Underground Gas Storage Process Optimization Using Integrated Subsurface Characterization, Dynamic Modeling and Monitoring - A Case Study

2021 ◽  
Author(s):  
Longxin Li ◽  
Yuan Zhou ◽  
Limin Li ◽  
John Tinnin* ◽  
Xian Peng ◽  
...  
Keyword(s):  
Supply And Demand ◽  
Initial Period ◽  
Gas Storage ◽  
Carbonate Reservoir ◽  
Initial Assessment ◽  
Surveillance Systems ◽  
Operating Pressure ◽  
Underground Gas Storage ◽  
Gas Field ◽  
Cap Rock

Abstract Underground gas storage (UGS) will be key to addressing supply and demand dynamics as natural gas consumption grows during the coming decades in response to cleaner energy initiatives. The XGS facility began UGS operations in a depleted gas field located in SW China in 2013. Following this initial period of utilization, the site was reassessed to safely increase deliverability during winter months to meet future peak gas demand. The XGS field is located in a high tectonic stress region and has a structurally complex and highly faulted geological setting. The carbonate reservoir is heterogeneous and naturally fractured. Initial assessment steps involved determination of maximum storage capacity and estimation of required working gas and cushion gas volumes using fully integrated geological, geophysical, petrophysical frameworks. Geomechanical modeling was embedded into the analysis to determine the long-term impact inferred by cyclical variations of pressures on the reservoir performance and cap rock containment and evaluate both safe operating pressure limits and monitoring requirements. The coupling of complex reservoir and geomechanical parameters was required to create a dynamic model within the stress regime that could be history-matched to the early gas depletion phase and subsequent gas storage cycles. Such a holistic approach allows the operator to optimize the number of wells, their placement, trajectories and completion designs to ensure safe and efficient operations and develop strategies for increasing withdrawal rates to meet anticipated future demand. Additionally, tight integration of subsurface understanding with surface requirements, such as turbo-compressors, is critical to meet the UGS designed performance and deliverability objectives and ensure sufficient flexibility to optimize the facility usage. A further important task of the final phase of UGS facilities design involves enablement of sustainable operation through a Storage Optimization Plan. The results of the analyses serve as a basis for the design of this plan, in combination with fit-for-purpose surveillance systems of the reservoir and cap-rock seal recording pressure, rock deformation and seismicity in real time, along with regular wellbore inspection.

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

2021 ◽  
Author(s):  
Romain Guises ◽  
Emmanuel Auger ◽  
Sanjeev Bordoloi ◽  
Ayodele Ofi ◽  
Colin Cranfield ◽  
...  
Keyword(s):  
Supply And Demand ◽  
Gas Storage ◽  
Initial Assessment ◽  
Underground Gas Storage ◽  
Seamless Integration ◽  
Efficient Operation ◽  
Subsurface Characterization ◽  
Facilities Design ◽  
The Impact

Abstract 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.

A Numerical Simulation Study of CO2 and N2 as Cushion Gas in an Underground Gas Storage

2021 ◽  
Author(s):  
Kang Tang ◽  
Xinwei Liao ◽  
Xiaoliang Zhao ◽  
Haojie Li ◽  
Xiaoxiao Li ◽  
...  
Keyword(s):  
Capital Investment ◽  
Molecular Diffusion ◽  
Supply And Demand ◽  
Diffusion Mechanism ◽  
Eastern China ◽  
Gas Storage ◽  
Scientific Basis ◽  
Good Choice ◽  
Underground Gas Storage ◽  
Efficient Operation

Abstract Underground gas storage (UGS) is a beneficial economic method of compensating for the imbalance between natural gas supply and demand, which is currently considered an important part of the gas chain. To reduce the capital investment of gas storage, the use of alternative gases as cushion gas is a good choice. However, the mixing of different gases in the UGS challenges the application of alternative gases(N2and CO2) as cushion gas. In this paper, we first conduct the thermodynamic analysis of two alternative gases, namely, N2and CO2. The feasibility of these two gases as cushion gas is discussed. Secondly, a gas storage located in Eastern China is selected. Based on the physical properties of the reservoir, a simulation model with coupled diffusion mechanism is conducted. Finally, the effect of molecular diffusion, gas category and ratio on the dynamic operation of UGS is studied. In addition, the CO2storage capacity under different operating parameters was also analyzed. This study provided a scientific basis for the efficient operation of UGS and the geological storage of CO2.

