Brine Reinjection Research Articles

Multi-lateral horizontal well with dual-tubing system to improve CO2 storage security and reduce CCS cost

This paper proposes a multi-lateral horizontal well with a dual-tubing (MLHW-DT) system to improve CO2 storage security and reduce the cost of carbon capture and storage (CCS) at a saline aquifer. In CCS, the production and re-injection of brine are efficient methods of relieving overpressure and improving the CO2 storage security simultaneously. In our previous study, a horizontal well with a dual-tubing (HW-DT) system operating on an onshore platform reduced CCS cost. In this study, the proposed MLHW-DT system is designed to implement the concept of the re-injection of produced brine to improve CO2 storage security while supplementing the shortcomings of the conventional brine production system by reducing CCS cost. When we vary the vertical-horizontal permeability ratio and dip angle of a saline aquifer, the CO2 storage security of the MLHW-DT system is improved compared with that of the overall HW-DT system because the re-injected brine induces the CO2 plume migration in the lateral direction. Furthermore, the CCS cost of the MLHW-DT system is reduced by 69.4% compared with that of the conventional brine production system if the MLHW is operated on an onshore platform. Based on these results, the MLHW-DT is a safe and economical operation system for a CCS project.

Energy and Exergy Analyses of Geothermal Organic Rankine Cycles Considering the Effect of Brine Reinjection Temperature

The organic Rankine cycles (ORCs) have been used to convert low-enthalpy geothermal brine into power. Parameter optimization and working fluid selection are the main approaches to enhance geothermal ORC performance. This work uses environmentally friendly fluids, including R1224yd(Z), R1233zd(E), R1336mzz(Z), R601 and R601a, as the geothermal ORC working fluids. The evaporation temperatures of the selected fluids were optimized to maximize the cycle net power outputs. The thermodynamic characteristics are investigated with the consideration of the influence of the allowed reinjection temperature (ARIT). Among the selected fluids, R1224yd(Z) has the highest optimal evaporation temperature with the maximum turbine power output for a brine inlet temperature (BIT) higher than 120 °C, especially at a lower allowed reinjection temperature. However, the parasitic power consumption by the pumps in an ORC with R1224yd(Z) is also higher than with the other four fluids. The net power output for ORC with R1336mzz(Z) is slightly more than that with R1224yd(Z). Although the optimal evaporation temperature for a RORC is lower than that for an ORC, the higher preheater inlet temperature leads to a higher geothermal heating exergy efficiency and more power output for a BIT less than 120 °C. The RORC with R1336mzz(Z) produces 2.6% more net power than an ORC for a brine inlet temperature of 100 °C. As the ARIT increases from 70 °C to 75 °C, the plant exergy efficiencies of ORCs are decreased by 6–8% for a geothermal brine inlet temperature of 100 °C.

Impact of Reservoir Heterogeneity on Diluted Geothermal Brine Reinjection

Many geothermal plants have been shut down due to reinjection problems with the heat-depleted brine. In Denmark, only one out of three plants that extract heat from a geothermal fluid distributed to the district heating system is still working. In general, the large salinity of heat-depleted geothermal brines can be used to produce electricity with the help of turbines and generators through an osmotic power unit known as a SaltPower plant. Harnessing more energy out of the reinjection of geothermal brines is feasible without compromising the overall reservoir assurance when the iron is kept under control. This study is an attempt to determine the feasibility of the reinjection of a diluted geothermal brine with ethylenediaminetetraacetic acid (EDTA) into homogeneous and heterogeneous sandstone rocks. The results from the coreflooding experiments show an improvement in the rock properties both in porosity and permeability for homogeneous and heterogeneous rocks. EDTA not only avoids the precipitation of Fe(III) oxides inside the porous media but can also be used for scale removal and matrix acidizing in geothermal reservoirs.

