University of Science and Technology Beijing

Beijing University of Technology

Anhui Earth-Panda Advance Magnetic Material Co., Ltd.

University of Science and Technology

Ming Yue

Weiyao Zhu

Zhiyong Song

Debin Kong

Zhen Chen

Yunfeng Liu

Wenchao Liu

Weiqiang Liu

Kun Huang

Dongtao Zhang

Baichuan Wang

Dongxu Ma

Meng Li

Hao Chen

Hua Li

Min Liu

He H Liu

Zhi Li

Yuqing Li

Jing Xia

Qinglin Shu

Bingbing Li

Chenglin Li

Yubao Gao

Xiaowen Yin

Jingwu Chen

Zenglin Wang

Xiaofei Yi

Shou Ma

Xiantao Li

Hongguo Zhang

Yantao Yin

Guodong Zou

Tongwen Jiang

Xiulian Huang

Qian Qi

Kai Luo

Aishan Li

Ziheng Zhou

Hongyan Han

Yuwei Liu

Yuxia Yin

Jianfa Wu

Ruijin Hu

A two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet belongs to the preparing technical field of rare earth permanent magnet materials. The compositions of the two main phase alloys are RE-Fe&#x2014;B (RE is Nd or Pr) and (Nd, MM)-Fe&#x2014;B (MM is mischmetal), respectively. First, PrHoFe strip-casting alloy is used as a diffusion source. Next, a PrHo-rich layer is uniformly coated on the surface of (Nd, MM)-Fe&#x2014;B hydrogen decrepitation powders. The higher anisotropic fields of PrFeB and HoFeB are used to improve the coercivity. Then, the ZrCu strip-casting alloy is used as a diffusion source. A Zr-rich layer is uniformly coated on the surface of the powders after the first-step diffusion, which prevents the growth of the MM-rich main phase grains during the sintering process and the inter-diffusion between the two main phases, thus obtaining high coercivity.

Two-step diffusion method for preparing high-performance dual-main-phase sintered mischmetal-iron-boron magnet

A method for identifying a medium structure coupling and a fracture network morphology of a shale gas reservoir includes the following steps. Firstly, performing a fracturing test on shale cores by using a modified Brazilian disc test and categorizing the fracture network morphology. Secondly, performing a shale matrix-fracture structure and stress sensitivity test on the shale cores having different fracture network morphology. After that, determining a stress sensitivity constant of different fracture network morphology according to indoor core data and finally preparing an identification chart of the fracture network morphology based on an indoor core stress sensitivity test combined with a production practice. The identification chart can be applied to an actual fracturing well, and the fracture network morphology is directly identified by a real-time effective stress and a normalized flow.

Method for identifying a medium structure coupling and a fracture network morphology of a shale gas reservoir

A method for developing shale gas by tapered gradient pressure drop with multi-stage fractured horizontal well is provided and the method comprises: acquiring fracturing crack form parameters of the multi-stage fractured horizontal well and reservoir characteristic parameters of nearby formation; dividing the formation near the shale gas multi-stage fractured horizontal well into strongly transformed area, weakly transformed area and matrix area; establishing pressure difference-flow models of gas-phase and water phase of the three areas respectively, and coupling the models of the three areas to establish production equation of the multi-stage fractured horizontal well; according to the production equation of the multi-stage fractured horizontal well, performing numerical simulation with different combinations of production pressure differences in the three stages of the multi-stage fractured horizontal well; and selecting a combination of production pressure differences with the greatest economic benefit as combination of production pressure differences.

Method and device for developing shale gas by tapered gradient pressure drop with multi-stage fractured horizontal well

A simulation method for flow field of multi-stage fracturing on horizontal well in tight oil reservoir is provided. The tight oil reservoir comprises multiple horizontal wells with multi-stage fracturing, and for any horizontal well of the multiple horizontal wells, the method comprises: establishing a seepage mathematical model involving threshold pressure gradient according to reservoir physical property data and production data of the horizontal well, and determining formation pressure distribution of the horizontal well after multi-stage fracturing production according to the seepage mathematical model; determining formation pressure field distribution of the horizontal well after multi-stage fracturing production according to the formation pressure distribution and basing on principle of complex potential superposition; and establishing a criterion for identifying effective producing range of the horizontal well according to the formation pressure field distribution, and determining flow field range of the horizontal well according to the criterion.

