Gas Storage Facilities Research Articles

Methane emissions from underground gas storage in California

Accurate and timely detection, quantification, and attribution of methane emissions from Underground Gas Storage (UGS) facilities is essential for improving confidence in greenhouse gas inventories, enabling emission mitigation by facility operators, and supporting efforts to assess facility integrity and safety. We conducted multiple airborne surveys of the 12 active UGS facilities in California between January 2016 and November 2017 using advanced remote sensing and in situ observations of near-surface atmospheric methane (CH4). These measurements where combined with wind data to derive spatially and temporally resolved methane emission estimates for California UGS facilities and key components with spatial resolutions as small as 1–3 m and revisit intervals ranging from minutes to months. The study spanned normal operations, malfunctions, and maintenance activity from multiple facilities including the active phase of the Aliso Canyon blowout incident in 2016 and subsequent return to injection operations in summer 2017. We estimate that the net annual methane emissions from the UGS sector in California averaged between 11.0 ± 3.8 GgCH4 yr−1 (remote sensing) and 12.3 ± 3.8 GgCH4 yr−1 (in situ). Net annual methane emissions for the 7 facilities that reported emissions in 2016 were estimated between 9.0 ± 3.2 GgCH4 yr−1 (remote sensing) and 9.5 ± 3.2 GgCH4 yr−1 (in situ), in both cases around 5 times higher than reported. The majority of methane emissions from UGS facilities in this study are likely dominated by anomalous activity: higher than expected compressor loss and leaking bypass isolation valves. Significant variability was observed at different time-scales: daily compressor duty-cycles and infrequent but large emissions from compressor station blow-downs. This observed variability made comparison of remote sensing and in situ observations challenging given measurements were derived largely at different times, however, improved agreement occurred when comparing simultaneous measurements. Temporal variability in emissions remains one of the most challenging aspects of UGS emissions quantification, underscoring the need for more systematic and persistent methane monitoring.

Comprehensive weighted matter-element extension method for the safety evaluation of underground gas storage.

This study focuses on a safety evaluation method for underground gas storage. Gas storage is usually constructed underground in complex environments, and the service life of such facilities is limited. To ensure the secure and long-term operation of gas storage facilities, safety evaluation has become the focus of management. The present paper provides an effective method for safety evaluation. An index system was established as the foundation of the analysis for this evaluation, and the matter-element extension method was applied to obtain a quantitative evaluation result. For the weight values of each index in the matter-element extension method, this paper presents a comprehensive weight computation method based on vague sets and entropy. By application of this method, the safety level of a gas storage facility in the Jintan salt mines (in Jiangsu, China) was calculated, and the evaluation result was 4.6433, which meant the safety level was V and the underground gas storage was slightly at risk. It indicated that the influence on the overall safety and tightness of this gas storage could be ignored in the operation process, but the frequency of regular monitoring should be increased. The defective indexes were also obtained, such as salt rock cohesion, the roof thickness, the volume contraction ratio, the interlayer content, the height of the casing shoe and the adjacent cavity pressure difference, which need to be monitored and modified. This paper evaluated the safety of the underground gas storage from a unique perspective. It is expected that the results of this research will contribute to the maintenance and operational decisions, and provide a reference for management in the energy industry.

A global gridded (0.1° × 0.1°) inventory of methane emissions from oil, gas, and coal exploitation based on national reports to the United Nations Framework Convention on Climate Change

