Natural Gas Hydrate Production Research Articles

Numerical and experimental investigation on a downhole gas-liquid separator for natural gas hydrate exploitation

Natural gas hydrate (NGH) is widely considered as an alternative energy source due to its tremendous reserves, cleanness and high energy density. During the exploitation process, discharging the gas-liquid phase to the surface for separation not only affects the pump performance but also increases the space requirements of the offshore platform. Taking NGH production test data in South China Sea for example, a downhole spiral gas-liquid separator is designed for high gas-liquid ratio (liquid content is less than 10%) in this paper. The forces of droplets in the separator are analyzed and the CFD model for gas-liquid two phase flow is established. The RNG k-ε turbulence model is used for analyzing the velocity field distribution and the pressure field distribution in the separator. The influence of structure parameters (pitch, cycle number of spiral piece, and the outer diameter of spiral pipe) and scale on the separation performance is investigated. The energy loss increases sharply after scaling in the separator and some necessary measures should be taken to avoid the generation of the sale and the secondary hydrate. Based on steepest ascent design, response surface methodology and particle swarm optimization, the optimal structure of the separator with high separation efficiency 87.26% and low pressure drop 2614.19Pa is obtained. The experimental platform is built for testing the gas-liquid separator. The comparison of numerical simulations and experiments show that the calculation model for the hydrate gas-liquid separation is correct and feasible. The separation device with the optimal structural parameters has good separation performance.

Controlled Production of Natural Gas Hydrates in an Experimental Device with an Internal Circulation Circuit

For countries with limited access to conventional hydrocarbon gases, methane hydrates have emerged as a potential energy source. In view of the European Union’s requirements to reduce the energy intensity of technological processes and increase energy security, it appears promising to accumulate natural gas and biomethane in the form of hydrate structures and release them if necessary. Storing gas in this form in an energy-efficient manner creates interest in developing and innovating technologies in this area. Hydrates that form in gas pipelines are generated by a more or less random process and are an undesirable phenomenon in gas transportation. In our case, the process implemented in the proposed experimental device is a controlled process, which can generate hydrates in orders of magnitude shorter times compared to the classical methods of generating natural gas hydrates in autoclaves by saturating water only. The recirculation of gas-saturated water has been shown to be the most significant factor in reducing the energy consumption of natural gas hydrate generation. Not only is the energy intensity of generation reduced, but also its generation time. In this paper, a circuit diagram for an experimental device for natural gas hydrate generation is shown with complete description, principle of operation, and measurement methodology. The natural gas hydrate formation process is analyzed using a mathematical model that correlates well with the measured hydrate formation times. Hydrates may become a current challenge in the future and, once verified, may find applications in various fields of technology or industry.

Experimental investigation on hydrate anti-agglomerant for oil-free systems in the production pipe of marine natural gas hydrates

During the production of marine natural gas hydrates, as gas hydrates are easily formed, they tend to agglomerate, deposit on the pipe walls, and eventually block the pipe. In this study, high-pressure autoclave and micromechanical force apparatus were used to investigate the effects of anti-agglomerants and kinetic inhibitors on the hydrate agglomeration in the oil-free gas–water system, and the anti-agglomeration mechanism was analyzed. The results indicate that when the hydrate conversion rate reached about 27%, a complete blockage occurred. In the oil-free system, conventional anti-agglomerants did not exhibit any anti-agglomeration performance; while kinetic inhibitors slowed down the hydrate formation, but could not inhibit their agglomeration. An amphiphilic amide compound, namely DCA, effectively prevented hydrate agglomeration and blockage under the simulated hydrate production conditions of 8-h stirring and subsequent 8-h shut-in. From the perspective of interparticle interaction, 1.0 wt% DCA reduced the cohesion force between cyclopentane hydrate particles by 62% and 70% in liquid cyclopentane and air, respectively. These effects were attributed to the adsorption of DCA on the surface of hydrate particles, which converted the surface characteristic from hydrophilic to hydrophobic; thus, no liquid bridge could be formed between particles. Moreover, DCA formed an isolating layer and offered steric hindrance, thus preventing the adhesion and agglomeration of hydrates.

