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Tang K.,Chengdu University of Technology | Zhou N.-N.,Xian Changqing Technology Engineering Co. | Fan X.-Y.,Petrochina
Wutan Huatan Jisuan Jishu

Due to the complex geological condition and changeable productivity, there are many factors effect on the productivity in low porosity and low permeability reservoir. It is difficult to predict productivity. Aiming at this problem and based on the data of sixteen wells of s2 gas pool of Zizhou gas field, 10 factors affecting the productivity are selected by using open flow potential as a evaluation index of the gas well productivity. Then we found the key factors by using the methods of grey slope relational analysis, principal component analysis and R cluster analysis. Although there are some differences in the key factors, effective thickness, gas saturation, storage coefficient and formation coefficient are in front. Finally comprehensive analysis indicates that the key factors effecting on the gas well productivity of the reservoir include effective thickness, gas saturation, storage coefficient and formation coefficient. This conclusion has some directive significances for wells and layers selection, fracturing design and fracturing operation. Source

Yu J.,Xian University of Architecture and Technology | Liu X.,Xian University of Architecture and Technology | Zhao Y.,Xian Changqing Technology Engineering Co.
Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology

Three different height-width ratio RC frame structures located in intensity region 8 (0.2 g) were designed and analyzed using monolithic model and joint model by OpenSees program. The results show that the degree of influence of joint on seismic performance of frame structure and the structure of component into the nonlinear construction related. Under small earthquakes, the structure is in elastic state, and the influence of construction joints can be neglected. In the moderate and strong earthquakes, the structure is in a nonlinear stress state. Influence of construction joints began to highlight, and are mainly shown in the increase of top displacement structure, of inter story displacement angle and the changes of the interlayer displacement angle displacement distribution of bottom displacement form aggravation of and the key components local reactions aggravate. It is necessary to consider the influence of construction joints from the seismic design. Based on the existing two stage design method, seismic design recommendations were proposed from concept design and calculation method. ©, 2015, Xi'an Jianzhu Keji Daxue Xuebao/Journal of Xi'an University of Architecture and Technology. All right reserved. Source

Yin X.-T.,CAS Wuhan Institute of Rock and Soil Mechanics | Zheng Y.-N.,Xian Changqing Technology Engineering Co. | Ma S.-K.,Chinese Research Institute of Highway
Yantu Lixue/Rock and Soil Mechanics

Inner scale ratio is a ratio between minimum crystal structure of material and its specimen size. Rock and soil material, being a type of different sizes mineral particles assembler under microscopic conditions, contains different scale raw faults. These size features of material structure will affect accuracy of rock and soil material characteristics test results. That is to say there exists inner scale ratio in rock and soil materials like that of metal material. So virtual uniaxial compression test done by inner embedded fish language of particle flow code is used to study inner scale ratio of geotechnical material. Twelve numerical specimens with twelve types of grain size such as 0.05, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 mm are designed and tested. According to failure shape and stress-strain curve of these specimens, effect of inner scale ratio on test results is analyzed. It is found that the computing time increases dramatically and computing efficiency decreases sharply if grain size less than 0.4 mm; and that test results tend to stability and accuracy if inner scale ratio less than 0.01, so as to prove existence of inner scale ratio in rock and soil material. Size effect in geotechnical material is reflection of inner scale ratio. Source

Zhu Y.-P.,Lanzhou University of Technology | Zhu Y.-P.,Northwest Center for Disaster Mitigation in Civil Engineering | Yang X.-H.,Lanzhou University of Technology | Yang X.-H.,Northwest Center for Disaster Mitigation in Civil Engineering | And 3 more authors.
Gongcheng Lixue/Engineering Mechanics

After earthquakes, most of gravity retaining walls in the earthquake zone emerge an instability phenomenon, and due to the change of the retaining wall working conditions, instable accidents might be produced. Thusly, the framework anchor with flexible prestress was used to reinforce gravity retaining walls. On the basis of limit equilibrium theory, the overall static stability of gravity retaining wall after flexible reinforcement was analyzed, and the solution formula for the safe stability coefficient of anti-slip and anti-overturning was derived. The dynamic formula of stability was also derived by energy analysis and limit equilibrium theory. Based on the comparative analysis of numerical examples, the result showed that: the safe stability coefficient of reinforced gravity retaining walls was significantly improved, and the aseismic capacity of space synergy among soil, framework, anchor, and retaining walls was also improved respectively. © 2015, Engineering Mechanics Press. All right reserved. Source

Liu H.,Southwest Petroleum University | Liu J.,China Oilfield Services Ltd. | Dai C.,China National Petroleum Corporation | Zhang Y.,Xian Changqing Technology Engineering Co.
Xinan Shiyou Daxue Xuebao/Journal of Southwest Petroleum University

This paper mainly discussed the abnormal responses of amplitude attenuation resistivity and phase shift resistivity detected by logging-while-drilling resistivity instruments in the borehole of large deviation and horizontal wells. Combining with the simulation results of EMF of the LWD resistivity responding in borehole environment, the paperwe analysed the major characteristics and reasons of abnormal corresponding of these two kinds of resistivity. And then, we listed the curves of the LWD amplitude attenuation and phase shift resistivity of three typical wells of Bozhong area of CNOOC company, which were logged by EWR-Phase 4 of Halliburton International company, The amplitude resistivity and phase shift resistivity of this three wellsto illustrate a typical unusual changes in the curve morphology. With discussion on lithology of the formation, permeability of reservoir, mud invasion, drilling velocity(ROP) and environment of borehole, the curves reading range and variation trend are examined for the X-Shallow, shallow, mediate and deep resistivity. In the endFinally, the paperwe summarizes that the abnormal corresponding types, such as Zorro effect, lace curtain effect and polarization angle effect, are most frequently encountered in the high angle and horizontal wells logged by EWR-Phase 4 tools. ©, 2015, Southwest Petroleum University/Xinan Shiyou Daxue. All right reserved. Source

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