Abstract. Individual countries report national emissions of methane, a potent greenhouse gas, in accordance with the United Nations Framework Convention on Climate Change (UNFCCC). We present a global inventory of methane emissions from oil, gas, and coal exploitation that spatially allocates the national emissions reported to the UNFCCC (Scarpelli et al., 2019). Our inventory is at 0.1∘×0.1∘ resolution and resolves the subsectors of oil and gas exploitation, from upstream to downstream, and the different emission processes (leakage, venting, flaring). Global emissions for 2016 are 41.5 Tg a−1 for oil, 24.4 Tg a−1 for gas, and 31.3 Tg a−1 for coal. An array of databases is used to spatially allocate national emissions to infrastructure, including wells, pipelines, oil refineries, gas processing plants, gas compressor stations, gas storage facilities, and coal mines. Gridded error estimates are provided in normal and lognormal forms based on emission factor uncertainties from the IPCC. Our inventory shows large differences with the EDGAR v4.3.2 global gridded inventory both at the national scale and in finer-scale spatial allocation. It shows good agreement with the gridded version of the United Kingdom's National Atmospheric Emissions Inventory (NAEI). There are significant errors on the 0.1∘×0.1∘ grid associated with the location and magnitude of large point sources, but these are smoothed out when averaging the inventory over a coarser grid. Use of our inventory as prior estimate in inverse analyses of atmospheric methane observations allows investigation of individual subsector contributions and can serve policy needs by evaluating the national emissions totals reported to the UNFCCC. Gridded data sets can be accessed at https://doi.org/10.7910/DVN/HH4EUM (Scarpelli et al., 2019).

Evaluation of Potential for Salt Cavern Gas Storage and Integration of Brine Extraction: Cavern Utilization, Yangtze River Delta Region

The Yangtze River delta region of China consumes a large amount of natural gas, but the current gas storage facilities of this region can provide only 19.6 × 108 m3 of natural gas for use, which will be far less than the required gas storage volume of 66.8 × 108 m3 in 2030. The reason is due to lacking suitable underground gas storage space. To meet the space demands of underground gas storage (UGS) in the Yangtze River Delta region, the feasibilities of UGS construction in salt formations including depth of mines, thickness of salt strata, distance to pipelines, and geologic safety of the salt mines are evaluated. The representative blocks of Huai’an salt mine and Fengxian salt mine are suggested as potential sites for UGS construction. To promote UGS construction operation quickly and economically, utilizing the existing caverns can be considered firstly. The evaluation indicates that the existing caverns can store about 12.91 × 108 m3 natural gas for UGS with a cavern utilization rate of 30%. To satisfy the space for residual gas storage, the idea of “integration of brine extraction and cavern utilization” is put forward; that is, salt mining enterprises carefully control the usability of newly increased cavern volume during brine extraction. The forecast shows that about 36.9% of the newly increased cavern volume is sufficient to meet the residual cavern demand of UGS to fulfill a gas store volume of 34.3 × 108 m3 in 2030 in the Yangtze River delta. This research provides an effective method to solve the space need for UGS in the Yangtze River delta; simultaneously, it also presents win–win cooperation for the utilization of abandoned caverns and energy storage.

Radar Interferometry as a Comprehensive Tool for Monitoring the Fault Activity in the Vicinity of Underground Gas Storage Facilities

Underground gas storage facilities are an important element of the natural gas supply system. They compensate for seasonal fluctuations in natural gas consumption. Their expected lifetime is in tens of years. Continuous monitoring of underground gas storage is therefore very important to ensure its longevity. Periodic injection and withdrawal of natural gas can cause, among other things, vertical movements of the terrain surface. Radar interferometry is a commonly used method for tracking changes in the terrain height. It can register even relatively small height changes (mm/year). The primary aim of our research was to verify whether terrain behavior above a relatively deep underground gas storage can be monitored by this method and to assess the possibility of detecting the occurrence of anomalous terrain behavior in an underground gas storage area such as reactivation of faults in the area. The results show a high correlation between periodic injection and withdrawal of natural gas into/from the underground reservoir and periodic changes in terrain height above it (the amplitude of the height changes is in centimeters), which may allow the detection of anomalous phenomena. We documented special behavior of storage structures in the Vienna Basin: the areas adjacent to the underground gas storages show exactly the opposite phase of vertical movements, i.e., while the terrain above the underground reservoirs rises as natural gas is injected, the adjacent areas subside, and vice versa. Based on the analysis of geological conditions, we tend to conclude that this behavior is conditioned by the tectonic fault structure of the studied area.

