Steam Injection Research Articles

Effect of diameter and inclination of steam injection pipe on chugging dynamics in direct contact condensation

Low mass flux of steam and high degree of subcooling are the prominent factors for occurrence of unstable direct contact condensation, commonly known as chugging, when steam is injected into a subcooled water pool. Such an arrangement is typically used in the pressure suppression pool of the primary containment vessel in a boiling water reactor. With an attempt to identify the conditions of minimum pressure oscillations during the chugging regime, the present study investigates the effect of internal diameter (0.5–1 in.) and inclination (8.75˚) of steam injection pipe on steam bubble dynamics, pressure transients and heat transfer characteristics at different steam mass flow rates (5–25 kg/hr) and submergence depths of steam pipe (1–13 cm) within the water pool. The study reveals that the condensation cycle time decreases with a decrease in the internal diameter of the pipe. Furthermore, the frequencies of fluctuations in the interfacial area of the steam bubble and pressure transients in the steam pipe exhibit an increasing trend with an increase in steam mass flow rate and a decrease in internal diameter of the steam injection pipe. The chugging frequencies in the inclined and vertical orientation of steam injection pipe lie within the range of 0.5–3 Hz. The average heat transfer coefficient increases with an increase in the internal diameter of pipe and steam mass flow rate. The amplitude of pressure oscillations has decreased significantly whereas heat transfer coefficient has increased marginally upon changing the orientation of steam injection pipe from vertical to inclined. Therefore, smaller diameter and inclined orientation of steam injection pipe are favourable for mitigation of pressure oscillations in applications of direct contact condensation.

Coupling a Gas Turbine Bottoming Cycle Using CO2 as the Working Fluid with a Gas Cycle: Exergy Analysis Considering Combustion Chamber Steam Injection

Gas turbine power plants have important roles in the global power generation market. This paper, for the first time, thermodynamically examines the impact of steam injection for a combined cycle, including a gas turbine cycle with a two-stage turbine and carbon dioxide recompression. The combined cycle is compared with the simple case without steam injection. Steam injection’s impact was observed on important parameters such as energy efficiency, exergy efficiency, and output power. It is revealed that the steam injection reduced exergy destruction in components compared to the simple case. The efficiencies for both cases were obtained. The energy and exergy efficiencies, respectively, were found to be 30.4% and 29.4% for the simple case, and 35.3% and 34.1% for the case with steam injection. Also, incorporating steam injection reduced the emissions of carbon dioxide.

Implementation of hot steam injection in steam turbine design: A novel mean-line method coupled with multi-objective optimization and neural network

Low-pressure turbines usually work in wet conditions which causes both lifetime and efficiency reduction. Hot steam injection (HSI) which has received great interest recently, is a suggested solution to reduce wetness. There is a research gap in implementing HSI in the mean-line procedure, which is a conventional method of designing and analyzing turbines. In this paper for the first time, an object-oriented in-house mean-line code is developed with the ability of HSI calculation for steam turbines. The validation of code is performed with the 3D simulation of a 2-stage axial steam turbine. In addition, considering that HSI may reduce efficiency of the turbine due to mixing entropy generation, a multi-objective genetic algorithm optimization and a neural network is used to redesign the steam turbine. Mass fraction and total temperature of injected flow from the trailing edge of blade rows are the decision variables and, liquid mass fraction and efficiency of turbine are the objective functions. The comparison of Pareto front points reveals that the maximum possible improvement of quality and power relative to baseline is 5% and 10%, respectively. Furthermore, if efficiency is the desired objective function, by enhancing 1% of steam quality, it can be increased by 0.1%.