Modeling of Underground Gas Storage in a Depleted Gas Field

2005 ◽  
Vol 27 (10) ◽  
pp. 913-920 ◽  
Author(s):  
F. Gumrah ◽  
Ö. Izgec ◽  
U. Gokcesu ◽  
S. Bagci
Keyword(s):  
Gas Storage ◽  
Underground Gas Storage ◽  
Gas Field

Resurrection at AGL Silver Springs and Wallumbilla: case study of bringing field and surface facilities back to life

2017 ◽  
Vol 57 (1) ◽  
pp. 124
Author(s):  
John Croker ◽  
Matthew Kidd ◽  
Evie Nicola ◽  
James Dean
Keyword(s):  
High Pressure ◽  
Supply And Demand ◽  
Underground Storage ◽  
Underground Gas Storage ◽  
Gas Field ◽  
Pressure Injection ◽  
Engineering Work ◽  
Gas Fields ◽  
High Pressure Injection

AGL acquired the Silver Springs reserves and operations from Mosaic Oil in 2010, including several depleted yet condensate-rich gas fields. Gas was sent from Silver Springs to the Wallumbilla LPG plant (acquired by AGL in 2011) to be refined into sales gas, LPG and condensate. AGL’s objective was to build a commercial underground gas storage facility by converting the Silver Springs gas field into an underground storage reservoir. The business intent was to run the reservoir in alternating injection and withdrawal mode to take advantage of supply and demand economics. Setting up for injection and withdrawal required the commissioning of 10 petroleum producing wells, bi-directional high-pressure flowlines and associated infrastructure. A high-pressure injection compressor was commissioned. Injection of dry sales gas into wells commenced in 2011. Withdrawal at a higher rate than original was facilitated by new separation and dehydration equipment. The Wallumbilla plant was refitted extensively, including flare and venting upgrades and recertification of the pipeline and every pressure vessel on-site. Withdrawal mode operations commenced in October 2015. The LPG plant operability was demonstrated; however, running at design rate was compromised by excessive chilling in the cryogenic section of the Wallumbilla plant, caused by lower than expected LPG quantities in the withdrawn gas. Process engineering work resulted in design of a regenerative heater to warm the sub-cooled gas. The presentation covers the extent of the improvement work and the process investigations, which have formed the basis to ensure future versatile operation.

Inventory Verification in Underground Gas Storage Rebuilt from Depleted Gas Reservoir: A Case Study from China

2021 ◽  
Author(s):  
Lina Song ◽  
Hongcheng Xu ◽  
Qiqi Wanyan ◽  
Wei Liao ◽  
Shijie Zhang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Winter Season ◽  
Gas Storage ◽  
Experimental Result ◽  
Operating Pressure ◽  
Underground Gas Storage ◽  
Gas Reservoir ◽  
Well Pattern ◽  
Geological Conditions ◽  
Depleted Gas Reservoir

Abstract Inventory verification is one of vital tasks in underground gas storage (UGS) management process. For one reason, it is possible to know exactly how much natural gas is actually in the gas storage and ensure that it can be produced and supplied to the market in winter season when needed. For another, possible natural gas leakage can be discovered in time by inventory verification, to ensure the safe and economic operation of the gas storage. HTB UGS is a gas storage facility rebuilt from a depleted gas reservoir in China, which has been commissioning in June 2013. After 7 years injection-withdrawal cycles, we calculated and analyzed the inventory of this gas storage. First and foremost, we analyzed the data of 13 observation wells, including monitoring of gas-water interface, caprocks, and faults of the HTB UGS. In addition, we carried out core experiments in the laboratory to simulate the multi-cycle injection and withdrawal of gas storage, and analyzed the microscopic pore seepage characteristics of the reservoir during the UGS operation. Next, based on the operating pressure test data of the gas storage, we corrected the formation pressure and calculated the effective inventory. Furthermore, combined with the simulation results that we have carried out in the previous period, the effective inventory of HTB UGS was comprehensively evaluated. The result shows that: 1) The complete monitoring system indicates that the HTB UGS has no gas escaping from the storage field through faults, caprocks or wellbore. 2) The experimental result shows that in the process of gas withdrawal, various forms of natural gas such as jams and bypasses in some areas of the reservoir cannot participate in the flow, leading to this part of natural gas cannot be used. 3) Inventory calculation shows that as of the end of gas withdrawal in March 2020, the book inventory of HTB UGS is 99.8×108m3，while the effective inventory is 91.8×108m3 and the working gas is 39.9×108m3. 4) By acidification or other measures to improve the geological conditions, intensifying the well pattern and extending the gas production time, HTB UGS can increase its effective inventory. With the great efforts in constructing underground gas storage in China and the market-oriented operation of UGS, inventory verification of gas storage will become increasingly important. The inventory analysis method established in this article can provide a certain reference.

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