Most shale producers in North America have given little thought to the flowback stage following hydraulic fracturing. Others have come to realize it represents a valuable opportunity to learn more about their wells. A rigorous modeling approach is developed for effective management and inventory analysis of natural-gas storage in underground salt caverns.
Local officials are calling on Massachusetts Gov. Charlie Baker to require studies of health and safety risks before approving new natural-gas infrastructure. In separate letters, boards of health representing 100 communities raise concerns about the state's reliance on natural gas as a fuel source. North Dakota oil drillers are falling far short of the state’s goals to limit the burning of excess natural gas at wellheads, 5 years after the state adopted the rules to reduce the wasteful and environmentally harmful practice. A new integrated modeling tool helps Canada analyze methane emissions to get a better understanding of the economic and environmental implications. While much progress has been made to reduce flaring, associated gas continues to be flared at thousands of oil production sites around the world.
Boersheim, Erik Clemens (Clausthal University of Technology) | Reitenbach, Victor (Clausthal University of Technology) | Albrecht, Daniel (Clausthal University of Technology) | Pudlo, Dieter (FSU Jena) | Ganzer, Leonhard (Clausthal University of Technology)
Hydrogen is portrayed as the fuel of the future. The storage of hydrogen in porous underground gas storages is a promising solution for large-scale energy storage in Germany. In theory, excess energy sourced from renewable sources would be converted to hydrogen and subsequently stored in underground porous media. This solution provides cost effective solutions whilst providing large capacities in comparison to other energy storage types, however hydrogen interactions in underground gas storage sites (UGS) is a perplexing topic due to its foreign nature and therefore its behavior in the subsurface could be unpredictable.
The implementation of autoclaves to recreate UGS with added hydrogen is a novel approach to investigate potential integrity issues that may arise during its lifetime. Where autoclaves can simulate conditions similar to UGS to analyze potential changes in the subsurface. The principal idea of autoclaves are to house samples which are exposed to pressures and temperatures equivalent that of typical Underground Gas Storages (max 200 bar, 120°C), allowing the recreation of any reservoir environment.
The Primary objective is to investigate interactions between subsurface materials combined with reservoir rock and hydrogen. Aforementioned interactions can be interpreted through the analysis of mineralogical, petrophysical, hydrochemical changes to ascertain information regarding to the productivity of the UGS, for examples reviewing changes in permeability and porosity.
Furthermore, the application of autoclaves can help to estimate the magnitude of hydrogen damage in subsurface equipment by providing insight into identifying key materials necessary to design a system preventing hydrogen damage to the subsurface; Supplementary implementation of conventional component inspection of mechanical properties of steels and cements through tensile strength testing and unconfined compressive strength testing, respectively, enable the extent of hydrogen damage inspection in UGS with added hydrogen. Predominantly API grade steels and API Grade G cement where used for this investigation. Preliminary autoclave experimentation results show that hydrogen can alter the characteristics of UGS, where API steels have shown to experience mild hydrogen damage and reservoir rock and API cement G samples have alterations in their chemical and physical characteristics.
Autoclaves provide flexible choice in testing parameters and can be used to recreate any UGS with any gas mixtures, allowing for limitless testing possibilities to test for potential integrity issues in porous UGS containing hydrogen.
The Abu Dhabi National Oil Company (ADNOC) has awarded South Korea’s SK Engineering and Construction Company a contract to build what it calls the largest underground project ever for oil storage. Under the terms of the deal, SKEC will construct three underground storage caverns in the Emirate of Fujairah on the eastern coast of the United Arab Emirates. Each cavern will have a capacity of 14 million bbl of crude oil, deep below ground- level. ADNOC said in a statement that the contract has a $1.21-billion value. When completed in 2022, the Fujairah Underground Storage facility will be able to store three different types of crude oil, which ADNOC said will give it “increased flexibility” to export crude through Fujairah’s Arabian Sea oil terminal.
The Abu Dhabi National Oil Company (ADNOC) has awarded South Korea’s SK Engineering and Construction Company a contract to build what it calls the largest underground project ever for oil storage. Under the terms of the deal, SKEC will construct three underground storage caverns in the Emirate of Fujairah on the eastern coast of the United Arab Emirates. Each cavern will have a capacity of 14 million bbl of crude oil, deep below ground- level. ADNOC said in a statement that the contract has a $1.21-billion value. This project is a testament to the strong strategic partnership between the UAE and South Korea and to the capability of SK Engineering and Construction,” Sultan Ahmed Al Jaber, UAE Minister of State and ADNOC Group CEO, said in a statement.
