Hydrothermal Jet Research Articles

Review of high-temperature geothermal drilling and exploitation technologies

Global warming induced by excessive carbon dioxide emission generated from fossil fuels consumption is becoming increasingly severe. Development and utilization of clean and renewable energy is a significant measure to contribute for the carbon neutrality. Geothermal resource is an important clean and renewable energy, because of its advantages of abundant reserves, exploitation without restrictions from the climate and season. Extracting heat from the high temperature geothermal reservoir requires well drilling, completion and fracturing. However, due to some particular conditions in geothermal development, such as high temperature, erosion, leakage, and hard rocks, traditional petroleum well drilling and completion technologies are not well applicable in the geothermal industry. In this paper, the state-of-the-art geothermal drilling, and completion technologies as well as several fracturing methods, such as foam drilling, air hammer drilling, hydrothermal jet drilling, expansion casing technology, high temperature resistant drilling fluid and cement, chemical stimulation and thermal stimulation are comprehensively reviewed. Besides, heat extraction performances of water and CO2 as working fluids in the geothermal system are discussed. A few novel heat extraction methods including closed loop, open loop, enhanced geothermal systems are compared and analyzed. This review is expected to provide suggestions for research fields worthy of study for geothermal drilling and exploitation.

Chemical Dissolution Drilling of Barre Granite Using a Sodium Hydroxide Enhanced Supercritical Water Jet

This experimental study focused on evaluating the technical feasibility of chemically enhancing rock comminution during supercritical hydrothermal jet drilling by increasing pH with additives. Comminution of the crystalline rock samples occurred under supercritical conditions at temperatures and pressures ranging from 535–580 °C and 22.5–27 MPa, respectively, using hydrothermal jets with sodium hydroxide concentrations ranging from 0.0725 to 0.345 mol/kg. Impinging hydrothermal jets induced thermal spallation and rock removal from 21 Barre granite specimens examined. These experimental conditions replicate those that would be encountered in drilling water-filled wells at depths greater than ~ 2300 m. The combination of accelerated mineral dissolution due to the presence of hydroxide ions, high solution temperature increasing reaction rates, and thermal stresses resulted in rates of rock removal up to 5.16 g in 10 min at 410 °C and 0.345 mol/kg NaOH. Comparison with published empirical quartz dissolution rates at high pH suggests granite mass removal primarily resulted from weakening of the rock matrix as a result of the accelerated dissolution of quartz minerals. Experimentally determined heat flux and surface temperature measurements indicated that the rock comminution occurred below the empirically determined minimum levels for the onset of continuous thermal spallation resulting from impinging low-density flame jets or high energy laser heating.

Dissolution and Thermal Spallation of Barre Granite Using Pure Water Hydrothermal Jets

Spallation induced by rapid hydrothermal heating was investigated as a possible method of drilling rock. In this study, an electrically-heated hydrothermal jet was impinged on the surface of cylindrical Barre Granite specimens (basement rock) contained in an autoclave reactor to induce localized thermal stress. Comminution of the rock surfaces was achieved at supercritical water conditions, temperatures from 535 to 580 °C and pressures of 22.5–27 MPa. These conditions simulate those encountered in drilling deep, water-filled wells at depths greater than about 2300 m. Preferential removal of quartz grains from the rock matrix was observed. This comminution cannot be attributed to erosion by either the jet’s momentum, or by differential pressure forces. Additionally, silica removal (primarily from quartz grains) was observed at rates greater than those that could be attributed to dissolution of quartz alone. This implied a secondary comminution mechanism associated with spallation caused by the local thermal stresses from the impinging hydrothermal jet. The experimentally determined heat flux and surface temperature measurements indicated that hydrothermal drilling occurred below the empirically determined minima for the onset of continuous thermal spallation reported in earlier studies for low-density, high-velocity and high-temperature flame jet drilling at temperatures in excess of 1000 °C jets impinging on rock surfaces at near-atmospheric pressures.

