Journal of Pipeline Systems Engineering and Practice

In the process of oil–gas mixing transportation, a too-high gas–oil ratio (GOR) will lead to instable flow pattern and high pipeline pressure, which has great safety risks. Therefore, it is important to determine the maximum GOR. At present, it relies mainly on commercial software to simulate the operation of the mixture transportation pipeline and the hydrothermal operating parameters to determine the maximum GOR under certain condition. This enumeration method is time-consuming and does not apply to continuously parameters. To solve this problem, a data-driven predictive model is developed. The new features are constructed by analyzing the factors influencing the transportable maximum gas–oil ratio (TMGOR), and the highly correlated features are selected from them as the new features. After analyzing the characteristics of the target variables, data mapping is performed, and the processed data set is fed into a neural network for training to obtain a data-driven predictive model of TMGOR. Finally, the validation is carried out with field data from an oilfield block in northwest China. The results showed that the average relative error of the model does not exceed 8.2% compared with the simulation results of commercial software, which has a high accuracy and can provide a rationale for the decision-making of mixed transfer in the field.

Concrete pipes both reinforced and unreinforced still serve as efficient subsurface infrastructure, especially when used as culverts and sewer lines. In which its structural performance greatly affected by pipe-soil interaction through installation types. In this study the effect of concrete bedding on the behavior of buried unreinforced concrete pipe is investigated through full-scale experimental testing program which the concrete pipes are embedded in gravelly sand soil that is loose and dense. With thickness of 30 cm over pipe crown and subjected to different surface loadings. Seven standard 300 mm internal diameter precast unreinforced concrete pipes were evaluated in a lab soil box test facility. Two loading conditions are used, namely earth fill that simulated by a uniform loading platform, and wheel load that simulated using a patch loading platform with dimensions of $254\times 508{\mathrm{mm}}^2$ ($10\times 20{\mathrm{in.}}^2$), which is used by AASHTO to mimic the wheel load of an HS20 truck. The results demonstrated that controlled installation utilizing dense compaction granular backfill could achieve 70% of the pipe strength acquired by employing the typical concrete bedding of the indirect design approach. For concrete bedding under patch loads, the greatest bedding factor (ratio between the supporting strength of buried concrete pipe to the three-edge bearing test strength) obtained is 4.53. The failure loads of pipes with concrete bedding is greater than pipes with compacted soil bedding by 30% for uniform loading and 43% for patch loading.

When a high-speed train is parallel with a pipeline, its power supply system provokes alternating current (AC) interference that results in the corrosion of the pipeline and a risk of electric shock to pipeline workers. Because trains are continuously moving, the AC interference on the pipeline changes, making mitigation design difficult. In this study, we used numerical simulation to study how the location of a high-speed train influences a pipeline. The results revealed the following: (1) AC interference on a pipeline mainly depends on the current in the rail, because a large amount of current leaks from the rail to the earth, generating a current imbalance. (2) While a train is running from TPSS to AT2, AC voltage peaks appear at the beginning, the ending of the parallel segment, and the middle of each AT section; therefore, the mitigating measurement, if needed, should be the priority at these positions. (3) Compared to the interference caused by a single train, the interference on pipeline is not doubled, but only increases slightly. Moreover, interference reaches its maximum not when two trains are at 5 and 15 km, but when they are at AT1 and 15 km. (4) Field testing was conducted on an actual gas pipeline in the Beijing area. The results showed that the field-tested AC voltage of the pipeline was generally consistent with the calculations.

To repair a pipeline system, an automatic welding process is used to carry out the sleeve welding. In this study, the repair performance of the sleeve was studied, and the research results will help improve the repair quality of pipeline systems in the future. The results show that the tensile strength of the fillet weld was lower than the minimum nominal tensile strength of X65 steel. There were small cracks at the root of the fillet weld. The fracture surfaces of the side bend test of the butt weld and the notching hammer break test of the fillet weld indicated defects to different degrees. The tensile tests of butt welds indicated breaks in the base metal, and the average tensile strength was 587 MPa. The ductile-brittle transition temperature of the butt weld and the fusion line ware both lower than $-60°\mathrm{C}$, and the average crack tip opening displacement (CTOD) values of $-10°\mathrm{C}$ fracture toughness tests of the butt weld and heat affected zone were 0.181 and 0.510 mm, respectively.