A study of subsurface integrity issues for the Mondarra underground gas storage field

2011 ◽  
Vol 51 (1) ◽  
pp. 215
Author(s):  
Jonathan Serfaty ◽  
Mark Pogson ◽  
Bashirul Haq
Keyword(s):  
Surface Integrity ◽  
Gas Storage ◽  
Operating Conditions ◽  
Reciprocating Compressor ◽  
Underground Gas Storage ◽  
Gas Reservoirs ◽  
Variable Permeability ◽  
Well Integrity ◽  
Large Pressure ◽  
Induced Changes

In gas reservoirs, issues related to declining deliverability and injectivity, well integrity and reservoir integrity are often found. These may become more common, however, in fields used for underground gas storage (UGS). This may be due to extreme operating conditions–primarily cyclical phases of production and injection often associated with large pressure and temperature fluctuations within the reservoir and wellbore, in addition to operating with significant pressure depletion. This study identifies specific sub-surface integrity issues that have affected the Mondarra gas storage facility. The Mondarra facility is Western Australia’s only UGS operation, owned and operated by the APA Group: Australia’s largest natural gas infrastructure business. Specific sub-surface integrity issues related to UGS were investigated. Results indicate that the production and injection cycles have decreased deliverability by 4.4% annually since 2007, primarily by plugging pore throats with inorganic precipitates, such as siderite and organic residues from the reciprocating compressor. Reservoir integrity, represented as a reduction in effective connected volume, has been identified as an issue following early re-pressurisation of the field. Detailed production monitoring and reservoir modelling has been used to investigate this risk and determine the likely range of outcomes. The mechanism of this reduced effective connected volume is uncertain; however, suggested reasons include: pressure-induced changes in the conductivity of micro-fractures and transmissibility of faults; compaction of the reservoir; or, water encroachment post depletion. Furthermore, sub-surface modelling has indicated a complex connectivity picture with multiple compartments and variable permeability layers impacting gas storage operations.

Development of a Digital Twin for Well Integrity Management in Underground Gas Storage Fields

2021 ◽  
Author(s):  
Carlo Busollo ◽  
Stefano Mauro ◽  
Andrea Nesci ◽  
Leonardo Sabatino Scimmi ◽  
Emanuele Baronio
Keyword(s):  
Flow Rate ◽  
Gas Storage ◽  
Fine Tuning ◽  
Digital Model ◽  
Health State ◽  
Underground Gas Storage ◽  
Digital Twin ◽  
Test Execution ◽  
Well Integrity ◽  
Integrity Management

Abstract Objective Digitalization is offering several chances to improve performance and reliability of Underground Gas Storage (UGS) infrastructures, especially in those sites where ageing would require investment improvement for maintenance and monitoring. In that context, well integrity management can benefit from the implementation of a well digital twin, integrated with real time monitoring. The work proposes a digital model of the well that can provide a valuable tool to analyse its non stationary states in order to evaluate the integrity of the barriers and its health state. Methods, Procedures, Process The key points on well integrity management are barriers testing/qualification and annular pressure monitoring, and in UGS operations it’s crucial the selection of the timing of barrier assessment and of diagnostic test execution to correctly evaluates the results. The digital model can provide a tool to help the well engineer to understand the health state of the well and to plan maintenance activities. It considers a physical model of the well composed by gas and liquid filled chambers in the annuluses and in the tubing case and all the potential leak paths that could connect the annuluses, the tubing case, and the reservoir to the external environment. Each chamber is modelled considering its mass and energy balance, while fluid resistances describe fluid leakage across the barriers. Appropriate models, selected according to the geometry and type of each well barrier, describe each fluid resistance. The input parameters are the well architecture, flowing tubing temperature and pressure and gas flow rate. The model provides pressure and temperatures trends and estimates of leak rates trends or annular liquid level movements during the observation time window. The fine tuning of the model of each well is carried out by seeking for the values of the parameters that best describe each single leak path, such as size and position of the leaking point, with a genetic algorithm. Results, Observations, Conclusions The model has been customised and validated over several wells, some of which with perfect integrity status and others with some integrity issues. Results showed a very good fit with field data, as well as high precision in identifying leak position and size. The tool can also be applied to forecast well behaviour after the application of mitigating action or to simulate the evolution of the leak. Example applications are the evaluation of the correct time to top up a casing with liquid or nitrogen or the effect on annular pressure of limiting withdrawal or injection flow rate.

scholarly journals Influence of geological reservoir heterogeneity on exploitation conditions of Garadagh field / underground gas storage (Azerbaijan)

2021 ◽  
Vol 6 (2) ◽  
pp. 105-113
Author(s):  
A. A. Feyzullayev ◽  
A. G. Gojayev
Keyword(s):  
Oil And Gas ◽  
Gas Storage ◽  
Gas Condensate ◽  
Underground Gas Storage ◽  
Gas Reservoirs ◽  
Well Productivity ◽  
Reservoir Heterogeneity ◽  
Reservoir Development ◽  
Condensate Reservoir ◽  
Lithological Composition

