sandstone and mudstones with small variables have smaller well-measured resistivity and a lower hydraulic conductivity. (iii) affected by compaction, the porosity tends to decrease with increasing depth. (iv) on the west side of the Pingtung Plain, the particle sizes are relatively consistent, and the hydraulic conductivity is 10 <sup>-3</sup>~10 <sup>-4</sup> m/s.</p><p>This study is using ERT to provide hydrological data analysis on small areas and large areas in the Pingtung Plain, and also contributes to groundwater operations and management</p>

Blocking borehole conductivity logs at the resolution of above-ground electromagnetic systems

Borehole conductivity logs provide an in situ measurement of the electrical conductivity of the subsurface. Despite the measurements being a proxy for the true earth structure, they are often used as ground truth when inferring subsurface electrical conductivity boundaries between lithologies. Borehole conductivity measurements are therefore commonly used to plan and benchmark electromagnetic (EM) surveys and to establish the credibility of a given inversion technique. A consequence of the diffusion physics of EM prospecting is that not all subsurface features present in a conductivity log can be resolved by an EM system, nor can they be recovered by a subsequent inversion. Quantification of the ability of an EM system to determine layer boundaries in the subsurface is therefore an issue meriting investigation. We have developed a reversible-jump Markov chain Monte Carlo (RJMCMC) method to segment borehole conductivity logs at the scale recoverable by a given EM system as the foundation for an objective comparison between the inversion results and conductivity logs. A common consequence of RJMCMC inversions for EM problems is that few layers are required to fit the data. Similarly, we find that a borehole log blocked at the scale sensed by an EM system consists of a limited number of segments. Segmentation of borehole conductivity logs is determined by the physics of EM prospecting and by factors such as base frequency, number of gates, system geometry, and noise levels. For a survey line intersecting a borehole near Carnarvon, Western Australia, we see that different inversion schemes result in images of the subsurface that are consistent with a borehole conductivity log segmented according to the mechanics of the EM system and accounting for the physics of EM prospecting.