Research on a TOPSIS energy efficiency evaluation system for crude oil gathering and transportation systems based on a GA-BP neural network

As the main link of ground engineering,crude oil gathering and transportation systems require huge energy consumption and complex structures.It is necessary to establish an energy efficiency evaluation system for crude oil gathering and transportation systems and identify the energy efficiency gaps.In this paper,the energy efficiency evaluation system of the crude oil gathering and transportation system in an oilfield in western China is established.Combined with the big data analysis method,the GA-BP neural network is used to establish the energy efficiency index prediction model for crude oil gathering and transportation systems.The comprehensive energy consumption,gas consumption,power consumption,energy utilization rate,heat utilization rate,and power utilization rate of crude oil gathering and transportation systems are predicted.Considering the efficiency and unit consumption index of the crude oil gathering and transportation system,the energy efficiency evaluation system of the crude oil gathering and transportation system is established based on a game theory combined weighting method and TOPSIS evaluation method,and the subjective weight is determined by the triangular fuzzy analytic hierarchy process.The entropy weight method determines the objective weight,and the combined weight of game theory combines subjectivity with objectivity to comprehensively evaluate the comprehensive energy efficiency of crude oil gathering and transportation systems and their subsystems.Finally,the weak links in energy utilization are identified,and energy conservation and consumption reduction are improved.The above research provides technical support for the green,efficient and intelligent development of crude oil gathering and transportation systems.

Reform Exploration for Safety Course System of Oil and Gas Storage and Transportation Facilities

In recent years,the safety of oil and gas storage and transportation facilities has been paid more attention by the state and enterprises due to frequent accidents.The oil and gas storage and transportation facilities safety courses in China University of Petroleum(Beijing)includes“Engineering mechanics”,“Strength design of pipelines and tanks”and“Safety and integrity management of oil and gas storage and transportation facilities”.The three courses lack relevance and the teaching mode is too rigid,resulting in students losing their initiative in learning.If students can’t use the knowledge flexibly,it will affect the achievement of the objectives of the training program.Therefore,oil and gas storage and transportation facilities safety courses are reformed,training plans are adjusted and teaching methods are improved.The practice shows that the reform enriches the teaching content,improves the teaching quality,stimulates classroom activity and gets a good evaluation of students.The reform of safety courses has a certain significance for cultivating compound talents who have the ability to solve practical problems in engineering.

CO_(2)flooding in shale oil reservoir with radial borehole fracturing for CO_(2)storage and enhanced oil recovery

This study introduces a novel method integrating CO_(2)flooding with radial borehole fracturing for enhanced oil recovery and CO_(2)underground storage,a solution to the limited vertical stimulation reservoir volume in horizontal well fracturing.A numerical model is established to investigate the production rate,reservoir pressure field,and CO_(2)saturation distribution corresponding to changing time of CO_(2)flooding with radial borehole fracturing.A sensitivity analysis on the influence of CO_(2)injection location,layer spacing,pressure difference,borehole number,and hydraulic fractures on oil production and CO_(2)storage is conducted.The CO_(2)flooding process is divided into four stages.Reductions in layer spacing will significantly improve oil production rate and gas storage capacity.However,serious gas channeling can occur when the spacing is lower than 20 m.Increasing the pressure difference between the producer and injector,the borehole number,the hydraulic fracture height,and the fracture width can also increase the oil production rate and gas storage rate.Sensitivity analysis shows that layer spacing and fracture height greatly influence gas storage and oil production.Research outcomes are expected to provide a theoretical basis for the efficient development of shale oil reservoirs in the vertical direction.

A Method Based on Thermo-Vibrational Effects for Hydrogen Transportation and Storage

Transporting and storing hydrogen is a complex technological task.A typical problem relates to the need to minimize the strength of fluid motion and heat transfer near the walls of the container.In this work this problem is tackled numerically assuming an infinite cavity of pipe square cross-section,located in a constant external temperature gradient.In particular,a method based on the application of vibrations to suppress the gravitational convection mechanism is explored.A parametric investigation is conducted and the limits of applicability of the method for small Grashof numbers(10e4)are determined.It is shown that it is possible to minimize the intensity of the vibrogravitational flow for any values of the problem parameters if correction factors are specified.The results obtained can be applied in technological processes associated with the transportation,storage and use of hydrogen:pumping the working fluid through pipes,storage in tanks,as well as flow processes in the combustion chambers of power plants.