Effect of dipotassium phosphate addition and heat on proteins and minerals in milk protein beverages

Our objective was to determine the effects of dipotassium phosphate (DKP) addition, heat treatments (no heat, high temperature, short time [HTST]: 72°C for 15 s, and direct steam injection UHT: 142°C for 2.3 s), and storage time on the soluble protein composition and mineral (P, Ca, K) concentration of the aqueous phase around casein micelles in 7.5% milk protein-based beverages made with liquid skim milk protein concentrate (MPC) and micellar casein concentrate (MCC). Milk protein concentrate was produced using a spiral wound polymeric membrane, and MCC was produced using a 0.1-µm ceramic membrane by filtration at 50°C. Two DKP concentrations were used (0% and 0.15% wt/wt) within each of the 3 heat treatments. All beverages had no other additives and ran through heat treatment without coagulation. Ultracentrifugation (2-h run at 4°C) supernatants of the beverages were collected at 1, 5, 8, 12, and 15-d storage at 4°C. Phosphorus, Ca, and K concentrations in the beverages and supernatants were measured using inductively coupled plasma spectrometry. Protein composition of supernatants was measured using Kjeldahl and sodium dodecyl sulfate-PAGE. Micellar casein concentrate and MPC beverages with 0.15% DKP had higher concentrations of supernatant protein, Ca, and P than beverages without DKP. Protein, Ca, and P concentrations were higher in MCC supernatant than in MPC supernatant when DKP was added, and these concentrations increased over storage time, especially when lower heat treatments (HTST or no heat treatment) had been applied. Dipotassium phosphate addition caused the dissociation of αS-, β-, and κ-casein, and casein proteolysis products out of the casein micelles, and DKP addition explained over 70% of the increase in supernatant protein, P, and Ca concentrations. Dipotassium phosphate could be removed from 7.5% of protein beverages made with fresh liquid MCC and MPC (containing a residual lactose concentration of 0.6% to 0.7% and the proportional amount of soluble milk minerals), as these beverages maintain heat-processing stability without DKP addition.

Reducing CO2 emissions and improving oil recovery through silica aerogel for heavy oil thermal production

Heavy oil reserves comprise more than 60% of global crude oil resources, and thermal oil recovery techniques, especially steam injection, are widely utilized for extracting heavy oil. However, these thermal production processes are characterized by high energy consumption and carbon emissions, which pose significant challenges in reducing CO2 emissions. In response to these challenges, this study presents a novel approach that combines silica aerogel with CO2-assisted thermal recovery technology. Our findings demonstrate that the incorporation of aerogel nanoparticles enhances the adsorption capacity of CO2 in the aqueous phase. The adsorption behavior of CO2 in silica aerogel aligns with the Langmuir model. When silica aerogel nanoparticles are employed in steam flooding, a notable improvement is observed in both oil recovery and CO2 sequestration rate. Molecular dynamics simulations reveal that the porous structure of aerogel enables the adsorption of light saturates molecules from crude oil, promoting their diffusion into the aqueous phase and ultimately enhancing oil recovery. The steam condensation experiments clearly demonstrate that the presence of aerogel and CO2 exerts a substantial influence on the condensation heat transfer of steam, resulting in a reduction in the condensation heat transfer rate between the steam and the cooling wall. Additionally, molecular dynamics simulations reveal that silica aerogel nanoparticles exhibit an affinity for adsorbing onto hydrophobic quartz surfaces, forming an insulating layer between steam and quartz, thereby facilitating CO2 sequestration. The introduction of silica aerogel nanoparticles expands the swept volume of steam heat. This study provides valuable insights into the underlying mechanisms responsible for improved CO2 sequestration and increased oil recovery through the implementation of silica aerogel nanoparticles, offering fresh perspectives on heavy oil recovery.

A systematic comparison of solvents and their concentrations in bitumen gravity drainage under controlled thermodynamic conditions