Numerical analysis of characteristics of reaction in hydrothermal jet drilling for geothermal energy

Hydrothermal jet technology is a drilling method, which is potentially suitable for the exploitation of geothermal energy in deep hard formations. The generation of a stable hydrothermal jet via combustion in the reaction chamber is an important subject for successful applications. In this paper, the Peng-Robinson equation of state and four combustion models are applied to simulate the reaction in the downhole chamber. Simulation results are compared with experimental data to obtain a suitable model. The reaction flow field and effects of several factors (i.e., fuel and oxygen flow rate, mass fraction, and wall temperature) are studied. Results show that under the conditions of this paper, the finite rate model is more suitable. It may be better to inject the maximum fraction of fuel for complete reaction to obtain the highest jet pressure and temperature simultaneously. The cooling water flow rate and temperature can be adjusted over a broad range to control the temperature of the reaction chamber within a suitable range. Results in this paper could provide guidance for further research on hydrothermal jet drilling.

An analytical model to evaluate the heating conditions for drilling in hard rock using an innovative hydrothermal spallation method

Hydrothermal jet spallation drilling (HJSD) is a new drilling method suitable for drilling deep wells in hard rock formations. The characteristics of HJSD are that the rock surface is impinged by a high-velocity hydrothermal jet, causing rock breaking into small spalls. In this study, we develop an analytical model to evaluate the heating conditions (surface temperature and surface heat flux) in HJSD, in which the effect of jet impact on the heating conditions is first considered. Meanwhile, we conduct thermal spallation experiment using sandstone and granite samples. After that, the effects of jet impact on the heating conditions are investigated. Furthermore, the impacts of all physical parameters on the heating conditions are compared to clarify the key factors. Additionally, we compare the rate of penetration and heating conditions between sandstone and granite, which can provide direct understanding about the suitability of HJSD for sandstone and granite. Our study provides a further understanding of critical physic affecting the rate of penetration and heating conditions in HJSD.

Numerical analysis of the downhole flow field with compressible fluid in hydrothermal jet drilling

A novel hydrothermal jet drilling technology is proposed, which is expected to be suitable for the exploitation of subsurface hydrocarbon resource or geothermal energy. The flow field is analyzed with compressible fluid. Influences of jet temperature, jet velocity, cooling water velocity, and cooling water temperature are discussed. Gray correlation method is used to compare the effects of different factors and further verification is performed. Simulation results are validated by results from experiments and analytical models. The values of specific heat are relatively high in the annulus because the hydrothermal jet undergoes the pseudo-critical point. Despite higher temperatures of the hydrothermal jet, the annular high temperature fluid can be effectively cooled. Considering both thermal effect and impact, it may be better to keep the hydrothermal jet temperature in the range of 700 K–800 K under the conditions of this paper. Under different cooling water velocities, the varying trend of the borehole wall temperature corresponds with that of the specific heat. The cooling water velocity has the most significant impact on the variation of the annular temperature, with the following sequence being jet temperature, jet velocity and cooling water temperature. Adjusting cooling water velocity may be the most efficient and cost-effective way for the hydrothermal jet drilling.

Analysis of temperature simulation in downhole reaction chamber of hydrothermal jet drilling

Hydrothermal jet is an alternative drilling method for the exploitation of oil and geothermal energy in deep hard formations. For the application of this novel technology, the successful generation of hydrothermal jet is very important. This paper focuses on investigating applications of different reaction, turbulence and radiation models to the supercritical water oxidation process in downhole reaction chamber of hydrothermal jet drilling. The objective is to identify the pros and cons of each model and determine a set of models that are the most appropriate for the reaction. Simulation models are tested and optimized through two different operating conditions. Simulation results are compared with experimental data. Results show that the entire space of the reaction chamber is in a high temperature state using the laminar finite rate model. The finite rate model is suitable for the simulation compared with other reaction models discussed. The Magnussen constant A and B in the finite rate model can be modified to be 7 and 0.5 to further reduce the error. In addition, the high temperature areas in k-omega model and SAS model are more concentrated, while they are more uniform in RNG k-epsilon model and standard k-epsilon model. The RNG k-epsilon model and DO or DTRM are the most appropriate turbulence and radiation models through comparison. Results in this paper can provide implications for the reaction simulation of hydrothermal jet drilling.

