An overview of induced seismicity in the Netherlands

We present an overview of induced seismicity due to subsurface engineering in the Netherlands. Our overview includes events induced by gas extraction, underground gas storage, geothermal heat extraction, salt solution mining and post-mining water ingress. Compared to natural seismicity, induced events are usually small (magnitudes ≤ 4.0). However, due to the soft topsoils in combination with shallow hypocentres, in the Netherlands events exceeding magnitude 1.5–2.0 may be felt by the public. These events can potentially damage houses and infrastructure, and undermine public acceptance. Felt events were induced by gas production in the north of the Netherlands and by post-mining water ingress in the south-east. Notorious examples are the earthquakes induced by gas production from the large Groningen gas field with magnitudes up to 3.6. Here, extensive non-structural damage incurred and public support was revoked. As a consequence, production will be terminated in 2022 leaving approximately 800 billion cubic metres of gas unexploited. The magnitudes of the events observed at underground gas storage, geothermal heat production and salt solution mining projects have so far been very limited (magnitudes ≤ 1.7). However, in the future larger events cannot be excluded. Project- or industry-specific risk governance protocols, extensive gathering of subsurface data and adequate seismic monitoring are therefore essential to allow sustainable use of the Dutch subsurface now and over the decades to come.

Determination of the lower boundaries of the natural gas hydrates stability zone in the subpermafrost horizons of the Yakut arch of the Vilyui syneclise, saturated with bicarbonate-sodium type waters

This paper considers the possibility of the underground gas storage facilities creating in a hydrate state on the north-western slope of the Yakut arch of the Vilyui syneclise. For this, the boundaries of the hydrate stability zone were determined for 6 promising areas of the considered geological structure. Equilibrium conditions of the natural gas hydrates formation in the model porous media containing bicarbonate-sodium type water (mineralization 20 g/l), characteristic for the subpermafrost horizons of the Yakut arch, have been studied by the method of differential thermal analysis. On the basis of the obtained results, the boundaries of the natural gas hydrates stability zone were determined. It was shown that the upper boundaries of the hydrate stability zone are located in the thickness of permafrost rocks. It was found that the lower boundaries of the natural gas hydrates stability zone in moist unsalted porous medium lie in the range from 930 to 1120 m. When the samples are saturated with mineralized water, the boundaries are located 80-360 m higher. The obtained experimental results allow us to conclude that in subpermafrost aquifers of the Yakut arch has favorable conditions for the formation of natural gas hydrates. Keywords: natural gas hydrates; aquifers; underground gas storage; hydrate stability zone; geothermal gradient; equilibrium conditions of the hydrate formation; bicarbonate-sodium type water.

Features of monitoring storage of methane-hydrogen mixtures

The storage of methane-hydrogen mixtures (MHM) in existing underground gas storage facilities (UGS) is a prerequisite for the development of a "carbonneutral" strategy of the Russian Federation. The use of technologies for storage and delivery of MHM in industrial volumes should be ensured by experimental research, the creation of a regulatory framework and the introduction of modern methods for maintaining the operational reliability of the existing Unified Gas Transportation System (UGSS). The need for scientific and project work is determined by the peculiarities of the storage of MHM and the assessment of the likelihood of negative technogenic and mechanical consequences during the operation of the equipment. The materials provide the main risk models of the processes that arise in the case of hybrid storage of MHM. The use of cluster technology for storage and transportation of MHM is proposed, and the need to ensure constant monitoring of the component composition of gas as part of the implementation of an integrated automated flow technology is shown. Keywords: methane-hydrogen mixtures; hydrogen energy; underground gas storage; hardware control; risks.