Solvent-assisted SAGD (SA-SAGD) has been studied as an alternative to improve the efficiency of SAGD. This paper reports a new set of experimental data for SA-SAGD and analyzes the characteristics of bitumen-solvent mixing in the experiments using history-matched numerical models. The dimensions of the sand pack were 3 in. in diameter and 15 in. in length, and the sand pack was contained in a 25-L cylindrical pressure vessel. An annular void space surrounded the sand pack with a gap thickness of 1 in., within which a steady state flow of the injected vapor phase maintained the controlled pressure, temperature, and composition. Therefore, the gravity drainage in the sand pack occurred at a set of specified thermodynamic conditions for the surrounding annular steam chamber, unlike transient conditions near the edge of a steam chamber in larger-scale steam injection processes. In addition to SAGD as the base case, five sets of SA-SAGD were performed: 20 mol% C4, 40 mol% C4, 10 mol% C8, 20 mol% C8, and 10 mol% condensate coinjected with steam at 3500 kPa.The peak oil production rate was 9.84 cm3/min with SAGD, 14.61 cm3/min with 20 mol% C4-SAGD, 16.34 cm3/min with 40 mol% C4-SAGD, 31.33 cm3/min with 10 mol% C8-SAGD, 12.36 cm3/min with 20 mol% C8-SAGD, and 12.33 cm3/min with 10 mol% condensate-SAGD. SAGD was the least effective in bitumen gravity drainage, while the 10 mol% C8-SAGD was the most effective. Increasing the C4 molar concentration from 20 to 40 mol% slightly increased the peak rate; however, the peak rate in C8-SAGD significantly was decreased by increasing the C8 concentration from 10 to 20 mol%. This counter-intuitive result was reported in a few simulation studies with heavy solvents (e.g., C7 and C12) in the literature, but had not been experimentally confirmed before this research.Although the condensate contained 93 mol% C7-like pseudo component (C7, eq), the peak rate of 10 mol% condensate-SAGD was much smaller than that of 10 mol% C8-SAGD. These experimental observations highlight the practical importance of understanding the sensitivity of bitumen gravity drainage to heavy-solvent concentrations near the edge of a steam chamber in SA-SAGD.

Investigation of steam utilization mode on performance and emissions characteristics of gasoline engine

In the present study, the steam utilization mode was discussed based on a gasoline engine. The thermodynamic processes of two steam utilization modes were investigated based on the validated model. And, the effects of in-cylinder direct steam injection (CDSI) and two steam expansion cylinders (TSEC) on engine performance were studied. The results show that the firing cylinder temperature decreases with both CDSI and TSEC engines. However, the in-cylinder pressure increases for the CDSI-engine. The CDSI method can greatly benefit engines from an emissions perspective, as it reduces NOx, HC, and CO by 79.0 %, 2.4 %, and 17.6 % respectively. It is worth noting that the TSEC method cannot improve engine performance through waste heat recovery. The results also demonstrate that the indicated power of the TSEC-engine is higher that the results achieved by using the CDSI method when the steam injection quantity is greater than 0.80 g. All these demonstrate that CDSI approach has great potential for application in gasoline engines. The present results provide strong evidence for the application in gasoline engines.

Techno-economic optimization and Nox emission reduction through steam injection in gas turbine combustion chamber for waste heat recovery and water production

Considering the persistent human need for electricity and fresh water, cogeneration systems based on the production of these two products have attracted the attention of researchers. This study investigates a cogeneration system of electricity and fresh water based on gas turbine (GT) as the prime mover. The wasted energy of the GT exhaust gases is absorbed by a heat recovery steam generator (HRSG) and supplies the superheat steam required by the steam turbine (ST). In order to produce fresh water, a multi-effect desalination (MED) system is applied. The motive steam required is provided by extracting steam from the ST. In order to reduce the environmental pollution of this cogeneration system, the steam injection method is proposed in the GT's combustion chamber (CC). This system is optimized by a multi-objective optimization tool based on the Genetic Algorithm (GA). The design variables include pressure ratio of compressor (CPR), inlet temperature of gas turbine (TIT), steam injection mass flow rate in the CC, HRSG operating pressure, HRSG evaporator pinch point temperature difference (PPTD), steam pressure of the MED ejector, ejector motive steam flow rate, number of MED effects, and return effect. The goals are to minimize the total cost rate (TCR), which includes the cost of initial investment and maintenance of the system, the cost of consumed fuel, and the cost of disposing of CO and NO pollutants, as well as maximizing the exergy efficiency. In the end, it is observed that the steam injection in the CC leads to the reduction of the mentioned pollutant index, and it is proposed as a suitable solution to reduce the pollution of the proposed cogeneration system.

