Oil and gas prediction basing on seismic inversion of elastic properties in Chaoshan depression, south China sea

The marine Mesozoic is widely distributed in the northeastern waters of the South China Sea and is an important field for oil-gas exploration in the South China Sea. The Chaoshan Depression is the largest residual depression in this sea. At a previous well, LF35-1-1, no oil and gas have been discovered with then pre-drilling prediction techniques. Post-drill analysis shows that the physical properties of the Mesozoic reservoir are not favorable there. So, in accurate prediction of the oil-gas reservoirs is necessary. Since the drilling at the LF35-1-1, extensive surveys and studies have been carried out which shows a number of favorable trapping structures. In the middle low bulge of the Chaoshan Depression, the DS-A structures found with potential reservoirs, complete trap structures, and dual source hydrocarbon supply on both sides, making it the most favorable zone for oil-gas accumulation. We apply the state of art prediction techniques for it using pre-stack seismic raw gather. The sensitivity analysis results of reservoir physical properties indicate that the difference in P- wave velocity between sand and mudstone is 500 m/s, the difference in density is 0.02 g/cm3, and the Poisson’s ratio ranges between 0.11 and 0.33. The Mesozoic sandstone reservoirs in the Chaoshan Depression have characteristics of high velocity and low Poisson’s ratio, and the P-wave velocity, density, and Poisson’s ratio are the main sensitive parameters for predicting reservoir and its oil-gas bearing properties. The density inversion, P-wave impedance inversion, and S-wave impedance inversion jointly characterize the “wedge-shaped” sand body in the DS-A structural area, with a maximum thickness of over 400 m and an area of ∼130 km2. The overlap of the sand body contour map and Poisson’s ratio inversion results indicates that the “wedge-shaped” sand body is an oil-gas bearing sand body. It can be concluded that pre-stack elastic parameter inversion is an effective method for reservoir prediction in deep-sea no-well exploration areas. It has the characteristics of high signal-to-noise ratio, strong stability and reliability, and high accuracy, which is conducive to reduce the non-uniqueness and uncertainty of seismic inversion. The inversion results predict that the DS-A structure is an oil-gas bearing structure

Hydrocarbon Detection Based on Phase Decomposition in Chaoshan Depression, Northern South China Sea

Located in the northern South China Sea, Chaoshan Depression is mainly a residual Mesozoic depression, with a construction of Meso-Cenozoic strata over 7000m thick and good hydrocarbon accumulation conditions. Amplitude attribute of -90°phase component derived by phase decomposition is employed to detect Hydrocarbon in the zone of interest (ZOI) in Chaoshan Depression. And it is found that there are evident amplitude anomalies occurring around ZOI. Phase decomposition is applied to forward modeling results of the ZOI, and high amplitudes occur on the -90°phase component more or less when ZOI is charged with hydrocarbon, which shows that the amplitude abnormality in ZOI is probably caused by oil and gas accumulation

Decrease in the production of beta-amyloid by berberine inhibition of the expression of beta-secretase in HEK293 cells

<p>Abstract</p> <p>Background</p> <p>Berberine (BER), the major alkaloidal component of <it>Rhizoma coptidis</it>, has multiple pharmacological effects including inhibition of acetylcholinesterase, reduction of cholesterol and glucose levels, anti-inflammatory, neuroprotective and neurotrophic effects. It has also been demonstrated that BER can reduce the production of beta-amyloid_40/42, which plays a critical and primary role in the pathogenesis of Alzheimer's disease. However, the mechanism by which it accomplishes this remains unclear.</p> <p>Results</p> <p>Here, we report that BER could not only significantly decrease the production of beta-amyloid_40/42and the expression of beta-secretase (BACE), but was also able to activate the extracellular signal-regulated kinase1/2 (ERK1/2) pathway in a dose- and time-dependent manner in HEK293 cells stably transfected with APP695 containing the Swedish mutation. We also find that U0126, an antagonist of the ERK1/2 pathway, could abolish (1) the activation activity of BER on the ERK1/2 pathway and (2) the inhibition activity of BER on the production of beta-amyloid_40/42and the expression of BACE.</p> <p>Conclusion</p> <p>Our data indicate that BER decreases the production of beta-amyloid_40/42by inhibiting the expression of BACE via activation of the ERK1/2 pathway.</p

