Development and technology status of energy storage in depleted gas reservoirs

Utilizing energy storage in depleted oil and gas reservoirs can improve productivity while reducing power costs and is one of the best ways to achieve synergistic development of"Carbon Peak–Carbon Neutral"and"Underground Resource Utiliza-tion".Starting from the development of Compressed Air Energy Storage(CAES)technology,the site selection of CAES in depleted gas and oil reservoirs,the evolution mechanism of reservoir dynamic sealing,and the high-flow CAES and injection technology are summarized.It focuses on analyzing the characteristics,key equipment,reservoir construction,application scenarios and cost analysis of CAES projects,and sorting out the technical key points and existing difficulties.The devel-opment trend of CAES technology is proposed,and the future development path is scrutinized to provide reference for the research of CAES projects in depleted oil and gas reservoirs.

Simulation study of hydrogen sulfide removal in underground gas storage converted from the multilayered sour gas field

A simulation study was carried out to investigate the temporal evolution of H_(2)S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H_(2)S (27.2 g/m^(3)), and the lower layer Jia-1 contains a low concentration of H_(2)S (14.0 mg/m^(3)). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H_(2)S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H_(2)S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H_(2)S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H_(2)S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H_(2)S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H_(2)S removal. After nine cycles, the produced gas’s H_(2)S concentration can be lowered to 20 mg/m^(3). Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H_(2)S concentration of the produced gas to 20 mg/m^(3), thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H_(2)S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites.

Performance analysis for underground gas storage reservoir in depleted gas field

The construction of underground natural gas storage is one of the most reasonable and effective ways for basically surmounting city seasonal peak shaving and stabilizing peak waving. Owing to the heterogeneity of geological structure used as underground natural gas storage and different capacities of storing and transmitting fluid in reservoir, it is necessary make a reasonable proration for each member of the injection and production wells within the storage during peak shaving. In this paper, through analyzing the injection production performance characteristics of the underground natural gas storage in depleted gas field, an accurate mathematical model of the underground gas storage of depleted gas field is set up; characteristics of the storage performance and permeating processes were studied,history processes of underground gas storage were stimulated and major influence factors were analyzed. Specific and typical examples from actural data are included to demonstrate the relevance of the method to simulation of storage operation.

Numerical Simulation and Analysis of Migration Law of Gas Mixture Using Carbon Dioxide as Cushion Gas in Underground Gas Storage Reservoir

One of the major technical challenges in using carbon dioxide( CO2) as part of the cushion gas of the underground gas storage reservoir( UGSR) is the mixture of CO2and natural gas. To decrease the mixing extent and manage the migration of the mixed zone,an understanding of the mechanism of CO2and natural gas mixing and the diffusion of the mixed gas in aquifer is necessary. In this paper,a numerical model based on the three dimensional gas-water two-phase flow theory and gas diffusion theory is developed to understand this mechanism. This model is validated by the actual operational data in Dazhangtuo UGSR in Tianjin City,China.Using the validated model,the mixed characteristic of CO2and natural gas and the migration mechanism of the mixed zone in an underground porous reservoir is further studied. Particularly,the impacts of the following factors on the migration mechanism are studied: the ratio of CO2injection,the reservoir porosity and the initial operating pressure. Based on the results,the optimal CO2injection ratio and an optimal control strategy to manage the migration of the mixed zone are obtained. These results provide technical guides for using CO2as cushion gas for UGSR in real projects.

Numerical simulation-based correction of relative permeability hysteresis in water-invaded underground gas storage during multi-cycle injection and production

By conducting relative permeability experiments of multi-cycle gas-water displacement and imbibition on natural cores,we discuss relative permeability hysteresis effect in underground gas storage during multi-cycle injection and production.A correction method for relative permeability hysteresis in numerical simulation of water-invaded gas storage has been worked out using the Carlson and Killough models.A geologic model of water-invaded sandstone gas storage with medium-low permeability is built to investigate the impacts of relative permeability hysteresis on fluid distribution and production performance during multi-cycle injection and production of the gas storage.The study shows that relative permeability hysteresis effect occurs during high-speed injection and production in gas storage converted from water-invaded gas reservoir,and leads to increase of gas-water transition zone width and thickness,shrinkage of the area of high-efficiency gas storage,and decrease of the peak value variation of pore volume containing gas,and then reduces the storage capacity,working gas volume,and high-efficiency operation span of the gas storage.Numerical simulations exhibit large prediction errors of performance indexes if this hysteresis effect is not considered.Killough and Carlson methods can be used to correct the relative permeability hysteresis effect in water-invaded underground gas storage to improve the prediction accuracy.The Killough method has better adaptability to the example model.

