With the continuous development of social economy, the scale of oil & gas storage and transportation industry in China increases year by year, and the technological and managerial levels are improved continuously. In this paper, the development history of oil & gas pipelines at home and abroad was reviewed, and current technological achievements of domestic oil & gas storage and transportation industry were summarized from the aspects of high-pour-point and high viscosity crude oil transportation, centralized control of oil & gas pipeline network, material and equipment localization, pipeline engineering and construction, and operation management. Then, the changes of energy consumption structure and the development of related technologies resulting from global energy revolution and technological revolution were analyzed, and the profound influence and great challenge to the oil & gas storage and transportation industry caused by these changes were discussed. Finally, the development direction of oil & gas storage and transportation industry was prospected in terms of facility safety, system reliability and big data application.

With the development of natural gas industry, the market progress speeds up continuously, global supply and demand of natural gas increase sustainably and the overall supply-demand pattern changes greatly. LNG is advantageous with safe storage and convenient transportation, and it further facilitates the development of global natural gas trading. In this paper, the status and prospect of global natural gas and LNG supply and demand were analyzed, and the development direction of global natural gas market was summarized. Then, combined with the development status of domestic natural gas industry, the basic idea that China shall speed up the overall market development and the related industry construction was put forward to provide the long-term mechanism for national energy supply security.

The distributed fiber optic sensor can sensitively monitor the local temperature changes caused by the leakage at any position of the pipeline. The mass monitoring data has obvious spatial-time nonstationary properties, so it is difficult to diagnose the leakage directly from the monitoring data. In this paper, a spatial-time big data analysis method based on movingwindow outlier analysis was developed in the framework of statistical pattern recognition. By virtue of this method, the intelligent identification of pipeline leakage is realized only based on the intrinsic characteristic of the distributed temperature sensing data. Then, the method to determine the lengths of the moving window and the abnormal state diagnosis window was proposed. Finally, the physical simulation was performed on the leakage detection of prototype pre-insulated steel pipe. It is indicated that the method developed in this paper can never make the false alarm when the pipeline is in the intact state, and it can quickly identify the leakage event and accurately locate the leakage once a leakage happens. In conclusion, this method is an unsupervised artificial intelligence approach of big data analysis, and its application prospect in the leakage detection of buried pipelines is promising.

Aiming at the safety problems of pipelines with corrosion defects caused by ground load occupation, a three- dimensional foundation-pipe-load finite element model was developed by means of ABAQUS software. The stress and deformation of buried pipeline subjected to ground load and corrosion defect were investigated. And the effects of pipeline burial depth, pipeline internal pressure, ground load and corrosion defect location on the mechanical properties of buried pipeline were studied. It is indicated that with the increase of pipeline burial depth, the stress distribution on the pipeline can be effectively alleviated, but the amount of excavation works will be increased. When the internal pressure of buried pipeline reaches a certain value, the maximum stress of the pipeline with corrosion defect is mainly dominated by the internal pressure and less affected by the ground load. The effect of pipe-soil tangential friction coefficient on the mechanical properties of buried pipeline is significant. The pipeline stress increases linearly with the increase of the pipe-soil tangential friction coefficient. And the stress of the buried pipeline with corrosion defect is maximum when its corrosion defect is located in the direction of a quarter past five to the pipeline section.

In order to evaluate the operational safety risk of municipal pipeline networks rapidly and scientifically, the operational safety accidents of pipeline networks were collected and analyzed by means of online survey and field investigations. Then, the accident impact mechanisms of key risk elements were studied, including third-party damage, corrosion, aging and temperature change. Based on this, the risk evaluation index system for operational safety of municipal pipeline networks was established. In the system, the index scores are determined by semiquantitative method and the index weights are computed by analytic hierarchy process. Finally, test was conducted on a certain industrial park and the risk of gas pipeline network was assessed. It is shown that the scoring criteria of each index can be determined easily and operated conveniently, and its evaluation results are in accordance with the survey results, so this risk evaluation index system is applicable to the fast risk evaluation of municipal pipe networks.

In order to study the stability of the salt-cavern gas storage with mudstone interbeds subject to the explosion of combustible gas, a numerical model for the deep salt-cavern gas storage was established using the finite differencesoftware FLAC3D. And the dynamic response of salt-cavern gas storage with mudstone interbeds to the explosion loads wasinvestigated, including the change of the stress state, the seismic dynamic amplitude and the stability of the surroundingrocks of the salt-cavern gas storage. It is shown that under the explosion effect of combustible gas, the change of the stressin mudstone interbeds is basically accordant with that in the salt rocks and there are no obvious weak parts. The impactof artificial fitted explosion shock wave to the surrounding rock is severer than that of the triangle explosion wave. Thedamage of the explosion of combustible gas to the surrounding rock of the cavern is limited and it attenuates rapidly with theincrease of the depth. The anti-explosion capability of the deep salt-cavern gas storages is much stronger than that of shallowcaverns, which is favorable for the stability of gas storage caverns.