Chelating agents for diluted geothermal brine reinjection

“Blue energy” could be produced by exploiting the large salinity gradient between geothermal fluids and freshwater through a SaltPower system. This study is an attempt to select the most favorable chemicals to avoid injectivity issues when a diluted geothermal fluid resulting from the SaltPower system is returned to the reservoir. Three synthetic chelating agents (oxalic acid, EDTA, and EDDS) and one natural (humic acid) were evaluated through speciation simulations and isothermal titration calorimetry (ITC) experiments. The speciation simulation results indicate that the degree of complexing is highly dependent on pH and chelating agent type. The ITC experiments show that the total heat for the formation of soluble metal–ligand complexes in the rock + geothermal brine system follows: EDTA > EDDS > oxalic acid > humic acid. The simulations and calorimetry results suggest that EDTA could be used to avoid the precipitation of Fe(III) oxides and other minerals (e.g., calcite and dolomite) inside the porous media upon the reinjection of diluted geothermal brine coming from SaltPower electricity production.

Recycling of drainage brines by means of re-injection in Udachny Mine

The permafrost zone in Levoberezhny 2 Site, represented by the Upper Cambrian carbonate–terrigenous rock strata up to 270 m thick, is studied. It is found that during injection, brines first flow along fractures and pores, and dissolve ice fill in them. The permafrost rocks degenerate as a result, and extra porosity is generated together with formation of a manmade aquifer. The analytical flow model of brine disposal in permafrost rocks in Udachny Mine represents the analytical flow model in dry soil, with rock permeability varied from zero to maximum values to describe frozen and thawed zones. The hydrogeological research of permeation by the numerical modeling method used GMS MODFLOW environment. The key complexity of the permeation problem consists in the fact that permeability coefficient and storage capacity of permafrost rocks greatly increase with time of injection. The highest degradation of ice takes place in the injection site; brines are displaced deeper in rock mass at the front velocity governed by density of joints, ice content, injection flow rate, mineralization of brines, temperature of rock mass and brines, etc. The permeation problem was solved using the method of alternation of quasi-stationary states in conformity with the modern hydrogeology and frost in the permafrost rock mass, and in accord with experience of drainage brine re-injection in Udachny Mine, subject to the key requirement of free flow of drainage brine into the permafrost rock zone at the eliminated discharge of water into local stream flows.

A novel working fluid selection and waste heat recovery by an exergoeconomic approach for a geothermally sourced ORC system

A novel working fluid selection methodology is proposed for organic Rankine cycles (ORCs) coupled with low-grade geothermal sources by employing an existing dataset of an operating binary geothermal plant that works with n-pentane. Thermodynamic and thermoeconomic aspects of power production are combined to evaluate 29 different single-component working fluid candidates from different chemical branches in four-step elimination methodology. In terms of working fluid classification from physical point of view, results indicate that there is a direct relationship between vapor expansion ratio (VER) and net work output for dry working fluids. On the other hand, it is shown that isentropic fluids behave differently from dry fluids. Based on the proposed methodology, R113 is selected as a new working fluid for the existing plant instead of n-pentane. Results indicate that by applying the proposed methodology, it is possible to increase first and second law efficiencies of plant 0.59% and 3.18%, respectively, while reducing the levelized electrical cost (LEC) around 11% in comparison to base plant outputs with n-pentane. Furthermore, a case study is presented in addition the plant level analysis by implementing a hypothetical waste heat recovery cycle, configurated with proposed methodology, in order to reduce exergy losses originating from brine re-injection. It is shown that it may be possible to further reduce the LEC around 1% and increase the overall efficiencies 0.1% for the first law and 0.26% for the second law. However, it is necessary to be deliberate about these final results since they also demonstrate the sensitivity of LEC to the increases in second law efficiency rather than levelized capital investments.

Systematic Study of Geothermal Brine Reinjection for SaltPower Generation Purposes: Citric Acid as a Potential Iron Control Agent

Geothermal brines are concentrated, saline fluids that could be mixed with fresh water to produce “green energy”. By exploiting the large salinity gradient between those fluids, more energy could be harnessed from heat depleted geothermal brines. This study is an attempt to determine the feasibility of adding citric acid to a geothermal brine before dilution. The possible rock-fluid and fluid-fluid interactions that could take place upon reinjection are analyzed though isothermal titration calorimetry (ITC) and core flooding experiments. The results from the ITC experiments show that citric acid in the diluted geothermal brine dissolves iron bearing-carbonate cement. The direct implication of those dynamic interactions is an increment in the rock properties (porosity and permeability), which was also confirmed by coreflooding experiments. Formation damage is only observed when Sønderborg brine and diluted Sønderborg brine were injected into a Berea sandstone core plugs. Those results confirm that the precipitation of Fe(III) oxides inside the porous media could be avoided by the help of citric acid.

