• Title/Summary/Keyword: reservoir exploitation

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Hydraulic fracture initiation pressure of anisotropic shale gas reservoirs

  • Zhu, Haiyan;Guo, Jianchun;Zhao, Xing;Lu, Qianli;Luo, Bo;Feng, Yong-Cun
    • Geomechanics and Engineering
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    • v.7 no.4
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    • pp.403-430
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    • 2014
  • Shale gas formations exhibit strong mechanical and strength anisotropies. Thus, it is necessary to study the effect of anisotropy on the hydraulic fracture initiation pressure. The calculation model for the in-situ stress of the bedding formation is improved according to the effective stress theory. An analytical model of the stresses around wellbore in shale gas reservoirs, in consideration of stratum dip direction, dip angle, and in-situ stress azimuth, has been built. Besides, this work established a calculation model for the stress around the perforation holes. In combination with the tensile failure criterion, a prediction model for the hydraulic fracture initiation pressure in the shale gas reservoirs is put forward. The error between the prediction result and the measured value for the shale gas reservoir in the southern Sichuan Province is only 3.5%. Specifically, effects of factors including elasticity modulus, Poisson's ratio, in-situ stress ratio, tensile strength, perforation angle (the angle between perforation direction and the maximum principal stress) of anisotropic formations on hydraulic fracture initiation pressure have been investigated. The perforation angle has the largest effect on the fracture initiation pressure, followed by the in-situ stress ratio, ratio of tensile strength to pore pressure, and the anisotropy ratio of elasticity moduli as the last. The effect of the anisotropy ratio of the Poisson's ratio on the fracture initiation pressure can be ignored. This study provides a reference for the hydraulic fracturing design in shale gas wells.

Stress field interference of hydraulic fractures in layered formation

  • Zhu, Haiyan;Zhang, Xudong;Guo, Jianchun;Xu, Yaqin;Chen, Li;Yuan, Shuhang;Wang, Yonghui;Huang, Jingya
    • Geomechanics and Engineering
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    • v.9 no.5
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    • pp.645-667
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    • 2015
  • Single treatment and staged treatments in vertical wells are widely applied in sandstone and mudstone thin interbedded (SMTI) reservoir to stimulate the reservoir. The keys and difficulties of stimulating this category of formations are to avoid hydraulic fracture propagating through the interface between shale and sand as well as control the fracture height. In this paper, the cohesive zone method was utilized to build the 3-dimensional fracture dynamic propagation model in shale and sand interbedded formation based on the cohesive damage element. Staged treatments and single treatment were simulated by single fracture propagation model and double fractures propagation model respectively. Study on the changes of fracture vicinity stress field during propagation is to compare and analyze the parameters which influence the interfacial induced stresses between two different fracturing methods. As a result, we can prejudge how difficult it is that the fracture propagates along its height direction. The induced stress increases as the pumping rate increasing and it changes as a parabolic function of the fluid viscosity. The optimized pump rate is $4.8m^3/min$ and fluid viscosity is $0.1Pa{\cdot}s$ to avoid the over extending of hydraulic fracture in height direction. The simulation outcomes were applied in the field to optimize the treatment parameters and the staged treatments was suggested to get a better production than single treatment.

Developing a comprehensive model of the optimal exploitation of dam reservoir by combining a fuzzy-logic based decision-making approach and the young's bilateral bargaining model

