The Experts below are selected from a list of 474 Experts worldwide ranked by ideXlab platform

Mengjiao Yu - One of the best experts on this subject based on the ideXlab platform.

  • determination of Equivalent Circulating Density of drilling fluids in deepwater drilling
    Journal of Natural Gas Science and Engineering, 2016
    Co-Authors: Vahid Dokhani, Mengjiao Yu
    Abstract:

    Abstract Evaluation of bottom-hole pressure is a critical concern for high-pressure/high temperature (HP/HT) and deepwater drilling operations. Accurate determination of drilling fluid temperature and pressure is a key step for the prediction of fluid Density. A simulator was developed to calculate the wellbore temperature and pressure during circulation and static conditions. The simulation includes effects of various operational parameters, such as rate of penetration, fluid loss as well as pump rate schedules. The mathematical model of heat transfer was developed for a deviated offshore well profile to make the algorithm flexible for different applications. The upwind numerical discretization scheme is used for determination of temperature profile. The temperature prediction of the model was verified with available analytical models for a vertical onshore well. The hydraulic model employs the yield power-law rheology model. The local Density of drilling fluid as a function of temperature and pressure is evaluated using the available PVT correlations. It is shown that when mud circulation stops, the Equivalent static Density slightly increases with time. The results of simulation also indicate that during circulation, a higher Equivalent Circulating Density is expected as compared to the case of constant fluid Density. The results of the developed method are compared with downhole temperature and pressure data in an offshore well. The comparison indicates that the developed model has a good accuracy to track the bottom-hole Circulating temperature and pressure. The proposed method can be integrated into various parts of a drilling simulator such as hydraulic design, wellbore stability and well control.

Vahid Dokhani - One of the best experts on this subject based on the ideXlab platform.

  • Effects of drill string eccentricity on frictional pressure losses in annuli
    Journal of Petroleum Science and Engineering, 2020
    Co-Authors: Vahid Dokhani, Tie Geng
    Abstract:

    Abstract It has been shown that drill pipe eccentricity can significantly reduce the annular pressure losses and must be taken in to account for accurate prediction of Equivalent Circulating Density (ECD). This study investigates effects of axial flow of Yield-Power-Law (YPL) drilling fluid on frictional pressure losses in eccentric annuli. A numerical model is developed to simulate the laminar flow of yield-power-law fluids in eccentric annular geometries. The governing equations are solved numerically using an implicit finite difference method and employing a non-uniform grid distribution system. The numerical solution yields velocity profile in the annular space, which is integrated to obtain the volumetric flow rate. The frictional pressure losses are calculated using an iterative scheme that is based on convergence of the calculated volumetric flow rate to the given flow rate. Comparing the frictional pressure loss predictions of the model with three previous numerical studies indicates an excellent agreement for the case of non-Newtonian fluids. The numerical model is validated through extensive comparisons between the predicted frictional pressure losses and experimental data derived from the literature. Our analysis indicates excellent agreement between the model prediction and the experimental data. The numerical results conclude that the reduction in frictional pressure losses due to eccentricity is more prominent at high radii ratios. Results of extensive simulation scenarios for yield-power-law fluids are fitted using non-linear regression analysis, which provides a new correlation for prediction of frictional pressure losses of yield-power-law fluids in eccentric annuli. Comparing the predictions of the developed correlation with the published correlation in the literature reveals more accurate estimation of frictional pressure losses for the proposed correlation and hence safer controlled drilling operations.

  • determination of Equivalent Circulating Density of drilling fluids in deepwater drilling
    Journal of Natural Gas Science and Engineering, 2016
    Co-Authors: Vahid Dokhani, Mengjiao Yu
    Abstract:

    Abstract Evaluation of bottom-hole pressure is a critical concern for high-pressure/high temperature (HP/HT) and deepwater drilling operations. Accurate determination of drilling fluid temperature and pressure is a key step for the prediction of fluid Density. A simulator was developed to calculate the wellbore temperature and pressure during circulation and static conditions. The simulation includes effects of various operational parameters, such as rate of penetration, fluid loss as well as pump rate schedules. The mathematical model of heat transfer was developed for a deviated offshore well profile to make the algorithm flexible for different applications. The upwind numerical discretization scheme is used for determination of temperature profile. The temperature prediction of the model was verified with available analytical models for a vertical onshore well. The hydraulic model employs the yield power-law rheology model. The local Density of drilling fluid as a function of temperature and pressure is evaluated using the available PVT correlations. It is shown that when mud circulation stops, the Equivalent static Density slightly increases with time. The results of simulation also indicate that during circulation, a higher Equivalent Circulating Density is expected as compared to the case of constant fluid Density. The results of the developed method are compared with downhole temperature and pressure data in an offshore well. The comparison indicates that the developed model has a good accuracy to track the bottom-hole Circulating temperature and pressure. The proposed method can be integrated into various parts of a drilling simulator such as hydraulic design, wellbore stability and well control.