CALCULATION OF THE BOTTOM-HOLE PARAMETERS OF THE HEAT CARRIER DURING ITS MOVEMENT ALONG THE WELLBORE OF A DIRECTIONAL WELL CONSIDERING THE FLOW STRUCTURE

Link for citation: Gilmanov A.Ya., Rodionova A.V., Shevelev A.P. Calculation of the bottom-hole parameters of the heat carrier during its movement along the wellbore of a directional well considering the flow structure. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 121-128. In Rus. The relevance of the research is caused by the need to involve fields with high viscosity oil in the development, since fields with low and medium viscosity oil are depleted. Oil viscosity directly depends on the temperature, therefore, thermal enhanced oil recovery methods are used to reduce the viscosity. From the point of view of using the heat injected into the formation, the most effective thermal method is the cyclic steam stimulation, i. e. cyclic steam injection into the well. However, when steam moves through the pipe, it condenses, that is why the production at the well bottom-hole are often has high water cut. Accurate calculation of the heat carrier parameters along the entire wellbore will help to avoid this problem. The main aim of the research is to determine the effect of the well inclination angle, steam quality at the wellhead, initial pressure and thermal conductivity of thermal insulation on the heat carrier characteristics in the wellbore, considering flow modes. Objects of the research are deposits with high-viscosity oil. Methods: physical and mathematical modeling of injection of a two-phase (steam-water) heat carrier into the reservoir based on the laws of conservation of mass, momentum and energy, considering the movement of the heat carrier along the wellbore of a directional well, heat loss through the walls of the well and fluid flow modes. Results. The calculation of the steam quality and heat carrier flow rate along the wellbore of a directional well was conducted. The influence of the well inclination angle on the parameters of the heat carrier at the well bottom-hole (steam quality, pressure and wellhead flow rate of the heat carrier) is analyzed. It is determined that the smaller the well inclination angle, the deeper the steam penetrates through the depth of the formation.

Modeling of multiple thermal fluid circulation in horizontal section of wellbores

The development of heavy oil reservoirs has broad prospects. Because heavy oil reservoirs have the characteristics of high viscosity and poor fluidity, they often need to be heated. For heavy oil reservoirs, the effect of simple steam injection development is limited. By mixing superheated steam or steam with non-condensable gas, the development effect of heavy oil can be improved. Due to the high viscosity of heavy oil reservoirs, the initial injection capacity of the heat carrier is poor, and cyclic preheating is often required. In this paper, through theoretical research, the process of multi-element thermal fluid injection in heavy oil reservoirs is studied. The circulation preheating characteristics of the multi-element thermal fluid inside the wellbore are analyzed. Results show that for different ratios of nitrogen to carbon dioxide: when the multi-element thermal fluid flows from the finger end (1000 m) to the heel end (0 m) of the annular space, the oil layer heat absorption rate first drops and then rises.

Development of a Design Method for Casing and Tubing Strings under Complex Alternating Loads

With the escalating intricacy of downhole operational scenarios, encompassing frequent well cycling, acidification, multi-stage fracturing, steam injection, and intensive extraction, the efficacy of traditional casing-string-design methods rooted in strength considerations is progressively unveiling its limitations. Henceforth, it becomes imperative to establish string-design method standards that embrace the entirety of a well’s lifecycle, encompassing the phases of drilling, completion, fracturing, and production operations. Beginning with an analysis of the advantages and limitations of traditional casing-string-design methods, this paper introduces the features of strain and sealing design methods developed for the full lifecycle of the string. The strain design method, a departure from conventional design philosophies, enables the design concept of the controllable deformation of the pipe string. The sealing design method currently stands as the sole standard method for the design of tubing strings. Simultaneously, this paper proposes the establishment of a time dimension-based lifecycle pipe string-design method standard. This approach considers the trend of pipe strength degradation, effectively addressing the safety concerns related to pipe string design in production and operation.

Integrity Assessment of High-Performance PVC Pipes for Thermal Wells.