Risk analysis of an underground gas storage facility using a physics-based system performance model and Monte Carlo simulation

This paper presents a quantitative risk analysis model to study operational reliability risk of an underground gas storage (UGS) facility. The model combines a thermo-hydraulic performance model for a gas storage facility consisting of a gathering system, compression system and transmission system with a Monte Carlo simulation of potential disruption events. The disruption events can impact the availability of one or more critical assets within the gas storage facility, which in turn affect the gas flow capability. The flow capability is compared against externally derived gas flow demand patterns to determine if shortfalls in supply can occur. The proposed model is highly configurable and can be used to quantitatively assess operational reliability risk in a UGS facility. A multitude of potential events that can affect a UGS facility can be analyzed. The integrated physics model means an analyst does not have to explicitly account for changes in system performance resulting from disruption events. As such, many combinations of asset configurations, system states and disruption events can be analyzed within a single modeling framework.

The Humbly Grove, Herriard and Hester's Copse fields, UK Onshore

Abstract The Humbly Grove Field has, for the UK, a unique development history. It was discovered as an oilfield in May 1980 and produced as an oilfield until 2000 along with small satellite fields Herriard (developed) and Hester's Copse (not developed). Peak production of 2219 bopd was achieved during July 1986 but, by October 1988, the rate had fallen to around 1000 bopd, a rate that was more or less maintained until October 1995 after which the production fell rapidly. At this point the decision was taken to reconfigure the field as a gas storage facility. Significant renewed pressure depletion occurred between 2000 and 2005, following which first cushion and then storage gas was injected into two reservoirs: the Middle Jurassic, Great Oolite Group and the uppermost Triassic, Rhaetian Westbury Formation. Gas storage operations commenced in 2005 and the reservoirs have undergone cyclical gas injection and gas withdrawal since that date. The cyclical injection of gas and re-pressuring of the Great Oolite reservoir causes mobile oil to be swept towards dedicated oil production wells. This operates effectively as an enhanced oil recovery scheme. The co-produced liquid hydrocarbons provide a valuable secondary income stream for the field.

On the Safety of Oil and Gas Storage and Transportation Facilities

On the Safety of Oil and Gas Storage and Transportation Facilities

Models for the development of multi-level gas supply systems

The article shows the relevance of hierarchical modeling in substantiating the optimal development of the gas industry in modern conditions. The questions of aggregation of calculation schemes of gas supply systems are considered. A set of mathematical models is proposed that allows us to consider it at three levels of the hierarchy, taking into account the improvement, refinement and detail of the information base being developed. Models are considered: 1) optimization of the structure of gas supply systems; 2) optimization of se-zone gas consumption, analysis and synthesis of reliability; 3) optimization of parameters of the main gas-wire taking into account reliability. The created information base on gas supply systems of the Russian Federation includes dynamics of development of demand for natural gas in the domestic and foreign markets, aggregated technical and technological, cost and reliability characteristics of system objects (main gas lines, fields, underground gas storage facilities) and forecasts of gas production. On the basis of mathematical models, studies of the development of multi-level gas supply systems in Russia for the period up to 2030 are performed: the rates and directions of development of the gas transport structure, commissioning of new fields and optimal gas flows through the Russian Federation are substantiated. A systematic assessment of the means of regulating seasonal unevenness of gas consumption and the means of ensuring the reliability of the North-Western district of the Russian Federation was carried out.

Method of determining gas storages volumes for settlements gas supply and analysis of energy indicators received in the result of the research

In order to ensure uninterrupted gas supply to the population, there is a need for its underground storage under high pressures. The value of this pressure depends on the type of soil and its mechanical strength. The volume of storage depends on the number of people living in the area and for what purposes the gas is used. Because it is used for heating, local heat supply and domestic purposes, it is crucial to determine which sources of heat are used by individual and central sources of heat. Therefore, such heat sources have been considered, whose thermal loads have been determined according to the particular region’s heat specific expenses and for the provision of local heat supply. Gas consumption was also determined by electric energy indicators of heat sources, heat losses during the transformation and transportation of the heat pipe. Accordingly, it is introduced a method to determine the storage volumes of gas storage facilities of settlements with different quantities of populations, the amount of electric power consumed by compressors and by electric drives for air cooling, the required surfaces.

