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A numerical method for determining the stuck point in extended reach drilling

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petroleum Science 2011年第3期8卷 345-352页

作者： Sun Lianzhong Gao Deli key laboratory of petroleum Engineering Ministry of Education China University of Petroleum Beijing 102249 China

A stuck drill string results in a major non-productive cost in extended reach drilling engineering. The first step is to determine the depth at which the sticking has occurred. Methods of measurement have been proved useful for determining the stuck points, but these operations take considerable time. As a result of the limitation with the current operational practices, calculation methods are still preferred to estimate the stuck point depth. Current analytical methods do not consider friction and are only valid for vertical rather than extended reach wells. The numerical method is established to take full account of down hole friction, tool joint, upset end of drill pipe, combination drill strings and tubular materials so that it is valid to determine the stuck point in extended reach wells. The pull test, torsion test and combined test of rotation and pulling can be used to determine the stuck point. The results show that down hole friction, tool joint, upset end of drill pipe, tubular sizes and materials have significant effects on the pull length and/or the twist angle of the stuck drill string.

关键词： Extended reach drilling stuck pipe torque and drag numerical method

Study of Chinese Sustainable Developing Project for Energy Resources

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地学前缘 2009年第S1期16卷 146-147页

作者： Kuangming Zhang,Wenhui Huang,Huajun Wang 1.School of Energy Resources,china university of Geosciences(beijing),beijing 100083,china. 2.key laboratory of Marine Reservoir Evolution and hydrocarbon accumulation mechanism,ministry of education,china university of Geosciences(beijing),beijing 100083,china

Since the last half century,the world has been being in theme of peace and development,and passed through another glorious period with the rapid development of the economy,science and technology. In the energy field of the globe,as the fuel with superior quality,the petroleum and gas gradually replaced the coal of the leading role in energy resources’ consumption,after the mineral energy replaced ***,various types of new energy are beginning to get application。

关键词： energy resources’ consumption economy environment sustainable development

Characteristics of non-Darcy flow in low-permeability reservoirs

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petroleum Science 2011年第1期8卷 55-62页

作者： Yao Yuedong Ge Jiali key laboratory of petroleum Engineering of the ministry of education China University of PetroleumBeijing 102249 China

Well testing is recognized as an effective means of accurately obtaining the formation parameters of low-permeability reservoirs and effectively analyzing the *** test models must comply with the particular characteristics of flow in low-permeability reservoirs in order to obtain reasonable well test *** present,non-Darcy flow in low-permeability reservoirs is attracting much *** this study,displacement tests were conducted on typical cores taken from low-permeability *** dimensionless variables were introduced to analyze the collected experimental *** results of the dimensionless analysis show whether non-Darcy flow happens or not depends on the properties of fluid and porous media and the pressure *** combination of the above three parameters was named as dimensionless criteria coefficient（DCC）.When the value of the DCC was lower than a critical Reynolds number（CRN）,the flow could not be well described by Darcy＇s law（so-called non-Darcy flow）,when the DCC was higher than CRN,the flow obeyed Darcy＇s ***,this paper establishes a transient mathematical model considering Darcy flow and non-Darcy flow in low-permeability reservoirs,and proposes a methodology to solve the *** solution technique,which is based on the Boltzmann transformation,is well suited for solving the flow model of low-permeability *** on the typical curves analysis,it was found that the pressure and its derivative curves were determined by such parameters as non-Darcy flow index and the flow *** results can be used for well test analysis of low-permeability reservoirs.

关键词： Low-permeability non-Darcy flow dimensionless analysis transient flow well testing

Holocene climate variation denoted by Barkol Lake sediments in northeastern Xinjiang and its possible linkage to the high and low latitude climates

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Science china Earth Sciences 2011年第4期54卷 603-614页

作者： XUE JiBin & ZHONG Wei 1 School of Geography,South china Normal university,Guangzhou 510631,china 2 key laboratory of Oasis Ecology(ministry of education) ,Xinjiang university,Urumqi 830046,china 3 key laboratory of Western china's Environmental Systems(ministry of education) ,Lanzhou university,Lanzhou 730000,china School of Geography South China Normal University Guangzhou China key laboratory of Oasis Ecology (ministry of education) Xinjiang University Urumqi China key laboratory of Western china’s Environmental Systems (ministry of education) Lanzhou University Lanzhou China

