Liaohe Oilfield Research Articles

Enhanced oil recovery and carbon sequestration in low-permeability reservoirs: Comparative analysis of CO2 and oil-based CO2 foam

Excessive CO2 emissions contribute to global climate change thus mandating effective methods for CO2 utilization and sequestering. In this study, one-dimensional flow simulation experiments on CO2 flooding, CO2 Huff-n-Puff, oil-based CO2 foam flooding, and oil-based CO2 foam Huff-n-Puff are conducted using low-permeability sandstone cores modeled after the Q131 block in Liaohe Oilfield, characterized by porosity ranging from 15% to 20% and permeability between 25 mD to 35 mD. Low permeability reservoirs are rich in oil resources and may effectively sequester CO2. Parameters pertaining to oil and gas production and carbon storage are collected. Nuclear magnetic resonance (NMR) is employed to determine the spatial variation of oil saturation in the cores. The experimental results show 8.03% and 41.21% increase in oil recovery factor by foam flooding and foam Huff-n-Puff relative to CO2 as the recovery agent. Moreover, NMR analysis confirms lower residual oil saturation in core samples using foam, suggesting better displacement agent. Oil-based CO2 foam recovery contributed to effective carbon sequestration, with carbon storage increasing by 34.24% and 315% relative to CO2 flooding and CO2 Huff-n-Puff, respectively. CO2 storage mechanisms for oil-based CO2 foam recovery method are detailed.

Analytical prediction model for edge water invasion flow rate in SAGD heavy oil reservoirs

SAGD (Steam Assisted Gravity Drainage) technology is a highly developed method for the extracting heavy oil. In the Liaohe Oilfield in China, there are 72 SAGD well groups within a massive heavy oil reservoir containing edge water and the risk associated with edge water invasion is substantial. Currently, the injected steam is less than 50 m away from the edge water, which increases the urgency to address the potential invasion of edge water. If the edge water flows into the reservoir, it will impact nearly 8.0 × 105 tons of crude oil production. Recognizing the importance of mitigating the edge water invasion, this paper proposes a prediction model for the edge water invasion flow rate in SAGD reservoirs. The model integrates mass and heat transfer dynamics between the steam chamber and edge water, the relative permeabilities of oil and water phases, and the viscosity-temperature relationship of water. The model is validated through numerical simulations and field data. The findings indicate that for SAGD reservoirs with a permeability greater than 1 D, maintaining a minimum distance of 25 m between the edge water and the steam chamber is advisable, especially when the pressure differential is 0.5 MPa. Furthermore, the prediction model is used to forecast the edge water breakthrough time and evaluate water invasion risk. A prediction chart for the edge water invasion flow rate is developed, providing a practical tool for estimating invasion flow rate curves. Also, a method of edge water invasion warning is established, with a corresponding chart that offers a quick assessment of water invasion risks in heavy oil reservoirs. Overall, this research lays a foundational framework for understanding and managing the edge water invasion in SAGD operations, offering critical insights for the future study aimed at addressing the challenge posed by edge water in heavy oil reservoirs.

Simulation of edge water invasion mitigation of the SAGD chamber by low temperature oxidation (LTO) coking air injection and optimization of operating parameters

During the long-term use of steam assisted gravity drainage (SAGD) in oil fields, the continuous expansion of the steam chamber often leads to edge water invasion, which significantly reduces thermal efficiency and oil production rate. To address this challenge, we hypothesize that a low temperature oxidation (LTO) coke formation air injection method may alleviate edge water invasion. To test our hypothesis, we developed a numerical SAGD model tailored to a typical SAGD field, the Guantao Du84 block in the Liaohe Oilfield, China. The model incorporates a four-step coke generation kinetics and considers the complexity of coke distribution. Our results reveal that coke generation (1) shifts the direction of edge water flow from the steam chamber to a vertical downward direction, (2) causes pore clogging, resulting in reduced flow velocity, (3) leads to reduced porosity and water cut, significantly improving oil recovery as compared to nitrogen injection (e.g., by 18.2% in the Guantao Du84 block), and (4) allows for proactive establishment of coke zones before the water cut reaches 85%. Through this numerical study, we investigate the feasibility of implementing the method of LTO coking air injection in SAGD fields and provide insights into its optimization.