Permeability analysis of gas hydrate-bearing sand/clay mixed sediments using effective stress laws

For natural gas hydrate reservoirs in the South China Sea, particle types of sediments and compaction of overlying rocks significantly affect the variation of porosity and permeability in sediment, leading to changes in gas production efficiency in natural gas hydrate reservoirs. In this paper, the permeability experiments ranged from 0 MPa to 5 MPa effective stress have been performed in a cylindrical reaction vessel with various conditions of hydrate saturations. The relationships between permeability and porosity and effective stress in methane hydrate bearing sediments made of quartz and quartz-montmorillonite mixture were investigated, accounting for hydrate saturation and particle types. The experiment results indicated that in quartz and quartz-montmorillonite mixture without methane hydrate, both permeability and porosity decrease gradually with the increase of effective stress. When the effective stress exceeds 2 MPa, the decrease of porosity and permeability of pure quartz-montmorillonite mixture is significantly higher than that of pure quartz. The permeability of quartz decreases with the increase of hydrate saturation, while permeability of quartz-montmorillonite mixture is opposite due to the loss of water and shrinkage of clay. In addition, the porosity and permeability of the two hydrate-bearing sediments decrease with the increase of effective stress. The porosity of the two types of methane hydrate samples changes with the effective stress in accordance with the law of exponential function. In addition, the relationship between permeability and effective stress in quartz and quartz-montmorillonite mixture sample is appropriate for the exponential law and power law, respectively. These results provide guidance for studying the effect of effective stress on porosity and permeability for different particle types sediment in the process of natural gas hydrate production in South China Sea.

Experimental Study and Prediction Model for Hydrate Plugging Formation in Single-Pass Gas-Dominated Pipes with Diameter Reduction

Summary Gas hydrate plugging in flowlines acts as a major blockage risk in oil, gas, and natural gas hydrate production. Current studies on hydrate plugging is mainly conducted in pipes with a constant diameter, whereas the effects of varying diameters have been less explored. Pipes with diameter reductions are very common in the oil and gas production process. Herein, by performing experiments with pipes of four different sizes, including one with a constant diameter and three with diameter reductions, the hydrate plugging in single-pass gas-dominated pipes with diameter reduction is investigated systematically, the results of which show that the existence of diameter reduction can facilitate the deposition of hydrate particles on pipe walls and the formation of a hydrate deposition layer. Meanwhile, hydrate sloughing occurs during the growth of the hydrate deposition layer under fluid shear force. With the increase in the diameter reduction ratio or subcooling for hydrate formation, the hydrate deposition is observed to increase significantly, thus resulting in the reduction of time for hydrate plugging. According to these results, the hydrate plugging mechanism in pipes with diameter reduction is proposed. Further, in combination with the hydrate deposition difference between the inside and outside of the arc-shaped low-speed area, a new numerical model is established for hydrate plugging prediction in the pipe with diameter reduction, which can predict the growth and evolution of the hydrate deposition layer accurately with the consideration of the diameter’s reduction. The results of this work provide a valuable guidance for the targeted prevention and management of hydrate plugging in flowlines with diameter reductions.

Plasma-assisted nanotechnology for enhancement of the rate of production and storage of natural gas hydrates: Experimental study and kinetic modeling

In the present work, the novel technique of dielectric barrier discharge (DBD) humid air plasma has been presented for processing and functionalization of nanoparticles and enhancing the rate of methane hydrate production. It is shown that the rate of gas to hydrate (GTH) production is significantly promoted by applying the proposed DBD plasma on the surface structure of graphene nanosheets (GN). The plasma processing leads to considerable enhancement of dispersion, stability and specific surface area of graphene nanoparticles such that the gas–liquid interfacial area and fluid microconvection rate and thus the GTH conversion rate are significantly increased. It is found that at the optimum operating conditions of 60 ppm of plasma treated graphene nanoparticles at a frequency of 6 kHz, a voltage of 8 kV, and a processing time of 6 min, it is possible to achieve a 5 fold increase in GTH conversion as compared to the case of pure water in a one-hour hydrate production process. A new kinetic model for prediction of the gas to hydrate energy conversion process is also presented and the predicted results are validated by using the experimental data at different operating conditions. The average absolute deviation percent (AAD%) and the coefficient of determination (R2-value) of the predicted gas consumptions regarding methane hydrate formation process are about 1.97% and 0.98 respectively suggesting the excellent accuracy of the proposed kinetic model. The proposed plasma functionalization technique is robust and eco-friendly without operational difficulty of conventional surfactants and can have potential application for considerable enhancement of the rate of production and storage of natural gas hydrates.