Xiuhua Zheng - One of the best experts on this subject based on the ideXlab platform.

  • Equivalent Circulation Density Analysis of Geothermal Well by Coupling Temperature
    Energies, 2017
    Co-Authors: Xiuhua Zheng, Chenyang Duan, Zheng Yan, Zhiqing Wang, Bairu Xia
    Abstract:

    The accurate control of the wellbore pressure not only prevents lost circulation/blowout and fracturing formation by managing the Density of the drilling fluid, but also improves productivity by mitigating reservoir damage. Calculating the geothermal pressure of a geothermal well by constant parameters would easily bring big errors, as the changes of physical, rheological and thermal properties of drilling fluids with temperature are neglected. This paper researched the wellbore pressure coupling by calculating the temperature distribution with the existing model, fitting the rule of Density of the drilling fluid with the temperature and establishing mathematical models to simulate the wellbore pressures, which are expressed as the variation of Equivalent Circulating Density (ECD) under different conditions. With this method, the temperature and ECDs in the wellbore of the first medium-deep geothermal well, ZK212 Yangyi Geothermal Field in Tibet, were determined, and the sensitivity analysis was simulated by assumed parameters, i.e., the Circulating time, flow rate, geothermal gradient, diameters of the wellbore, rheological models and regimes. The results indicated that the geothermal gradient and flow rate were the most influential parameters on the temperature and ECD distribution, and additives added in the drilling fluid should be added carefully as they change the properties of the drilling fluid and induce the redistribution of temperature. To ensure the safe drilling and velocity of pipes tripping into the hole, the depth and diameter of the wellbore are considered to control the surge pressure.

  • Equivalent Circulation Density Analysis of Geothermal Well by Coupling Temperature
    2017
    Co-Authors: Xiuhua Zheng, Chenyang Duan, Zheng Yan, Zhiqing Wang, Bairu Xia
    Abstract:

    The accurate wellbore pressure control not only prevents from lost circulation/blowout and fracturing formation by managing Density of drilling fluid, but also improves productivity by mitigating reservoir damage. The geothermal pressure calculated by constant parameters for geothermal well would bring big error easily, as the changes of physical, rheological and thermal properties of drilling fluids with temperature were neglected. This paper researches the wellbore pressure coupling by calculating the temperature distribution with existed model, fitting the rule of Density of drilling fluid with temperature and establishing mathematical models to stimulate the wellbore pressures, which is expressed as the variation of Equivalent Circulating Density (ECD) under different conditions. With this method, temperature and ECDs in the wellbore of the first medium-deep geothermal well ZK212 Yangyi Geothermal Field in Tibet were determined, and the sensitivity analysis was simulated by assumed parameters, i.e. Circulating time, flow rate, geothermal gradient, diameters of wellbore, rheological models and regimes, the results indicated the geothermal gradient and flow rate were the most influence parameters on the temperature and ECD distribution, and additives added in drilling fluid should be careful which would change the properties of drilling fluid and induce the temperature redistribution. To make sure the safe drilling, velocity of pipes tripping into the hole, depth and diameter of wellbore are considered to control the surge pressure.

  • Pressure Analysis of ZK212 Well of Yangyi High Temperature Geothermal Field (Tibet, China)☆
    Energy Procedia, 2015
    Co-Authors: Xiuhua Zheng, Haiyang Liu, Zhanxue Bai
    Abstract:

    Abstract Pressures are critical for safe drilling of high temperature geothermal reservoir. In this paper, fracturing pressure, formation pressure, leaking pressure and annular friction loss and Equivalent Circulating Density of the first medium-deep geothermal well ZK212 is calculated and analyzed by conducting leakoff test and observing the wellbore water table, and contour map of zero pressure point is drawn by the integration of investigation data in 1990s, which could be used to aid designing drilling fluid system avoiding blowout and fracturing formation.

Qing Bao Meng - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of Equivalent Circulating Density in Deep Water Dynamic Kill Drilling
    Applied Mechanics and Materials, 2011
    Co-Authors: Xiao Ling Jiang, Qing Bao Meng
    Abstract:

    Dynamic kill drilling is a technology which is applied in order to control the deep water drilling shallow gas or shallow wells flowing by establish a normal cycle automatically in the deepwater shallow wells section. Equivalent Circulating Density (ECD) is an important parameters to control the bottom hole pressure, in the ECD estimate, if we don’t consider the effects of low temperature on rheological parameters of drilling fluid, it will result in errors in ECD estimates. Considering the impact of low temperature on the rheological parameters, this paper determines the temperature, rheological parameters and the annulus Circulating pressure loss of each well section. Then Superposing each well section annular Circulating pressure loss together, and finally calculate the Equivalent Circulating Density. The deeper the water the greater of difference between ECD prediction model and the results calculated by rheological parameters on ground, and the more shallow wells the larger of difference. Therefore, in the process of deep water surface layer dynamic killing, We need to predict the Equivalent Circulating Density of drilling fluids (ECD) accurately.