The climate over the closed inland Barkol Lake,which is located in northeastern Xinjiang Uygur Autonomous Region,is significantly influenced by westerly winds *** improve our understanding of past climate processes in westerly wind influenced regions in northwestern china,a 250-cm sediment section was retrieved from this *** taking the carbon reservoir effect into consideration,the chronological sequence of this section was reconstructed based on seven conventional radiocarbon dates of bulk samples,and the bottom age of this section was determined to be about 9400 cal a ***-proxy datasets,includingδ18O car,δ13C car of authigenic carbonate,and total organic carbon were examined using wavelet analysis and singular spectrum analysis *** show that the Holocene in the Barkol Lake region can be divided into four stages:(1) a cold and dry early stage before～8000 cal a BP;(2) a moderately warm and wet middle stage between～8000 and 6000 cal a BP;(3) a warm and dry stage,along with a cooling-wetting tendency from 6000 to 2700 cal a BP;and(4) a fluctuating cooling and wet stage between 2700-800 cal a BP,and a drier stage since 800 cal a *** general trend of Holocene climatic changes revealed by Barkol Lake sediments was in agreement with that of adjacent *** infer that climatic changes during the Holocene in the Barkol Lake region were influenced not only by high latitudes,especially the North Atlantic region climate,but also tropical low-latitude processes,such as the El Nio/La Nia-Southern *** study demonstrates that the enhanced activities of ENSO may have played an important role in climatic changes in northeastern Xinjiang during the *** results also suggest that climatic patterns may be temporally different in the northern Xinjiang area in response to the changing predominant control of either the Westerly or the Asian summer monsoon,depending on the contrast of their relative strengths.

关键词： Barkol Lake Holocene climate change tropical processes northern high-latitude climate

Numerical experiments for the conductive properties of saturated rock

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Science china Earth Sciences 2008年第S2期51卷 174-180页

作者： YUE WenZheng & TAO Guo State key laboratory of petroleum Resource and Prospecting,china university of petroleum,beijing 102.49,china State key laboratory of petroleum Resource and Prospecting China University of Petroleum Beijing China

The reservoir evaluation as a key technology in oil exploration and production is based on the electrical transport property (ETP) of saturated rock that is described in a mathematical form with Arhcie’s equa-tion. But there have been increasing cases observed in many researches indicating that the ETP is non-Archie especially for the complex reservoir with low porosity and permeability. In this paper,the numerical experiments based on the Lattice Boltzmann method (LBM) have been employed to study the effect of porous structure and fluids on the ETP for revealing the nature of non-Archie phenomenon in micro-scale. The results of numerical experiments have proved that the saturation exponent n is a function of water saturation and porosity instead of being a constant in Archie’s equation. And then,a new formula has been developed for the EPT through combining the result of numerical simulation with that of laboratory measurements. The calculations from the new formula show very good agreement with laboratory measurements to demonstrate the efficiency of the new formula over the conventional methods in non-Archie rock.

关键词： electrical transport property non-Archie phenomenon fluid saturation porous media Lattice Boltzmann method

L^2-Algebraic Decay Rate for Transient Birth-Death Processes

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Chinese Annals of Mathematics,Series B 2012年第4期33卷 583-594页

作者： Lijuan CHENG1 Yingzhe WANG2 1laboratory of Mathematics and Complex Systems, the ministry of education of china School of Mathe-matical Sciences, beijing Normal university, beijing 100875, china. 2laboratory of Mathematics and Complex Systems, the ministry of education of china School of Mathematical Sciences, beijing Normal university, beijing 100875, china. laboratory of Mathematics and Complex Systems the Ministry of Education of China School of Mathematical Sciences Beijing Normal University Beijing China

This paper is a continuation of the study of the algebraic speed for Markov processes. The authors concentrate on algebraic decay rate for the transient birth-death processes. According to the classification of the boundaries, a series of the sufficient conditions for algebraic decay is presented. To illustrate the power of the results, some examples are included.