Integrity control analysis of natural gas hydrate production wellbore using system method and game theory

Natural gas hydrate (NGH) is an outstanding alternative to conventional energy due to its cleanliness and excellent energy density. However, there are still a series of problems needed to be solved before the commercial production of hydrates is realized, one of which is wellbore integrity. Different from the traditional fossil energy wellbore, the integrity degradation of hydrate wellbore has obvious man-machine and complex system characteristics. Hence, NGH production wellbore barrier classification is defined firstly, as well as failure level and consequence judgment. The system-theoretic accident model and process (STAMP) and system-theoretic process analysis (STPA) methods are applied to establish a hierarchical control and closed-loop model of the NGH production wellbore system. Through inappropriate integrity control actions (ICAs) analysis, well integrity engineers play a leading role in the control loop, and a comprehensive monitoring network helps engineers make effective decisions. Game theory is utilized to study the senior superintendent's supervision strategy and the oil service company's investment strategy for wellbore integrity management selection preference in the test production cycle. The results show that the strategic preference of the executor is related to the frequency of maintenance and supervision, and basically does not change during the production cycle. The growth rate of policy preference value for supervisor decreases with the increase of ratio of partial strategy, but it does not affect the initial preference value. The findings of this study can provide support for wellbore integrity management during test or commercial production of offshore hydrates.

Reverse Time Migration of Vertical Cable Seismic Data to Image Hydrate-Bearing Sediments With High Resolution

Marine vertical cable seismic (VCS) is a promising survey technique for submarine complex structure imaging and reservoir monitoring, which uses vertical arrays of hydrophones deployed near the seafloor to record seismic wavefields in a quiet environment. Recently, we developed a new type of distributed VCS system for exploration and development of natural gas hydrates preserved in shallow sediments under the seafloor. Using this system and air-gun sources, we accomplished a 3D VCS yield data acquisition for gas hydrates exploration in the Shenhu area, South China Sea. In view of the characteristics of VCS geometry, we implement reverse time migration (RTM) on a common receiver gather to obtain high-resolution images of marine sediments. Due to the unique acquisition method, it is asymmetrical for the reflection path between the sources and the receivers in the VCS survey. Therefore, we apply accurate velocity analysis to common scatter point (CSP) gathers generated from common receiver gathers instead of the conventional velocity analysis based on common depth point gathers. RTM with this reliable velocity model results in high-resolution images of submarine hydrate-bearing sediments in deep water conditions. The RTM imaging section clearly shows the bottom simulating reflector (BSR) and also the reflection characteristics of the hydrate-bearing sediments filled with consolidated hydrates. Moreover, its resolution is relative to that of acoustic logging curves from the nearby borehole, and this imaging section is well consistent with the synthetic seismogram trace generated by the logging data. All these results reveal that VCS is a great potential technology for exploration and production of marine natural gas hydrates.

Gas–liquid–hydrate flow characteristics in vertical pipe considering bubble and particle coalescence and breakage

The gas–liquid flow behavior laden by hydrate particles is significant for the flow assurance of submarine natural gas hydrate production. An integrated multiphase flow model considering the coalescence and breakage of bubbles and hydrate particles was developed to investigate the gas–liquid–hydrate flow problem in a vertical pipe. The population balance theory was adopted to describe the evolution of the bubble and hydrate particle sizes in a flow field. The effects of particle behavior on flow pattern transition were analyzed. The results indicated that the phase distribution became inhomogeneous during the flow process, and bubbles tended to aggregate at the central region of the pipe. Most hydrate particles agglomerated in the liquid film region, and the particle size increased. The coalescence and breakage of bubbles induced a flow pattern transition from a bubbly to slug and churn flows. However, the agglomeration of hydrate particles increased the viscosity of the liquid phase, further reduced the turbulent intensity, and enhanced the stability of the bubbles. Thus, a higher gas superficial velocity was required for the formation of slug and churn flows. An annular flow was easier to form because the hydrate particles entrained in the liquid phase stabilized the liquid film. This study contributes to the flow assurance of submarine natural gas hydrate production and relevant multiphase flow modeling studies with hydrate particles.

