Proppant transport in rough fractures of unconventional oil and gas reservoirs

A method to generate fractures with rough surfaces was proposed according to the fractal interpolation theory.Considering the particle-particle,particle-wall and particle-fluid interactions,a proppant-fracturing fluid two-phase flow model based on computational fluid dynamics(CFD)-discrete element method(DEM)coupling was established.The simulation results were verified with relevant experimental data.It was proved that the model can match transport and accumulation of proppants in rough fractures well.Several cases of numerical simulations were carried out.Compared with proppant transport in smooth flat fractures,bulge on the rough fracture wall affects transport and settlement of proppants significantly in proppant transportation in rough fractures.The higher the roughness of fracture,the faster the settlement of proppant particles near the fracture inlet,the shorter the horizontal transport distance,and the more likely to accumulate near the fracture inlet to form a sand plugging in a short time.Fracture wall roughness could control the migration path of fracturing fluid to a certain degree and change the path of proppant filling in the fracture.On the one hand,the rough wall bulge raises the proppant transport path and the proppants flow out of the fracture,reducing the proppant sweep area.On the other hand,the sand-carrying fluid is prone to change flow direction near the contact point of bulge,thus expanding the proppant sweep area.

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.

Investigation of flue gas water-alternating gas (flue gas–WAG) injection for enhanced oil recovery and multicomponent flue gas storage in the post-waterflooding reservoir

Flue gas fooding is one of the important technologies to improve oil recovery and achieve greenhouse gas storage.In order to study multicomponent fue gas storage capacity and enhanced oil recovery(EOR)performance of fue gas water-alternating gas(fue gas-WAG)injection after continuous waterfooding in an oil reservoir,a long core fooding system was built.The experimental results showed that the oil recovery factor of fue gas-WAG fooding was increased by 21.25%after continuous waterfooding and fue gas-WAG fooding could further enhance oil recovery and reduce water cut signifcantly.A novel material balance model based on storage mechanism was developed to estimate the multicomponent fue gas storage capacity and storage capacity of each component of fue gas in reservoir oil,water and as free gas in the post-waterfooding reservoir.The ultimate storage ratio of fue gas is 16%in the fue gas-WAG fooding process.The calculation results of fue gas storage capacity showed that the injection gas storage capacity mainly consists of N_(2) and CO_(2),only N_(2) exists as free gas phase in cores,and other components of injection gas are dissolved in oil and water.Finally,injection strategies from three perspectives for fue gas storage,EOR,and combination of fue gas storage and EOR were proposed,respectively.

The Research about Storage and Transportation of Natural Gas Based on LNG Technology

Nowadays, we are in great lack of the technology theory for the storage and transportation of gas hydrate. Under this condition, after checking out related theory of these, we established the technology roadmap of the storage and transportation of gas hydrate by LNG technology. Study has shown that the technology of LNG is more saving than that of pipeline. Then we came out with the new idea of storage and transportation of hydrate by LNG technology.

Main Indexes of Pipeline Transportation of Crude Oil and Gas

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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.

Exploration prospects of oil and gas in the Northwestern part of the Offshore Indus Basin, Pakistan

Oil and gas resources are short in Pakistan and no commercially viable oil and gas sources have been yet discovered in its offshore areas up to now.In this study,the onshore-offshore stratigraphic correlation and seismic data interpretation were conducted to determine the oil and gas resource potential in the Offshore Indus Basin,Pakistan.Based on the comprehensive analysis of the results and previous data,it is considered that the Cretaceous may widely exist and three sets of source rocks may be developed in the Offshore Indus Basin.The presence of Miocene mudstones has been proven by drilling to be high-quality source rocks,while the Cretaceous and Paleocene–Eocene mudstones are potential source rocks.Tectonic-lithologic traps are developed in the northwestern part of the basin affected by the strike-slip faults along Murray Ridge.Furthermore,the Cretaceous and Paleocene–Eocene source rocks are thick and are slightly affected by volcanic activities.Therefore,it can be inferred that the northwestern part of Offshore Indus Basin enjoys good prospects of oil and gas resources.

