62 research outputs found
Reasonable production allocation model of gas wells for deep tight gas reservoirs with the edge water
Deep tight gas reservoirs are one of the important unconventional gas reservoirs. Deep burial, tight reservoirs have many characteristics, including diverse accumulation patterns, multiple accumulation regulations, low natural energy generation, complex gas–water relationship, and intricate seepage mechanism. These features of gas reservoirs put forward the requirement for new methods for a reasonable production allocation of horizontal wells and optimization of such allocations from the perspective of stress sensitivity. While CO2 huff-and-puff-based models, numerical simulation models, and thermos-hydrodynamic models have been built to solve these issues, there is still a lack of theoretical guidance for reasonable production allocation, especially with the edge-water problem. Here, we present a new one-dimensional mathematical and physical model to capture the stable movement of the gas–water interface in deep tight edge-water gas reservoirs. Our results show that there is a starting pressure in deep tight gas reservoirs. The starting pressure gradient increases with the growth of water saturation, which is far greater than the starting pressure gradient of medium, shallow gas reservoirs under the same water saturation. In addition, by considering the stable movement of the gas–water interface under the starting pressure, we found that the gas well has a larger upper limit of production differential pressure, a smaller seepage velocity, and a lower upper limit of production allocation. Finally, we make a comparison between our model results and production characteristics of real gas wells and find a consistency between the model results with real data. Our model provides a theoretical framework for reasonable production allocation of gas wells in deep tight gas reservoirs with the edge water
The emission positions of kHz QPOs and Kerr spacetime influence
Based the Alfven wave oscillation model (AWOM) and relativistic precession
model (RPM) for twin kHz QPOs, we estimate the emission positions of most
detected kHz QPOs to be at r=18+-3 km (R/15km) except Cir X-1 at r = 30\+-5 km
(R/15km). For the proposed Keplerian frequency as an upper limit to kHz QPO,
the spin effects in Kerr Spacetime are discussed, which have about a 5% (2%)
modification for that of the Schwarzchild case for the spin frequency of 1000
(400) Hz.The application to the four typical QPO sources, Cir X-1, Sco X-1, SAX
J1808.4-3658 and XTE 1807-294, is mentioned.Comment: Science China, Physics, Mechanics & Astronomy, 2010, 53, NO.
Strong Neel ordering and luminescence correlation in a two-dimensional antiferromagnet
Magneto-optical effect has been widely used in light modulation, optical
sensing and information storage. Recently discovered two-dimensional (2D) van
der Waals layered magnets are considered as promising platforms for
investigating novel magneto-optical phenomena and devices, due to the
long-range magnetic ordering down to atomically-thin thickness, rich species
and tunable properties. However, majority 2D antiferromagnets suffer from low
luminescence efficiency which hinders their magneto-optical investigations and
applications. Here, we uncover strong light-magnetic ordering interactions in
2D antiferromagnetic MnPS3 utilizing a newly-emerged near-infrared
photoluminescence (PL) mode far below its intrinsic bandgap. This ingap PL mode
shows strong correlation with the Neel ordering and persists down to monolayer
thickness. Combining the DFT, STEM and XPS, we illustrate the origin of the PL
mode and its correlation with Neel ordering, which can be attributed to the
oxygen ion-mediated states. Moreover, the PL strength can be further tuned and
enhanced using ultraviolet-ozone treatment. Our studies offer an effective
approach to investigate light-magnetic ordering interactions in 2D
antiferromagnetic semiconductors
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