Experimental study on pore forming characteristics of simulated hydrate broken by high pressure water jet

Natural gas hydrate is a research hotspot at present. However, the current exploitation technology can’t meet the demand of commercial exploitation of natural gas hydrate. In order to improve the efficiency of hydrate production, this paper believes that the idea of using high-pressure water jets for sandblasting perforation is expected to constitute an effective way to extract natural gas hydrates. The experimental study on sandblasting perforation and hydraulic slitting of simulated reservoirs was carried out by using large-scale ground fracturing equipment and full-scale hydraulic blasting perforating equipment. The driving pressure is analysed under the action of high-pressure water jet. The influence of diameter on the effect of simulated reservoir fracture. The results show that the diameter of the perforation increases with the increase of pressure; This experimental study can provide an experimental basis for the use of abrasive jet blasting perforating technology to improve the efficiency of natural gas hydrate production.

Prediction of hydrate formation and plugging in the trial production pipes of offshore natural gas hydrates

Hydrate plugging in pipes is a serious issue that affects flow safety in the trial production of offshore natural gas hydrates. Current research on hydrate flow assurance has primarily focused on conventional oil-and-gas production and transportation processes. Therefore, models for predicting the hydrate formation region and hydrate deposition in the trial production pipes of offshore natural gas hydrate were developed in the present study, which can be used to estimate the risk of hydrate plugging in the production pipes. The results revealed that hydrate formation conditions could be satisfied in the water production pipe at a low water production rate, and hydrate generation was possible in a certain region in the gas production pipe. The hydrate deposition layer formed in the gas production pipe grew in a non-uniform manner; the longer the production time, the more obvious was the non-uniform distribution; this resulted in a high risk of hydrate plugging after a certain process time. Additionally, as the rate of gas production increased, the hydrate formation region in the gas production pipe gradually moved upward and decreased in size, and the degree of hydrate deposition also slightly decreased. Finally, the installation of a heater at the bottom of the gas pipe at a high production rate was proposed to increase the gas temperature, thereby decreasing the possibility of hydrate formation and plugging. For the water production pipe, a low dose of kinetic inhibitors or anti-agglomerants could be injected to avoid the risk of hydrate plugging and reduce the corresponding prevention costs. This study can provide a theoretical basis and technical support for the efficient prevention of hydrate plugging during production trials or long-term production of offshore natural gas hydrates.

Time-dependent mechanical characteristics of natural gas hydrate production test casing under exploitation disturbance

Production tests of natural gas hydrate in deepwater have been successfully conducted twice in China in 2017 and 2019. However, exploitation disturbance caused huge threat to the security of production well, as hydrate production was characterized by complicated phase variation in coupled seepage process, which made conventional analysis approach of oil and gas production well futile. This paper aimed at proposing a mechanical analysis method for casing in hydrate production test well based on the self-developed phase transition solver, which was employed to address exploitation disturbance induced by the varying hydrate saturation, reservoir strain state and physical parameters. By developing a multi-field coupling model and the corresponding algorithm, dynamic changes of casing boundary condition were achieved, and temporal-spatial distribution of casing stress was revealed. A case study was presented to illustrate the application of the proposed methodology. Results indicated that casing stress presented a distribution of “8” and a trend of decreasing first and then increasing with the progress of production test, reaching 112.95 MPa at the 60th day. Meanwhile, this trend was affected by production pressure and in-situ stress inhomogeneity. Moreover, as in-situ stress inhomogeneity, initial hydrate saturation and initial pore pressure changed from 1.05 to 1.3, 0.3 to 0.6 and 19 MPa–15 MPa, casing maximum stress increased by 2.3 times, 13.9% and 11.2%, respectively. The proposed approach could be used to provide theoretical reference for safety design of hydrate production test well.

Study on mechanical properties of natural gas hydrate production riser considering hydrate phase transition and marine environmental loads

A dynamic analysis model for natural gas hydrate (NGH) production riser was established considering the internal phase transition of hydrate multiphase flow and the external marine environmental loads. The model was numerically discretized by the finite element method (FEM) and solved by Newmark β method. The correctness of the analysis model was verified by an experiment and field testing data. The results indicate that the NGH begins to rapidly decompose in the middle of the riser, causing the sudden pressure drop in the riser. The internal NGH decomposition will significantly increase the axial tension and Von Mises stress of the riser. The Von Mises stress reaches maximum at the top end of the riser subjected to the distribution of effective axial tension. The lateral displacement and bending moment of the riser increase with the increase of flow rate and mixed fluid density in the middle and lower sections, and the stress decreases with the increase of flow rate and mixed fluid density. The increase of hydrate content and seawater temperature will decrease the lateral displacement and bending moment and the upper part stress of the riser, but it will significantly increase the stress in the lower part.