枯竭油气藏储气库出砂机理及防砂研究进展

枯竭油气藏储气库出砂会导致储层损害、井下管柱磨蚀及地面辅助设备故障等危害,严重影响储气库安全运行和有效储气能力。本文从油气藏开发阶段与储气库运行阶段出砂的异同出发,调研分析了现有枯竭油气藏储气库出砂机理、临界出砂生产压差预测以及防砂工程措施,对储气库出砂研究进展进行分析总结,指出了现有研究的不足以及未来攻关的方向。

地下储氢技术现状及在中国加快发展的可行性

随着能源转型升级需求的日益迫切,氢能以其零污染、零碳排、无次生污染的优势,将成为中国能源体系的重要组成部分,也是中国石化新能源业务的主要主攻方向。目前,中国主要采用高压气态储氢、低温液态储氢和固态合金储氢等地面储氢方式,其储氢成本高,储氢效率低。与地面储氢相比,地下储氢以其规模大、成本低、更高的安全性,展现出更为广阔的发展潜力和应用前景。在国际上,混合储氢技术已在法国、德国等国家实现了一定规模的应用;纯氢气地下存储技术在美国取得较好的应用效果,但在中国这一领域的应用和研究近乎空白,尚处于起步阶段。针对氢气强流动性、高泄漏风险及强腐蚀性的特点,通过研究明确地下储氢面临的技术挑战,包括对圈闭密封性、地层条件、完井材料、地面工艺等方面。从枯竭油气藏资源、盐岩资源、储气库建设与运行管理技术等方面出发,分析中国开展地下储氢技术的可行性。中国西部和中东部拥有多个大型油气藏,枯竭油气藏资源丰富,具备开展地下混合氢储试验和氢储能的条件;盐岩分布广泛,用盐穴储存纯氢或氢储能切实可行;中国在气藏型储气库和盐穴型储气库建设与运行管理技术方面已积累了丰富经验和技术储备。综合分析认为中国具备了开展地下储氢的条件和技术。

Comparison of three methods for natural gas dehydration

This paper compares three methods for natural gas dehydration that are widely applied in industry：（1） absorption by triethylene glycol, （2） adsorption on solid desiccants and （3） condensation. A comparison is made according to their energy demand and suitability for use. The energy calculations are performed on a model where 105 Nm3/h water saturated natural gas is processed at 30 °C. The pressure of the gas varies from 7 to 20 MPa. The required outlet concentration of water in natural gas is equivalent to the dew point temperature of -10 °C at gas pressure of 4 MPa.

气藏型地下储气库天然气损耗量研究进展与建议

天然气损耗量是直接影响地下储气库(以下简称储气库)安全生产和效益运营的关键参数,随着储气库的注采运行,天然气损耗准确评价显得越来越重要。国内对天然气损耗量的评价技术目前仍处于初级阶段,现有评价体系适用性较为受限。为此,在调研国内外关于地下储气库天然气损耗产生原因、天然气损耗量评价方法、天然气损耗监控措施等方面研究的基础上,梳理了储气库天然气损耗量评价和控制方法,并对预防我国储气库天然气损耗方面提出了管理建议。研究结果表明:①天然气损耗产生的原因主要包括储气地质体因素、井筒因素和地面设施因素,其中井筒因素和地面设施因素造成的损耗量低、易监控和计量,储气地质体因素造成的损耗隐蔽、难以直接计量。②定容气藏型储气库损耗计算方法主要有库存核实法和状态方程法,强水驱气藏型储气库主要采用产能变化分析法来估算损耗量。③成熟天然气市场国家的储气库建有完备的监检测系统,在运行过程中会持续跟踪与优化生产情况,定期开展天然气损耗量评价,并利用四维地质力学方法进行仿真模拟与在线预警。结论认为,我国储气库应完善储气地质体-井筒-地面“三位一体”的监检测系统,重视全生命周期动态监测与损耗评价,保障储气库安全高效运行。

