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  • Open Access


    An Investigation into the Effects of Oil-Well Cement Expansion Agent on the Integrity of Cement Sheath

    Chunqin Tan1, Shenglai Guo2,3,*, Juanjuan Huang4

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.5, pp. 1291-1300, 2023, DOI:10.32604/fdmp.2022.022233

    Abstract Generally, the so-called expansion agent is very effective in eliminating all the micro-annuli that exist between the casing and the cement sheath or between the cement sheath and the formation. However, this approach can detrimentally affect the sealing ability of cement sheath if the expansion agent is used in an unreasonable way. For these reasons, in the present work, numerical simulations have been conducted to analyze the effect of elasticity modulus of cement sheath, the elasticity modulus of formation, the expansion rate of cement, the geo-stress on the micro-annulus caused by cement expansion, and the cement sheath expansion on the… More >

  • Open Access


    Analysis of the Microstructure of a Failed Cement Sheath Subjected to Complex Temperature and Pressure Conditions

    Zhiqiang Wu1,2, Yi Wu2, Renjun Xie2, Jin Yang1, Shujie Liu3, Qiao Deng4,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.2, pp. 399-406, 2023, DOI:10.32604/fdmp.2022.020402

    Abstract One of the main obstacles hindering the exploitation of high-temperature and high-pressure oil and gas is the sealing integrity of the cement sheath. Analyzing the microstructure of the cement sheath is therefore an important task. In this study, the microstructure of the cement sheath is determined using a CT scanner under different temperature and pressure conditions. The results suggest that the major cause of micro-cracks in the cement is the increase in the casing pressure. When the micro-cracks accumulate to a certain extent, the overall structure of the cement sheath is weakened, resulting in gas channeling, which poses a direct… More >

  • Open Access


    Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

    Lingyun Zhao1,2, Heng Yang3,4,*, Yuanlong Wei1,2,*, Yuhuan Bu3,4, Shaorui Jing3,4, Peiming Zhou1,2

    FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.2, pp. 329-344, 2023, DOI:10.32604/fdmp.2022.020216

    Abstract Perforation and fracturing are typically associated with the development of coalbed methane wells. As the cement sheath is prone to failure during this process, in this work, the effects of the casing pressure, elastic modulus of the cement, elastic modulus of the formation, and casing eccentricity on the resulting stresses are analyzed in the frame of a finite element method. Subsequently, sensitivity response curves of the cement sheath stress are plotted by normalizing all factors. The results show that the maximum circumferential stress and Mises stress of the cement sheath increase with the casing internal pressure, elastic modulus of the… More > Graphic Abstract

    Integrity and Failure Analysis of Cement Sheath Subjected to Coalbed Methane Fracturing

  • Open Access


    Determination of the Cement Sheath Interface and the Causes of Failure in the Completion Stage of Gas Wells

    Xuesong Xing1, Renjun Xie1, Yi Wu1, Zhiqiang Wu1, Huanqiang Yang2,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.6, pp. 1719-1735, 2022, DOI:10.32604/fdmp.2022.019799


    The bonding quality of the cement sheath interface decreases during well completion because of the change in the casing pressure. To explore the root cause of such phenomena, experiments on the mechanical properties and interface bonding strength of a cement sheath have been carried out taking the LS25-1 high-temperature and high-pressure (HTHP) gas field as an example. Moreover, a constitutive model of the cement sheath has been defined and verified both by means of a full-scale HTHP cement sheath sealing integrity evaluation experiment and three-dimensional finite element simulations. The results show that the low initial cementing surface strength is the… More >

  • Open Access


    Experimental Evaluation of the Mechanical Properties of Cement Sheath under High-Temperature Conditions

    Pei Zou1, Zhiqiang Huang1,*, Yian Tong2, Leichuan Tan3, Rui Li4, Kai Wei1,5, Deng Qiao1,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.3, pp. 689-699, 2022, DOI:10.32604/fdmp.2022.019470

    Abstract The sealing integrity of cement sheath in offshore wells is seriously threatened under high-temperature conditions, resulting in gas channeling and other problems. Given the lack of experimental results, in this study relevant samples of a cement slurry sealing section of a typical offshore high-temperature well have been prepared and analyzed. In particular, the mechanical properties have been assessed with a triaxial pressure servo instrument and a high-temperature curing kettle. The density and the Poisson’s ratio of the samples have also been tested. The stress-strain curve has been drawn to obtain the elastic modulus and the compressive strength. The rock brittleness… More >

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