A multi-mechanism numerical simulation model for CO_(2)-EOR and storage in fractured shale oil reservoirs

Under the policy background and advocacy of carbon capture,utilization,and storage(CCUS),CO_(2)-EOR has become a promising direction in the shale oil reservoir industry.The multi-scale pore structure distribution and fracture structure lead to complex multiphase flow,comprehensively considering multiple mechanisms is crucial for development and CO_(2) storage in fractured shale reservoirs.In this paper,a multi-mechanism coupled model is developed by MATLAB.Compared to the traditional Eclipse300 and MATLAB Reservoir Simulation Toolbox(MRST),this model considers the impact of pore structure on fluid phase behavior by the modified Peng—Robinson equation of state(PR-EOS),and the effect simultaneously radiate to Maxwell—Stefan(M—S)diffusion,stress sensitivity,the nano-confinement(NC)effect.Moreover,a modified embedded discrete fracture model(EDFM)is used to model the complex fractures,which optimizes connection types and half-transmissibility calculation approaches between non-neighboring connections(NNCs).The full implicit equation adopts the finite volume method(FVM)and Newton—Raphson iteration for discretization and solution.The model verification with the Eclipse300 and MRST is satisfactory.The results show that the interaction between the mechanisms significantly affects the production performance and storage characteristics.The effect of molecular diffusion may be overestimated in oil-dominated(liquid-dominated)shale reservoirs.The well spacing and injection gas rate are the most crucial factors affecting the production by sensitivity analysis.Moreover,the potential gas invasion risk is mentioned.This model provides a reliable theoretical basis for CO_(2)-EOR and sequestration in shale oil reservoirs.

Shale oil development techniques and application based on ternary-element storage and flow concept in Jiyang Depression,Bohai Bay Basin,East China

The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression.

A Time-Domain Method for Hydroelastic Analysis of A Moored Oil Storage Vessel in Wind,Irregular Waves and Currents

The hydroelastic behavior of a moored oil storage vessel subjected to arbitrary time-dependent external loads,which include wind,waves,and currents with different incident directions,is investigated with the time-domain modal expansion method.First,the water boundary integral equations on the body surface of a quarter model,which can be obtained via the free-surface Green’s function method,are established.Then,the time-dependent elastic deflection of the moored oil storage vessel is expressed by a superposition of modal functions and corresponding modal amplitudes,and a Galerkin scheme is applied to derive the linear system of equations for the modal amplitudes.The second-order linear differential equations for modal amplitudes are solved via the fourth-order Runge−Kutta method.The present model is validated against existing frequency domain results for a truncated cylinder and a VLFS.Numerical calculations for the moored oil storage vessel are then conducted to obtain the time series of various modal amplitudes and elastic displacements of the measurement points and the corresponding spectra with different incident directions.

Design and operation problems related to water curtain system forunderground water-sealed oil storage caverns

The underground water-sealed storage technique is critically important and generally accepted for the national energy strategy in China. Although several small underground water-sealed oil storage caverns have been built in China since the 1970s, there is still a lack of experience for large-volume underground storage in complicated geological conditions. The current design concept of water curtain system and the technical instruction for system operation have limitations in maintaining the stability of surrounding rock mass during the construction of the main storage caverns, as well as the long-term stability. Although several large-scale underground oil storage projects are under construction at present in China, the design concepts and construction methods, especially for the water curtain system, are mainly based on the ideal porosity medium flow theory and the experiences gained from the similar projects overseas. The storage projects currently constructed in China have the specific features such as huge scale, large depth, multiple-level arrangement, high seepage pressure, complicated geological conditions, and high in situ stresses, which are the challenging issues for the stability of the storage caverns. Based on years’ experiences obtained from the first large-scale （millions of cubic meters） underground water-sealed oil storage project in China, some design and operation problems related to water curtain system during project construction are discussed. The drawbacks and merits of the water curtain system are also presented. As an example, the conventional concept of “filling joints with water” is widely used in many cases, as a basic concept for the design of the water curtain system, but it is immature. In this paper, the advantages and disadvantages of the conventional concept are pointed out, with respect to the long-term stability as well as the safety of construction of storage caverns. Finally, new concepts and principles for design and construction of the underground water-sealed oil storage caverns are proposed.

Experimental Study and Simulation Principles of An Oil-Gas Multiphase Transportation System

Presented is an experimental study on the performance of an oil-gas multiphase transportation system, especially on the multiphase flow patterns, multiphase pumping and multiphase metering of the system. A dynamic simulation analysis is conducted to deduce simulation parameters of the system and similarity criteria under simplified conditions are obtained. The reliability and feasibility of two-phase flow experiment with oil and natural gas simulated by water and air are discussed by using the similarity criteria.