The synthetic effect of traditional-thermodynamic-factors (temperature, salinity, pressure) and fluid flow on natural gas hydrate recovery behaviors

The commercial exploitation of natural gas hydrates (NGHs) has been a growing research focus due to its features of enormous reserves and clean fuel. To guarantee the safe and efficient production of NGHs, we have proposed a novel strategy of water flow erosion to promote methane hydrate (MH) decomposition based on the tremendous seawater resource and the fundamental process of water-gas flow during NGHs exploitation. In this study, the synthetic effects of traditional-thermodynamic-factors (temperature, salinity, pressure) and fluid flow on MH decomposition characteristics, which is known little about yet, are comprehensively analyzed via in-situ magnetic resonance imaging (MRI). The temporal-spatial behaviors of MH decomposition are visually investigated. The results indicate that the pressure, salinity, temperature and water flow synergistically increased MH decomposition efficiency. Additionally, the propagation of the decomposition front along the interface between MH and ambient phase shows that the water flow rate and heat transfer are two crucial factors for accelerating MH decomposition. The higher water flow rate also efficiently complements the insufficient decomposition driving force due to the heat loss during MH decomposition process. The highest average decomposition rate (1.1%/min) and the relatively less water injection volume (320 mL) can be archived in this study. Furthermore, the decomposition rate has a significant dependence on temperature under lower water flow rate.

A Review of the Resource and Test Production of Natural Gas Hydrates in China

A Review of the Resource and Test Production of Natural Gas Hydrates in China

An exergy-based energy efficiency analysis on gas production from gas hydrates reservoir by brine stimulation combined depressurization method

Before performing commercial scale production of natural gas hydrates (NGHs), it is inevitable to estimate the productivity, production period, optimal operation parameters, and further evaluate the technical and economic feasibilities of NGHs field production. The dissociation of gas hydrates is an endothermic process. This needs to compensate additional energy, such as chemical energy, geothermal energy and electricity, etc., in order to keep high dissociation rate. Exergy is a basic parameter that used for various energy systems as a potential tool for design, analysis and optimization. This work provided an exergy analysis method to evaluate the economic efficiency of NGHs exploitation process by brine stimulation combined depressurization method. The input data including cumulative volume of gas production, mass of water production and gas-to-water ratio was obtained by the numerical simulation of TOUGH + HYDRATE. Through the exergy analysis, the total productivity and production period could be determined. These have rarely been reported. The influences of operation parameters, such as well spacing, injection temperature and injection rate of brine on net exergy production were investigated for guiding the set of optimal operating conditions. Since the cost may be one of the biggest challenges for NGHs production, this work suggests making full use of all kinds low-level energy sources to improve energy efficiency, such as brine with high concentration produced by desalination, tidal energy, wind energy, etc.

Design and optimization of offshore ship-based natural gas storage technologies in the South China Sea

China’s second offshore natural gas hydrate production reveals the urgency and potential demand for ship-based gas storage and transportation technology. Three possible gas storage processes including hydrate-based natural gas (HNG), pressurized liquefied natural gas (PLNG), and compressed natural gas (CNG) processes were simulated and optimized from aspects of specific energy consumption (SPC), exergy efficiency, equipment weight, and capital expenditure (CAPEX) respectively. The SPC of HNG, PLNG, and CNG was 0.22, 0.48, and 0.24 kW h kg−1 respectively. While the CAPEX of HNG, PLNG, and CNG for gas storage production was 363.3, 405.0, and 384.8 103 US Dollars respectively. And HNG showed a payback period of 1 year in the evaluation of natural gas value chain. The comparison results indicate that HNG has low SPC, CAPEX, equipment weight, and short payback period but high exergy efficiency among the three processes, which provides a promising offshore ship-based gas storage process to offshore small-scale natural gas production.