Comparison of numerical analysis on the downhole flow field for multi-orifice hydrothermal jet drilling technology for geothermal wells

Newly developed hydrothermal jet drilling technology has the potential of being economically advantageous over conventional drilling techniques for drilling deep wells in hard formations. By applying coiled tubing techniques and modulating fluid media in the bottomhole reaction chamber, there can be a high temperature and high velocity jet striking and conducting heat to break the rock. So far, there has been no specific study on the influence of nozzle structure on the flow field of multiple hydrothermal jets. This paper presents hydrothermal jet models with different numbers of orifices to investigate the features of flow field, carrying capacity, drilling ability and cooling effect. Results show that for two models in the absence of cooling water, the bottomhole center temperature and pressure are higher than the two sides under multiple hydrothermal jets conditions. This is similar to the flow pattern for a single jet. Additionally, for the five-orifice nozzle with cooling water injected, the entire high temperature region is cylindrical. Ambient cooling water envelops the inner hot water. By comparing different models, the five-orifice nozzle model without cooling water shows a circular symmetric distribution of the bottomhole temperature. With cooling water injected, the central high temperature region becomes rectangular, while the margin of the well bottom is cooled by the peripheral cooling water. The bottom rock average temperature in five-orifice model is lower than for the four-orifice model due to more drastic thermal and kinetic transfer between the hydrothermal jet and the cooling water. The five-orifice nozzle model is better than the four-orifice nozzle model in terms of bottomhole temperature, bottomhole pressure and carrying capacity. Therefore, the five-orifice nozzle should be adopted for hydrothermal jet drilling. It is also feasible to pump down relatively high temperature cooling water to guarantee the high temperature downhole environment. Meanwhile, the cooling water pressure should be controlled during the drilling process for better cooling efficiency. All results in this paper are relevant to the parameters design for multi-orifice hydrothermal jet drilling technology.

Numerical analysis of the impact flow field of multi-orifice nozzle hydrothermal jet combined with cooling water

Hydrothermal jet technology is a novel drilling technology and has just been studied for several years. This technology uses a high temperature and high velocity jet to break rocks and has the potential to be more efficiently advantageous than conventional techniques for deep hard formations and geothermal well drilling. This paper presents a multi-orifice hydrothermal jet model with cooling water to investigate the features of the flow field by CFD methods. First, a transient impact flow field is analyzed. Besides, influences of jet temperature, cooling water temperature and cooling water pressure on the flow field and annular cooling effect are predicted and compared. Predictions are found to be in good agreement with the published heat transfer theory for hydrothermal jet temperatures ranging from 650K to 800K. Results indicate that ambient cooling water envelops the high temperature hydrothermal jet in the middle. There is a second peak of bottomhole temperature and the pseudo-critical point is located. Controlling the hydrothermal jet temperature at the vicinity of the pseudo-critical point or far larger than the pseudo-critical temperature can have a better heat transfer effect. The simultaneous effect of both the hydrothermal jet and cooling water results in the non-uniform distribution of bottom temperature, which leads to higher rate of penetration. It is recommended that the cooling water pressure should be larger than the hydrothermal jet pressure, which might result in higher rate of penetration and cool the coiled tubing and borehole wall simultaneously. Results in this paper are beneficial to the parameters design for the hydrothermal jet drilling technology.

Numerical analysis on the impact of the flow field of hydrothermal jet drilling for geothermal wells in a confined cooling environment

Hydrothermal jet technology is a novel drilling method expected to be suitable for the exploitation of deep geothermal resources, in which the rocks are broken coupled by thermal spallation effect with high velocity impact. Because of the high temperature return fluid, the cooling of the drill string and wellbore is one major problem in hydrothermal jet drilling. This paper presents two cooling configurations in downhole conditions: the lateral configuration and downward configuration. The investigation on the impact of the flow field of the hydrothermal jet in a confined cooling environment is estimated using CFD methods. The influences of jet velocity, jet temperature, cooling water velocity and standoff distance are analyzed. For both cooling configurations, the impact of the flow field of a hydrothermal jet in downhole conditions is divided into three zones: the jet zone, the return zone and the eddy zone. The hydrothermal jet impinges on the bottom rock, and then returns from the annulus mixed with the cooling water. The temperature in the jet zone stays constant, while it decreases in the return and the eddy zone. The temperature around the wellbore is higher due to the return flow of the cooling water. There is a high bottomhole temperature region, while the annulus is cooled by the cooling water in the lateral cooling configuration. In addition, the jet velocity, the cooling water velocity and the standoff distance have a large influence on the pressure and temperature fields, while the jet temperature has a small influence. For the downward cooling configuration, the length of the potential core of the hydrothermal jet is positively correlated to the maximum axial velocity. Finally, two cooling configurations are compared. The lateral cooling plan is suitable for reaming operation. The lateral cooling configuration is better in the cuttings carrying capacity due to the higher annular return velocity. Results in this paper could guide for parameters design of hydrothermal jet drilling technology.