The development status and the prospect of the pipeline robots in the oil and gas storage and transportation industry

In the process of the constant development of the oil and gas storage and transportation technology, the maintenance of the large pipelines is an important task. At present, China vigorously promotes the use of the pipeline robots, for the maintenance of the oil and gas pipelines by the unique characteristics of the robots. In this paper, the author carries out the detailed analysis on the current situation of the development of the pipeline robots in the oil and gas storage and transportation industry, and compares the different applications of the pipeline robots at home and abroad. Starting from the principles of the operation of the robots, the author analyzes the characteristics of the different types of the robots, and combined with the existing conditions of the oil and gas storage and transportation in our country, the author tries to find the most favorable way of the working of the pipeline robots, to continuously improve the development of the oil and gas storage and transportation industry using the robot technologies.

The challenges facing the oil and gas storage and transportation technology and its developing direction

In recent years, our country is increasingly dependent on the use of the oil resources, and the degree of the oil mining is also continuously upgrading. After the completion of the tasks related to the oil mining in the lands, the technologies for the development of the offshore oil mining are particularly important. Among these problems, after the exploitation, the storage and transportation of the offshore oil and gas is worthy of the discussion of the technical personnel. From the experience of the oil and gas storage and transportation in the long years, in some environmentally degraded areas, there are problems in the efficiency and safety in the long pipeline transportation and the oil and gas mixed transportation, and in the transportation, there are also big shortcomings. In this paper, the author carries on the analysis of the existing questions encountering in our country＇s oil and gas storage and transportation~ and proposes the direction of the researches in the future oil and gas storage and transportation, and the purpose is to better improve the security of Cbina＇s oil and gas storage and transportation and to enhance the efficiency of the use of the oil and gas.

Current State and Prospects of CNPC's Oil and Gas Storage and Transportation

Oil and gas transportation facilities are important for a country to secure an energy supply and maintain social stability and economic development.Social capitals in China are now encouraged by the government to invest in the construction of oil and gas infrastructures in the country.With China's growing economy and new reforms in the oil and gas sector,more opportunities are available for private companies seeking to get involved in energy infrastructure.It is estimated that the future market of energy infrastructure projects in China is valued at nearly RMB 2 trillion.This paper is trying to offer some clues regarding investment in energy infrastructure in China by giving a brief introduction to the current situation of CNPC's oil and gas infrastructure construction.

Classification and Integration of Storage and Transportation Engineering Technologies in Potato Producing Areas of China

Considering the development of potato （Solanum tuberosum） industry in China, the existing technologies of potato storage and transportation in the produc- ing area were analyzed through investigation on four main potato production areas. Unear classification was used to conduct the technology classification. According to the technical attributes and characteristics, the potato technologies of storage and transportation in producing area were classified with large classes, middle classes, small classes and subclasses, into the agricultural production area processing and storage engineering technology system, to reveal the structure and functions. Mean- while, the widely used technologies were integrated and summarized into 5 principal technology integration programs, which could be used for the technology integration of the new management subjects such as planting professional cooperatives, family farms, enterprises and so on.

A STAMP-Game model for accident analysis in oil and gas industry

Accidents in engineered systems are usually generated by complex socio-technical factors.It is beneficial to investigate the increasing complexity and coupling of these factors from the perspective of system safety.Based on system and control theories,System-Theoretic Accident Model and Processes(STAMP)is a widely recognized approach for accident analysis.In this paper,we propose a STAMP-Game model to analyze accidents in oil and gas storage and transportation systems.Stakeholders in accident analysis by STAMP can be regarded as players of a game.Game theory can,thus,be adopted in accident analysis to depict the competition and cooperation between stakeholders.Subsequently,we established a game model to study the strategies of both supervisory and supervised entities.The obtained results demonstrate that the proposed game model allows for identifying the effectiveness deficiency of the supervisory entity,and the safety and protection altitudes of the supervised entity.The STAMP-Game model can generate quantitative parameters for supporting the behavior and strategy selections of the supervisory and supervised entities.The quantitative data obtained can be used to guide the safety improvement,to reduce the costs of safety regulation violation and accident risk.