In wells with high-viscosity crude oil, steam injection is used to improve the fluidity of the heavy oil. Screens made of steel are employed for sand control, with corrosion being a serious problem. Non-metallic pipe materials, such as novel high-strength PVC, are therefore being tried out. This paper presents the results of an integrity assessment of large-diameter hard PVC pipes under compressive loading. Plain, built-up, and slotted pipes were subjected to a 3-month aging process in saline water. Strain gauge sets were used for dynamic testing of longitudinal and transverse deformations. Values of fracture strength, total deformation, and anisotropy (Poisson's ratio) were extracted from the stress-strain graphs and analyzed. Upon aging in saline water, the stiffness of all pipes increased and was the highest for slotted pipes. Maximum stress after soaking was reduced by 11-12%. The ductility was the highest for plain pipes and the lowest for built-up pipes. Poisson's ratio remained almost constant for all pipes and aging conditions. The good news for field applications is that overall, aging had only a minor impact on the major compressive properties. The main conclusion was that corrosion-prone steel pipes and sand screens can be successfully replaced by corrosion-free high-strength PVC pipes and screens for water transport applications in thermal wells. This work provides a scientific basis for the structural integrity assessment of this new PVC and helps field engineers in the proper pre-deployment selection of pipes for target oilfields.

Thermal Integration of Solid Oxide Electrolysis Cell Systems with External Heat Sources to Maximize Heat Recuperation and Exergetic Efficiency

Green hydrogen is expected to play a significant role as an energy carrier in the future energy system. As the issue of climate change due to greenhouse gas emissions has recently emerged, efforts are being made to change from a carbon-based energy society to a hydrogen-based energy society worldwide. Among several hydrogen production technologies, green hydrogen refers to hydrogen that does not generate carbon dioxide at all in production processes such as water electrolysis by using renewable energy. The hydrogen production through water electrolysis is more mature than other green hydrogen production technologies and is the most popular green hydrogen production method because it is easy to mass-produce with a modular structure. In particular, a solid oxide electrolysis cell (SOEC) system, which has the highest efficiency among electrolysis systems, is drawing significant attention.The high efficiency of SOEC systems originates from heat utilization for water electrolysis, which makes it critical to have optimal thermal integration. The SOEC systems operating at the high temperature above 700°C need a significant amount of thermal energy for steam generation and inlet gas heating. To deal with these thermal energy requirements, the internal heat recuperation and the external heat source integration with system components must be implemented in an effective manner. The thermal integration is the most important part of the SOEC system design. However, the majority of previous studies have concentrated on the performance of unit-cells and stacks, ignoring thermal energy consumption of the systems and heat integration.The purpose of this study is to explain the basis of thermal integration and to investigate the effects of internal and external thermal integration on the whole system performance. The basic concept of the thermal integration of SOEC system is presented while considering internal heat recuperation and coupling with external heat sources. By using temperature-heat transfer analysis, the procedure to design the optimal thermal integration of the SOEC system is described. Based on the proposed system, a parametric study with respect to stack operating conditions (i.e., stack inlet temperature, air utilization, steam conversion, hydrogen fractions) is conducted in order to elucidate their effect on the system level performance. Then, the effects of external heat sources such as steam injection, indirect heat transfer with hot fluids and heat supply by an electrical heater are examined, with pinch analysis and exergetic performance evaluation. The results show that high temperature external heat is not always a prerequisite for the SOEC system. The systematic comparison with several heat integration methods provides a clear guideline to maximize the exergetic efficiency when designing and operating SOEC systems. Through the analysis, this study provides understanding the internal and external characteristics of the thermal integration.

Laboratory Determination of Productivity of Bomu Oil Field (Oml 11 as Case Study) Using MEOR Process and Calcium Oxide Nanoparticles

The need for petroleum products in the world is increasing daily, this product can only be gotten from the refining of crude oil a naturally occurring mineral resource which is produced by degradation of organic materials. This crude is gotten from several wells drilled for the sole purpose of the production of this mineral resource but this wells are being shut-down and abandoned because of the decrease in the well’s productivity which causes losses to the operators and poor finances for the petroleum industry. Therefore, the need to increase the recovery of a well is been considered, these methods are called enhanced oil recovery method. These methods include Gas injection method, Steam Injection method, Chemical injection method (chemicals such as surfactants, polymers etc) Microbial method and the use of nanoparticles as additives to help increase the recovery process. The type of enhanced oil recovery used in this work is the microbial enhanced oil recovery, this method makes use of biosurfactants which can also be referred to as microbe surfactants. The biosurfactants are gotten from microorganism they act as surfactants which reduces the interfacial tension between the molecules of the substance and the interface, this biosurfactants can be used for many industrial purposes which includes bioremediation, oil recovery etc. Nanoparticles are also another aspect of the recent technology which can increase the recovery of our well providing more crude and finance for the petroleum industry. This work shows how biosurfactants and nanoparticles when used together can increase oil recovery. The ever-rising global demand for energy and the issue of large volumes of unrecovered oil after primary and secondary oil production operations are driving the development and/or advancement of enhanced oil recovery (EOR) techniques. Conventional EOR processes include thermal, immiscible and miscible gas injection, chemical, and microbial enhanced oil recovery