  • Evaluation of Equivalent Circulating Density in Deep Water Dynamic Kill Drilling
    Applied Mechanics and Materials, 2011
    Co-Authors: Xiao Ling Jiang, Qing Bao Meng
    Abstract:

    Dynamic kill drilling is a technology which is applied in order to control the deep water drilling shallow gas or shallow wells flowing by establish a normal cycle automatically in the deepwater shallow wells section. Equivalent Circulating Density (ECD) is an important parameters to control the bottom hole pressure, in the ECD estimate, if we don’t consider the effects of low temperature on rheological parameters of drilling fluid, it will result in errors in ECD estimates. Considering the impact of low temperature on the rheological parameters, this paper determines the temperature, rheological parameters and the annulus Circulating pressure loss of each well section. Then Superposing each well section annular Circulating pressure loss together, and finally calculate the Equivalent Circulating Density. The deeper the water the greater of difference between ECD prediction model and the results calculated by rheological parameters on ground, and the more shallow wells the larger of difference. Therefore, in the process of deep water surface layer dynamic killing, We need to predict the Equivalent Circulating Density of drilling fluids (ECD) accurately.

Bairu Xia - One of the best experts on this subject based on the ideXlab platform.

  • Equivalent Circulation Density Analysis of Geothermal Well by Coupling Temperature
    Energies, 2017
    Co-Authors: Xiuhua Zheng, Chenyang Duan, Zheng Yan, Zhiqing Wang, Bairu Xia
    Abstract:

    The accurate control of the wellbore pressure not only prevents lost circulation/blowout and fracturing formation by managing the Density of the drilling fluid, but also improves productivity by mitigating reservoir damage. Calculating the geothermal pressure of a geothermal well by constant parameters would easily bring big errors, as the changes of physical, rheological and thermal properties of drilling fluids with temperature are neglected. This paper researched the wellbore pressure coupling by calculating the temperature distribution with the existing model, fitting the rule of Density of the drilling fluid with the temperature and establishing mathematical models to simulate the wellbore pressures, which are expressed as the variation of Equivalent Circulating Density (ECD) under different conditions. With this method, the temperature and ECDs in the wellbore of the first medium-deep geothermal well, ZK212 Yangyi Geothermal Field in Tibet, were determined, and the sensitivity analysis was simulated by assumed parameters, i.e., the Circulating time, flow rate, geothermal gradient, diameters of the wellbore, rheological models and regimes. The results indicated that the geothermal gradient and flow rate were the most influential parameters on the temperature and ECD distribution, and additives added in the drilling fluid should be added carefully as they change the properties of the drilling fluid and induce the redistribution of temperature. To ensure the safe drilling and velocity of pipes tripping into the hole, the depth and diameter of the wellbore are considered to control the surge pressure.

  • Equivalent Circulation Density Analysis of Geothermal Well by Coupling Temperature
    2017
    Co-Authors: Xiuhua Zheng, Chenyang Duan, Zheng Yan, Zhiqing Wang, Bairu Xia
    Abstract:

    The accurate wellbore pressure control not only prevents from lost circulation/blowout and fracturing formation by managing Density of drilling fluid, but also improves productivity by mitigating reservoir damage. The geothermal pressure calculated by constant parameters for geothermal well would bring big error easily, as the changes of physical, rheological and thermal properties of drilling fluids with temperature were neglected. This paper researches the wellbore pressure coupling by calculating the temperature distribution with existed model, fitting the rule of Density of drilling fluid with temperature and establishing mathematical models to stimulate the wellbore pressures, which is expressed as the variation of Equivalent Circulating Density (ECD) under different conditions. With this method, temperature and ECDs in the wellbore of the first medium-deep geothermal well ZK212 Yangyi Geothermal Field in Tibet were determined, and the sensitivity analysis was simulated by assumed parameters, i.e. Circulating time, flow rate, geothermal gradient, diameters of wellbore, rheological models and regimes, the results indicated the geothermal gradient and flow rate were the most influence parameters on the temperature and ECD distribution, and additives added in drilling fluid should be careful which would change the properties of drilling fluid and induce the temperature redistribution. To make sure the safe drilling, velocity of pipes tripping into the hole, depth and diameter of wellbore are considered to control the surge pressure.