Assessment of CO2 Sequestration Capacity in a Low-Permeability Oil Reservoir Using Machine Learning Methods

The CO2 sequestration capacity evaluation of reservoirs is a critical procedure for carbon capture, utilization, and storage (CCUS) techniques. However, calculating the sequestration amount for CO2 flooding in low-permeability reservoirs is challenging. Herein, a method combining numerical simulation technology with artificial intelligence is proposed. Based on the typical geological and fluid characteristics of low-permeability oil reservoirs in the Liaohe oilfield, the CMG 2020 version software GEM module is used to establish a model for CO2 flooding and sequestration. Meanwhile, a calculation method for the effective sequestration coefficient of CO2 is established. We systematically study the sequestration rules in low-permeability reservoirs under varying conditions of permeability, reservoir temperature, and initial reservoir pressure. The results indicate that, as the permeability and sequestration pressure of the reservoir increase, oil recovery gradually increases. The proportion of structurally bound sequestration volume increases from 55% to 60%. Reservoir temperature has minimal impact on both the recovery rate and the improvement in sequestration efficiency. Sequestration pressure primarily improves sequestration efficiency by increasing the dissolution of CO2 in the remaining oil and water. The calculation chart for the effective sequestration coefficient, developed using artificial intelligence algorithms under multi-factor conditions, enables accurate and rapid evaluation of the sequestration potential and the identification of favorable sequestration areas in low-permeability reservoirs. This approach provides valuable technical support for CO2 flooding and sequestration in pilot applications.

In Situ Combustion Characteristics of Heavy Oil in the Liaohe Oilfield at Different Temperatures

This study conducted in situ combustion oxidation experiments on crude oil from Block D within the Liaohe Oilfield, utilizing a kettle furnace low-pressure oxidation reaction method at various temperatures. The molecular composition of oxidation products was analyzed using gas chromatography–mass spectrometry (GC–MS) and high-resolution mass spectrometry. The results reveal that the molecular composition of the products remains relatively stable up to 300 °C, exhibiting a slight increase in C13-C30 alkanes. The ratio of the peak area for C21 to bisnorhopane is 0.082. From 300 °C to 450 °C, compounds with long alkyl chains gradually undergo thermal cracking, resulting in a significant increase in the production of alkanes within the C10–C30 range. The concentration of saturated hydrocarbons produced through thermal cracking reaches its maximum at a temperature of 400 °C. The most abundant peak of n-alkane is observed at C21, with a quantified ratio of peak area for C21 to bisnorhopane at 6.5, indicating a two-order magnitude increase compared to crude oil. From 500 °C to 600 °C, compounds undergo more profound thermal cracking and condensation processes. The predominant hydrocarbons consist of aromatic molecules containing two to six rings substituted with short side chains. The double bond equivalent (DBE) values of carbazoles and carboxylic acids are determined as 30 and 25, respectively. At 600 °C, the peak area ratio of naphthalene to biodecane is 300, indicating a remarkable increase of five orders of magnitude compared to the crude oil. The present study elucidates the correlation between the characteristics of combustion components in crude oil and the corresponding combustion temperature. Primary cracking reactions within crude oil are promoted effectively when keeping the combustion zone at 350 °C and 450 °C. This process significantly reduces the viscosity of heavy oil and enhances its fluidity.

Pilot test of CO2-EOR and Storage in Extra-Low-Permeability Reservoirs in the Liaohe Oilfield, Northeast China

Pilot test of CO2-EOR and Storage in Extra-Low-Permeability Reservoirs in the Liaohe Oilfield, Northeast China

Investigating the CO2 Geological Sequestration Potential of Extralow-Permeability Reservoirs: Insights from the Es1 Member of the Shahejie Formation in the Dawa Oilfield

Investigating the CO2 Geological Sequestration Potential of Extralow-Permeability Reservoirs: Insights from the Es1 Member of the Shahejie Formation in the Dawa Oilfield

Deformation Monitoring and Primary Driving Factor Analysis in the Coastal Area of Liaohe Oilfield Utilizing MT-InSAR and PCA

Deformation Monitoring and Primary Driving Factor Analysis in the Coastal Area of Liaohe Oilfield Utilizing MT-InSAR and PCA