The gas sector of Ukraine: past and future

The Ukrainian gas sector has a long history. Ukraine ranks third in Europe in terms of gas potential. Regardless of such great potential, Ukraine still imports gas. There are three gas-bearing regions in Ukraine – Carpathian, Dnipro-Donetsk and Black sea region. Gas production began at the beginning of the 20th century. After the Second World War, Ukraine was the main exporter of gas from the USSR to Eastern Europe. Today, private companies provide the majority of gas production in Ukraine. Currently, the largest gas deposits are mature, and the newly discovered deposits require large investment outlays. The Ukrainian gas pipeline system has strategic importance and it is connected to underground gas storage facilities. Currently, the system works only on 50% of its own capacity due to the decrease in the volume of gas transit through Ukraine from Russia. The biggest problems in the gas sector are corruption related to the issuing of licenses for the development of new deposits and the lack of an appropriate pace of energy reforms. The proper implementation of the 2035 Energy Strategy may help improve the situation in this sector.

GPS observed horizontal ground extension at the Hutubi (China) underground gas storage facility and its application to geomechanical modeling for induced seismicity

Induced earthquakes and ground displacements were seldom reported in relation to gas injection or extraction. The Hutubi underground gas storage (HUGS) facility is the largest one in China and is also a unique case with both earthquakes and ground displacements detected during multiple cycles of injection and extraction since 9 June 2013. Unlike previous studies with a primarily seismological focus, here, we conducted quantitative analysis on the geomechanics of seismicity induced by the HUGS through developing a hydrogeologic framework, which systematically integrated geodetic, geophysical and geological data. First, we measured horizontal ground extension and shortening on the order of cm in response to gas injection and extraction of the HUGS at depth using a local GPS network, which was not reported in other regions with induced seismicity. Second, we synthesized a variety of data, including seismic reflection profiles, a newly acquired local velocity model, rock physics measurements, well drilling and logging data, to build up a 2D geomechanical model for the HUGS. Third, based on fully-coupled poroelasticity, we proposed two methods to optimize the permeability of the upper aquifers as well as the reservoir porosity and permeability with constraints from well level, GPS and well pressure data. Numerical simulations using the calibrated 2D model revealed that the horizontal extension due to the reservoir dilation is larger than ground uplift. The observed seismicity on faults without hydraulic connections to the gas repository was probably induced by the poroelastic effect of reservoir dilation. Our study provided a prototype scheme for detecting and characterizing the geomechanical behavior of cyclic fluid injection and extraction in a deep reservoir, which would be applicable to other UGS facilities.

Characterization of Historical Methane Occurrence Frequencies from U.S. Underground Natural Gas Storage Facilities with Implications for Risk Management, Operations, and Regulatory Policy.

Defining a baseline for the frequency of occurrences at underground natural gas storage facilities is critical to maintaining safe operation and to the development of appropriate risk management plans and regulatory approaches. Currently used frequency-estimation methods are reviewed and broadened in this article to include critical factors of cause, severity, and uncertainty that contribute to risk. A Bayesian probabilistic analysis characterizes the aleatoric historical occurrence frequencies given imperfect sampling. Frequencies for the three main storage facility types in the United States (depleted oil-and-gas field storage, aquifer storage, solution-mined salt cavern storage) are generally on the order of 3 to 9 × 10-2 occurrences, of all causes (surface, well integrity, subsurface integrity) and severities (nuisance, serious, catastrophic), per facility-year. Loss of well integrity is associated with many, but not all, occurrences either within the subsurface or from there up to the surface. The probability of one serious or catastrophic leakage occurrence to the ground surface within the next 10 years, assuming constant number of facilities, is approximately 0.1-0.3% for any facility type. Storage operators and industry regulators can use occurrence frequencies, their associated probabilities and uncertainties, and forecasts of severity magnitudes to better prioritize resources, establish a baseline against which progress toward achieving a reduction target could be measured, and develop more effective mitigation/monitoring/reduction programs in a risk management plan.