THERMODYNAMIC ANALYSIS OF A BINARY GEOTHERMAL POWER PLANT

A geothermal plant located in southwestern Turkey is evaluated from thermodynamic and economic perspectives. The first and second law efficiencies of the plant are calculated to be 4.82% and 25.7% respectively. On plant level, brine re-injection process is found out to be primarily responsible for exergy losses (21.9%). Major sources of losses at ORC systems are turbines and pumps (25.44%), heat exchangers (21.78%) and condensers (10.8%). Thermal losses from heat exchangers are calculated to be around 444 kW which corresponds 0.27% of heat transfer value at heat exchangers. Applicability of water-cooled condensers instead of existing air-cooled condensers is also discussed. Results indicate that it is possible to reduce the initial capital investment around 20%. Furthermore, it may be possible to further increase the exergetic efficiency of these hypothetical water-cooled condensers by increasing the rejection temperature and subsequently decrease initial capital investment by 1.4% and reduce heat release to the environment.

The importance of long-term well management in geothermal power systems using fuzzy control: A Western Anatolia (Turkey) case study

Effective geothermal power generation depends on two main elements: geothermal reservoir management and maintenance of the power plant. Reservoir management consists of both the fluid production and reinjection of brine to the underground. The management of wells is important to ensure the sustainability of the reservoir. Thus, the flow rate control systems are essential to protect geothermal reservoirs under long-term power production. The second issue is the daily change in electricity prices and the load change process is complex because geothermal well controls are not flexible operations. The well management thus requires control approaches, and fuzzy control can be one effective solution. In this study, a fuzzy control system has been developed to control flow rates of the wells in Kızıldere geothermal field and its performance has been compared with the real data taken from the Kızıldere Power Plant. The results of comparison show that the fuzzy controllers achieved the target energy production in 2 h instead of 5 h, compared to the real data. Based on the real data, the reinjection was only able to stabilize at the end of the fourth hour and the process took only 2 h when using the fuzzy controllers.

Study of geothermal brine reinjection by microcalorimetry and core flooding experiments

SaltPower electricity generation can be used to harvest more energy from heat depleted geothermal brines. This study is an attempt to determine rock–fluid interactions by a synergy between isothermal titration calorimetry (ITC) and core flooding experiments. The results from the ITC experiments show dynamic rock–fluid and fluid–fluid interactions that take place in the reservoir upon brine reinjection. The direct implication of those dynamic interactions is the stabilization of clay particles loosely attached to the pore surfaces. Formation damage is observed when Thisted and diluted Thisted brines are reinjected into Berea sandstone core plugs. Fe(III) oxides precipitation inside the porous media is the main reason for that permeability reduction.

Numerical modelling of the interaction between geothermal injectate-non condensable gas solutions and greywacke

In response to global warming, it is important to explore alternative disposal technologies for greenhouse gas emissions in the geothermal power sector. One alternative which has received widespread focus is co-injection of non-condensable gases with the waste fluids from geothermal operations.Passarella et al. (2015) simulated the interaction between brine with dissolved CO2 and H2S, and a sample of greywacke in their laboratory. The present work aimed to numerically model the results from the experiment using TOUGHREACT. The goal of this study was to develop numerical simulation techniques to investigate the effects of the reinjection of brine with dissolved NCG. The resulting model provided insights into the geochemical interaction of greywacke with brine-NCG solutions under simulated reservoir conditions. The numerical simulations show that mineral dissolution occurred to a greater degree than precipitation, leading to increased permeability and porosity. It was also observed that the mineral reactive surface areas evolved as mineral dissolution progressed, through etch pit formation. Additionally, flow rate had an impact on the overall reaction rates such that a decrease in injection rate led to a corresponding decrease in reaction rates. Lastly, both experimental data and model outputs indicated that CO2 was minimally sequestered in the simulation, while H2S was clearly captured as pyrite.A similar numerical investigation was conducted on the co-injection of NCG with steam condensates subsequently. The modelling results indicate predominant mineral dissolution, CO2 is expected to be captured as magnesite within the reactor, while H2S is still captured as pyrite.