Injection-production gas capacity, storage capacity and working gas volume are important indexes for measuring the capacity of underground gas storage (UGS). Dynamic characteristics analysis is an important means to evaluate the capacity of UGS. Based on the multi-cycle injection-production performance of a certain UGS rebuilt from the carbonate sour gas reservoir with bottom water, the injection-production capacity of horizontal well was evaluated by analyzing the dynamic characteristics of UGS during its operation. Then, the storage capacity of UGS was checked by using two methods. Finally, the change of the mass concentration of H2S in the gas reservoir was analyzed, and the operation mode of desulfurization was evaluated. It is indicated that this UGS is high in single well productivity, storage capacity implementing degree and efficient development potential, but its operation mode of desulfurization still needs exploring. What’s more, the water flooding mechanism of Well AH1 leading to its off production was studied, and the specific technological measures for restoring the production capacity of gas well were put forward and successfully applied on site. The research results play an important role in guiding the production, operation and gas storage capacity evaluation of UGSs rebuilt from carbonate gas reservoirs with bottom water in China.

In order to study the flow-pattern transition laws of gas-liquid two-phase flow and establish the gas-liquid hydraulic calculation model with high precision, three flow-pattern-prediction models, i.e. the general model, the modified Taitel-Dukler model and the slug characteristic analysis model, were introduced, and their application effects to predict the flow pattern of gasliquid tow-phase flow were verified based on the experimental data from Shoham and Kokal. Then, based on these three flow-pattern-prediction models, the flow pattern prediction maps were plotted and compared with the experimental data. Finally, the characteristics of the three models were summarized. It is shown that the unified flow-pattern-prediction model and the model via slug characteristic analysis do better in the flow pattern prediction of gas-liquid twophase flow and the unified model is more applicable to different situations. The research results provide the basis for selecting the flow pattern prediction algorithm used for the hydraulic calculation of gas-liquid two-phase flow.

Underground gas storage (UGS) is playing an irreplaceable role in peak shaving and gas supply guarantee. Salt cavern UGS is a kind of cavern-type storage and its construction is characterized by long construction period, high investment and complex engineering technology, but it doesn't need ramp up time and it can be put into production while being constructed. In addition, its ratio of cushion gas is lower and it can be recovered completely. Its operation is characterized by great gas production capacity, flexible gas injection and production, and low coefficient of gas losses. Salt cavern UGSs can not only satisfy the conventional demand of seasonal peak shaving, but also the demand of daily, hourly and emergency peak shaving. In this paper, the construction and operation data of salt cavern UGSs at home and abroad were analyzed, and the important role of Jintan Underground Gas Storage in the actual operation was described. Then, some thoughts on the function orientation of salt cavern UGSs were put forward. The research results provide a reference for the further optimization and reasonable development of salt cavern UGSs.

Periodic variation of production pressure in underground gas storages can generate alternating loads acted on skeleton rocks. Under alternating loads of intensive injection and production, rocks will be damaged and their mechanical properties will change. And as a result, the stability of borehole wall and skeleton rock will be impacted and sand production will be induced. In this paper, the sand production law of injection/production wells under the alternating load of intensive injection and production was experimentally simulated. Then, the sand production index formula was modified by using rock damage severity, loading times, loading frequency and other parameters. Finally, the sand production risk of injection/production wells was analyzed and the sand production time was predicted. In this way, the influence law of injection/production cycle on sand production of injection/production wells was figured out. By virtue of the modified sand production index formula, the sand production period and degree of injection/production wells can be predicted. And it also plays an effective role in guiding the selection of early sand control completion mode of injection/production wells in underground gas storages and formulating reasonable production system to control sand production of injection/production wells so as to ensure the smooth operation of underground gas storages.

Landslide is one of the geological disasters which threaten the safety of buried pipelines. The mechanical state of the pipeline under the action of landslide is controlled by the pipeline structure and the relationship between the landslide and the extension direction of the pipeline. The stress state of polygonal-shape transverse pipeline is the most complicated. The gas pipeline of Zhongwei-Guiyang tie line K1224 at the slope is a typical polygonal-shape transverse buried pipeline. Due to rainfall and road excavation at the toe of the slope, the slide of this slope leads to pipeline deformation. In this paper, based on numerical modeling and in-situ monitoring, the destruction characteristics of landslide deformation under different operating conditions and the corresponding mechanical response of the pipeline were analyzed by means of the incomplete coupling of pipe-soil separation. It is indicated that the activity of the landslide is intensified by road excavation at the toe of the slope together with rainfall. The horizontal displacement of the pipeline along the sliding direction of the slope is particularly obvious, and the phenomena of sudden displacement increase occur near the turning points of the pipeline. The stress near the turning points of the pipeline is much higher than that in straight sections. Due to the uneven landslide displacement controlled by microtopography and its moment, the stress concentration degree near the turning point in the southern side of the pipeline is the highest. What’s more, the stress near the turning point in the southern side of the pipeline is close to the stress limit of the pipe material, so this part is the most dangerous area of this pipeline section.