Why Has China’s Final Consumption Rate Declined Since 1978? Causes and Implications

China, Consumption rate, Income distribution, Propensity of consumption, Housing reform,

Seismically Imaged Crustal Breakup in the Southwest Taiwan Basin of the Northeastern South China Sea Margin

Abstract The Southern Depression of the Southwest Taiwan Basin is an ENE‐trending wide rift in the northeastern South China Sea margin. Though known as highly thinned, the maximum degree of crustal extension remains unclear. Here, we present three NW‐trending multi‐channel seismic profiles crossing the depression askew, and another profile traversing it, all of which image the basement and Moho clearly. The basement deepens toward the rift axis while the Moho shoals toward the axis, indicating significant crustal thinning. Faults appear with only small throws and are usually untraceable to depth. As the integral fault offset seems insufficient to match the horizontal crustal extension, the high crustal thinning is mainly accommodated by detachment faults. Only small‐scale post‐rift magmatic bodies and sporadic sills are observed, and syn‐rift magmatism is poor. The depression shows a recumbent V‐shaped valley opening to the northeast with the width increasing from 50 km on the southwestern profile to 96 km on the northeastern profile. Along the valley axis, the crust thins from 8.1 to 3.6 km and more thinner to the northeast, demonstrating enhanced extensional degree toward the northeast. A unique conch‐shaped package (up to ∼2 s two‐way travel time thick) with moderately coherent reflections is imaged atop the axial mantle on the northeastern profile. It was possibly formed by mantle exhumation, syn‐rift sedimentary uplift, or volcanic eruption. All these possibilities indicate that the crust probably broke up there, which represents a special style of crustal thinning different from other magma‐poor margins

Hydrocarbon Accumulation Analysis Based on Quasi-3D Seismic Data in the Turbulent Area of the Northern South China Sea

The Mesozoic strata in the northern South China Sea have good potential for oil and gas exploration. The Dongsha Waters, where the study area is located, have complex seismic and geological characteristics; in particular, turbulence is very prominent in this area, so it is difficult to implement 3D seismic data collection. The &ldquo;single-source and single-cable quasi-3D seismic survey&rdquo; method integrates some key technologies in acquisition and processing, thus improving the quality of seismic imaging. Based on the interpretation of the existing research results and new data, structure B-1 has good source&ndash;reservoir&ndash;cap combination conditions. The oil&ndash;gas accumulation mode is predicted, and the drilling well B-1-1 is given. In addition, the large-scale distribution of bottom-simulating reflectors (BSRs) and the discovery of gas seepage areas in the study area suggest the presence of gas hydrate. We suggest that deep thermogenic gas from the Mesozoic strata has migrated into the overlying strata along the fault system and mixed with microbial gas to form hydrate

Foraging areas of Rousettus leschenaulti on the Hainan Island of China

We investigated the foraging area of three individuals (1 female and 2 males) of Rousettus leschenaulti (Chiroptera, Pteropodidae) in suburban Haikou City, Hainan Province, South China from November 2005 to January 2006 using radio telemetry. These animals left the daytime roosting sites about 90 min after sunset with no significant difference in departure time between the male and female bats. The average active times were 391.8 min for males and 533.7 min for the female, respectively. By reconstructing 93 radio-telemetry recording positions, we found that the long axis of foraging area of the bats ranged from 7.45 to 11.70 km. The foraging area of the female (3867 ha) was larger than that of the males (1138 ha), and there was overlap between the foraging areas of different individuals. These bats usually kept the same flight routes across a few successive days from the daytime roosting site to the foraging areas. Our findings suggested that female R. leschenaulti may explore a larger foraging area than males. No obvious territorial behaviors were observed in our studied area [Current Zoology 56 (4): 479–484, 2010]