The impact of connate water saturation and salinity on oil recovery and CO2 storage capacity during carbonated water injection in carbonate rock

Carbonated water injection(CWI)is known as an efficient technique for both CO2 storage and enhanced oil recovery(EOR).During CWI process,CO2 moves from the water phase into the oil phase and results in oil swelling.This mechanism is considered as a reason for EOR.Viscous fingering leading to early breakthrough and leaving a large proportion of reservoir un-swept is known as an unfavorable phenomenon during flooding trials.Generally,instability at the interface due to disturbances in porous medium promotes viscous fingering phenomenon.Connate water makes viscous fingers longer and more irregular consisting of large number of tributaries leading to the ultimate oil recovery reduction.Therefore,higher in-situ water content can worsen this condition.Besides,this water can play as a barrier between oil and gas phases and adversely affect the gas diffusion,which results in EOR reduction.On the other hand,from gas storage point of view,it should be noted that CO2 solubility is not the same in the water and oil phases.In this study for a specified water salinity,the effects of different connate water saturations(Swc)on the ultimate oil recovery and CO2 storage capacity during secondary CWI are being presented using carbonate rock samples from one of Iranian carbonate oil reservoir.The results showed higher oil recovery and CO2 storage in the case of lower connate water saturation,as 14%reduction of Swc resulted in 20%and 16%higher oil recovery and CO2 storage capacity,respectively.

Pore-scale mechanisms and characterization of light oil storage in shale nanopores:New method and insights

A new method is proposed to analyze the pore-scale mechanisms and characterization of light oil storage in shale nanopores,which is based on the Hydrocarbon Vapor Adsorption(HVA)and Pore Calculation Model(PCM).First,the basic principle of the HVA-PCM method is introduced,and the experimental/mathematical analysis processes are given.Then,the HVA-PCM method is applied to shale samples to analyze the mechanisms and characterization of light oil storage in shale nanopores.The results provide insights into the pore-scale oil storage mechanisms,oil storage structure,oil film thickness,oil distribution within different sized pores,and the oil storage state.Finally,the advantages and limitations of the HVA-PCM method are discussed,and suggestions for further improvement are proposed.Overall,the HVA-PCM method is a powerful tool for extracting quantitative information on the light oil storage in shale nanopores.

Navigating the hydrogen prospect:A comprehensive review of sustainable source-based production technologies,transport solutions,advanced storage mechanisms,and CCUS integration

The review is a comprehensive discussion of current research advances,commercial scale developments,challenges,and techno-eco nomics for the entire H_(2) value chain,including production,mainly focusing on sustainable sources,storage,and transport.The challenges,advantages,and uses of H_(2) energy are included at length.Moreover,apart from the sustainable production approaches,the approaches and current developments for combating the carbon dioxide(CO_(2))emissions from existing H_(2) production facilities are highlighted in terms of ca rbon capture,utilization,and storage(CCUS).Concisely,the review discusses current material and recent technological adva ncements in developing pilot projects and large-scale establishments for viable and rapidly emerging sou rce-ba sed H_(2) productio n.Moreover,the review also aims to provide an in-depthdiscussion and explore current developments based on the advantages of H_(2) energy in terms of its utilization,based on its high energy density,and its ability to be used as a feedstock and fuel.On the other hand,the challenges of H_(2) are also elabo rated.Next,the role of CCUS in a carbon-neutral economy and value chain for minimization of emissions from existing facilities is thoroughly deliberated,and the recent commercial-scale implementation of CCUS technologies is highlighted.Extending the utilization and recycling of captured CO_(2) emissions along with H_(2) to produce e-fuels in terms of current advances is detailed in this review.Fu rthermore,the most applicable,efficient,a nd develo ping approaches are discussed for physical and chemical H_(2) storage,considering recent la rge-scale implementations of liquid carriers and liquid organic hydrogen carriers as storage options.Lastly,the review elaborates on recent insights into advances in H_(2) transport infrastructure,including compressed and liquid H_(2) delivery via roads,ships,pipelines,and flight cargo.The review gives precise insights into the recent scenario through an elaborated conclusion of each discussion topic separately and a discussion of future perspectives.The current review will help researchers to fully understand the ongoing research advancements and challenges in the H_(2) value chain for formulating new solutions for sustainable H_(2) production,alo ng with focusing on suitable approaches for its storage and tra nsport to make the production and utilization of H_(2) applicable on a large scale.