Phase segregation, boiling, and reinjection at the Los Azufres Geothermal Field, Mexico, monitored by water stable isotopes, chloride, and enthalpy

Monitoring the impact of brine reinjection is crucial to the sustainable exploitation of geothermal resources. Reinjection monitoring at the Los Azufres Geothermal Field (Mexico) has historically been carried out by investigating the temporal and spatial evolution of chloride and the stable isotopic composition of water. Here, we review the evolution of the stable isotopic composition of the total fluid discharge (TD) since the earliest measurements in 1980, integrating new data obtained in 2014. Based on δDTD and δ18OTD values measured in 2014, two groups of fluids were identified. The first group is characterized by δDTD and δ18OTD similar to those measured in previous survey years, 1980–1982, 1983–1986, and 2000. The second group shows a large positive shift in the hydrogen isotopic composition (ΔDTD of +10‰) compared to the first group. The evolution of reinjected brines and production wells over time between 1980 and 2014 shows δ18OTD and δDTD enrichment until 2000. This is followed, between 2000 and 2014, by a slight decrease in δ18OTD values and a net increase in δDTD, explained by extensive phase segregation and boiling, at temperatures of over 280 °C. The observed trend suggests that a steam phase, caused by boiling, is invading the reservoir, and the phenomenon is observed in both production and reinjected fluids. A comparison of the spatially kriged 2000 and 2014 δ18OTD and δDTD datasets reveals that reinjected brine is spreading progressively to the eastern part of the field, mainly in the southern production zone (SPZ), and through E-W corridors delimited by the E-W fault systems, which underlie the secondary permeability of the reservoir. However, reinjection is still not able to suppress boiling in the main production zone. This situation needs to be taken into account in developing future reinjection strategies to counterbalance the substantial fluid extraction from the field.

Energy and exergy analysis of cold and power production from the geothermal reservoir of Torre Alfina

Geothermal power plants can provide clean and renewable energy and can be proposed as integrated units for simultaneous production of cooling and power. This paper presents a cascade arrangement of an organic Rankine cycle (ORC) and a water/lithium bromide (LiBr) absorption chiller (ABS). Starting from a literature reference layout which is taken as benchmark, some improvements are proposed at system level.To assess the performance of the system, a thermodynamic model is developed in EES and the energy and exergy balance is calculated. The proposed system is re-evaluated with reference to resource conditions corresponding to a planned power plant in central Italy, Torre Alfina (TA). A sensitivity analysis is performed in order to investigate the operating range of the plant and the possibility of adapting its design to the requirements of the customers. Under optimized conditions, the TA Case (targeted on a 5 MW power output) showed an energy utilization factor (EUF) of 46.2% and an exergy efficiency of 27.7%, neglecting the brine reinjection loss. The highest exergy destructions occur in the ORC economizer (8.6%), in the ABS generator (6.3%) and absorber (5.5%). The good resource conditions in TA case drive the design optimization to production of power rather than cold.

Thermodynamic and thermoeconomic analysis of a 21 MW binary type air-cooled geothermal power plant and determination of the effect of ambient temperature variation on the plant performance