Chemicals-CO2 mechanisms of inhibiting steam heat transfer and enhancing oil film strip: Steam flow through the wall-adhering oil film surface in porous medium

The CO2 and Sodium Dodecyl Sulfate (SDS) assisted steam flooding technology was an effective approach addressed the persistent issues that have hindered the stable development of high-viscosity cold oil through steam injection. However, in the process of steam flow through porous media, the synergistic influence of the oil film adsorbed in near wellbore porous media, and the CO2-SDS on steam heat transfer has not been investigated. Steam heat transfer is the key factors affecting heavy oil recovery. The primary objective of this study was to research the effect of CO2-SDS on steam heat transfer and oil film stripping by designing experiments. The study results demonstrated that in the initial stage of displacement, the heat transfer resistance between the steam and the porous medium was increased by the oil film adsorbed in near wellbore area. In additional, the condensation mode of the steam was altered from bead condensing to film condensing by the composite thermal fluid flooding, preventing the steam heat dissipation near wellbore area and transferring more thermal to the long-distance area. At the later stage of displacement, the interfacial tension between oil-water and oil-gas was reduced by CO2-SDS, improving the fluidity of oil and providing the seepage channel for steam, and increasing the steam thermal sweep range. Compared to the sandpack experiment of steam flooding, the temperature at the output end of the sandpack model increased from 69.8 °C to 88.7 °C, indicating an expansion of the steam heat sweep range and successful long-distance heat transfer during composite thermal fluid flooding. In the process of composite thermal fluid flooding, the maximum displacement pressure difference increased from 2.28 MPa to 3.07 MPa, and the maximum oil recovery rate increased from 2.48 g/mL to 2.81 g/mL. The peak of the high production period was raised, resulting in a 40.97% to 51.86% increase in recovery rates.

A dual-parameter measuring method for wet steam based on the characteristics of differential pressure under phase-isolation state

To achieve accurate measurement of steam injection volume in the process of steam-driving heavy oil, a low-cost online metering device for wet steam flows is urgently needed. Primarily, the traditional Venturi device has a relative error due to the wet steam flow patterns. Therefore, a new physical model for wet steam measurement composed of a swirler and a Venturi was designed, based on the phase-isolation technology for multi-phase flow measurement. A theoretical explanation of the differential pressures was then proposed. Numerical simulations were conducted to investigate wet steam measurement, specifically under the condition of 10∼20 MPa. A new correlation for the steam quality and mass flow rate with the pressure drop was developed by the multiphase flow model via Eulerian. A novel wet steam dual-differential pressure measurement model was established by considering the effects of temperature and pressure, which predicts the wet steam overall mass flow rate and steam quality of the measurement device. Block P601 and Block P6 of the oilfield located in eastern China were selected as the development test area, and the differential pressure prediction was carried out for 68 different working conditions of two Wells based on the dual-parameter measurement model, which was then calibrated. The experimental fieldwork on Block P601 demonstrated that the feasibility of the dual-parameter measuring method was verified, with relative deviations of ±7% between the predicted and experimental values of differential pressure. After calibration of the measurement model, the predicted values were compared with the experimental values, yielding relative deviations of ±3.5% and ±5% for mass flow rate and steam mass measured online for wet steam, with Mean Absolute Percentage Errors (MAPE) of 1.73% and 2.21%. Thus, the dual-parameter measuring method has a certain engineering significance for the steam injection technology of heavy oil in oilfields.