Hydrocarbon migration after plug and abandonment (P&A) operations negates well integrity and threatens the environment. A section milling procedure for P&A that achieves rock to rock bond eliminates the risk of releasing fluids and gases to surface. This section milling procedure usually involves milling a window in the inner casing and then creating another window in the adjacent outer casing. The tool developed for this process is commonly known as dual string section milling (DSSM) tool. Simulations using advanced finite element analysis (FEA) and computational fluid dynamics (CFD) prior to prototype manufacturing is an extremely useful guide for predicting performance, optimizing design and avoiding costly oversights. This results in higher quality of design of pioneering or innovative products while reducing development costs and time to deliver tools to field.
The scope of this paper is to discuss design optimization using CFD that resulted in efficient flow distribution leading to elimination of wash out issues during field runs, while highlighting case studies summary based on design changes made to the new dual string section milling tool. Initial testing of dual string section milling tool design was done on test drilling rig that revealed some erosion prone areas in the tool; this design was modified using CFD to eliminate these erosion prone areas. However, during field runs in salt dome reservoir applications, the erosion issues reappeared in critical flow areas. Further CFD analysis was conducted to eliminate erosion in critical areas to formulate the final product design. The goal was to develop an optimized design delivering extended milling times when the section window requirements were 100 feet or more without any washout or erosion issues while using high pump flow rates.
This paper discusses the optimized dual string section milling technology using advanced computational techniques. The development of this technology is an enormous time saving for operators versus using conventional methods- in one offshore field case it resulted in more than 20 days savings in milling time.
During circular process of gas injection and withdrawal, the salt cavern for gas storage experience rapid temperature changes. The thermal effect coupling with the boundary conditions generates thermal stress, which induce the micro-fractures rock salt at the wall of underground cavity. Based on DEM, the Particle Flow Code is used to simulate the rock salt with interlayers. A novel hybrid DEM model is proposed, incorporating the rheological behavior of the pure rock salt, and the brittle character of interbedded mudstone. This model is capable of representing the macro-mechanical rock properties of laboratory observations. The high temperature decreases the compressive strength, makes the behavior of rock salt become more ductile instead of being brittle. The presence of interlayer induces more complex micro-cracking path, due to the heterogeneous heat transfer. Results illustrates the significant influence of temperature on the rock salt, resulting in the attenuation of the strength, induced thermal tensile cracking, and form weak zone around the interface of interlayers. The investigation of micro-mechanical response to the temperature influence can help us to predict the evolution of the damage zone around the interbedded salt cavern gas storage.
Rock salt is commonly accepted as host media for natural gas storage, as well as disposal of nuclear wastes, due to its characters, such as high solubility in pure water, very low permeability (Berest and Brouard 2003), creep behavior (Guessous et al., 1987), great potentiality of self-healing after damage (Chen et al., 2013), and relatively mechanical stability (Li et al., 2014; Zhu et al., 2016). The properties of non-halite evaporates varies different from one to another. (Jackson and Hudec, 2017), the behavior also changes when response to different temperature and confining pressure. High temperature changes the crystal structure of rock salt, which results in the variation of physical properties (Soppe et al., 1994; Cuevas 1997). Underground Gas Storage (UGS) is usually exposed to different temperature environment as the depth of its location varies. Therefore, an adequately capture and characterization of salt rock under different temperatures is essential for the design, construction, and operation of UGS.
As an alternative and promising simulation method, Discrete Element Method (DEM) can be applied to investigate the complexity of rock according to its discontinuum basis (i.e. the discrete element is independent to move from rock mass). DEM treats the rock material as an assembly comprising individual particles bonded at certain contacts modes, for simulating microscopic rock behavior including crack and deformation. Different from the conventional simulation methods, such as Finite Element Method (FEM), or Boundary Element Method (BEM), the cracks in PFC Modeling is the spontaneous consequence of breakage of bonds at which the bond strength is being exceeded by the motion of particles. The simulated fracture can be regarded as extensive microcracks to investigate its complex constitutive behavior. PFC modeling has advantage in study of micro-mechanical behavior of unconsolidated as well as complex non-elastic characters, according to direct application of Newton’s second law (Cundall and Strack 1979; Jing and Stephansson, 2007; Martinez, 2012).
Toyoda, Koichi (Japan Oil, Gas and Metals National Corporation) | Imai, Junji (Japan Oil, Gas and Metals National Corporation) | Chang, Chuan Sheng (Tokyo Electric Power Service Company) | Iwahara, Tatsuya (Japan Oil, Gas and Metals National Corporation) | Maejima, Toshio (Kajima Technical Research Institute) | Aoki, Kenji (Kyoto University)
Water curtain borehole system is a series of boreholes drilled above the underground storage caverns to provide water pressure for ensuring air-tightness. In operation phase, conventional water curtain borehole system is directly connected to the access tunnel or water curtain tunnel and one has difficulty to control the water quality. Consequently, seawater intrusion and clogging on water curtain boreholes issues have been indicated in previous studies.
