Investigation of low water recovery based on gas-water two-phase low-velocity Non-Darcy flow model for hydraulically fractured horizontal wells in shale

Various mechanisms are employed to interpret the low water recovery during the shale-gas production period, such as extra-trapped water in the fracture network, water imbibition due to osmotic pressure and capillary pressure. These lead to the difficulty of water flow, which could be described by low-velocity non-Darcy's law known as threshold pressure gradient (TPG). In this paper we firstly employ the low-velocity non-Darcy's law to describe the water flow and use Darcy flow accounting for slip flow and free molecular flow mechanisms to model gas flow in the shale formation. The sensitive study using numerical simulation shows that the proposed flow model could model the low fracturing liquid recovery and that large pseudo TPG leads to lower fracturing liquid recovery. Thus, the proposed model would give new insight to model the low water recovery in shale formations

Method for producing aluminum matrix composites through pressureless infiltration

The present invention deals with the production of aluminum matrix composites through pressureless infiltration, where a preform, made from the mixtures of at least one kind of reinforcements materials and aluminum or aluminum alloy powder, is spontaneously infiltrated by molten matrix aluminum or aluminum alloys under a protective environment, at a temperature ranging from 700 °C to 1500 °C

Microstructure and mechanical properties of milled fibre/SiC multilayer composites prepared by tape casting and pressureless sintering

In the present work, milled carbon fibre with high mechanical properties was used to reinforce silicon carbide, and Csf/SiC multilayer composites were prepared by tape casting and pressureless sintering. The milled C fibres were firstly dispersed in solvents with the aid of dispersant (Triton X-100) and then mixed with SiC slurry to make green Csf/SiC tapes to limit fibre breakage. The average length of C fibres slightly decreased with the increase of mixing time in the present duration, indicating that mixing the SiC slurry with the fibre-predispersed solution is an effective method for adding fibres with limited breakage. Fibres were homogeneously distributed in the tapes and tended to align fairly well along the tape casting direction. The relative density of the composite containing milled C fibres decreased with the fibre amount. The Csf/SiC multilayer composites demonstrated significant anisotropic shrinkage behaviour in different directions, while the addition of short C fibres hindered the shrinkage in the plane containing the fibres during sintering. Elastic modulus and bending strength decreased with increased porosity, which implies that bending properties are affected more significantly by residual porosity rather than fibres' propertie

Thermophysical properties of SiC multilayer prepared by tape casting and pressureless sintering

In present work, SiC multilayer samples for thermal conductivity test in X (along tape casting direction), Y (perpendicular to tape casting direction and thickness direction) and Z (through thickness direction) directions were successively prepared by tape casting and pressureless sintering. Effect of oxidation treatment on the thermal diffusivity and conductivity was investigated. Elongated SiC grains were observed in three directions, especially in Y direction. The specific heat capacity of SiC multilayer increased with temperature, which could be well fitted. The relative length change of SiC multilayer increased with variation of temperature in X, Y and Z directions, and no significant difference among the thermal expansion behavior in three directions was observed. Regardless of testing directions and oxidation treatment, the thermal diffusivities and conductivities of SiC multilayer in three directions decreased with the increase of temperature. SiC multilayer demonstrated the lowest thermal diffusivity and conductivity in Z direction mainly due to the presence of interface between SiC layers. Because of the formation of silica with low thermal conductivity, the oxidation treatment could slightly decrease the thermal diffusivity and conductivity in all directions

Gray matter regions of interest (ROIs) definition in the cervical spinal cord.

<p>The rsfMRI scanning field of view (FOV) and slice location that cover vertebrae C1 to C7 (a); the gray matter was drawn on post-processed echo planar imaging (EPI) images (b); the gray matter ROI was then delineated and split into ROI1 (ventral horn) and ROI2 (dorsal horn) (c); left and right parts of each horn were also furtherly separated; finally 60 ROIs were extracted from each subject (d).</p

ALFF values of healthy subjects and CSM patients (mean ± SEM).

<p>ALFF values of healthy subjects and CSM patients (mean ± SEM).</p

ALFF comparison between healthy subjects and CSM patients.

<p>In the whole cervical cord (CC) and each segment from C2 to C6, amplitude of low frequency fluctuation (ALFF) had the trend of healthy subjects < CSM patients. From two sample t-test results, all of the differences were significant (a). After separating CSM patients into mild (JOA≥13, 8 patients, age = 49±11 years, age ranged from 26 to 67 years) and severe (JOA<13, 10 patients, age = 67±7 years, age ranged from 59 to 83 years) groups, Anterior-Posterior Compression Ratio (APCR) of each patients in mild and severe groups was compared. The difference of APCR between mild and severe CSM patients was not significant (b). ALFF had the trend of mild CSM patients < severe CSM patients. From two sample t-test results, all of the differences were significant (c) (*: P<0.05, significant, ns: P>0.05, not significant).</p