With the depletion of conventional light crude oil, heavy crude oil will occupy an increasing share of the energy structure in the 21st century. Heavy crude oil is characterized by an API gravity of 10 to 22.3 or a viscosity of 0.09 to 10 Pa·s. The flow of heavy crude oil in the pipeline is laminar in the higher viscosity range and turbulent in the lower viscosity range, and its flow resistance comes from the viscous force between the oil and the wall or the additional stress of turbulent flow. Hence, pipeline transportation of heavy crude oil is faced with a huge loss of frictional resistance, which means a reduction of the transportation efficiency. To decrease pump power consumption, improving the transportation efficiency of heavy crude oil pipelines is a key factor. In recent years, some biomimetic technologies that reduce the flow resistance of viscous oils have made new progress in improving their fluidity and have not yet been put into use in commercial pipelines. Therefore, it is important and appropriate to discuss the breakthrough achievements and progress made by researchers in the drag reduction (DR) of heavy crude oil and to summarize its advantages, disadvantages, and potential problems. This review discusses boundary layer control methods for heavy crude oil drag reduction. First, conventional DR technologies, such as polymers, surfactants, fiber suspensions, oil–water core annular flow (CAF) and oil–aqueous foam CAF, and potential DR technologies, including oleophobic surfaces, flexible walls, biomimetic microgrooves, and ferrofluid annular DR under magnetic confinement, are presented. Second, the mechanism of DR is investigated and summarized; the highlights and progress of the technology are reviewed, and new ideas to improve the existing DR technology are proposed. Finally, the challenges and prospects of DR are presented.
Water-lubricated oil–water flow is an effective low-energy consumption method for pipeline transportation. This study proposes a novel wellbore lubrication fitting (WLF) for developing a core-swirling flow to reduce flow resistance and enhance lubrication efficiency. The pressure drop across the lubricating fitting, the maximum oil volume fraction at the overflow outlet and the drag reduction percentage of core-swirling flow were taken as the indicators, and the fluid calculation software Ansys Fluent was applied to optimize the structural parameters of the WLF with orthogonal and single-factor methods. The experimental study was carried out with mineral oil and tap water. The results indicate that the swirl generator can develop a stable and low-viscosity liquid annulus to isolate the oil from the pipe wall and reduce the flow resistance of viscous oil. The optimized WLF demonstrates the clear core-swirling flow with input velocity between 0.48 and 0.62 m/s. The experimental pressure drops deviate from the simulated data within ±25%. The drag reduction percentage of the core-swirling flow is above 90% with the input velocity above 0.51 m/s. The results of this study have important engineering value for efficient application of WLFs.
At present, there are many information security issues in the digitization of intangible cultural heritage (ICH).The digital information of ICH is vulnerable to malicious tampering, stealing or attacks.The blockchain technology has the characteristics of distribution, un-tamper and traceability, which enhances security in the process of protecting digital information.Therefore, this paper discusses the integrity protection and the encryption protection from the perspective of blockchain encryption technology and provides a reference for the network security research of the ICH digital resources.
Summary Downhole explosions adversely affect air drilling; however, the explosion limit can facilitate the adjustment of the flow rate to prevent downhole explosions. The downhole explosion limit, comprising lower and upper limits, can be determined through diverse methodologies. In this study, the interrelation between absolute enthalpy and adiabatic flame temperature (AFT) enabled the deduction of the lower explosion limit (LEL) prediction method, and an equilibrium between heat generation and heat transfer formed the basis for the upper explosion limit (UEL) prediction method. Additionally, a variable-volume apparatus was established to measure the explosion limit and adjust the pressure precisely without changing the amount of gas. The explosion limit of methane in the air was determined using both predicted and experimental methods, mirroring the scenarios of natural gas entering the wellbore during air drilling. The theoretical model exhibited the same reliability as the experimental results, and the prediction method for the explosion limit proved more efficient. Moreover, the effects of initial temperature and pressure on the explosion limit are discussed. The LEL decreased by an average of 15.5% when the initial pressure increased from 0.1 MPa to 2 MPa, while the UEL experienced a significant increase by an average of 152%. The UEL exhibited a logarithmic dependence on the initial pressure. The effect of the initial temperature on the explosion limit was noticeably less pronounced than that of the initial pressure. This study provides the essential theoretical basis and experimental results for avoiding downhole explosions during air drilling.
Water production in the bottom hole is a frequent occurrence during gas drilling, posing a significant threat to the safety of the process. Obtaining the water flow rate quickly is critical to making further engineering decisions. This paper proposes a rapid calculation method of water flow rate based on the principle of pressure drop. The method can quickly identify the multiphase flow pattern and calculate the flow pressure drop, thereby establishing the relationship between the gas injection pressure and the water flow rate. At the gas drilling site, the gas injection pressure is continuously monitored in real-time, which enables rapid acquisition of the real-time water flow rate. The concept of ultimate water-carrying kinetic energy is introduced, which combined with the boundary of annular flow to other flow patterns, can determine the maximum water-carrying flow rate. The feasibility of this method is validated using the field-measured data of well X8-3.
In the context of China's rural revitalization policy, the article aims to realize the integration and development of Rural Cultural Creative Industry and Bed&Breakfast Industry(＂RCCIBBI＂) on the premise of the creativity of rural culture. The path of the integration and development of Rural Cultural Creative Industry and Bed&Breakfast Industry from four aspects: rural agricultural culture, rural legend culture, rural ethnic culture and rural traditional residential culture were discussed. Based on the analysis and discussion of the research status of the development of domestic RCCIBBI integration, the article puts forward new suggestions for the four aspects of the path discussion.
The wellbore downhole strings corrosion has attracted extensive interest as most of the oilfields in China enter the high water-cut period. Injection of corrosion inhibitors, one of the most effective corrosion protection methods, is employed to mitigate the wellbore corrosion. Nevertheless, its wider application suffers from insufficient knowledge regarding the distribution of corrosion inhibitors inside the tubing, particularly with different inhibitor injection cycles. Thus, in this study, the computational fluid dynamics (CFD) method was first attempted to investigate the hydrodynamics in a tubing and the interactions between the corrosion inhibitor and produced fluid with high water-cut. Key factors including the time, wellbore heights, injection rates, oil phase velocities and corrosion inhibitor viscosities were discussed in detail as regards how they affect the corrosion inhibitor distribution inside the tubing. Feasible formulas were established for predicting the volume fraction of the corrosion inhibitor at different wellbore heights, which showed good agreement with the simulation results. It is noted that the determination of the corrosion inhibitor injection rate depends on both the film quality of the corrosion inhibitor and the stability of the annular flow. Based on the interphase diffusion effect, a new method for determining the intermittent injection cycle of corrosion inhibitor was proposed to maintain the integrity of corrosion inhibitor film at the tubing inner wall.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