Measurement of steam dryness using one-dimensional acoustic waves in pipelines

Heavy oil, extra-heavy oil and bitumen exceed 6 trillion barrels, roughly three times the world total Conventional oil and gas reserves. Thermal-chemical flooding (TCF) is an effective alternative to enhance heavy oil recovery after steam injection. In the steam injection and extraction process of oil, the accurate measurement of water steam dryness can provide a strong guarantee for the efficient exploitation of oil fields. The traditional steam dryness measurement device is affected by the steam flow state, and the error generated will affect the enthalpy calculation of the injected steam, which affects the judgment of energy efficiency of oil well injection in the field. Firstly, this paper proposes a mathematical model for calculating water steam dryness using mixed sound velocity and operating temperature, which is based on the mathematical relationship between water steam dryness and gaseous volume fraction, combined with Wood's formula and the density and sound velocity calculation formula for each region in the IAPWS-IF97 model to derive the monotonic correspondence function of sound velocity and dryness. Secondly, the one-dimensional acoustic wave model of the pipeline is applied to establish a set of sound velocity equations for the frequency-domain data of the array sensors, and the traversal iteration method is used to solve the mixed sound velocity of water steam. Finally, the dryness of steam injection under the operating condition of 270°C∼290°C at the wellhead was measured in the experimental area H33 in Xinfanguan of Liaohe Oilfield, and compared with the standard dryness value, the relative error of the experiment was -3.33% and the repeatability was 1.24%, the accuracy met the requirements of energy efficiency calculation, which verified the feasibility of the sound velocity method to measure the dryness of water steam. Therefore, it is of great engineering guiding significance to utilize sound velocity method to realize the measurement of dryness in the thick oil steam injection process.

An Experimental Study and Numerical Simulation Analysis of Thermal Oxidation Characteristics Based on Kinetic Parameters in Heavy Oil Reservoirs

In situ combustion (ISC), an efficient and economical method for enhancing heavy oil recovery in high-pressure, high-viscosity, and thermally challenged reservoirs, relies on the kinetics of crude oil oxidation. Despite an increased focus on kinetic models, there is a gap in understanding how oxidation kinetic parameters impact ISC effectiveness in heavy oil reservoirs. This study addresses this by selecting heavy oil samples from the G Block in the Liaohe oilfield and the M Block in the Huabei oilfield and conducting ramped temperature oxidation (RTO), pressure differential scanning calorimetry (PDSC), and thermogravimetric analysis (TGA) experiments. RTO detailed the thermal conversion process, categorizing oxidation into low-temperature oxidation (LTO), fuel deposition (FD), and high-temperature oxidation (HTO) stages. PDSC and TGA provided thermal characteristics and kinetic parameters. The feasibility of fire flooding was evaluated. Using CMG-STARS, an ISC model was established to analyze the impact of kinetic parameter changes. Activation energy significantly affected coke combustion, while the pre-exponential factor had a notable impact on cracking reactions. The recommended values for activation energy and the pre-exponential factor are provided. This study not only guides fire flooding experiments but also supports field engineering practices, particularly for in situ combustion in heavy oil reservoirs.

Study on the Rule of Change of Reservoir Rocks under Subcritical Steam Effect

This paper examines the lithology, pore throat, and fluid characteristics of the reservoir in Liaohe Oilfield Block 3624, using group V rocks as an example, combining a high-temperature and high-pressure reaction still with other equipment such as a rock mechanics tester and a scanning electron microscope. This study also designs and develops three controlled variable experiments, including the subcritical steam reservoir rock dissolution experiment, the subcritical steam reservoir rock mineral composition transformation experiment, and the subcritical steam reservoir rock mineral mechanical property experiment, also making clear the rule of change on the part of the rocks in the deep and heavy oil reservoirs after the injection of subcritical steam. Experimental results reveal the following: (1) Steam causes the dissolution of rocks, and when the steam temperature is in the subcritical region, dissolution is visible. After a 350 °C subcritical steam treatment, the relative melting temperatures of the components of rock materials are substantially greater than the melting point of the cement holding them together, causing the cement to significantly dissolve and a secondary crack network to emerge. (2) The mineral composition of the rocks changes as a result of elevated temperatures, with various mineral transformation trajectories being recorded after various steam treatments. Montmorillonite in reservoir rocks is converted into minerals like illite and chlorite in the subcritical steam temperature range. Another element influencing the creation of secondary cracks on rock surfaces is the reciprocal transformation of minerals, which alters the cohesiveness among mineral components. (3) Rocks suffer thermal damage and changes to their mechanical characteristics as a result of high-temperature steam dissolution and mineral transformations; the severity of these changes increases with the steam temperature.