Abstract The thermodynamic and thermoeconomic performances of a 21 MW geothermal power plant with air-cooled two level binary type organic Rankine cycle was numerically investigated based on its design and operating data. The investigated plant is the Sinem Geothermal Power Plant in Germencik, Aydin, Turkey. The paper provides a detailed comparison of the exergetic performance of this plant with other eight similar type of plant units, which make use of geothermal resources with similar specific exergies. Results indicate that the exergetic efficiency of the Sinem Geothermal Power Plant is the highest with 48.2% and the others vary between 9.6% and 42.7%. This result is mainly related to the exergy losses due to suppression of heat transfer in this plant, via low temperature brine reinjection, small temperature difference in the heat exchangers and high efficiencies of the individual components. First and second law efficiencies, as well as the exergy losses and improvement potentials of each component in the plant are also calculated. In air-cooled geothermal power plants, since ambient temperature is a critical parameter for the plant performance, both thermal and economic analysis of the plant is performed based on variation in ambient air temperature. Specifically, thermoeconomic analysis of the plant is evaluated to determine the exergoeconomic factor, the relative cost difference and the sum unit cost of the product (SUCP) of the plant. The effect of ambient temperature on the SUCP of the power plant, power generation, energy and exergy efficiencies are also examined in the present study. The results showed that; when the ambient temperature increases from 5 °C to 35 °C the reduction in power generation is 6.8 MW, energy efficiency decreases from 13.7% to 9.2% while exergy efficiency decreases from 54.9% to 36.7 and SUCP of the plant increases from nearly 230 $/GJ to 330 $/GJ.

Signature of ongoing brine reinjection on noble gas isotopes and fluid chemistry at Las Tres Vírgenes geothermal field, Mexico

A geochemical survey of the Las Tres Vírgenes geothermal field (LTVGF), Baja California Sur, Mexico, was carried out to determine the origin and evolution of its fluids, along with the influence of injection of local brines, and inhibitors intended to manage carbonate scaling issues. Major and minor cations, Cl, Br, Sr, O, H, and noble gas (He, Ne, Ar, Kr and Xe) isotopes were measured in fluids collected from four production wells, two injection wells, and one fumarole (El Azufre) in 2016 and 2018. Variations in the stable isotopes of water (δD and δ18O) and halogens (δ37Cl, δ81Br) over the years suggest that local brine reinjection might have started to modify the pristine chemistry of the fluids. However, relevant information on the original geothermal fluids has been preserved. The Na/Br and Cl/Br ratios suggest that LTVGF brines are seawater having leached evaporite deposits (halite). These deposits are absent in the area, but were likely present during the Miocene, prior to the breakup of the Gulf of California, suggesting that the saline fluid end-member at the LTVGF could be several million years old. Measured 3He/4He ratios (R) normalized to the atmospheric ratio Ra (= 1.384 × 10−6) plotted against the 4He/20Ne ratios suggest mixing between a mantle fluid with a R/Ra of 6.19, typical of the sub-continental lithospheric mantle and an atmospheric helium component. The R/Ra versus the 132Xe/36Ar ratio normalized to air suggests mixing between a mantle-rich pre-production fluid and air. The source of air appears to be linked to local gravity-controlled flow reinjection which causes the entrapment of air bubbles, leading to a fluid supersaturated in atmospheric noble gases. This pattern suggests that reinjection fluids are impacting the production area.

Prediction of permeability reduction due to silica scale deposition with a geochemical clogging model at Sumikawa Geothermal Power Plant

In experiments, flow rates through porous media were measured using raw brine (pH = 6.5, [SiO2] = 1130 mg/L) at Sumikawa Geothermal Power Plant in 2016. The flow rates decreased by up to 25% of the initial flow rate after 11 days. A geochemical clogging model with data from 2003 was used to predict the permeability reduction due to silica precipitation. This model considers the type of silica deposited (amorphous and aluminum–silica scales) and calculates the optimized conditions for keeping the concentration of SiO2 below 300 mg/L to lessen the reduction of permeability during the reinjection of geothermal brines.

Performance optimization of low-temperature geothermal organic Rankine cycles using axial turbine isentropic efficiency correlation

Present study deals with parametric optimization and performance evaluation of an air-cooled organic Rankine system for the low-temperature geothermal source, especially considering the effects of turbine isentropic efficiency. Turbine isentropic efficiency is predicted with turbine size parameter and volume ratio, using the well-known correlation for single-stage axial turbine. Optimal performances with the objective of maximizing system exergy efficiency are compared with the common used working fluid R245fa and two environmental friendly working fluids R1234ze(E) and R1234ze(Z). Highest turbine isentropic efficiency is achieved for working fluid R1234ze(Z). The optimal turbine inlet vapor is overheating for Working fluid R1234ze(E) with the limitation of allowable minimum geothermal brine reinjection temperature. Due to the influence of turbine isentropic efficiency, optimal system exergy efficiency for working fluid R1234ze(E) is 0.4576 for the 100 kg/s geothermal source, which is slightly higher than the value of 0.4487 for the 10 kg/s geothermal source.

