Research Achievements - International conference proceedings -

Development of artificial neural networks for estimating static formation temperature

Kaneko, S., Naganawa, S., Bjarkason, E.K.

Geothermal Resources Council Transactions   48   2268 - 2278   2024.10  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Preliminary evaluation of cesium tracer adsorption for geothermal applications: Implications for temperature decline predictions

Bjarkason, E.K., Hawkins, A.J.

Proceedings of International Symposium on Earth Science and Technology 2023     370 - 373   2023.11

Research paper (international conference proceedings)   International Co-author

Experimental analysis of how the form of biodegradable resin drilling fluid additives affects filtration properties and lost circulation prevention performance

Onuki, M, Bjarkason, E.K, Naganawa, S.

Geothermal Resources Council Transactions   47   1104 - 1114   2023.10  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Modelling of geothermal cuttings transportation during drilling—A case study of well PW-03B in Paka geothermal field, Kenya

Miyora, T., Bjarkason, E.K., Naganawa, S.

Geothermal Resources Council Transactions   47   1045 - 1059   2023.10  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Optimization of drilling parameters for PDC bit drilling medium-to-hard formations

Ishizawa, K., Bjarkason, E.K., Naganawa, S.

Geothermal Resources Council Transactions   47   1019 - 1028   2023.10  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Thermal stress analysis considering casing eccentricity in a supercritical geothermal well

Shimomura, R., Sugawara, H., Bjarkason, E.K., Naganawa, S.

Geothermal Resources Council Transactions   47   3033 - 3042   2023.10  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Application of Drilling Fluid Circulation Technology to Lifting System for Deep-Sea Mineral Resources

Kitago, R., Naganawa, S., Bjarkason, E.K.

Proc., ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering ( American Society of Mechanical Engineers )  9   2023.06  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Abstract

Various types of deep-sea mineral resources such as mud containing rare earth elements, manganese nodules, cobalt-rich crusts, and methane hydrate are found on deep-water seabeds around the world. Lifting systems for mining these resources using a gas lift approach or submersible pumps have been studied by many researchers. As an alternative to these lifting systems, this study proposes a rare earth mud lifting system using a hydraulic jet pump, like those used for artificial lifting in oil wells. The objective of this study is to investigate the design of this lifting system to maximize the mud suction rate of the hydraulic jet pump by numerical simulation. The hydraulic jet pump simulations involved two-phase flow of seawater as the working fluid and rare earth mud slurry as the production fluid. The simulation results showed that all the considered hydraulic jet pump designs could suck in highly viscous rare earth mud slurry at an ocean depth of about 7,000 m. A design with three sets of suction lines and diffusers gave the best performance and could transport a rare earth mud slurry at commercially viable combinations of flow rates and mud concentrations. At a suction line diameter of 1″, the produced mud rate exceeded the commercial reference standard, with mud recovery rates of 10,500 ton/day and 15,800 ton/day when the volumetric mud concentration of the slurry entering the pump was 20% and 40%, respectively.

DOI

Application of Insulated Drill Pipe to Supercritical/Super-Hot Geothermal Well Drilling

Ajima, K., Naganawa, S., Bjarkason, E.K.

Proc., ASME 2023 42nd International Conference on Ocean, Offshore and Arctic Engineering ( American Society of Mechanical Engineers )  9   2023.06  [Refereed]

Research paper (international conference proceedings)   Domestic Co-author

Abstract

In Japan, a research and development project is ongoing that is aimed at developing supercritical geothermal exploration and power generation methods. The extremely high formation temperatures encountered during supercritical geothermal drilling presents a challenge for the durability of downhole tools. Thus, it is essential to design an effective method of downhole cooling during drilling. To protect commonly used downhole tools from thermal damage, the objective is to reduce the downhole temperature in supercritical geothermal wells to below 175°C, which coincides with the lowest heat resistant temperature of most downhole equipment. In this study, the authors carried out numerical simulations focusing on the effectiveness of using insulated drill pipes to reduce downhole fluid circulation temperatures during drilling through formations with temperatures high enough for a supercritical reservoir. It was found that use of insulated drill pipes effectively controlled the downhole temperature by reducing the heat influx conducted from the formation. Considering the additional cost of using insulated drill pipes, we also looked at cases where the insulated drill pipes were only applied along two-thirds of the entire drillstring. Considering the flow rate of the circulating fluid and the inflow temperature, the temperature simulation was performed to keep the downhole temperature below 175°C. We also considered the additional pressure loss that could be expected from using the narrower insulated drill pipe.

DOI

Filtration of Biodegradable Fiber-Containing Drilling Fluids for Offshore Shallow Weak Formations

Takahashi, K., Naganawa, S., Bjarkason, E.K., Mukai, R.

Proceedings of the Annual Offshore Technology Conference ( Offshore Technology Conference )    2023.05

Research paper (international conference proceedings)   Domestic Co-author

Abstract

Fiber-containing drilling fluids are expected to improve hole cleaning efficiency and have filtration properties that help to form a strong mud cake on the borehole wall. The objective of this study is to evaluate the filtration properties of drilling fluids containing a novel biodegradable polymer fiber.

The novel 100% bio-based polymer, named PHBH (TM), biodegrades easily in a seawater environment. The filtration properties of drilling fluids containing PHBH fibers were investigated through static filtration tests using an API (LPLT) filter press and a high-temperature and high-pressure (HPHT) filter press. The HPHT tests were conducted at 93°C (200°F). The tested base fluids contained 1.5wt% of bentonite or sepiolite clay, and 0.1 to 0.4wt% of polyanionic cellulose (PAC-HG) as a viscosifier. Sepiolite was considered since it is more thermally stable than bentonite.