  • M.J. Shirangi;H. Babazadeh;E. Shirangi;A. Saremi
    • Membrane and Water Treatment
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    • v.14 no.2
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    • pp.65-76
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    • 2023
  • Given the limited water resources and the presence of multiple decision makers with different and usually conflicting objectives in the exploitation of water resources systems, especially dam's reservoirs; therefore, the decision to determine the optimal allocation of reservoir water among decision-makers and stakeholders is a difficult task. In this study, by combining a fuzzy VIKOR technique or fuzzy multi-criteria decision making (FMCDM) and the Young's bilateral bargaining model, a new method was developed to determine the optimal quantitative and qualitative water allocation of dam's reservoir water with the aim of increasing the utility of decision makers and stakeholders and reducing the conflicts among them. In this study, by identifying the stakeholders involved in the exploitation of the dam reservoir and determining their utility, the optimal points on trade-off curve with quantitative and qualitative objectives presented by Mojarabi et al. (2019) were ranked based on the quantitative and qualitative criteria, and economic, social and environmental factors using the fuzzy VIKOR technique. In the proposed method, the weights of the criteria were determined by each decision maker using the entropy method. The results of a fuzzy decision-making method demonstrated that the Young's bilateral bargaining model was developed to determine the point agreed between the decisions makers on the trade-off curve. In the proposed method, (a) the opinions of decision makers and stakeholders were considered according to different criteria in the exploitation of the dam reservoir, (b) because the decision makers considered the different factors in addition to quantitative and qualitative criteria, they were willing to participate in bargaining and reconsider their ideals, (c) due to the use of a fuzzy-logic based decision-making approach and considering different criteria, the utility of all decision makers was close to each other and the scope of bargaining became smaller, leading to an increase in the possibility of reaching an agreement in a shorter time period using game theory and (d) all qualitative judgments without considering explicitness of the decision makers were applied to the model using the fuzzy logic. The results of using the proposed method for the optimal exploitation of Iran's 15-Khordad dam reservoir over a 30-year period (1968-1997) showed the possibility of the agreement on the water allocation of the monthly total dissolved solids (TDS)=1,490 mg/L considering the different factors based on the opinions of decision makers and reducing conflicts among them.

Developing a tool for quick assessment of climate change impacts on exploitation effect of reservoirs in central provinces of Vietnam

  • Tung, H.T.
    • Proceedings of the Korea Water Resources Association Conference
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    • 2016.05a
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    • pp.200-200
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    • 2016
  • Climate changes have impacted to many sectors including water resources in Vietnam. Vietnam is agricultural development country having a lot of reservoirs. These reservoirs play a very important role in flow regulation for water supply to economic sectors. In the context of undesirable impacts of climate change such as increasing temparature, evaporation, changing rainfall and rainfall pattern, water demands and inflow to reservoirs also are being influenced. This leads to changes of resevoir exploitation effects that needs to be assessed for adaptation solutions. This arcticle summaries the development of a tool for quick assessement of climate change impacts on exploitation effect of reservoir in central provinces of Vietnam.

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Molecular Spinless Energies of the Modified Rosen-Morse Potential Energy Model

  • Jia, Chun-Sheng;Peng, Xiao-Long;He, Su
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2699-2703
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    • 2014
  • We solve the Klein-Gordon equation with the modified Rosen-Morse potential energy model. The bound state energy equation has been obtained by using the supersymmetric shape invariance approach. The relativistic vibrational transition frequencies for the $6^1{\Pi}_u$ state of the $^7Li_2$ molecule have been computed by using the modified Rosen-Morse potential model. The calculated relativistic vibrational transition frequencies are in good agreement with the experimental RKR values.

Bubble breakup dynamics and flow behaviors of a surface-functionalized nanocellulose based nanofluid stabilized foam in constricted microfluidic devices

  • Wei, Bing;Wang, Yuanyuan;Wen, Yangbing;Xu, Xingguang;Wood, Colin;Sun, Lin
    • Journal of Industrial and Engineering Chemistry
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    • v.68
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    • pp.24-32
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    • 2018
  • Nanocellulose was surface-functionalized toward the applications in enhanced oil recovery (EOR) as a green alternative. The focus of this paper is on the effect of this material based nanofluid (NF) on foam lamella stabilization through studying its bubble breakup dynamics and flow behaviors in constricted mircofluidic devices. The NF stabilized foam produced an improved flow resistance across the capillary largely due to the capillary trapped bubbles at the contraction. The "snap-off" caused the NF stabilized foam to produce finer textured bubbles, which can migrate readily forward to the deep porous media, as revealed by the pressure profiles.