关键词： Transient Birth-death processes Algebraic decay

Advanced fluid-typing methods for NMR logging

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petroleum Science 2011年第2期8卷 163-169页

作者： Xie Ranhong Xiao Lizhi State key laboratory of petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China key laboratory of Earth Prospecting and Information Technology China University of Petroleum Beijing 102249 China

In recent years, nuclear magnetic resonance （NMR） has been increasingly used for fluid- typing in well-logging because of the improved generations of NMR logging tools. This paper first discusses the applicable conditions of two one-dimensional NMR methods： the dual TW method and dual TE method. Then, the two-dimensional （T2, D） and （T2, T1） NMR methods are introduced. These different typing methods for hydrocarbon are compared and analyzed by numerical simulation. The results show that the dual TW method is not suitable for identifying a macroporous water layer. The dual TE method is not suitable for typing gas and irreducible water. （T2, T1） method is more effective in typing a gas layer. In an oil-bearing layer of movable water containing big pores, （T2, T1） method can solve the misinterpretation problem in the dual TWmethod between a water layer with big pores and an oil layer. The （T2, T1） method can distinguish irreducible water from oil of a medium viscosity, and the viscosity range of oil becomes wide in contrast with that of the dual TW method. The （T2, D） method is more effective in typing oil and water layers. In a gas layer, when the SNR is higher than a threshold, the （T2, D） method can resolve the overlapping T2 signals of irreducible water and gas that occurs due to the use of the dual TE method. Twodimensional NMR for fluid-typing is an important development of well logging technology.

关键词： NMR logging one-dimensional NMR two-dimensional NMR reservoir evaluation fluidtyping

Wide/narrow azimuth acquisition footprints and their effects on seismic imaging

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petroleum Science 2008年第4期5卷 308-313页

作者： Di Bangrang Xu Xiucang Wei Jianxin key laboratory of CNPC Geophysical Exploration China University of Petroleum Beijing 102249 China State key laboratory of petroleum Resource and Prospecting China University of Petroleum Beijing 102249 China key laboratory of Earth Prospecting and Information Technology China University of Petroleum Beijing 102249 China

Acquisition footprint is a new concept to describe the seismic noise in three-dimensional seismic exploration and it is closely related to geometry and observation shuttering. At present, the study on acquisition footprints has become a hot spot. In partnership with the Dagang Oilfield, we used the channel sand body seismic physical model to study the characteristics of wide/narrow azimuth acquisition footprints and analyzed and compared the two types of footprints and their effects on target imaging. In addition, the footprints caused by data processing of the normal moveout offset （NMO） stretching aberration were discussed. These footprints are located only in the shallow or middle layer in the time slice, and possibly affect the imaging of shallow target layers, and have no influence on deep target imaging. Seismic physical modeling has its advantages in the study of acquisition footprints.

关键词： Wide/narrow azimuth geometry acquisition footprint stretching aberration time slice seismic imaging

Nd-doped barium titanate ceramics with various Ti/Ba ratios prepared by sol-gel method

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Science china Chemistry 2005年第Z1期48卷 60-64页

作者： SHI Qizhen,CUI Bin,WANG Hui,TIAN Jing,CHANG Zhuguo & HOU Yudong Department of Chemistry,Northwest university,Shaanxi key laboratory of Physico-lnorganic Chemistry,Xi’an 710069,china key laboratory of Advanced Functional Materials of china education ministry,beijing university of Technology,beijing 100022,china Department of Chemistry Northwest University Shaanxi Key Laboratory of Physico-lnorganic Chemistry Xi’an China key laboratory of Advanced Functional Materials of china education ministry Beijing University of Technology Beijing China

The Nd-doped BaTiO3 nanocrystalline powders and ceramics with different Ti/Ba ratios were prepared by sol-gel method. Phases and microstructures of the Nd-doped BaTiO3based powders and ceramics were characterized by XRD, SEM and TEM methods. The results revealed that the powders synthesized by sol-gel method were nanometer scale (30-60 nm)and were mainly composed of cubic BaTiO3 with a small amount of BaCO3. After sintering at high temperature, both cubic BaTiO3 and BaCO3 were transformed into tetrahedron BaTiO3 *** dielectric properties of the ceramics were also determined and the influence of Ti/Ba ratio on the dielectric properties was discussed. The Tc did not change with the variation of Ti/Ba ratio,while the εmax increased firstly and then decreased. The excess TiO2 is benefit for the modification of ceramics' microstructure and dielectric properties.

关键词： sol-gel method, dielectric properties, nanometer materials, Nd-doped barium titanate, Ti/Ba mole ratio.