Numerical analysis of characteristics of multi-orifice nozzle hydrothermal jet impact flow field and heat transfer

Hydrothermal jet technology is a new drilling method in which the rocks are broken by the combination of thermal spallation and high velocity impact effect. This technology uses a high temperature and high velocity jet to break rocks and has the potential to be more economically advantageous than conventional techniques for geothermal well drilling. Previous related studies primarily examine numerical simulation on one hydrothermal jet flow field, and to the best of our knowledge, no specific study addresses the thermo-physical interaction between wellbore fluid and ambient rock. This paper presents a multi-orifice nozzle model to investigate the features of a flow field with multiple hydrothermal jets and the heat transfer to ambient rocks. A transient impact flow field with multiple hydrothermal jets is analyzed in terms of axial temperature, bottomhole temperature, and bottomhole pressure. Also, downhole velocity field is specifically investigated. Next, influences of time, jet temperature, and jet pressure difference on the flow field and heat transfer between wellbore fluid and ambient rocks are predicted and compared. The results indicate that the bottomhole central temperature and pressure are higher than the two sides under multiple hydrothermal jets conditions, which is similar to the flow pattern with a single jet. Moreover, the distribution of axial velocity has three peaks at cross-sections, and the centerline axial velocity is the highest. There is a negative relationship between the maximum radial velocity and the ratio between axial distance and nozzle diameter (L/D). Also, the position of the maximum radial velocity moves to the side wall as the ratio (L/D) increases. Second, the bottomhole temperature increases uniformly with increase in jet temperature. The bottomhole temperature becomes decreasingly sensitive to the variance of pressure difference, and the bottomhole pressure exhibits a ladder distribution. Finally, while an increase in either jet temperature or pressure difference can enhance the multiple hydrothermal jets heat transfer effect, increasing the jet temperature is considerably more effective. All of these results are beneficial to the parameters design for the hydrothermal jet drilling technology.

Characteristics of the ore forming fluid from the zinc poly-metallic deposit in the Mopan mine area, Guangxi Nandan

Fluid inclusions from samples from the layered and veined mineralized belt in the Mopan mine area were studied using microscopic temperature measurements and laser Raman spectroscopy. Further studies were conducted on the nature and source of the ore forming fluid and on the mechanism of deposit formation. The results show that there are three types of inclusions that occur in both the layered and veined ore body. These are liquid inclusions, CO2 inclusions with a liquid phase, and NaCl–H2O multi-phase inclusions. The fluid inclusions in both the layered and veined ore bodies have similar characteristics. The ore forming fluid is strongly reducing, was exposed to low to medium temperatures, salinity, and pressures. The source of this ore forming fluid was a mix of submarine volcanic spring (blow-piping), magmatic hydrothermal jet, and underground water.

Hydrothermal Fe–Si–Mn oxide deposits from the Central and South Valu Fa Ridge, Lau Basin

A series of samples from the Hine Hina hydrothermal field (HHF) and the Mariner hydrothermal field (MHF) in the Central and Southern Valu Fa Ridge (VFR), Lau Basin were examined to explain the source origin and formation of the hydrothermal Fe–Si–Mn oxide deposits. The mineralogy was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, and energy-dispersive spectroscopy (EDS). For the Fe–Mn oxide crusts in the HHF, varying amounts of volcanic fragments and some seawater contributions were recognized, along with higher concentrations of Mn, Al, Co, Ni, Zn, Sr, Mo, elevated ∑REE and negative Ce anomalies. In contrast, the Si-rich oxide samples of the MHF were enriched in Cu, Pb and Ba, indicative of proximity to a hydrothermal jet. Moreover, conductive cooling of hydrothermal fluid evoked the Si-rich deposit formation in the MHF. The Sr, Nd and Pb isotope data provided further constraints regarding the source and formation of the Fe–Si–Mn deposits in the VFR by showing that the samples of the HHF are a mixture of three components, namely, hydrothermal fluid, seawater and volcanic materials, whereas the samples of the MHF were dominated by hydrothermal fluids. The seawater had a minor influence on the Nd isotope data, and the Pb isotope data exhibited a close association with the substrate rock and preformed volcaniclastic layers in this area. The occurrence of relatively high Mn/Fe ratios in the hydrothermal deposits of this area may be a good indicator of the propagating activities of the VFR over geological time.