Study on the distribution law and influencing factors of pressure field distribution before exploitation in heavy oilfield

  • Zhang, Xing;Jiang, Ting T.;Zhang, Jian H.;Li, Bo;Li, Yu B.;Zhang, Chun Y.;Xu, Bing B.;Qi, Peng
    • Geomechanics and Engineering
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    • v.18 no.2
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    • pp.205-213
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    • 2019
  • A calculation model of reservoir pressure field distribution around multiple production wells in a heavy oil reservoir is established, which can overcome the unreasonable uniform-pressure value calculated by the traditional mathematical model in the multiwell mining areas. A calculating program is developed based on the deduced equations by using Visual Basic computer language. Based on the proposed mathematical model, the effects of drainage rate and formation permeability on the distribution of reservoir pressure are studied. Results show that the reservoir pressure drops most at the wellbore. The farther the distance away from the borehole, the sparser the isobaric lines distribute. Increasing drainage rate results in decreasing reservoir pressure and bottom-hole pressure, especially the latter. The permeability has a significant effect on bottom hole pressure. The study provides a reference basis for studying the dynamic pressure field distribution before thermal recovery technology in heavy oilfield and optimizing construction parameters.

Cementing failure of the casing-cement-rock interfaces during hydraulic fracturing

  • Zhu, Hai Y.;Deng, Jin G.;Zhao, Jun;Zhao, Hu;Liu, Hai L.;Wang, Teng
    • Computers and Concrete
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    • v.14 no.1
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    • pp.91-107
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    • 2014
  • Using the principle of damage mechanics, zero-thickness pore pressure cohesive elements (PPCE) are used to simulate the casing-cement interface (CCI) and cement-rock interface (CRI). The traction-separation law describes the emergence and propagation of the PPCE. Mohr-coulomb criteria determines the elastic and plastic condition of cement sheath and rock. The finite element model (FEM) of delamination fractures emergence and propagation along the casing-cement-rock (CCR) interfaces during hydraulic fracturing is established, and the emergence and propagation of fractures along the wellbore axial and circumferential direction are simulated. Regadless of the perforation angle (the angle between the perforation and the max. horizontal principle stress), mirco-annulus will be produced alonge the wellbore circumferential direction when the cementation strength of the CCI and the CRI is less than the rock tensile strength; the delamination fractures are hard to propagate along the horizontal wellbore axial direction; emergence and propagation of delamination fractures are most likely produced on the shallow formation when the in-situ stresses are lower; the failure mode of cement sheath in the deep well is mainly interfaces seperation and body damange caused by cement expansion and contraction, or pressure testing and well shut-in operations.

Molecular Spinless Energies of the Morse Potential Energy Model

  • Jia, Chun-Sheng;Cao, Si-Yi
    • Bulletin of the Korean Chemical Society
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    • v.34 no.11
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    • pp.3425-3428
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    • 2013
  • We solve the Klein-Gordon equation with the Morse empirical potential energy model. The bound state energy equation has been obtained in terms of the supersymmetric shape invariance approach. The relativistic vibrational transition frequencies for the $X^1{\sum}^+$ state of ScI molecule have been computed by using the Morse potential model. The calculated relativistic vibrational transition frequencies are in good agreement with the experimental RKR values.

3-Dimensional Hydrodynamic and Water Quality Change Simulation of Jingyang Reservoir Using EFDC-WASP (EFDC-WASP을 이용한 진양호의 3차원 수리.수질 변화 모의)

  • Jeong, Young-Won;Kim, Young-Do;Kim, Jeong-Kon
    • Proceedings of the Korea Water Resources Association Conference
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    • 2010.05a
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    • pp.1079-1083
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    • 2010
  • Due to summer rainfall is concentrated in the construction of the reservoir and the dam was inevitable. The character of these structures are different from the common rivers have been characterized. According to this problem, we need to adopt to this area with three dimensional model. Construction of dams for preservation of land, utilization of water resources, and exploitation of energy potential, which is a basic element of countries' development, is regarded as indispensable for peoples. In addtion, the development of the Nakdong River nutrient and pathogen Total Maximum Daily Loads (TMDL) required that the full range of pollutants, sources, and flow conditions, typical of heavily urbanized areas, be addressed for a single water body with 1-D simulation model (river) and 3-D simulation model (reservoir). The objective of this study is to simulate the applicability of reservoir with the coupling of 3-D hydrodynamic and water quality models to estimate water balance and pollutant loading in Namgang Dam(Jinyang reservoir).

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