Fluid Charging and Paleo-pressure Evolution in the Ledong Slope Zone of the Yinggehai Basin,South China Sea

Large numbers of gas reservoirs have been discovered in overpressure basins.Fluid charging has a close relationship with paleo-pressure evolution,affecting the migration of gas reservoirs.To study fluid charging and the related pressure system,we analyzed burial histories and fluid inclusion(PVTx)simulations and conducted basin modeling of the Ledong Slope Zone in the Yinggehai Basin as an example.On the basis of fluid-inclusion assemblages(FIAs),homogenization temperature(Th),final melting temperature(Tm,ice)and Raman spectroscopy in fluid inclusions,there are three stages of fluid charging:during the first and second stage,methane-dominated fluid was charged at 2.2–1.7 Ma and 1.7–0.9 Ma,respectively.In the third stage,CO_(2)-rich hydrothermal fluid was charged since 0.9 Ma.It could be concluded from the well-logging data that the disequilibrium compaction in the Yinggehai Fm.,along with the fluid expansion and clay diagenesis in the Huangliu and Meishan formations,resulted in the overpressure in the Ledong slope zone.The evolution of paleo-pressure was affected by the sedimentation rate of the Yinggehai Fm.,as well as the hydrocarbon generation rate.Additionally,the Ledong Slope Zone is less affected by diapir activity than the nearby diapir area.Based on fluid inclusions,paleo-pressure,basin modeling and geological background,the gas migration history of the Ledong Slope Zone can be divided into four stages:in the first stage,excess pressure was formed around 5 Ma;from 2.2 to 1.7 Ma,there was a reduction in the charging of hydrocarbon fluid and steadily increasing excess pressure;during the 1.7–0.9 Ma period a large amount of hydrocarbon was generated,excess pressure increasing significantly and hydraulic fractures forming in mudstones,With gas reservoirs developing in structural highs;since 0.9 Ma,CO_(2)-rich hydrothermal fluid accumulated in reservoirs adjacent to faults and the pressure coefficient remained stable.The research results are helpful in the study of fluid migration and accumulation mechanisms in overpressure basins.

Multi-Stage Fluid Charging and Critical Period of Hydrocarbon Accumulation of the Sinian Dengying Formation in Central Sichuan Basin

Objective The natural gas exploration of the Sinian reservoirs in the central Sichuan Basin has made a significant breakthrough in recent years, and has thus attracted much attention among geologists. The Sichuan Basin is known to have complicated geological settings, which has experienced multiple stages of tectonic evolution, fluid charging and hydrocarbon accumulation. This research aims to determine the geochemical characteristics of each stage of fluids, the features and time interval of fluid activity in different geologic periods, and further to restore the critical period and geological age of the hydrocarbon accumulation.

Study on the 3D Green＇s functions of the fluid and piezoelectric bimaterials

Because most piezoelectric devices have interfaces with fluid in engineering, it is valuable to study the coupled field between fluid and piezoelectric media. As the fundamental problem, the 3D Green＇s functions for point forces and point charge loaded in the fluid and piezoelectric bimaterials are studied in this paper. Based on the 3D general solutions expressed by harmonic functions, we constructed the suitable harmonic functions with undetermined constants at first. Then, the couple field in the fluid and piezoelectric bimaterials can be derived by substitution of harmonic functions into general solutions. These constants can be obtained by virtue of the compatibility, boundary, and equilibrium conditions. At last, the characteristics of the electromechanical coupled fields are shown by numerical results.

Class of Charged Fluid Balls in General Relativity

In the present study, we have obtained a new analytical solution of combined Einstein-Maxwell field equations describing the interior field of a ball having static spherically symmetric isotropic charged fluid within it. The charge and electric field intensity are zero at the center and monotonically increasing towards the boundary of the fluid ball. Besides these, adiabatic index is also increasing towards the boundary and becomes infinite on it. All other physical quantities such as pressure, density, adiabatic speed of sound, charge density, adiabatic index are monotonically decreasing towards the surface. Causality condition is obeyed at the center of ball. In the limiting case of vanishingly small charge, the solution degenerates into Schwarzchild uniform density solution for electrically neutral fluid. The solution joins smoothly to the Reissner-Nordstrom solution over the boundary. We have constructed a neutron star model by assuming the surface density . The mass of the neutron star comes with radius 14.574 km.

Relativistic charged stellar modeling with a perfect fluid sphere

In this report we present the generalization of a solution to Einstein's equations with perfect fluid for the case of Einstein–Maxwell with perfect fluid.The effect of the charge is reflected by a parameter,ν,and its interval is determined by the positivity condition from the pressure in the interior of the star.It is shown that the solution is stable according to the Zeldovich criteria as well as in relation to the criteria of the adiabatic index.The compactness,u=GM/c^(2)R,of this charged model is greater than it is for the chargeless case as a result of the effect of the presence of the charge.This allows it to represent stars with a high compactness,in particular a graphic analysis is presented for the star SAX J1808.4-3658 with mass M=1.435M_(⊙)and radius R=7.07 km.From these data and employing the solution,we obtain that the total maximum charge for the star is Q=2.4085×10^(20)C.

Investigation of the Rayleigh–Taylor instability in charged fluids

The present study shows that the Rayleigh–Taylor(RT)instability and its growth rate are strongly dependent on the charge-mass ratio of charged particles in a charged fluid.A higher charge-mass ratio of the charged fluid appears to result in a stronger effect of the magnetic field to suppress the RT instability.We study the RT instabilities for both dusty plasma(small chargemass ratio of charged particles)and ion-electron plasma(large charge-mass ratio of charged particles).It is found that the impact of the external magnetic field to suppress the RT instability for ion-electron plasma is much greater than that for dusty plasma.It is also shown that,for a dusty plasma,in addition to region parameters such as the external magnetic field,region length,its gradient,as well as dust particle parameters such as number density,mass,and charge of dust particles,the growth rate of the RT instability in a dusty plasma also depends on parameters of both electrons and ions such as the number densities and temperatures of both electrons and ions.