Liu B.,Harbin Institute of Technology |
Liu B.,Northeast Petroleum University |
Wang C.-H.,Harbin Institute of Technology |
Li W.,Harbin Institute of Technology |
And 2 more authors.
Harbin Gongye Daxue Xuebao/Journal of Harbin Institute of Technology | Year: 2012
The graph of operator in closed-loop system and the robust stability margin are defined in the frame of the coprime factorization, and the sufficient and necessary conditions for feedback system are given by the graph of the plant and the inverse graph of the controller. A new multi-linear model approach is used to control a strongly nonlinear system, and reasonable operation points for nonlinear system are selected to design the corresponding optimal robust compensator with the largest generalized stability margin. Then the global robust controller is built from a weighted combination of local controllers whose outputs are weighted by the functions of generalized robust margin. The designed control system has good performance and robust stability for nonlinear system.
Li D.-P.,University of Science and Technology Beijing |
Zhu Z.-R.,Production Engineering and Research Institute of Daqing Oilfield Co. |
Zhang L.,University of Science and Technology Beijing |
Chen L.-J.,China National Petroleum Corporation |
And 2 more authors.
Corrosion and Protection | Year: 2013
The effect of thermal treatment temperature on localized corrosion of G3 corrosion resistant alloy (CRA) was studied by SEM, SSRT and weight loss methods. The results show that G3 CRA has excellent pitting corrosion resistance. The formation and dissolution of precipitates are the major factors influencing the pitting of G3 alloy, the large number of precipitates can make considerable damage to the uniformity of the passive film, the susceptibility to pitting increases. With the increase of thermal treated temperature, the formation of large amounts of precipitates deteriorates the protection of the passive film, and the crevice corrosion resistance becomes low. The crevice corrosion resistance was the lowest after annealing at 700 °C for 2 h. When the allay was annealed at 900 °C for 2 h, the precipitates were enriched at local area as a result of re-crystallization and the crevice corrosion resistance of G3 CRA was improved. The fractures of G3 CRA changed from ductile fracture to brittle fracture after annealing at 700 °C for 2 h, and the susceptibility to stress corrosion cracking was significant increased.
Xu D.,Production Engineering and Research Institute of Daqing Oilfield Ltd Company |
Zhong F.,Production Engineering and Research Institute of Daqing Oilfield Ltd Company |
Wang F.,Production Engineering and Research Institute of Daqing Oilfield Ltd Company |
Wang J.,Production Engineering and Research Institute of Daqing Oilfield Ltd Company |
And 7 more authors.
Society of Petroleum Engineers - Abu Dhabi International Petroleum Exhibition and Conference 2012, ADIPEC 2012 - Sustainable Energy Growth: People, Responsibility, and Innovation | Year: 2012
Daqing oilfield has entered the late period of extra high water production. With the development of horizontal well technology, coning of injected water is one of the most important production problems in the Daqing oilfield. The water cut of many wells in old depleted areas is more than 80%, and still rising. With the use of horizontal well technology in depleted areas, the problem will continue. An adjustable water system or smart well (intelligent completion) technology is urgently needed to solve the practical production problems in this oilfield. This article first identifies the smart well (intelligent completion) technology, and the major companies using it. Secondly, the paper shows the development of smart well technology in China, the reason why we use smart well technology in the Daqing oilfield, the adjustable water cut system in the Daqing oilfield, and the application of smart well technology in the Daqing oilfield. Finally, a smart well is introduced, and some of advanced downhole devices and the prospects for their application in the Daqing oilfield are detailed. Copyright 2012, Society of Petroleum Engineers.
Zhang Y.-G.,Production Engineering and Research Institute of Daqing Oilfield Company Ltd |
Zhang H.,Production Engineering and Research Institute of Daqing Oilfield Company Ltd |
Wang X.-J.,Production Engineering and Research Institute of Daqing Oilfield Company Ltd |
Zhang Z.-Y.,Production Engineering and Research Institute of Daqing Oilfield Company Ltd |
And 3 more authors.
Zhongguo Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of China University of Petroleum (Edition of Natural Science) | Year: 2012
By introducing the complex of hydrolyzed polyacrylamide and hydroxypropyl guar as the thickener and organic zirconium as the delayed crosslinker, a novel ultra-high temperature fracturing fluid was developed and its rheological behaviors were investigated. The results show that the crosslinked network structure of this new type fracturing fluid is optimized by introducing the complex thickener and delayed crosslinker of organic zirconium. In particular, by introducing organic zirconium as the delayed crosslinker, the fracturing fluid is crosslinked once again during the process of shearing at high temperature. As a result, the high temperature resistance of the fracturing fluid is improved significantly. The shear viscosity of this novel fracturing fluid is larger than 80 mPa · s even if this fracturing fluid is sheared more than two hours under the shear rate of 170 s -1 and at the temperature of 200°C. This suggests that this novel fracturing fluid can be applied to stimulate the tight and high temperature natural gas reservoirs with the depth of 4.7-5.0 km in Daqing Oilfield.
Wenhai M.,Southwest Petroleum University |
Wenhai M.,Production Engineering and Research Institute of Daqing Oilfield Company Ltd |
Yonggang D.,Southwest Petroleum University |
Dapeng L.,University of Science and Technology Beijing
Corrosion Science and Protection Technology | Year: 2015
With the increasingly exploiting the gas field, several corrosion related failure cases, such as perforation and fracture of tubing steel did occurr in Xushen gas fields, which was thought to be the result of CO2 induced localized corrosion. In order to reveal the nature of those failure cases, the corrosion behavior of N80 steel a commonly used material for pipelines, in a high temperature and high pressure environment was studied, which arms to simulate the CO2 induced localized corrosion in the actual gas well processing practice, thereby to figure out the relation of the sensitivity to corrosion of the tubing steel with the relavant processing parameters. By characterizing the corrosion morphology and the sensitivity to localized corrosion and summing up the effect of environmental factors (temperature and CO2 partial pressure) on the CO2 induced localized corrosion of N80 steel, a corrosion map could be constructed to describe the relation of corrosion types of the N80 steel with the processing parameters temperature and CO2 partial pressure etc., thereafter, a prediction model for configuring a range of environment parameters, within which the N80 steel would be sensitive to the CO2 induced localized corrosion. Finally, it is noted that the prediction of corrosion types and the range of parameters responsible to the CO2 induced localized corrosion of N80 steel show a good agreement with the observation of the practical failure cases in Xushen gas fields. ©2015 Chinese Academy of Sciences. All rights reserved.