Underground oil and gas reservoirs (formations) are characterized by spatial variability of their structure, material composition and petrophysical properties of its constituent rocks: particle size distribution, porosity, permeability, structure and texture of the pore space, carbonate content, electrical resistivity, oil and water saturation and other properties. When assessing development and exploitation conditions for underground gas storages, created in depleted underground oil and gas reservoirs, the inherited nature of the reservoir development should be taken into account. Therefore, identifying the features of variations in well productivity is a crucial task, solution of which can contribute to the creation of more efficient system for underground gas storage exploitation. The paper presents the findings of comparative analysis of spatial variations in well productivity during the exploitation of the Garadagh underground gas storage (Azerbaijan), created in the depleted gas condensate reservoir. An uneven nature of the variations in well productivity was established, which was connected with the reservoir heterogeneity (variations in the reservoir lithological composition and poroperm properties). The research was based on the analysis of spatial variations of a number of reservoir parameters: the reservoir net thickness, lithological composition and poroperm properties. The analysis of variations in the net thickness and poroperm properties of the VII horizon of the Garadagh gas condensate field was carried out based on the data of geophysical logging of about 40 wells and studying more than 90 core samples. The data on of more than 90 wells formed the basis for the spacial productivity variation analysis. The analysis of productivity variation in the space of well technological characteristics (based on data from 18 wells) in the Garadagh underground gas storage (UGS) was carried out through the example of the volume of cyclic gas injection and withdrawal in 2020–2021 season. The studies allowed revealing non-uniform spacial variations in the volumes of injected and withdrawn gas at the Garadagh UGS, created in the corresponding depleted gas condensate reservoir. The features of the UGS exploitation conditions are in good agreement with the features of the reservoir development conditions (variations in the well productivity). The inherited nature of the reservoir development and the underground gas storage exploitation is substantiated by the reservoir heterogeneity caused by the spatial variability of the reservoir lithological composition and poroperm properties. Assessing and taking into account the reservoir heterogeneity when designing underground gas storage exploitation conditions should be an important prerequisite for increasing UGS exploitation efficiency.

Explosion and fire safety of underground gas storage objects

2021 ◽  
pp. 30-35
Author(s):  
O.V. Melekhina ◽  
M.A. Hamula ◽  
R.A. Eredzhibok
Keyword(s):  
Technological Process ◽  
High Power ◽  
Fire Safety ◽  
Power Analysis ◽  
Gas Storage ◽  
Transportation System ◽  
Operating Conditions ◽  
Underground Gas Storage ◽  
Emergency Situations ◽  
Explosion And Fire Safety

Underground gas storage is an element of the gas transportation system. This is the technological process of injection, offtake, storage of gas. Emergency situations associated with burst releases are possible. An absorber is potentially dangerous equipment in the location of main structures. The loss of containment and violation of operating conditions leads to explosions of high power. Analysis of accidents involving loss of containment in equipment is carried out.

Implementation of the Advanced Passive Acoustics Hardware and Software Complex for Well Integrity Diagnostics

2020 ◽  
pp. 56-62
Author(s):  
A.M. Aslanyan ◽  
◽  
I.Yu. Aslanyan ◽  
R.R. Kantyukov ◽  
Yu.Yu. Petrova ◽  
...  
Keyword(s):  
Gas Storage ◽  
Industrial Safety ◽  
Underground Gas Storage ◽  
Passive Acoustics ◽  
Wavelet Filtration ◽  
Software Complex ◽  
Software Technology ◽  
Well Integrity ◽  
Demand Fluctuations ◽  
Storage Facilities

To ensure operational stability of the unified gas supply system depending on the seasonal gas demand fluctuations, the underground gas storage facilities are effectively used. Well integrity diagnostics using the advanced logging techniques facilitate timely identification of potential problems (pinpointing cross-flows behind casing, detecting leaks in production casing and other well construction components, locating sustained annulus pressure sources etc.), and, thereby extension of the safe operation life of functioning of the underground gas storage facilities. The results of the complex of field and geophysical studies in several underground gas storage wells are given in this article. Different types of the underground gas storages are reviewed: the ones located in an aquifer, salt dome, and mature field. The diagnostics was carried out based on the complex of downhole logging including a passive acoustic tool. The passive acoustics hardware and software technology can capture and interpret acoustic signals generated by the wellbore or reservoir flows. To recognise and interpret the captured signals, the temporal coherence algorithms, data wavelet filtration, and neural networks are used. The use of this technology allows to significantly improve the safety of well operation. The information obtained is used both in the preparation of industrial safety expert reports and for the development of effective programs for major repairs of the underground gas storage wells located in the depleted gas and water fields, as well as in the salt caverns. Hardware and software technology of passive acoustics is being used in almost all the major oil and gas provinces in the world, receiving recognition from the largest domestic and foreign companies, however, this is the first time that underground gas storage facilities are used to check the technical condition of the wells.

Maintaining Well Integrity in Underground Gas Storage Wells in China Using a Novel Cementing Technology

2014 ◽  
Author(s):  
Lin juan Wu ◽  
Li Yi ◽  
Salim Taoutaou ◽  
Kun quan Yao ◽  
Yu Fan ◽  
...  
Keyword(s):  
Gas Storage ◽  
Underground Gas Storage ◽  
Well Integrity
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