地下储氢库发展现状及气藏型储氢库高效建库十大技术挑战

地下储氢技术利用地下构造空间实现氢气大规模高压气态储存,具有安全性高、成本低、规模大、周期长的优势,但中国地下储氢库研究起步较晚,尚无地下构造空间储氢实践,亟待形成完整的地下储氢库高效建库方案。为此,在总结国内外用于地下储氢构造空间的类型,回顾地下储氢技术发展历史与现状的基础上,系统梳理了气藏型储氢库高效建库亟待解决的十大技术挑战,研究结果表明:①气藏型地下储氢库的潜在库址与新能源发电资源具有高度的空间重合,便于绿电就地消纳,最适宜我国大规模发展;②气藏型地下储氢库高效建库需重点解决十大技术挑战,即完整性与选址地质评价、氢气与储层介质的反应机理、氢损耗及氢纯度对储氢效率的影响、垫层气类型与占比优选、注采渗流理论与库容设计、氢用特种管材及管道工程关键技术、建库及注采工程关键技术装备、运行期监测与动态分析、风险评估与应急处置方案、生命周期评估等。结论认为:①中国发展地下储氢库具有潜在枯竭/衰竭气藏库址众多的资源优势,复杂地质条件储气库创新实践的技术优势,氢能产业链上下游协同发展的产业优势和未来市场应用前景广阔的规模优势,具备实现工业化发展的条件和基础;②针对气藏型储氢库建库难题,需开展系统性技术攻关,构建地质综合选址评价体系,优化储库注采运行方案,研发氢用配套管材与设备,形成运营监测与风险管理系统,建立适应中国地质条件的综合建库理论技术体系。

水淹衰竭型地下储气库的达容规律及影响因素

水淹衰竭型地下储气库库容动态变化过程中的驱水达容规律具有复杂性和普遍性,是研究地下储气库达到设计库容时间及最终能达到库容量的重要依据。为此,以大港地下储气库群5个投产运行多年的水淹衰竭型地下储气库为例,通过含水岩心气驱扩容室内实验,揭示了地下储气库的达容规律:①地下储气库库容量呈现逐渐增加的趋势,并最终趋于最大库容量;②地下储气库投产初期库容增速快,后期增速变缓;③地下储气库地下垫气量与工作气量呈正增长关系,但增长不同步。进而总结出了影响地下储气库达容的主要因素:地下储气库的构造特征、储层物性、注采能力、水体分布以及扩容方式。

砂岩枯竭型气藏改建地下储气库方案设计配套技术

我国地下储气库建设尽管发展迅猛,但水平仍处于起步阶段,较为成熟实用的地下储气库设计技术与方法尚不多见。为此,总结了中国石油大港油田公司利用砂岩枯竭型气藏改建6座地下储气库的地质方案设计配套技术。该技术创新了大型地下储气库地质方案设计方案,明确了方案设计应遵循的主要程序及主体内容,创建了7项行之有效的配套设计技术,提出了26项气库评价与运行指标,形成了较为系统的方案设计模式与技术系列,对我国正在火热推进的地下储气库建设工作具有指导和借鉴意义。

枯竭油气藏型地下储气库事故分析及风险识别

目前世界上76.2%的地下储气库是利用枯竭油气藏改建而成的,影响该类储气库安全问题的风险因素很多,机理复杂。为此,在储气库事故资料统计分析的基础上,借鉴输气管道风险评价方法,归纳总结出了枯竭油气藏型地下储气库存在注采井或套管损坏、注气过程中气体迁移和储气库地面设施失效的三类主要事故类型,对储气库系统中的潜在风险因素进行12大类、33小类的初步分类,并根据风险因素与时间的关系将风险分为依赖时间、稳定不变以及随机出现三种类型,进而采用事故树分析的风险评价方法,排查并分析了造成主要事故类型失效的风险因素,对主要事故风险因素进行了识别,提出了相应的风险评价程序,为制订枯竭油气藏型地下储气库事故防范措施和安全管理决策提供了依据。

水淹枯竭气藏型地下储气库盘库方法

地下储气库多周期运行盘库,是研究气库运行规律、分析漏失、进一步提高气库运行效率和降低气库运行成本的关键环节。已建立的未水淹气藏型地下储气库盘库数学模型却并不适用于水淹枯竭气藏型地下储气库,评价结果明显高于实际注采气量。为此,通过深入分析水淹枯竭气藏型地下储气库气驱排水扩容机理、多周期注采运行过程中气水两相宏观与微观运动规律及可能的分布状态,创新性提出了可动用库存量的概念,以注采气量与视地层压力在一个注采周期内满足定容压升降方程为评价准则,建立了水淹枯竭气藏型地下储气库盘库模型。实例验证结果表明,该模型计算的结果与实际吻合,可用于水淹枯竭气藏型地下储气库多周期运行盘库计算和分析。为储气库运行、管理及调整提供了依据。

相国寺储气库注采气井的安全风险及对策建议

四川盆地相国寺地下储气库是我国西南地区第一个储气库，其安全平稳运行关系到整个西南地区的用气需求和经济发展。国内外地下储气库事故的统计分析结果表明，注采气井的安全风险相对较大。目前相国寺储气库地层运行压力为11．7～28．0MPa，CO2分压为O．53MPa，加之生产前期天然气中还含有钻井液、盐酸、凝析水以及少量H2S等物质，腐蚀环境也较为复杂。为此，根据相国寺注采气井油、套管的材质、固井水泥体系、井下安全阀和封隔器的类型，结合相关文献和实验资料，开展了注采气井的安全风险分析。结果表明：注采气井的油管和套管主要因腐蚀、冲蚀和应力变化的影响导致失效；水泥胶结质量和测井方法的影响将导致固井质量存在缺陷；井下安全阀主要因液压系统和控制线路故障、冲蚀和人为操作不当等原因导致失灵；封隔器主要因应力变化、腐蚀及密封元件变形等原因导致封隔失效。根据存在的这些安全风险，提出了相应的对策措施建议，可为相国寺及类似地下储气库的安全生产和管理提供参考。