Simulation method for flow field of multi-stage fracturing on horizontal well in tight oil reservoir

The present invention provides a device and a method for measuring overburden of injected gas in cyclic gas injection development of condensate gas reservoir. The device comprises sand packed model and temperature control system. The temperature control system is nested outside the sand packed model. The sand packed model comprises sand pack cell, four gas inlets, four gas outlets, bracket, direction control component, rotating shaft, upper cover, lower cover, fixing bolts, two top pressuring inlets, pressure transmission rods, pressure transfer piston and multiple gas sampling ports. The sand pack cell can be filled with quartz sand of different particle size and composition, and the angle of the whole device is adjusted by the direction control component.

Device and method for measuring overburden of injected gas in cyclic gas injection development of condensate gas reservoir

A device and a method for evaluating a gas-water two-phase flow fracture conductivity of a fractured shale. The device includes a seepage system, an injection system, a data collecting and processing system and a three-axis shale core holder, wherein the seepage system is subjected to two stages including a water injection stage and a gas flooding stage. When using the device, firstly the initial permeability and initial mass of the shale sample are determined; the water influx test is performed by injecting water to the shale sample until flow rate of the water discharged from the shale core is stable, then the water injection is ended. After the drying device is installed, the shale sample is subjected to gas flooding, and the aqueous fracturing fluid discharged by the gas flooding is collected until the flow meter determines that the gas volume is stable, and then the gas flooding is ended.

Device and method for evaluating gas-water two-phase flow fracture conductivity of fractured shale

A method of optimizing well spacing for shale gas development is provided. It belongs to the technical field of hydrocarbon reservoir exploration and development. The method comprises: firstly verifying block area based on the explored geological structure; analyzing the connection situation of a shale reservoir, identifying the minimum developing area units; calculating the recoverable reserves of the units, confirming the candidate units; drilling representative shale cores and analyzing related physical properties; calculating seepage field and pressure field using unified multi-field, multi-flow-regime, and multi-scale mathematical models; calculating the effective recoverable area of each well; and arranging wells based on the rule that the interference among wells is not larger than 10%. Considering the fluid-solid coupling effects, the method can define appropriately well spacing for shale gas exploration and enhance effectively the output of shale gas.

Methods of optimizing well spacing for shale gas development

The present disclosure provides a method for optimizing bunch distance of fractured horizontal wells of shale gas, which relates to the technical field of oil exploration. The method comprises first establishing a stress field distribution model for a single fracture; then establishing an induced stress distribution model of segmented single-bunch fracturing for a horizontal well; later establishing an induced stress distribution model of segmented multi-bunch fracturing for a horizontal well; last optimizing fracturing parameters and fracture distance according to the distribution pattern of the induced stress difference. The method considers the stress barrier, stress interference effects, and the variation of the effective net pressure during the synchronous expansion of fractures, so the calculation model is more in line with the actual working conditions, has higher precision, and can provide more accurate theoretical guidance for the optimization design of segmented multi-bunch fracturing of a horizontal well.

Methods for optimizing bunch distance of fractured horizontal wells of shale gas

This patent invents a heat-resistant isotropic bonded NdFeB magnet and its preparation technology, belonging to the field of magnetic materials. In present invention, isotropic NdFeB magnetic powders is used as magnetic material, sodium silicate is used as principal binder, and epoxy resin is used as auxiliary binder to prepare heat-resistant isotropic bonded NdFeB magnets. The prepared magnets have greatly increased heat resistance to stand an operating temperature of 200&#xb0; C., and have advantages of penetration and corrosion resistance. The invented heat-resistant isotropic bonded NdFeB magnets feature good magnetic properties and high operating temperature. During the preparation process, it has the advantage of simple equipment, easy operation, low cost. The technology is easy to large scale production, and has high economic value and huge application prospect in the field of permanent magnetic materials.

Heat-resistant isotropic bonded NdFeB magnet and its preparation technology

The present invention discloses a short process preparation technology of sintered NdFeB magnets from the NdFeB sludge, which relates to a field of recycle technology of NdFeB sludge. The present invention comprises the following steps: water bath distillation of organics in sludge, ultrasonic cleaning, calcium reduction and diffusion, ultrasonic rinsing in a magnetic field and drying, powders mixing and sintering. NdFeB sludge as raw materials was directly prepared from recycled sintered magnets with high magnetic properties. Most of the organics in the sludge could be removed by a vacuum distillation process with stepwise heating. The ultrasonic rinsing process in a magnetic field could effectively remove the remaining organics. The recycled sintered magnets exhibited good maximum energy product [(BH)] of 35.26 MGOe. The present invention has important features, such as the short processing time, efficient environmental protection, high recycling rate and effective utilization rate of rare earth metals.

Short-process method for preparing sintered NdFeB magnets with high magnetic properties recycling from NdFeB sludge

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Beijing, China

Ming Yue