ANALISIS REMOVAL SCALING SILIKA PADA JALUR RE-INJEKSI BRINE PEMBANGKIT LISTRIK ENERGI PANAS BUMI DENGAN MENGGUNAKAN ASAM FLUORIDA

Silica scale formation on the brine re-injection lines of geothermal power plants can lead to serious problems because it increased pressure drop and failure of the safety devices. One of the most effective methods to solve the problem is acidification of silica scaling using hydroflouric acid (HF). HF has a unique characteristic that is highly reactive with SiO2, easily obtained in the market and cheap. The use of HF can increase the rate of material corrosion in re-injection lines material. The use of HF should be adjusted to the appropriate concentration so it can dissolve silica scale optimally without shortening its life service. The concentration of HF used in the experiment were 5, 10, and 15% wt. The results showed that the optimum concentration of HF in dissolving silica at 15%. This is due to its ability to dissolve the crust mostly greatest than most other concentration that is equal to 21% of the total dissolved silica. The rate of corrosion on the material re-injection line with a concentration of 15% is equal to 0.647 mm/y and provide about 4.63 years life time of pipe.

Potential assessment of methane and heat production from geopressured–geothermal aquifers

Geopressured–geothermal aquifers of the US Gulf Coast contain a significant amount of geothermal energy and dissolved methane. This study investigates the effect of brine reinjection on the production of heat and methane from these aquifers. First, the range of uncertainty of aquifer properties was inspected to build the reservoir model of typical aquifers. A sensitivity analysis was then performed to find favorable conditions for production with and without reinjection, and the economic criteria for both scenarios were defined. This study concludes that reinjection has several advantages, such as increasing the sustainability of production, reducing reservoir connectivity risk, and disposing of produced brine in the same formation.

Exploring the potential linkages between oil‐field brine reinjection, crystalline basement permeability, and triggered seismicity for the Dagger Draw Oil field, southeastern New Mexico, USA, using hydrologic modeling

AbstractWe used hydrologic models to explore the potential linkages between oil‐field brine reinjection and increases in earthquake frequency (up to Md 3.26) in southeastern New Mexico and to assess different injection management scenarios aimed at reducing the risk of triggered seismicity. Our analysis focuses on saline water reinjection into the basal Ellenburger Group beneath the Dagger Draw Oil field, Permian Basin. Increased seismic frequency (>Md 2) began in 2001, 5 years after peak injection, at an average depth of 11 km within the basement 15 km to the west of the reinjection wells. We considered several scenarios including assigning an effective or bulk permeability value to the crystalline basement, including a conductive fault zone surrounded by tighter crystalline basement rocks, and allowing permeability to decay with depth. We initially adopted a 7 m (0.07 MPa) head increase as the threshold for triggered seismicity. Only two scenarios produced excess heads of 7m five years after peak injection. In the first, a hydraulic diffusivity of 0.1 m2 s−1 was assigned to the crystalline basement. In the second, a hydraulic diffusivity of 0.3 m2 s−1 was assigned to a conductive fault zone. If we had considered a wider range of threshold excess heads to be between 1 and 60 m, then the range of acceptable hydraulic diffusivities would have increased (between 0.1–0.01 m2 s−1 and 1–0.1 m2 s−1 for the bulk and fault zone scenarios, respectively). A permeability–depth decay model would have also satisfied the 5‐year time lag criterion. We also tested several injection management scenarios including redistributing injection volumes between various wells and lowering the total volume of injected fluids. Scenarios that reduced computed excess heads by over 50% within the crystalline basement resulted from reducing the total volume of reinjected fluids by a factor of 2 or more.