Three-dimensional surface deformation from multi-track InSAR and oil reservoir characterization: A case study in the Liaohe Oilfield, northeast China

Oil productions can result in pore pressure drop in the reservoir, generating an increase in effective stress and leading to reservoir compaction. The compaction in the subsurface reservoir translates to the earth's surface, which is manifested as a loss of elevation (land subsidence), causing damages to oil production facilities and surface infrastructures. The Liaohe oilfield, located in Liaohe River Delta (LRD), northeast of China, is one of the most significant subsidence areas in China as a direct consequence of oil extraction from the reservoir. Previous studies carried out in this area assumed the oil production-induced displacement retrieved from Interferometric Synthetic Aperture Radar (InSAR) corresponds only to vertical deformation. In this work, for the first time, we proposed a method to retrieve the full three-dimensional (3D) displacement field over the oilfield. We retrieved the vertical and east-west displacement components by combining the multiple-geometry InSAR line-of-sight (LOS) observations and retrieved the north-south component based on the assumption of a physical relationship between the horizontal and vertical displacement. Two ascending and two descending datasets from Sentinel-1 satellite covering the area were processed by an InSAR time series analysis over the 2017 to 2021 period, providing consistent displacement rate maps and displacement time series in the LOS direction. Spatial local-scale land subsidence was found in several producing fields over the deltaic region, including Shuguang, Huanxiling, and Jinzhou oilfields. The 3D displacement decomposition was then conducted in Shuguang oilfield. The derived 3D displacement field exhibit a circular subsidence bowl with a maximum subsiding rate reaching 212 mm/year, accompanied by a centripetal pattern of horizontal displacements with maximum rates up to 50–60 mm/year moving towards the subsidence center. The retrieved 3D displacements are in good agreement with predictions from the geomechanical modeling by assuming a disk-shaped reservoir subject to a uniform reduction in pore fluid pressure. Finally, we show the importance of knowing both the vertical and horizontal displacement in characterizing the lateral boundary of the subsurface reservoir.

Permeability Enhancement Mechanism of Acidizing in Steam-Assisted Gravity Flooding Wells

Steam-assisted gravity oil drainage (SAGD flooding) is a cutting-edge technology for the development of oils which is gradually replacing steam huff and puff and is being used more and more widely. Low-permeability interlayers are generally developed in oil reservoirs in China, which may shield the migration of steam, oil and gas. Targeted acidizing fracturing was proposed to break through the low-permeability interlayers, and hence, the problem that the hindrance to the expansion of the steam chamber led to heat loss and seriously affected the development effect could be solved. A typical kind of well with SAGD flooding actually applied in China, Shuyi District of Liaohe Oilfield, was taken as the example for studying the optimization of crack parameters. Based on the study of reservoir sensitivity characteristics in this well, the formulations of working fluids for targeted acidizing fracturing were developed by optimizing the weight percentages of main acid solution and additives. The formula of ‘4% hydrochloric acid + 2% polyphosphoric acid + 5% fluoroboric acid + 4% acetic acid’ could be used as the acidizing fracturing working fluid for typical blocks of the Shuyi District of Liaohe Oilfield, which can increase the permeability of the natural core by 40.19–57.06%. Studies on targeted acidizing fracturing are beneficial for enhancing the oil recovery of oil reservoirs.

Development and Application of The Graft Coated Viscosity Reducer

The graft coated viscosity reducer was developed for the high cost of mixing light oil. The viscosity reducing mechanism is that the polar hypertonic agents in thSe viscosity reducer dissociate the net structures of the resin and asphalt and then form eutectic grafting with these dissociated macromolecules when the heavy oil in the water was broken or in the solution of associating state. The heavy oil takes shape of small particles while the resin is out of structure and not easy to get agglomerated. The released resin and the coating agent for the viscosity reducer form a layer of film on the surface of small oil particles to prevent the resin and asphalt from network structuring again. The heavy oil particles are not easy to be in coalescence concerning electrical repulsion and solution association among the coating in between. The heavy oil particles are dispersed in the medium to achieve the stabilization of viscosity reduction. For example, the viscosity of the crude oil from Liaohe Oilfield is 87.2mP•s after adding the agent at 50°C (the original viscosity was 4919mP•s). The viscosity reducer did not corrode the pipelines and wellbores and had no effect on the dehydration of united stations. The construction was carried out by continuously dripping the viscosity reducer into the 16 wells of Liaohe Oilfield. The viscosity all decreased to below 100mP•s afterwards. The current, load and other parameters all decreased along with the application. So this method could take the place of mixing light oil.

