Geochemistry of Thermal Waters of Continental Margin of Far East of Russia   总被引：2，自引：0，他引：2  

Ivan V. BRAGIN  Georgy A. CHELNOKOV  Oleg V. CHUDAEV  Natalia A. KHARITONOVA  Sergey V. VYSOTSKIY 《《地质学报》英文版》2016,90(1):276-284

Studied waters belong to warm(T=30-50℃),alkaline(pH=8.9-9.3),low mineralized(TDS235 mg/1)Na-HCO_3 or Na-SO_4-HCO_3 thermal waters with high content of SiO_2(up to 81 mg/l)and F(up to 3.9 mg/1),occur on modern volcano-tectonic rejuvenated areas of Eastern Sikhote-Alin orogenic belt.Low~3He concentration as well as N_2/O_2 and N_2/Ar ratios exclude influence of deep mantle fluid.New rare earth element data constrain our understandmg of water-rock interaction occurring in the water source region.Meteoric origin of waters is proved by stable isotope values varying from-71‰to-136.1‰and from-10.8‰to-18.8‰forδ~2U andδ~(18)O respectively.REE patterns reflect high pH,resultfing from water-rock interaction and oxidative conditions.Calculations of deep aquifer temperature using Na-K and quartz geothermometers show 116.8-131.1°C and 82.2-125.8℃respectively.Presence of deep faults both with abnormal thermal gradient(~45-50 K/km)define unique geochemical shape of thermal waters of Sikhote-Alin,area,where no present volcanic activity is registered.  相似文献   

Wind Farm Support Vessel Extreme Roll Assessment While Docking in the Bohai Sea     

XU Xiao-sen  Oleg Gaidai  Oleh Karpa  WANG Jun-lei  YE Ren-chuan  CHENG Yong 《中国海洋工程》2021,35(2):308-316

Robust prediction of extreme motions during wind farm support vessel(WFSV)operation is an important safety concern that requires further extensive research as offshore wind energy industry sector widens.In particular,it is important to study the safety of operation in random sea conditions during WFSV docking against the wind tower,while workers are able to get on the tower.Docking is performed by thrusting vessel fender against wind tower(an alternative docking way by hinging is not studied here).In this paper,the finite element software AQWA has been used to analyze vessel response due to hydrodynamic wave loads,acting on a specific maintenance ship under actual sea conditions.Excessive roll may occur during certain sea conditions,especially in the beam sea,posing a risk to the crew transfer operation.The Bohai Sea is the area of diverse industrial activities such as offshore oil production,wave and wind power generation,etc.This paper advocates a novel method for estimating extreme roll statistics,based on Monte Carlo simulations(or measurements).The ACER(averaged conditional exceedance rate)method and its modification are presented in brief detail in Appendix.The proposed methodology provides an accurate extreme value prediction,utilizing available data efficiently.In this study the estimated return level values,obtained by ACER method,are compared with the corresponding return level values obtained by Gumbel method.Based on the overall performance of the proposed method,it is concluded that the ACER method can provide more robust and accurate prediction of the extreme vessel roll.The described approach may be well used at the vessel design stage,while defining optimal boat parameters would minimize potential roll.  相似文献   

Upper mantle roots of Siberian craton basement structures along the Rift DSS profile     

V.D. Suvorov  Z.R. Mishen’kina  E.A. Melnik 《Russian Geology and Geophysics》2010,51(8):885-897

We investigate the upper mantle velocity structure through processing first arrival data from peaceful nuclear explosions. The reported 2D model has been obtained by ray tracing for a spherical Earth, unlike the classical plane-approximation approach with subsequent spherical symmetry corrections, which is not always applicable to a laterally heterogeneous subsurface. The upper mantle velocity highs and lows imaged to 200–220 km depths show obvious correlation with major structures of the craton basement. Namely, low-velocity zones are observed beneath basins, the largest (to 8.0–8.1 km/s) under the Vendian–Early Cambrian Sayan–Yenisei syneclise. A discontinuous high-velocity layer (8.6–8.7 km/s) at depths between 150 and 240 km is underlain by a zone of lower velocity (8.50–8.55 km/s) down to the 410 km discontinuity, where the velocity at the top of the transition zone is 9.4–9.5 km/s.  相似文献   

Dynamics of two-phase conduit flow of high-viscosity gas-saturated magma: large variations of sustained explosive eruption intensity   总被引：1，自引：0，他引：1  

Oleg Melnik 《Bulletin of Volcanology》2000,62(3):153-170

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Evaluation of formation pore pressure behind the casing using borehole gravity data     

Yuliy A. Dashevsky  Semen Petrov  Alexandr N. Vasilevskiy  Oleg B. Bocharov  Gleb V. Dyatlov 《Studia Geophysica et Geodaetica》2017,61(1):69-92

Reliable estimates of the fluid pressure in the pore space of rocks are critical for different aspects of petroleum exploration and production including injection operations and scenarios of water flooding. Numerous approaches are available for formation pore pressure evaluation, however, these measurements become a challenge inside a cased borehole, and a list of possible options is short: either the casing is to be perforated, or the production tubing needs to be disconnected to perform the pressure tests. We present a method for through-casing evaluation of formation pore pressure without shutting down production. We suggest equipping an observation well with a borehole gravimeter and acquiring time variations of the vertical component of the gravity field. Changes in gravity occur during gas production and are related to time variations of formation pore pressure. Gravity changes obtained in the observation well are supposed to be inverted for time-dependent formation pore pressure variations beyond the casing. Our results and recommendations are based on numerical modeling of pore pressure spatial distribution during gas field exploitation and relevant changes in borehole gravity. Benchmark models were elaborated in order to consider a dynamic process of pressure changes in time and space under conditions similar to those in the Medvezhye gas field (Russia). Different modeling scenarios are considered for early and late stages of gas field exploitation. The sensitivity analysis was performed to estimate quantitatively a sensitivity of borehole temporal gravity changes to variations in formation pore pressure behind the casing. Based on resolution analysis we justify the possibility to extract the gravity measurements directly related to changes in pore pressure from the total changes in the gravity field due to reservoir exploitation. The impact of pore pressure on the gravity field measured in boreholes during the water flooding is also evaluated, and obtained results are discussed.  相似文献