Solid Particles in Natural Gas from a Transportation Network: A Chemical Composition Study

This paper aims to provide the elemental composition of particles found in natural gas. Particle sampling is performed on cellulose filters obtained from an industrial gas storage facility, and the qualitative particle composition is determined by scanning electron microscopy and energy dispersive X-ray spectroscopy. Our results establish that natural gas may contain solid particles, with sizes ranging from less than 1 μm to more than 50 μm. The observed particles are composed of numerous elements, such as aluminum (Al), silica (Si), sulphur (S), chloride (Cl), chromium (Cr), zinc (Zn), sodium (Na), manganese (Mg), calcium (Ca), iron (Fe), titanium (Ti), nickel (Ni), vanadium (V), potassium (K), copper (Cu), manganese (Mn), silver (Ag), cobalt (Co), iodine (I), and barium (Ba), with relative occurrences ranging from 1 to 85%. Moreover, metallic elements enable the formation of larger particles as a result of the agglomeration of smaller particles.

Understanding the Scales Formation Inhibition Mechanism on C-Steel in a Sour Media

Corrosion control in sour environments is a severe challenge for the oil and gas industries with respect to sour media. One of the approaches to mitigate such a problem is to use corrosion inhibitors (CI). The selection of a single (or a mixture of) CIs for a particular oil or gas production, transportation system or storage facility depends on its condition. In sour oil or gas media, depending on the ratio between carbon dioxide and hydrogen sulfide in the gas, pH, pressure, temperature, and brine chemistry, various kinds of iron sulfide and iron carbonate product layers can be formed. To control such formation scales of iron sulfides, it is essential to understand the mechanisms of corrosion inhibition in H2S systems. In this work, the electrochemical behaviour of C-steel in sour (i) de-ionised water (DIW) and (ii) in different NaCl solutions were examined in an H2S system. A series of experiments were conducted at ambient (RT), 50 oC and at 80 oC using different combinations of inhibitors (A and B). The corrosive behaviour of C-steel was investigated by measuring the open circuit potential (OCP), linear polarisation resistance (LPR), and potentiodynamic polarisation (PDP) in addition to scanning electron microscopy (SEM) coupled with an energy dispersive X-ray (EDX) and Raman spectroscopy (RS). The outcome has shown that the corrosion rate of C-steel initially decreased and then stabilised with time in the CI solution that might be linked to the inhibition effect of the corrosion product layers on the iron surface. SEM analysis shows that no film of corrosion products existed. CIs control the corrosion process and prevent passive film formation (iron sulfide), even with the presence of H2S in all tests.

Seismological Investigations of Induced Earthquakes Near the Hutubi Underground Gas Storage Facility

AbstractThe Hutubi underground gas storage facility in Xinjiang, China, with a maximum gas storage capacity of 10.7 billion m3, provides a good opportunity to study seismicity potentially induced by the annually cyclic injection and extraction of natural gas. To statistically distinguish induced seismicity from the tectonic background, we investigate the background seismicity probability of each event using the space‐time epidemic‐type aftershock sequence model and a stochastic declustering method. Our statistical results suggest a potential link between gas injection and two groups of seismicity, with very low background seismicity probabilities during the first and second injection periods in August 2013 and May 2014, respectively. To better understand the earthquake physics, we relocate earthquakes by incorporating a dedicated mobile seismic network after refining the regional 1D velocity model by utilizing an artificial source. After double‐difference relocations, those two groups of earthquakes move much closer to the faults bounding the rock storage units and are situated at a depth around 4 km, slightly deeper than the reservoir formation. Focal mechanism solutions of the two largest earthquakes (Mw 2.8 and 3.0) in August 2013 show a possibly unmapped reverse fault gently dipping to the south. Based on our high‐resolution earthquake locations, we propose that these on‐fault earthquakes are not hydrologically connected with the reservoir formation but are likely induced by poroelastic stress perturbations due to gas injection. Poroelastic stressing can have a larger impact on seismicity rate than pore pressure diffusion at large distances; hence, the distributions and sizes of preexisting faults might play a key role in seismic hazard assessments in our study region.

Experimental study on repair characteristics of damaged rock salt of underground gas storage

Damage in rock salt has significant implication on permeability, which affects the tightness of underground salt cavern gas storage in further. During the leaching of a salt cavern, the brine with formation temperature and pressure can promote the self-healing of rock salt in the excavation damage zone (EDZ). Laboratory tests were conducted to study the promoting effect. The permeability of two intact rock salt specimens was tested. Then they were damaged into two kinds of the state respectively through uniaxial compression. After that, they were put in saturated brine (with a temperature of 50 °C and pressure of 12 MPa, which we called the repair environment in this paper) for 7 d. Finally, the permeability and mechanical properties were obtained after the damaged specimens being repaired. The results show that the permeability of intact rock salt is below 10−19 m2; the permeability increases by more than two orders because of damage; the permeability decreases significantly after being repaired, which can be comparable to its intact state. Discussions of the repair mechanisms are presented (especially the mechanism of recrystallization), which may help to provide significant guidance for the study of the tightness and stability of gas storage facilities in China.