Optimal Design and Research on Honeycomb-Like Structure Geothermal Production and Irrigation Well Network

Inspired by the honeycomb shape structure, this structural shape was applied to the design of the geothermal well network, and the CMG simulation software with STARS as the core was used to establish a geothermal resource geological conceptual model of the Liaohe Oilfield Shenyang Oil Production Plant Oilfield. This model applied hydrothermal coupling simulation technology, studied the heat recovery effects of different production and irrigation well networks, conducted comparative analysis, and finally optimized the production and irrigation well network design and chose an inclined seven-point well network. The main advantages of using this honeycomb structure are reduced investment, maximum utilization of space, and larger Covers heat storage area to obtain maximum heat recovery, and it is easy to convert to other good network forms and adjust later.

Numerical Tracking of Natural Gas Migration in Underground Gas Storage with Multilayered Sandstone and Fault-Bearing Caprocks

The structure of caprocks is often greatly altered by different scales of faults or fissures in long-term geological tectonic evolution, and the sealing performance may be deteriorated. In this paper, a simplified geological model characterized as multilayered sandstone and fault-bearing caprocks extracted from the Shuang 6 underground gas storage located in the Liaohe oilfield was established. Different fault geometry (e.g., fault length, fault dip angle, and fault type) and seepage attributes (porosity and permeability) were considered to illustrate their impacts on natural gas migration during the cyclic high rate of injection and production of natural gas. The results showed that the seepage anisotropy and the natural gas front are strongly affected by the formation properties and, especially, are hindered by the low permeability sandstone layers. The difference in the lateral migration distance of natural gas in different layers can reach 110 m at the end of the injection period, with an annual injection volume of 108 m3. The migration of natural gas along the fault zone is mainly controlled by the permeability of faults, followed by fault scale, fault dip angle, and fault type. The sealing failure of caprocks in the fault zone does not occur based on the simulated gas migration distribution, showing that a very limited amount of natural gas migrates into the caprocks.

Application of SAGD technology in the development of super heavy oil reservoir buried medium deep

Continental super heavy oil reservoirs in China are characterized by deep burial depth, strong reservoir heterogeneity and high oil viscosity. The steam huff and puff technology are used to develop this type of reservoir, but in this development method, its oil recovery rate, oil steam ratio, and ultimate recovery are low. The benefit of the reservoir development is losses in this high cost per ton of oil. Many vertical wells injecting steam and one horizontal well-producing liquids pattern of SAGD technology (abbreviated as VERTIHORIONATAL pattern SAGD) were Innovated to solve the problems based on SAGD technology introduced from Canada. The SAGD technology introduced in Canada was made of double horizontal wells. The above horizontal well injects steam and the other horizontal well produces liquids continued (abbreviated as DOUBLE HORIZONTAL pattern SAGD). The VERTIHORIONATAL SAGD technology makes full use of the original well pattern of huff and puff and takes advantage of the thermal connectivity and underground temperature field formed by early development; At the same time, the VERTIHORIONATAL pattern SAGD technology can effectively solve the problem of steam cavity uneven expansion caused by reservoir heterogeneity by adjusting the location of steam injection vertical wells. It can also balance the liquid production in good horizontal sections and improve steam cavity formation speed by adjusting steam injection well sections and steam injection parameters. The technology has been successfully applied in the medium-deep super heavy oil reservoir in the Shu-1 area, Du84 block, Liaohe Oilfield. Seven oil wells with a daily output of 100 tons have been cultivated, and a stable production of million tons for four consecutive years. It has been built as China’s largest SAGD development demonstration area for medium-deep super-heavy oil.