From the results of API and HPHT filtration tests, adding 0.4wt% PHBH fibers reduced the amount of filtrate by approximately 5 to 7%, and the thicknesses of mud cake by approximately 24 to 34%. Among the 3, 5, 10, and 14 mm-long fibers tested, 14 mm long fibers resulted in the maximum reductions in filtrate and mud-cake thickness. Analysis of the solid concentration in the suggested that thin and strong mud cakes might form by adding the PHBH fibers for both bentonite- and sepiolite-based fluids.

Compared to the existing commercial fiber additives, the novelty of application of the new biodegradable fiber-containing drilling fluids to prevention of lost circulation or borehole wall strengthening in offshore shallow weak formations is highly environmentally-friendly for sustainable oil and gas developments. The biodegradable fiber-containing fluids can be applied in various uses like completion fluid, cementing spacer, etc.

DOI

Subsea Lifting System for Deep-Seabed Rare-Earth Rich Mud

Kitago, R., Naganawa, S., Bjarkason, E.K.

Proceedings of the Annual Offshore Technology Conference ( Offshore Technology Conference )    2023.05

Research paper (international conference proceedings)   Domestic Co-author

Abstract

Deep-seabed mud containing a high concentration of rare-earth elements, including yttrium, has been discovered in the western North Pacific Ocean near Minami-Torishima Island, Japan. However, production of the rare-earth rich mud is challenging because of its location at water depths of over 6000 m. We propose a new subsea lifting system for deep-seabed rare-earth rich mud. The lifting system consists of a small diameter marine riser and an inner work string. At the lower end of the work string, a hydraulic jet pump is equipped so that rare-earth rich mud slurry can be easily sucked from a sea-bottom mud collecting device and lifted through the riser annulus. The jet pump is driven with power fluid pumped from a floating mining vessel. To evaluate the suction performance of the jet pump and the flow assurance in the annulus, numerical simulations were performed for various kinds of power fluid rates and jet pump configurations. The simulation results suggested that the proposed lifting system could, in principle, lift slurry containing rare-earth rich mud continuously to a surface floating vessel. Also, the hydraulic jet pump mechanism could be optimized to maximize the suction caused by the Venturi depressurization effect and to achieve a commercially feasible mud lifting rate of 3500 ton/day. For a pump configuration with three pairs of diffusers and suction lines, a drive fluid flow rate of 700 gal/min was found to be sufficient to meet the economic production criteria.

DOI

How precise can thermal breakthrough predictions be that are derived from adsorptive tracer tests?

Bjarkason, E.K.

Proc., 48th Workshop on Geothermal Reservoir Engineering     243 - 251   2023.02

Research paper (international conference proceedings)   Single author

Fixed and random effects error models for geothermal simulator calibration

Maclaren, O.J., O'Sullivan, J.P., O'Sullivan, M.J., Gravatt, M.J., Bjarkason, E.K., Nicholson, R.

Proc., 44th New Zealand Geothermal Workshop     2022.11  [Refereed]

Research paper (international conference proceedings)   International Co-author

Testing spatially flexible bottom boundary parameter schemes and priors for geothermal reservoir models

Bjarkason, E.K., Maclaren, O.J., O'Sullivan, J.P., O'Sullivan, M.J., Suzuki, A., Nicholson, R

Proc., 43rd New Zealand Geothermal Workshop     1 - 9   2021.11  [Refereed]

Research paper (international conference proceedings)   International Co-author

Verification of novel parameterization methods for uncertainty quantification of geothermal reservoir models

Bjarkason, E.K., Nicholson, R., Maclaren, O.J., Suzuki, A.

Proc., 21st International Symposium on Advanced Fluid Information     2021.10

Research paper (international conference proceedings)   International Co-author

Accelerating the solution of geothermal inverse problems using adjoint methods in Waiwera: Case studies on Kerinci and Wairakei

Gonzalez-Gutierrez, B., Nicholson, R., O'Sullivan, J.P., Yeh, A., Bjarkason, E.K., O'Sullivan, M.J., Maclaren, O.J.

Proc., World Geothermal Congress 2020+1     1 - 8   2021.04  [Refereed]

Research paper (international conference proceedings)   International Co-author

Uncertainty quantification of highly-parameterized geothermal reservoir models using ensemble-based methods

Bjarkason, E.K., Maclaren, O.J., Nicholson, R., Yeh, A., O'Sullivan, M.J.

Proc., World Geothermal Congress 2020+1     1 - 13   2021.04  [Refereed]

Research paper (international conference proceedings)   International Co-author

Representation of unknown parameters in geothermal model calibration

Nicholson, R., Maclaren, O.J., O'Sullivan, J.P., O'Sullivan, M.J., Suzuki, A., Bjarkason, E.K.

Proc., 42nd New Zealand Geothermal Workshop     1 - 8   2020.11  [Refereed]

Research paper (international conference proceedings)   International Co-author

New parameterization methods for uncertainty quantification of geothermal models

Bjarkason, E.K., Nicholson, R., Maclaren, O.J., Suzuki, A.

Proc., the 20th International Symposium on Advanced Fluid Information     2020.10

Research paper (international conference proceedings)   International Co-author

Accounting for model and observation error in geothermal thermal breakthrough models

Bjarkason, E.K., Suzuki, A.

Proc., 16th International Conference on Flow Dynamics     2019.11

Research paper (international conference proceedings)  

Non-uniqueness of geothermal natural-state simulations

Bjarkason, E.K., Yeh, A., O’Sullivan, J.P., Croucher, A., O’Sullivan, M.J.

Proc., 41st New Zealand Geothermal Workshop     1 - 8   2019.11  [Refereed]

Research paper (international conference proceedings)   International Co-author