Tracking boil off gas generation into liquefied natural gas supply chain using HYSYS simulator

Liquefied natural gas (LNG) is becoming one of the prominent clean energy sources with its abundance, high potential energy, and low emission and price. Unavoidable reality is that boil off gas (BOG) generates, because of low temperature of LNG, about -162.5 °C at 101.3 kPa for storage and transportation of liquefied natural gas. As natural gas productions increasing globally, BOG and handling problems become serious critical subject in both economic and environment regulations. In this work, liquefied natural gas storage facilities and loading facilities are simulated to investigate the generated BOG by calculating the heat leaks through cargo tank, pipelines, storage tank, and the generated heat by equipment’s. Later, boil off gas rates are estimated for each sector into LNG supply chain with different operational conditions, parameters and voyage time. Factors that affect BOG such as operation temperatures and pressures, methane content, and nitrogen content are presented. Current study would help to properly store and transport LNG to minimize the venting of BOG into supply chain, and thus reducing greenhouse emissions, save energy, and reducing waste of natural gas.

Associations among particulate matter, hazardous air pollutants and methane emissions from the Aliso Canyon natural gas storage facility during the 2015 blowout

In October of 2015, a large underground storage well at the Aliso Canyon natural gas storage facility experienced a massive methane leak (also referred to as “natural gas blowout”), which resulted in the largest ever anthropogenic release of methane from a single point source in the United States. Additional sampling conducted during the event revealed unique gas and particle concentrations in ambient air and a characteristic “fingerprint” of metals in the indoor dust samples similar to samples taken at the blowout site. We further investigated the association between the Aliso Canyon natural gas storage site and several measured air pollutants by: (a) conducting additional emission source studies using meteorological data and correlations between particulate matter, methane, and hazardous air pollutants (HAPs) collected during the natural gas blowout at distances ranging from 1.2 to 7.3 km due south of well SS25, (b) identifying the unique i/n-pentane ratio signature associated with emissions from the blowout event, and (c) identifying characteristics unique to the homes that tested positive for air pollutants using data collected from extensive indoor environmental assessment surveys. Results of air quality samples collected near Aliso Canyon during the final weeks of the event revealed that elevated levels of several HAP compounds were likely influenced by the active natural gas blowout. Furthermore, the final attempts to plug the well during the days preceding the well kill were associated with particle emissions likely from the well site. Together, this investigation suggests uncontrolled leaks or blowout events at natural gas storage facilities have the potential to release harmful pollutants with adverse health and environmental consequences into proximate communities. With this evidence, our recommendations include facility-specific meteorological and air quality data-collection equipment installed at natural gas storage facilities and support of environmental surveillance after severe off-normal operation events.

About this title - Groundwater in Fractured Bedrock Environments: Managing Catchment and Subsurface Resources

Fractured bedrock aquifers have traditionally been regarded as low-productivity aquifers, with only limited relevance to regional groundwater resources. It is now being increasingly recognised that these complex bedrock aquifers can play an important role in catchment management and subsurface energy systems. At shallow to intermediate depth, fractured bedrock aquifers help to sustain surface water baseflows and groundwater dependent ecosystems, provide local groundwater supplies and impact on contaminant transfers on a catchment scale. At greater depths, understanding the properties and groundwater flow regimes of these complex aquifers can be crucial for the successful installation of subsurface energy and storage systems, such as deep geothermal or Aquifer Thermal Energy Storage systems and natural gas or CO 2 storage facilities as well as the exploration of natural resources such as conventional/unconventional oil and gas. In many scenarios, a robust understanding of fractured bedrock aquifers is required to assess the nature and extent of connectivity between such engineered subsurface systems at depth and overlying receptors in the shallow subsurface.