Performance of high temperature steam injection in horizontal wells of heavy oil reservoirs

Steam huff and puff and steam flooding are important development methods for heavy oil reservoirs. At present, there are certain deficiencies in the research on the timing and methods of steam stimulation, steam flooding, and subsequent steam flooding. In addition, the research on the mass and heat transfer characteristics of high temperature steam injection in heavy oil reservoirs is still in the initiation stage. This article first studies the high temperature steam flow model in the horizontal wellbore of the SAGD process. On this basis, a horizontal well pattern model was established through numerical simulation software to analyze the heat and mass transfer characteristics of high temperature steam huff and puff and high temperature steam flooding. Results show that: (a) for heavy oil reservoirs with high temperature steam injection huff and puff, the first cycle of steam injection ends (day 22): the temperature near the well pattern of the horizontal well pattern is higher. In the area between the horizontal well patterns, the temperature rise is not obvious; (b) when the high temperature steam injection huff and puff phase of the heavy oil reservoir ends (900 days), most of the heat energy is recovered, and the formation residual heat is less; (c) After the huff and puff transfer, the thermal connectivity between the horizontal well patterns is better.

Effects of nanoparticles on mechanical and microstructural properties of cement composite pastes at high temperature and high pressure

This study aims to investigate the effects of nanoalumina (nano-Al2O3, NA) and nanotitanium dioxide (nano-TiO2, NT) particles on the mechanical and microstructural properties of oil well cement composite pastes. Eleven groups of cement composite pastes mixed with NA (0.5–2.5 wt.%), NT (0.5–2.5 wt.%) particles and silica flour were designed by central composite response surface design method (CCD method). Meanwhile, a reference group (SF-OWC) consisting of oil well cement and silica flour was designed. These pastes were cured at 300 °C/13.0 MPa in an autoclave to simulate the downhole condition during the steam injection process in steam injection wells. The compressive strength and Young's modulus of cured cement composite pastes were tested, and mathematical models were developed to evaluating the response of NA and NT particle content on compressive strength and Young's modulus. Moreover, the mineralogy and microstructural evolution of the pastes were investigated using multi-technique methods. The results showed that the compressive strength of the mixed nanoparticles modified SF-OWC composite pastes increased by 7.5%–36.4% compared to the reference group. Moreover, this enhancement is more significant when the incorporated NA or NT particles dominate the mixed nanoparticles. The model prediction results show that adding 2.5 wt.% NA and 0.5 wt.% NT particles or adding 0.5 wt.% NA and 2.5 wt.% NT could increase the compressive strength of cement composite pastes by 58.8% and 37.5%, respectively. The mechanism analysis showed that when the incorporated mixed nanoparticles were mainly NT particles, the improvement of mechanical properties was mainly attributed to the filling effect and nuclear effect of NT particles. When the incorporated mixed nanoparticles were mainly NA particles, more C-(A)-S-H gels were retained and tightly filled and bonded with xonotlite, which made the microstructure of the cement composite pastes more dense, stronger bonding, and more conducive to resistance to load or stress variations.

Combustion of n-heptane with steam injection in a laboratory spray burner

Combustion of n-heptane with steam injection in a laboratory spray burner

Improving hydrogen-rich gas production from biomass catalytic steam gasification over metal-doping porous biochar

Biomass to green H2 is a new route to produce sustainable energy. This study aimed to boost H2-enriched gas production via gasification-catalytic steam reforming (GCSR) process of wheat straw (WS) over Ni, Fe, or Zn-doped carbon materials (MDCMs). Initially, steam injection rate (1 g/min) and residence time (15 min) was optimized based on the tradeoff between energy consumption and H2-rich gas generation. The largest gas yield (90.77 mmol/g) and the lowest H2 production efficiency (ƞ: 7.89 g CO2/g H2) were observed for WS-derived biochar. Clearly, it was found MDCMs were favorable for reducing CO2 production due to the strengthened CO2 reforming reactions catalyzed by metal active sites. A higher ƞ (6.72 g CO2/g H2) was achieved for Ni-doping biochar (Ni/C). Importantly, Ni/C showed the ultrahigh carbon conversion efficiency (99.47%) and great tar elimination performance. Overall, GCSR process over MDCMs is a newly promising way to valorize biomass into H2-rich gas.