Progress and prospects of carbon dioxide capture,EOR-utilization and storage industrialization

Carbon dioxide capture,EOR-utilization and storage(CCUS-EOR)are the most practical and feasible large-scale carbon reduction technologies,and also the key technologies to greatly improve the recovery of low-permeability oil fields.This paper sorts out the main course of CCUS-EOR technological development abroad and its industrialization progress.The progress of CCUS-EOR technological research and field tests in China are summarized,the development status,problems and challenges of the entire industry chain of CO_(2) capture,transportation,oil displacement,and storage are analyzed.The results show a huge potential of the large-scale application of CCUS-EOR in China in terms of carbon emission reduction and oil production increase.At present,CCUS-EOR in China is in a critical stage of development,from field pilot tests to industrialization.Aiming at the feature of continental sedimentary oil and gas reservoirs in China,and giving full play to the advantages of the abundant reserves for CO_(2) flooding,huge underground storage space,surface infrastructure,and wide distribution of wellbore injection channels,by cooperating with carbon emission enterprises,critical technological research and demonstration project construction should be accelerated,including the capture of low-concentration CO_(2) at low-cost and on large-scale,supercritical CO_(2) long-distance transportation,greatly enhancing oil recovery and storage rate,and CO_(2) large-scale and safe storage.CCUS-EOR theoretical and technical standard system should be constructed for the whole industrial chain to support and promote the industrial scale application,leading the rapid and profitable development of CCUS-EOR emerging industrial chain with innovation.

A sensitivity analysis of factors affecting in geologic CO_(2) storage in the Ordos Basin and its contribution to carbon neutrality

To accelerate the achievement of China’s carbon neutrality goal and to study the factors affecting the geologic CO_(2)storage in the Ordos Basin,China’s National Key R&D Programs propose to select the Chang 6 oil reservoir of the Yanchang Formation in the Ordos Basin as the target reservoir to conduct the geologic carbon capture and storage(CCS)of 100000 t per year.By applying the basic theories of disciplines such as seepage mechanics,multiphase fluid mechanics,and computational fluid mechanics and quantifying the amounts of CO_(2)captured in gas and dissolved forms,this study investigated the effects of seven factors that influence the CO_(2)storage capacity of reservoirs,namely reservoir porosity,horizontal permeability,temperature,formation stress,the ratio of vertical to horizontal permeability,capillary pressure,and residual gas saturation.The results show that the sensitivity of the factors affecting the gas capture capacity of CO_(2)decreases in the order of formation stress,temperature,residual gas saturation,horizontal permeability,and porosity.Meanwhile,the sensitivity of the factors affecting the dissolution capture capacity of CO_(2)decreases in the order of formation stress,residual gas saturation,temperature,horizontal permeability,and porosity.The sensitivity of the influencing factors can serve as the basis for carrying out a reasonable assessment of sites for future CO_(2)storage areas and for optimizing the design of existing CO_(2)storage areas.The sensitivity analysis of the influencing factors will provide basic data and technical support for implementing geologic CO_(2)storage and will assist in improving geologic CO_(2)storage technologies to achieve China’s carbon neutralization goal.

Science and Technology of China Onshore Petroleum Industry Towards 21st Century（Part 4）

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Status and Prospect of CTL and SNG Industry

Since the beginning of this century, revolutionary progress has been made in the understanding of resources and in the mining technologies of the oil and gas industry. Advances in petroleum engineering technology represented by horizontal wells and large-scale fracturing have promoted the scale development of low-grade and unconventional oil and gas resources. After the rapid growth of natural gas production in China for more than 10 consecutive years, the replacement of conventional natural gas resources has been weak and unconventional natural gas has become the major force for increasing production. Coal based SNG(synthetic natural gas) has also become a major competitor in the domestic market. The development of CTL(coal-toliquids) and SNG industries has brought coal resources into the oil and gas product market, expanding the concept of traditional oil and gas resources. The continuous improvement of petroleum engineering technology has promoted the development of deep underground coal gasification technology, which has given economic value to the huge amount of deep coal resources that are unable to be exploited by underground mining, and provides a tremendous resource guarantee for the sustainable development of the traditional oil and gas industry. A preliminary calculation shows that deep underground coal gasification has a competitive advantage in cost compared with high-cost, low-grade, unconventional gas and coal-based natural gas. Deep underground coal gasification is a typical cross-disciplinary and cross-sectoral sophisticated technology. Domestic oil and gas enterprises have dominant advantages in the engineering technology of this field. Further technical integration innovation and multi-industry joint research are needed to eventually realize the commercial application of this deep underground coal gasification technology.

Large Potential Exists in China's Oil & Gas Transportation System

As China in the decades ahead is to go through significant reorganization in the power sector and the petrochemical industry will see considerable growth,the transportation infrastructure for petroleum and gas should have a new shape. Implementing the largest infrastructure projects and creating on this basis a modern transportation network will not only see a new reincarnation of traditional industrial centers, but also open wider opportunities for regional development.