Path optimization of natural gas pipeline based on two-dimensional plane can hardly reflect the actual environment. In this paper, high-resolution discrete 3D terrain data was extracted using Global Mapper of GIS software and the Digital Elevation Model (DEM) was established. Based on the DEM, the path optimization model for the pipelines in hilly areas was established with the minimum length of natural gas pipeline as the evaluation index and the curvature radius of elastic installation as the constraint. Then the optimal surface path between two points was solved by the modified Dijkstra algorithm (A* algorithm) in the mode of heuristic search. Finally, it was applied to simulate the actual landform. It is indicated that the DEM based on Global Mapper has the advantages of small workload and high precision and it can be used as the simulated landform effectively. Besides, the A* algorithm is better in global convergence and calculation robustness and applicable to the solution of pipeline path optimization model. By virtue of A* algorithm, the total pipeline length and the path fluctuation degree can be decreased effectively.

Secondary distribution of product oil is an important part of the oil product supply chain. Different distribution schemes will directly affect the profit of product oil sales enterprises. It is particularly necessary to formulate an appropriate route planning schemes for oil tank trucks. Taking the shortest total distribution route as the objective function, and the actual oil tank truck quality and the oil demand of gas station as constraint conditions, considering the time window of oil product unloading, an optimization model of secondary distribution of product oil is established, and a solution method based on hybrid genetic simulated annealing algorithm is proposed. The model and algorithm are tested using an example with and without a time window. The results show that: Compared with the product oil secondary distribution scheme before optimization, the example without time window shortens the total distance by 3.66%; the example with time window only takes 9.54 s to solve, which is fast in calculation and can meet the distribution requirements. The optimization model of the secondary distribution route of product oil based on hybrid genetic simulated annealing algorithm can not only improve the calculation efficiency, but also search more comprehensively and obtain better solution.

The severe slug flow occurred in the multiphase pipelines among 8-3A platform, 14- 3A platform and 116FPSO of Wenchang oilfield group was theoretically analyzed and experimentally studied. The flow state in 14-3A sea pipe was theoretically analyzed according to the judging criterion of severe slug flow. The experimental platform for pipeline S-shaped riser with severe slug flow was designed and reconstructed based on the size of the sea pipe, and the flow patterns of oil, gas and water in the sea pipe and their transformation processes were simulated. A set of automatic control program of throttle valve based on pressure signals along the pipeline was put forward according to slug flow elimination theory and classical PID control theory, and it effectively eliminated the severe slug flow in the experiment. After the transformation of 116FPSO is conducted, this technology is applied in Wenchang oilfield group. And owing to its application, the fluctuation amplitudes of lower sea pipe pressure and upper FPSO pressure are reduced significantly, and oil and gas production is improved.

To investigate the formation process and blockage of hydrates in deepwater oil-gas multiphase pipelines, the formation process of hydrates in subsea risers and subsea horizontal transportation pipelines was numerically simulated by OLGA, based on the phase equilibrium curve of hydrate formation from condensate gas and the hydrate kinetic model (CSMHyKv2.0). It is shown that under the process parameters of one certain subsea pipeline, a large amount of hydrates are formed in both risers and horizontal transportation pipelines, and the viscosity of hydrate slurry increases 10 times in risers and 18 times in horizontal transportation pipelines. The formation rate of hydrate in risers decreases from the sea floor to the sea level and finally approaches to zero, while that in horizontal transportation pipelines remains unchanged. The area of hydrate formation and the viscosity of hydrate slurry decrease with the decline of pipeline outlet pressure. When the outlet pressure of risers and horizontal transportation pipelines are controlled at 3 MPa and 2 MPa, respectively, the formation of hydrates can be avoided and the smooth flow of pipelines can be ensured.

In order to research the maintenance problems of the submarine pipelines with pitting corrosion, this paper put forward a method for calculating the variation of pipeline failure probability and reliability index over the time for different pipe materials and surrounding environments. By virtue of this method, the ultimate failure probability and reliability index under the constraint of reliability were calculated. Then, the incomplete preventive maintenance model for the submarine pipelines with pitting corrosion was established. In this model, the effect of each pipeline maintenance is characterized using virtual age and improvement factor, and the sensitivity analysis is carried out on the improvement factor, so that it can accurately reflect the effect of pipeline maintenance. Finally, the method for calculating pipeline life and cost was put forward. In addition, the above mentioned methods were applied to a case calculation of one certain submarine pipeline which had been in operation for many years, and the pipeline life and maintenance cost under different maintenance cycles were compared. It is indicated that the model can provide the best preventive maintenance cycle at a more reasonable cost while reflecting the pipeline maintenance effect accurately. The applicability and correctness of this method is verified.