Journal: Journal of Natural Gas Science and Engineering

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Elsevier

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2018 - 201922020 - 20222
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Publications 1 - 4 of 4
  • Effect of casing surface roughness on the removal efficiency of non-aqueous drilling fluids
    Item type: Journal Article
    Zhang, Zhidong; Scherer, George W.; Prod’Homme, Robert K.; et al. (2018)
    Journal of Natural Gas Science and Engineering
  • Permeability prediction using hybrid techniques of continuous restricted Boltzmann machine, particle swarm optimization and support vector regression
    Item type: Journal Article
    Gu, Yufeng; Bao, Zhidong; Cui, Guodong (2018)
    Journal of Natural Gas Science and Engineering
  • A novel approach to optimising well trajectory in heterogeneous reservoirs based on the fast-marching method
    Item type: Journal Article
    Lyu, Zehao; Lei, Qinghua; Yang, Liang; et al. (2021)
    Journal of Natural Gas Science and Engineering
    To achieve efficient recovery of subsurface energy resources, a suitable trajectory needs to be identified for the production well. In this study, a new approach is presented for automated identification of optimum well trajectories in heterogeneous oil/gas reservoirs. The optimisation procedures are as follows. First, a productivity potential map is generated based on the site characterisation data of a reservoir (when available). Second, based on the fast-marching method, well paths are generated from a number of entrance positions to a number of exit points at opposite sides of the reservoir. The well trajectory is also locally constrained by a prescribed maximum curvature to ensure that the well trajectory is drillable. Finally, the optimum well trajectory is selected from all the candidate paths based on the calculation of a benefit-to-cost ratio. If required, a straight directional well path, may also be derived through a linear approximation to the optimised non-linear trajectory by least squares analysis. Model performance has been demonstrated in both 2D and 3D. In the 2D example, the benefit-to-cost ratio of the optimised well is much higher than that of a straight well; in the 3D example, laterals of various curvatures are generated. The applicability of the method is tested by exploring different reservoir heterogeneities and curvature constraints. This approach can be applied to determine the entrance/exit positions and the well path for subsurface energy system development, which is useful for field applications.
  • Evaluating essential features of proppant transport at engineering scales combining field measurements with machine learning algorithms
    Item type: Journal Article
    Hou, Lei; Wang, Xiaoyu; Bian, Xiaobing; et al. (2022)
    Journal of Natural Gas Science and Engineering
    The behaviours of the particle settlement, stratified flow and inception of settled particles are essential features that determine the proppant transport in low-viscosity fracturing fluids. Although great efforts have been made to characterize these features, limited research work is performed at field scales. To test the laboratory outcomes, we propose a machine-learning-based workflow to evaluate the essential features using the measurements obtained from shale gas fracturing wells. Over 430,000 groups of fracturing data (1 s time interval) are collected and pre-processed to extract the particle settlement, stratified flow and inception features during fracturing operations. The GRU and SVM algorithms, trained by these features, are applied to predict fracturing pressure. Error analysis (the root mean squared error, RMSE) is carried out to compare the contributions of different features to the pressure prediction, based on which the features and the corresponding calculations are evaluated. Our result shows that the stratified-flow feature (fracture-level) possesses better interpretations for the proppant transport, in which the Bi-power model helps to produce the best predictions. The settlement and inception features (particle-level) perform better in cases where the pressure fluctuates significantly. The features characterize the state of proppant transport, based on which the development of subsurface fracture is also analyzed. Moreover, our analyses of the remaining errors in the pressure-ascending cases suggest that (1) an introduction of the alternate-injection process, and (2) the improved calculation of proppant transport in highly-filled fractures will be beneficial to both experimental observations and field applications.
Publications 1 - 4 of 4