Reform of Elastic-Plastic Mechanics and Strength Design of Pipelines Based on Ideological and Political Education

Oil and gas storage and transportation safety courses are very important in oil and gas storage and transportation engineering.With the ideological and political construction of the course in the new period,the mode of professional knowledge teaching cannot meet the teaching requirements.The teaching team has been practicing in the course for many years.By inserting typical characters,typical projects,national policies and industry trends into the course,students'patriotism,academic confidence and environmental protection awareness have been cultivated,and remarkable results have been achieved.At the same time,it can provide some reference for the ideological and political education of engineering majors.

小样本预测埋地管道外腐蚀速率

为解决现有线性回归模型、单一支持向量机和遗传算法优化支持向量机(GA-SVM)等管道腐蚀速率预测准确率低的难题,选取总含盐量、氧化还原电位、pH值、氯离子浓度、硝酸根浓度、硫酸根浓度、溶解氧含量、自然腐蚀电位等埋地管道外腐蚀速率的主要影响因素作为输入变量,采用麻雀搜索算法优化支持向量机算法,建立了麻雀搜索优化的支持向量机(SSA-SVM)腐蚀速率预测模型。测试集验证结果表明,SSA-SVM模型的决定系数R2为0.9919,高于线性回归模型(0.7189)、单一支持向量机(0.8442)和GA-SVM(0.9137);均方根误差为0.0686 mm/a,低于其他3种模型的0.1166、1.7745、0.1183 mm/a;平均绝对误差为0.0902 mm/a,低于其他3种模型的0.1474、1.7056、0.0977 mm/a;平均相对误差为3.94%,低于其他3种模型的25.59%、32.29%和6.42%。采用此模型随机选择B管道8组检测数据预测埋地管线外腐蚀速率,与现场实际年腐蚀速率对比预测精度为0.9642,高于GA-SVM的预测精度0.6690,表明该模型可应用于埋地管道的外腐蚀量和腐蚀速率预测,为埋地管道的安全运行提供数据支持。

基于TRIZ理论的专创融合教学探索与实践

专创融合课程建设是高校创新创业教育深化改革的方向,也是高校培养创新人才的重要途径,旨在解决当前面临的创新创业教育与专业教育结合不紧、创新课程与专业课程脱钩的棘手难题。油气储运工程是石油化工领域的特色交叉专业,基于TRIZ理论探索油气储运工程专业课程的融合创新,对深化专创融合、提升教学质量具有重要的指导意义。

油气储运工程研究生国际化人才培养模式研究

随着新工科建设新时代的到来,工科专业的教育有了新的内涵。油气储运工程是石油与天然气行业不可或缺的一部分,行业内对该专业的人才培养有着更高的要求与期待。研究生作为高校培养出的高端、创新型人才,对研究生的培养更是建设创新型国家的重要基石。从国际化的师资组建、教学方式以及考核方式分析指出现阶段油气储运工程研究生国际化人才培养的不足,并从以上三个方面对油气储运工程未来的人才培养模式的改进方法进行阐述,对于国外的人才培养模式取其精华,并就现阶段高校的教学方式提出具体的建议。

高职院校石化专业产教融合实训基地建设探索

文章采用文献研究法和实地调研法,对油气储运技术产教融合实训基地的建设与运行进行了系统研究,旨在探索油气储运技术产教融合实训基地的建设和运行模式,为培养高素质的油气储运人才提供有效的实训平台和教学资源,为油气储运产业的健康发展提供人才支撑和智力支持。

基于SAC的炼厂原油储运调度方法

目前对于炼厂原油储运调度决策的研究大多采用基于数学规划的静态调度方案,求解时间较长并且无法针对环境的变化进行实时高效的储运调度优化。为此,本文结合深度强化学习算法建立了考虑炼厂生产约束的原油资源储运动态实时调度决策算法。该算法首先将炼厂原油资源调度问题转换为马尔可夫决策过程,其次提出了一种基于软演员-评论家(soft actor-critic,SAC)的深度强化学习算法来同时确定调度过程中的传输目标等离散决策以及传输速度等连续决策。结果表明,算法学习到的策略可行性较好,与基线算法相比,油轮在港时间、调度方案事件数量、加工计划执行率等重要指标方面均得到了较好的效果,在求解时间方面大幅提升至毫秒级,并有效控制随机事件对整体决策的影响范围。该算法可为沿海炼厂原油储运调度快速决策提供新的思路。