Progress and prospect of carbon dioxide capture, utilization and storage in CNPC oilfields

The development history of carbon capture,utilization and storage for enhanced oil recovery(CCUS-EOR)in China is comprehensively reviewed,which consists of three stages:research and exploration,field test and industrial application.The breakthrough understanding of CO_(2) flooding mechanism and field practice in recent years and the corresponding supporting technical achievements of CCUS-EOR project are systematically described.The future development prospects are also pointed out.After nearly 60 years of exploration,the theory of CO_(2) flooding and storage suitable for continental sedimentary reservoirs in China has been innovatively developed.It is suggested that C7–C15 are also important components affecting miscibility of CO_(2) and crude oil.The mechanism of rapid recovery of formation energy by CO_(2) and significant improvement of block productivity and recovery factor has been verified in field tests.The CCUS-EOR reservoir engineering design technology for continental sedimentary reservoir is established.The technology of reservoir engineering parameter design and well spacing optimization has been developed,which focuses on maintaining miscibility to improve oil displacement efficiency and uniform displacement to improve sweep efficiency.The technology of CO_(2) capture,injection and production process,whole-system anticorrosion,storage monitoring and other whole-process supporting technologies have been initially formed.In order to realize the efficient utilization and permanent storage of CO_(2),it is necessary to take the oil reservoir in the oil-water transition zone into consideration,realize the large-scale CO_(2) flooding and storage in the area from single reservoir to the overall structural control system.The oil reservoir in the oil-water transition zone is developed by stable gravity flooding of injecting CO_(2) from structural highs.The research on the storage technology such as the conversion of residual oil and CO_(2) into methane needs to be carried out.

Norwegian oil and gas storage in rock caverns-Technology based on experience from hydropower development

Underground storage in rock caverns is widely used in Norway for many different petroleum products,such as crude oil,fuel,propane and butane.Basically,the caverns for such storages are unlined,i.e.containment is ensured without using any steel lining or membrane.The main basis for the storage technology originates from the extensive hydropower development in Norway.As part of this activity,about 4500 km of tunnels and shafts have been excavated,and around 200 large powerhouse caverns have been constructed.The hydropower tunnels are mainly unlined,with hydrostatic water pressure on unlined rock of up to 1000 m.Some of the projects also include air cushion chambers with volumes of up to 1×10^(5)m^(3)and air pressure up to 7.7 MPa.Many lessons which are valuable also for underground oil and gas storage have been learnt from these projects.For a storage project to become successful,systematic,well planned design and ground investigation procedures are crucial.The main steps of the design procedure are first to define the optimum location of the project,and then to optimize orientation,shape/geometry and dimensions of caverns and tunnels.As part of the procedure,ground investigations have to be carried out at several steps integrated with the progress of design.The investigation and design procedures,and the great significance of these for the project to become successful will be discussed.Case examples of oil and gas storage in unlined rock caverns are given,illustrating the relevancy of experience from high-pressure hydropower projects for planning and design of unlined caverns for oil and gas storage.

Assessing the Viability of Gandhar Field in India’s Cambay Basin for CO_(2) Storage

Our research is centered on the Gandhar oil field, which was discovered in 1983, where daily oil production has declined significantly over the years. The primary objective was to evaluate the feasibility of carbon dioxide(CO_(2)) storage through its injection into the siliciclastic reservoirs of Ankleshwar Formation. We aimed to obtain high-resolution acoustic impedance data to estimate porosity employing model-based poststack seismic inversion. We conducted an analysis of the density and effective porosity in the target zone through geostatistical techniques and probabilistic neural networks. Simultaneously, the work also involved geomechanical analysis through the computation of pore pressure and fracture gradient using well-log data, geological information, and drilling events in the Gandhar field. Our investigation unveiled spatial variations in effective porosity within the Hazad Member of the Ankleshwar Formation, with an effective porosity exceeding 25% observed in several areas, which indicates the presence of well-connected pore spaces conducive to efficient CO_(2) migration. Geomechanical analysis showed that the vertical stress(Sv) ranged from 55 MPa to 57 MPa in Telwa and from 63.7 MPa to 67.7 MPa in Hazad Member. The pore pressure profile displayed variations along the stratigraphic sequence, with the shale zone, particularly in the Kanwa Formation, attaining the maximum pressure gradient(approximately 36 MPa). However, consistently low pore pressure values(30-34 MPa) considerably below the fracture gradient curves were observed in Hazad Member due to depletion. The results from our analysis provide valuable insights into shaping future field development strategies and exploration of the feasibility of CO_(2) sequestration in Gandhar Field.