Prospect of marine natural gas hydrate stimulation theory and technology system

The key to realize the commercial production of natural gas hydrate (NGH) is to increase theNGH productivity significantly in the scale of magnitude. Whether NGH production can be commercialized depends on two aspects. The first is whether the in-situ recoverable reserves are large enough to support the basic production period for commercial production. The second is whether the average productivity can reach the standard for commercial production. In this paper, we will analyze mainly about the potential stimulation technologies for NGH development, and discuss about the basic principles, the evaluation methods, and the technical bottlenecks for NGH production and stimulation. The results indicate that the main mechanisms for increasing theNGH productivity are in three respects, namely enlarging the drainage area, increasing the NGH dissociation efficiency, and improving the seepage conditions. With complex-structure wells and multiple-well patterns, combined with novel production methods and/or reservoir stimulation technologies, the NGH productivity can be increased greatly. Particularly, the complex-structure wells and well patterns are very important for increasing NGH productivity. With complex-structure wells and well patterns, combined with heat injection and/or reservoir stimulation, NGH productivity can be increased on a magnitude scale. Currently, in fundamental researches, there are some technical bottlenecks for the studies of NGH production, mainly in sample preparation, simulated reservoir monitoring, and mechanical coupling technologies. Therefore, it is suggested that the study focuses should be on the above technical bottlenecks during the basic research on how to increase the NGH productivity. It is concluded that the combined application of complex-structure wells (horizontal wells and multi-lateral wells), well-pattern production models (with multi-cluster/group well production), the novel production methods (mainly thermal stimulation, together with depressurization), and reservoir stimulation technologies (hydraulic fracturing) are the keys to increase NGH productivity in the scale of magnitude.

Investigating hydrate formation rate and the viscosity of hydrate slurries in water-dominant flow: Flowloop experiments and modelling

Water dominated flow is typically encountered in mature oil and gas fields after water breakthrough has occurred; gas hydrate formation in these systems is generally associated with a high risk of flowline blockage. With the move towards production of natural hydrate deposits as an abundant source of gas, understanding water dominated flow will become increasingly important, particularly as these systems inherently operate near or within the hydrate equilibrium region. In this work, we present an improved mass-transfer limited hydrate growth rate model, which includes the effect of hydrate slurry viscosification on formation. This is validated through several methane hydrate formation experiments employing a 10 mm ID flowloop operating at high water cut (100 vol% water).The model is based on understanding mass transfer limitations for hydrate slurry systems; the mass transfer coefficient itself was estimated by the small eddy cell model and considers changes in the viscosity and diffusion coefficient due to an increase in hydrate volume fraction. Further, differential effective medium theory was employed to predict the viscosity of the hydrate slurry. The gas-water interfacial area was directly estimated (without any correlations) by employing high quality images captured through an in-line camera instrumented on the flowloop. Experimental results obtained from the flowloop were used to validate the overall growth rate predictions of our model. Overall, this work offers a pathway to improve predictive capabilities for the coming generation of natural gas hydrate production, and to increase confidence in our ability to actively manage hydrate formation for water dominant systems.

Optimization and analysis of gravel packing parameters in horizontal wells for natural gas hydrate production

Horizontal well is preferred for marine natural gas hydrate (NGH) production, while a robust completion method is required to control the associated sand production. In this paper, technical challenges, evaluation workflow, and deployment constraints of gravel packing in horizontal wells for marine NGH production are comprehensively analyzed. A virtual horizontal well located at the site SH2, northern South China Sea is involved to optimize packing operation parameters and analyze factors that affect the safety and effectiveness of packing operation. The results indicate that the extremely narrow safe operational window and high fluid-loss ratio are the main obstacles that affect packing effectiveness in marine NGH production horizontal wells. The safe operational window becomes narrower with the decrease of hydrate saturation within the reservoir; hence, the packing failure risk increases significantly. As for the virtual horizontal well located at the site SH2, the safe operational windows are 1.38–1.56 m3/min and 1.38–1.82 m3/min given the average hydrate saturation is 30% and 70%, respectively. However, the horizontal well is unpackable when hydrate saturation is less than 15%. Furthermore, the maximum packable lengths in horizontal wells for marine NGH production are found to be affected by hydrate saturation, fluid-loss ratio, gravel density, gavel concentration, and density/viscosity of sand-carrier. A joint application of lightweight gravel, low concentration slurry, viscosity reducer additives, and multiple β-wave packing technique could prolong the maximum packable length.