Analysis of heat exchanger corrosion failure in 800,000 light hydrocarbon plant in Liaohe Oilfield

Heat exchangers, as the major equipment for forced heat exchange, are now widely utilized in all areas of life, however in real usage, corrosion failure can frequently occur and cause catastrophic mishaps. In this study, the composition of the corrosion products in the heat exchanger's head section was examined using XRF and XRD, and the corrosion of Q345D steel in the head section was examined using the dynamic potential polarization curve test method in conjunction with SEM under various CO2 and O2 partial pressure and temperature conditions. Fluent simulation software was also used to simulate the impact of erosion corrosion on the heat exchanger's head section. Results indicate that the main corrosion products in the regenerative heat exchanger E-303 are Fe3O4, with minor amounts of Fe2O3 and FeOOH; in terms of temperature, CO2 and O2, these three influencing factors on the heat exchanger head Q345D steel corrosion results, the temperature on the steel corrosion damage is significantly greater than the local corrosion caused by CO2 and O2, but when the temperature is higher than the solution boiling point of its corrosion in and out will occur. The flow rate scouring on the heat exchanger head high temperature inlet that is caused by the damage is much greater than the head low temperature outlet, corrosion damage is primarily concentrated in the lower inlet baffle, which is also consistent with the actual conditions of the site heat exchanger.

Preparation of graphene supported Ni–Fe bimetallic nanocatalyst and its catalytic upgrading and viscosity reduction performance for heavy oil

Graphene supported single metal catalyst can improve the dispersion of active components and enhance the viscosity reduction effect of heavy oil. However, there is little research on graphene-supported bimetallic catalysts in the field of heavy oil upgrading and viscosity reduction. In this paper, super heavy oil of Liaohe Oilfield was taken as the research object. Graphene was selected as the carrier material, and nickel and iron chlorides were used as precursors. Graphene-supported nickel-iron bimetallic nanocatalysts were prepared by solvothermal method, and their synthesis feasibility was proved by microscopic characterization. Then the prepared catalyst was used in the evaluation experiment of catalytic upgrading and viscosity reduction performance of Liaohe heavy oil. By analyzing the parameters of oil samples before and after catalytic upgrading and viscosity reduction, the catalytic upgrading and viscosity reduction effect was evaluated and the viscosity reduction mechanism was revealed. The results showed that the viscosity reduction rate of heavy oil with graphene supported Ni–Fe bimetallic catalyst was 42.38%. With the aid of decalin, the viscosity reduction rate of heavy oil could reach 71.43%. At this time, the content of heavy components, the average molecular weight of heavy components and the aromaticity fA of oil samples decreased after catalytic upgrading and viscosity reduction, while the aromatic condensation degree HAU/CA and the branched chain index BI increased, and the modification effect was significant. Among them, the average molecular weight of asphaltene decreased from 2266 to 1444, with the most obvious decrease. The decrease of heteroatom content in asphaltene led to a significant decrease in intermolecular force and hydrogen bonding, which was the main reason for the catalytic upgrading and viscosity reduction of heavy oil by graphene supported Ni–Fe bimetallic catalyst.

Corrosion Behaviors of N80 and 1Cr Tubing Steels in CO2 Containing Downhole Environment—A Case Study of Underground Gas Storage in LiaoHe Oil Field

In order to evaluate the effect of chromium content in carbon steel on the corrosion resistance of carbon steel materials, the corrosion behavior of 1Cr and N80 steels was investigated in this study by immersion weight loss method under three different CO2 partial pressure and temperature conditions in formation water for 72, 168 and 336 h. Detailed material surface morphological characterization was performed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and confocal laser scanning microscopy (CLSM). The results show that the pitting corrosion of N80 carbon steel is serious at medium temperature and low CO2 partial pressure (50 °C, 0.30 MPa), and the corrosion rate is significantly higher than that of 1Cr steel. However, at high-temperature and high CO2 partial pressure (100 °C/0.63 MPa and 114 °C/0.73 MPa), 1Cr steel is more inclined to the mesa corrosion dominated by local corrosion characteristics, and the corrosion rate is seriously higher than that of N80 steel with uniform corrosion. From the experimental results, we can know the corrosion resistance of carbon steel and 1Cr steel is not only affected by the corrosion environment, but also depends on the formation process of the product film, as well as its compactness and integrity characteristics. At low-temperature and low CO2 partial pressure, 1 wt.% chromium content can provide a certain degree of corrosion resistance, while high temperature and high partial pressure can broaden the application window of carbon steel N80 and weaken the corrosion inhibition effect of chromium.