With the rising consumption of oil resources, major oil companies around the world have increasingly engaged in offshore oil exploration and development, and offshore oil resources have accounted for an increasing proportion. Offshore oil engineering projects are capital intensive, and the development of offshore oil fields faces a tough battle, especially in a period of low oil prices. Thus, a comprehensive evaluation model is highly needed to help assess economic benefits and provide meaningful and valuable information for operators and investors to make sensible decisions. This study firstly proposed a realistic and integrated evaluation model for offshore oil development based on actual historical project data. This evaluation model incorporated modules from the underwater system to the platform system and processes from oil reservoir extraction to oil, gas and water treatment. The uncertain parameters in the evaluation process are dealt with by sensitivity analysis and Monte Carlo simulation. The proposed model is applied to a typical offshore oil development project in Bohai Bay, China. The results reveal that the recovery factor and oil price have the greatest impact on the economic benefits. In the case of deterministic analysis, the breakeven oil price of the project is 40.59 USD/bbl. After considering the uncertainty of project parameters, the higher the oil price, the greater the probability of NPV > 0. When the oil price is higher than 70 USD/bbl, even with uncertain project parameters, the probability of NPV > 0 can still be as high as 97.39%.
To address the problem of reduced face recognition accuracy in masked scenarios, this paper proposes a masked face reconstruction algorithm DeMaskGAN, which uses the TRH module to restore the masked face features, and uses the TSH module as an aid so that the TRH module focuses on the masked face region and reconstructs the face to an unmasked state while maintaining the identity information. To improve the model performance, identity consistency, key point consistency, and perceptual consistency supervision mechanisms for faces are proposed to assist in training the model, and data augmentation methods are used to generate Mask-FFHQ datasets adapted to the mask-obscured face segmentation and reconstruction tasks, the experimental results show that the reconstructed face images enable the face recognition algorithm MobileFaceNet to achieve an AUC metric of 0.9743, which is 0.039 better than the direct use of MobileFaceNet to recognize masked faces.
Abstract Herein, a two-dimensional numerical model was established to examine the effect of Reynolds number on local scour around a pipeline under steady current by solving the Naiver-Stokes equation with shear stress turbulence (SST) k - ω closure. Suspended load and bedload transport rates were considered in the model. The numerical results revealed that the Reynolds number can considerably affect the local scour around the pipeline. However, earlier works often ignored the effect of Reynolds number on local scour. An empirical equation for the variations in the maximum scour depth with Reynolds number was presented based on present study.
Abstract Transitional shale gas is an important area for oil and gas exploration. It has a wide distribution area and large resource potential, accounting for about 25% of the total shale gas resources in China. The method of reservoir fracture prediction by seismic attributes has been relatively established. However, seismic attributes are often limited by factors such as seismic data frequency and resolution. Characteristics of transitional shale reservoirs, such as complex combinations of lithologies, frequent lithological changes, low resolution and frequent frequency changes of seismic data and the existence of strong reflection shielding in coal seams, greatly affect the prediction of fracture. A single seismic attribute technique is difficult to provide a comprehensive and accurate prediction of fractures in transitional reservoirs. In this study, the discontinuity information of large fractures, fine fractures, and fractures shielded by strong reflections from coal seams are extracted by variance attributes, amplitude contrast attributes and amplitude of diffracted waves, respectively. The discontinuity features extracted by the three methods are tracked using ant-tracking technique and fused. Fractures in the work area are systematically characterized. The pre-stack wide-azimuth gathers is analyzed by the near-offset Rüger formula method. Anisotropic gradients and anisotropic directions are obtained. The prediction results of the fracture are interpreted and verified with assistance. A combined pre-stack and post-stack seismic multi-scale fracture prediction methodology is developed. The strong reflection shielding effect of the coal seam is effectively removed. The characterization of fractures in transitional shale reservoirs is improved.
To meet the need of the structural design of penstocks with the Load Coefficient Limiting State method,the theory of stationary binomial random process or the extreme value statistical method should be used for the analysis of such variable loads as static pressure waterhammer.The characteristics(annual occurrence sustaining period and probability distribution) of the static and dynamic hydraulic loads are studied in detail,and a practical example of structural design of a penstock is presented.It is deemed that the hydraulic pressure should be treated as two individual stochastic variable loads—the static pressure and the dynamic pressure, and different load coefficients should be adapted,respectively,to reflect their physical features.Especially,the probability distribution of the maximum value in design standard period is employed when dealing with the static hydraulic load, while that of the annual maximum value is utilized for dynamic hydraulic load.
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