文96地下储气库注采井完井技术

文96地下储气库属于典型的枯竭气藏储气库,储层压力较低且层间压力差异大,射孔层位厚、层段多、跨度大,储层保护和安全投产难度很大。针对文96地下储气库储层特点以及储气库注采井强注强采要求,通过合理设计注采井完井管柱结构,优化射孔工艺参数,采用油管传输多级起爆负压射孔技术,同时配合低伤害完井液体系等措施,解决了储气库气藏储层保护以及井控安全矛盾突出的问题。现场应用表明,该技术能有效保护储层,缩短作业周期,注采井达到产能设计要求。

枯竭气藏改建储气库需要关注的几个关键问题

到2020年,中国地下储气库的工作气需求量将超过500×108m3,其中60%~70%的工作气量将通过枯竭型气藏改建地下储气库而获得。为此,分析指出枯竭气藏型地下储气库的建设与气藏开发本身具有较大的差异性,两者在建库与开发条件、开采方式、设计准则、运行过程、工程要求、储层改造及监测7个方面都存在着较大差异。因此,在地下储气库的建设和运行管理过程中,不能照搬气藏开发的模式,必须关注地下储气库建设的5个关键问题：库容参数设计、井网部署、气库安全、气库监测和气库运行优化。做好以上5个方面的工作,将会大大缩短建库周期,提高枯竭气藏改建储气库的运行效率。

大港油田地下储气库可行性研究

通过对大港油田已枯竭的板８２０气藏的更加深入的地质研究，重新评价了该气藏的储集层和盖层，论证了作为地下储气库的地质可行性；通过对开发史分析研究，论证了作为地下储气库的开发可行性，并计算了气藏开发动态储量。根据多年来对天津市供气规律，确定了储气库调峰周期和基本参数。设计了注采井生产能力和注采方案。根据经济评价，认为利用废弃气藏作为地下储气库经济效益显著。图２表１（郭海莉摘）

川渝地区相国寺地下储气库库址选择

为确保川渝地区天然气季节性调峰和供气的安全性,充分发挥"中卫—贵阳联络线"管道系统的输气能力,迫切需要建设配套的地下储气库。川渝地区处于"中卫—贵阳联络线"中段,天然气需求旺盛,天然气资源较丰富,因天然气开发历史长,具有多个可用于建设地下储气库的枯竭性气藏。在借鉴和对比国内外地下储气库库址选择方法和建库经验的基础上,提出了适合川渝地区地下储气库库址优选的标准:地理位置优越、地质条件符合建库要求、注采能力和库容满足应急与调峰需要以及储气库气源有保障等。利用该标准对现有的几个气藏进行了筛选,其中相国寺气田石炭系枯竭气藏建设地下储气库地质上具有完整性,气库功能和气库库址具有明显优势,进而分析了用其建库的可行性;最后对相国寺地下储气库进行了初步规划设计。

中石化地下储气库建库关键技术研究进展

随着天然气需求量的增加和天然气对外依存度的上升,为了保障安全、平稳、连续、可靠的天然气供应,我国加大了地下储气库(以下简称储气库)的建设力度及相关技术攻关。为此,梳理了中国石油化工集团有限公司(以下简称中石化)储气库建设现状,分析了面临的机遇与挑战,总结了中石化储气库建库关键技术的研究进展。研究结果表明:①中石化储气库建设起步较晚,但发展潜力大;②中石化建库地质条件复杂,相对较差,但库址资源靠近消费区;③初步形成了包括库址筛选与评价、储气库动态密封性评价、地质重构、有效库容评价、库容参数与建库方案优化设计、全生命周期完整性评价等一系列复杂地质条件气藏型储气库建库关键技术;④同时开展了含水圈闭资源筛选、含水圈闭改建储气库地质评价、有效气顶形成机理、关键库容参数优化等关键技术研究,探索了含水层储气库建库关键技术;⑤攻关了盐穴储气库腔体设计与稳定性评价、多夹层垮塌与腔体形态控制等关键技术,厚夹层盐穴储气库建库技术取得突破性进展。结论认为,一系列建库关键技术有力地支撑了中石化储气库的建设和发展,助推了中石化天然气业务的快速有效发展。