Assessment results of soil properties by engineering-geophysical studies

В статье излагаются результаты инженерно-геофизических исследований на территории новой компрессорной станции Специального подземного хранилища газа (СПХГ) в г. Абовян (Армения). Учитывая то, что Республика Армения находится в сейсмоактивной зоне, проведение данных исследований является весьма актуальными, а новая компрессорная станция Специального подземного хранилища газа является особо важным объектом. Целью работы является выявление для данной территории особенности удельного электрического сопротивления грунтов, наличие блуждающих токов (БТ), оценка коррозийной агрессивности грунтов, изучение сейсмических условий и оценка ожидаемой сейсмической интенсивности на территории, намеченной под строительство. Методы работы. Определение удельного (кажущегося) электрического сопротивления грунтов исследуемой территории производилось методом электропрофилирования с использованием симметричной четырехэлектродной установки Веннера. В статье представлены пункты измерения удельного электрического сопротивления грунтов на территории новой компрессорной станции Абовянского СПХГ, выявлено наличие блуждающих токов, приведены таблицы степени коррозионной агрессивности грунтов, указаны места наличия опасного уровня блуждающих токов. Также проведены работы по сейсмическому микрорайонированию для определения величины ожидаемой сейсмической интенсивности конкретной территории компрессорной станции. Ожидаемая сейсмическая интенсивность на данной территории определена на основе анализа инженерно-геологических материалов с учетом результатов полевых инженерно-сейсмометрических инструментальных исследований. С помощью малоглубинной сейсморазведки были определены скорости распространения сейсмических волн. Измерения проводились горизонтально-ориентированным сейсмоприемником СМ-3 (вертикальный удар). Ударные волны создавались импульсным возбуждением. Для обеспечения необходимой мощности возбуждения импульсное воздействие создавалась с помощью падающего груза. Результаты работы. В статье приведены сейсмические условия территории, результаты сейсмометрических исследований,данные по наблюдениям микросейсм, спектры Фурье преобладающих периодов по некоторым точкам наблюдений, схема инженерно-сейсмометрических наблюдений. В результате проведенных исследований установлено, что грунтовые условия данной территории относятся к грунтам первой категории по сейсмическим свойствам. Ожидаемую сейсмическую опасность исследованной территории необходимо характеризовать следующими значениями: I=7 баллов или PGA=0,24 g. The article presents the results of engineering-geophysical studies on the territory of the new compressor station of the Special Underground Gas Storage (SPGS) in the city of Abovyan (Armenia). Considering that the Republic of Armenia is located in a seismically active zone, these studies are highly relevant, and the new compressor station of the Special Underground Gas Storage is especially important object. The Aim of the presented work is to identify the features of the specific electrical resistivity of soils, the presence of stray currents, assess the corrosive aggressiveness of soils, seismic conditions of the territory and the expected seismic intensity in the area designated for construction. Methods. The determination of the specific (apparent) electrical resistivity of the soils of the study area was carried out by the method of electrical profiling using symmetrical four-electrode Wenner setup. The article presents the points of measuring the electrical resistivity of soils in the territory of the new compressor station of the Abovyan SPGS, revealed the presence of stray currents, tables of the degree of corrosiveness of soils are given, the locations of the presence of a dangerous level of stray currents are indicated. Also works on seismic microzoning were carried out, the values of the expected seismic intensity of the compressor station territory were determined. The expected seismic intensity in this area has been determined based on analysis of engineering-geological materials, taking into account the results of field engineering-seismometric instrumental studies. By using shallow seismic surveys have determined the speed of seismic velocity. Measurements were carried out horizontally oriented seismic receiver SM-3 (vertical impact). Shock waves were generated by pulsed excitation. To provide the required excitation power the impulse action was created using a falling weight. Results. The article presents the seismic conditions of the territory, the results of seismometric studies, data on observations of microseisms, Fourier spectra of prevailing periods for some observation points, a scheme of engineering seismometric observations. As a result of the research carried out, it was found that that the soil conditions composing this territory belong to the soils of the first category in terms of seismic properties, the expected seismic hazard of the investigated area should be taken as I = 7 points or PGA = 0.24 g.

Climatic resources as objects of natural resource legal relations

The article is devoted to the study of scientific approaches to the characteristics of the objects of natural resource relations. Theoretical positions of the representatives of legal science on the definition of the concept of natural resources as objects of natural resource legal relations, the separation of their legal features are revealed. Scientific approaches to the legal nature of climatic resources and their place in the modern system of natural resource legal relations are analyzed. Natural resource relations consist of the use and reproduction of natural resources or their properties (for example, the potential energy of water, which is converted into electricity, water surface for water transport, the properties of atmospheric air to contain and dissolve (reduce concentration) pollutants, the property of subsoil underground gas storage facilities, etc.). Climatic resources are called inexhaustible natural resources, which include solar energy, moisture, wind energy, etc. and are determined by the peculiarities of the climate. The use of certain properties of climatic resources as, first of all, alternative energy sources is extremely important. Climatic resources in most of Ukraine are favorable for the development of alternative energy. However, the current state of legal regulation of activities aimed at ensuring the rational and efficient use of climate resources needs to be improved. Keywords: natural resource law, natural resource legal relations, natural resources, climatic resources, climate

The Importance of Subsurface Characterization and Monitoring During Development and Operation of Underground Gas Storage Facilities

Natural gas consumption is expected to grow significantly in coming decades in response to cleaner energy initiatives. Underground gas storage (UGS) will be key to addressing supply and demand dynamics for this transition to be successful. This technical paper will demonstrate the importance of an integrated subsurface characterization and monitoring approach not only for the construction of UGS, but also to guarantee safe and efficient operation over many decades. Key to long-term success of UGS is maximizing working capacity with respect to volume and pressure and maintaining well injection and withdrawal capabilities. Initial assessment steps involve determination of maximum storage capacity and an estimation of required cushion gas volumes. In similar manner to conventional field evaluation, we perform an integrated geological, geophysical, petrophysical and geomechanical characterization of the subsurface. However, for UGS facilities, the impact of cyclic variations of reservoir pressures on subsurface behavior and cap rock integrity also needs to be evaluated to determine safe operating limits at every point in time during the life of the UGS project. The holistic approach described above allows the operator to optimize the number of wells, well placement, completion design, etc. to ensure long-term safe and efficient operations. Furthermore, close integration of subsurface understanding with optimization of surface facilities, such as the compression system, is another critical component to ensure optimum UGS performance and deliverability. Moreover, another important task of the final phase of UGS facilities design involves enablement of sustainable operation through an asset integrity management plan. This phase is articulated around reservoir surveillance plans that monitor pressure, rock deformation and seismicity, in addition to regular wellbore inspection. Through close operations monitoring and the utilization of advanced data analytics, observations are compared to existing models for validation and operation optimization. Importantly we show that adapted monitoring programs provide critical long-term insight regarding the field response during successive cycles, leading to significant improvement in working gas capacity. A key consideration of this integrated UGS development strategy is based on the seamless integration of subsurface characterization, wellbore construction and well completions to ensure technical and commercial flexibility. The approach also emphasizes the integration with surface facilities design to ensure a true "Storage to Consumer" view for effective de-bottlenecking. Coupled with integrated subsurface integrity monitoring, this ensures a faster, cost efficient and safe response to the construction and operation of UGS facilities.