For the constructions of Namikata and Kurashiki sites, the authors initially developed a new water curtain borehole system to secure the hydraulic containment ability and the water quality surround the storage cavern. The packers and independent pipe water supply system of the water curtain boreholes in construction phase were continuously utilized in the operation phase, also the desalination facilities was constructed to ensure the quality of injection water for water curtain boreholes. Additionally, the injection boreholes were designed with duplex pipes to enable circulation in each borehole for cleaning in both construction and operation phase. The water injection rate of the water curtain system is continuously measured and the water in the operation shaft and storage caverns are periodically sampled and examined the quality. In Namikata site, all the seepage in storage caverns, water injection rate and water quality express stable evolution and indicate the performance of the advance water curtain system on preventing the clogging phenomena and corrosion in the operation phase.
Underground energy storage caverns apply groundwater level higher than the potential of storage cavern to ensure the hydraulic containment ability and tightness. This concept was initially suggested by Hagerman and Morfeldt in 1938 (Hagerman, T. and Morfeldt, C. O., 1955) and the first unlined storage cavern was achieved years in an abandoned feldspar mine at Harsbacka, Sweden. The first pressurized LPG storage cavern was constructed in Goteborg, Sweden, 1968. The storage cavern was excavated at 90m below the ground and the groundwater level was at around EL. −10.5m to ensure the hydraulic containment ability and to prevent the gas leakage. In 1984, the water curtain borehole system, patented by I. Janelid, was firstly employed for the mined propane storage cavern at Lavera site, France (Lindblom, U, 1989). The water curtain borehole system is a series of water injection boreholes, drilled at the vicinity of storage caverns to ensure higher surrounding hydraulic potential than the cavern pressure. The water curtain borehole system and improved excavation technologies achieve the large-scale storage caverns. Increasing trend of the storage capacity is much more significant in Asian countries. At present, new mined LPG storage caverns were constructed in Korea, China, Japan and India and most of them the storage capacities are greater than 200,000m3.
Underground Gas Storage (UGS) is used to balance demand and supply of natural gas between producers and markets. Since 1915 an increasing number of countries have used UGS at various scales and in various settings. This paper gives an overview of the functional requirements given its main purpose, and the most relevant screening criteria for planning UGS facilities. The authors compiled information from technical journals to provide an overview of the requirements.
With the world population expected to grow to 8.5 billion by 2030, gas is expected to play an increasing role in the energy mix for heating, cooling, cooking and power generation in general. To provide an uninterrupted supply matching demand, UGS is also likely to continue to grow in the future. Gas usage in any country is known to vary over time due to various reasons, such as diurnal swings in need for heating/cooling or the seasonal rise and fall in temperatures requiring more heating and/or more cooling. With stable field production, the UGS functionality is used to match the swing in the market demand. Geological underground storage provides the necessary solution to manage the fluctuating need for gas. These UGS facilities provide extra capacity to meet gas demand peaks which exceed the gas field production capacity or pipeline constraints. Storage of natural gas is also used as an economic means to manage price fluctuations from demand and supply imbalances. Gas storage can be a vital part of the value chain and often serves the security of supply in a country.
The functional requirements and general screening criteria for a new underground gas storage system are discussed in this paper, outlining the following areas: fundamental technical aspects in geology, geographical considerations and infrastructure underground gas storage in Europe - overview of numbers and types key screening criteria for planning and operating an underground gas storage system
fundamental technical aspects in geology, geographical considerations and infrastructure
underground gas storage in Europe - overview of numbers and types
key screening criteria for planning and operating an underground gas storage system
Worldwide there are 685 storage systems today, with more than 200 of them in Europe. The specific purpose of each UGS may vary depending on market conditions and consumer behaviour, as well as country regulations. Our focus will be on Europe to explain the features and typical aspects of the underground storage of gas. The authors recognize that there are specific aspects of US Underground Gas Storage which are not covered here.
The paper presents the results of a multiparametric analysis of the helium saturation zone after its injection into a porous gas reservoir, the dynamics of its content in a withdrawn gas mixture and the helium recovery factor (target parameters). The calculations are performed on a three-dimensional composite hydrodynamic sector model of a homogeneous anisotropic reservoir of a virtual gas deposit. Based on the results obtained, the geological and technological factors are ranked according to the absolute value of the change of target parameters when the input parameters change. The dynamics of the influence of geological and technological factors on the target parameters is described concerning different withdrawn gas volume from the initial reserves. The identified relationships can be useful for planning of the experimental helium injection and the placement of exploitation wells at underground helium storage.