I. Geological selection of CO2 transportation pipelines
China is a vast country, and the geological problems involving the safety of CO2 transportation pipelines are complicated. The natural environment, geography, topography, geological structure, neotectonic movement, geologic disaster, geotechnical media conditions along the existing pipelines vary from place to place. Especially the hidden danger of pipeline safety caused by geologic hazards and the complex section of long-distance pipeline passing through due to the big topographic undulation and complicated geological conditions determine that the selection of CO2 transmission pipeline is particularly important. In order to better solve the routing problems in complex areas, the concept of geological routing was introduced (Xixin, 2002). Accordingly, it is initially proposed to increase the large-scale super-excursion geological work and scheme comparison study of CO2 transport pipeline when carrying out the investigation and evaluation of geological storage of CO2, so as to combine the line selection of CO2 transport pipeline and geological investigation, and to provide geological basis for the scheme of CO2 transport pipeline.
According to the research of Xixin (2002), the long distance of long-distance pipeline route is long, and often has to pass through some complex sections. Because of the complex section of the terrain undulation, complex geological conditions, can be compared with more line program. Complex section of the line in addition to the need to consider the topography, construction difficulty, regional level, economic factors, etc., should also consider the geological factors (such as the distribution of active fracture zones, the degree of development of geologic hazards, etc.) on the line program is the main content of the geologic line selection.
1. The main problems of complex lot routing
At present, China's long-distance pipeline passes through more and more territories, more and more complex geomorphological units, resulting in more and more complex lot routing. Some shortcomings in the past route selection are gradually exposed, the main problems are:
1) Due to the limitations of the pipeline routing band work area, the scope of the program study is too narrow, often resulting in the important geological background and macro-geological issues are ignored or lack of understanding, and it is easy to omit the selection of valuable routes.
2)Complex line selection comparable programs, involving a large area, according to the conventional survey arrangements for time and financial input, it is difficult to do a good job of in-depth study of the program and selection, some complex hidden geological problems are difficult to find out, directly affecting the quality and depth of the complex line selection.
3) large rivers through (cross), tunnels and other line control engineering geology, single use of drilling-based conventional survey method cycle is long, high cost, it is difficult to meet the requirements.
2. Complex section of the main investigation of the geological selection line
1) multi-program research selection. According to the preliminary formulation of the line towards the regional geological situation, taking into account the terrain and geomorphology, construction difficulty, regional level and other factors, combined into a variety of different programs, multi-program research and selection. First determine the maximum area that may be involved in the complex section of the program, and initially screen out the representative advantage of the program.
2)Deepen the geological work in advance, and carry out large geological survey. Based on the largest area that may be involved in the CO2 pipeline and in order to find out the major geological problems (such as active fractures and geological hazards that pose a hazard to the construction of long-distance pipeline), combine with remote sensing interpretation to select the line, carry out the evaluation of the activity of fractures in the complex sections along the line and assessment of geological hazards and other thematic contents, find out the macroscopic geologic factors that control the selection of the line program and its distribution, evaluate the regional geologic conditions, and put forward the basis for further optimization and screening. screening basis.
3)According to the scheme screened out in the small-scale survey stage, the geotechnical and engineering geological conditions of the route scheme will be further investigated in the large-scale survey stage by making full use of the results of the previous stage of the survey to carry out the second screening of the scheme, so as to continuously deepen the depth and precision of the scheme comparison.
In summary, CO2 long-distance pipeline is a construction project with a strip extension, and the geological investigation of pipeline geological survey industry is carried out along the strip direction of the line. However, in areas with complicated terrain and geological conditions, especially in some key control projects such as the crossing of some large rivers and tunnels, the scope of ribbon work seems to be too narrow, which is easy to cause the omission of good programs and major geological phenomena, and sometimes may cause irreparable design errors.
It has been proved in practice that only by grasping the regional geological control factors that have a great influence on major projects and the differences in the distribution of these factors, can we make a good choice of programs. Therefore, to carry out the national small-scale and key areas of large-scale CO2 geological storage survey, should be synchronized to carry out the CO2 long-distance pipeline geological survey work, from different scales, different levels and the purpose of the study, to obtain a wealth of geologic information, CO2 long-distance pipeline than the selection of options.
Two, CO2 long-distance pipeline geological disaster investigation
According to Zhao Zhonggang et al. (2006), the impact of geological disasters on pipeline safety is multifaceted, in order to ensure the safe operation of the pipeline, it is necessary to assess the development and evolution process and stage of various disasters and their factors, etc., and based on the pipeline geologic disasters disaster mechanism, the pipeline may be encountered by the geologic disaster Take corresponding preventive countermeasures.
(I) Types of pipeline geohazards
Based on the geohazards encountered by existing oil and gas pipelines in China, the geohazards affecting the safe operation of pipelines are divided into three major categories (Zhao Zhonggang et al., 2006): the first one is the geohazards caused by intracrustal dynamics of geologic effects, including earthquakes, ground subsidence, ground fissure and fracture hazards, etc.; the second is the geohazards caused by extracrustal dynamics, including landslides, slides and ruptures; the second is the geohazards caused by extracrustal dynamics of geologic effects, including slides, slides and fractures. The second category is for the crust outside the dynamic geological hazards, including landslides, landslides, mudslides and flood erosion, sand burial and wind erosion disasters, etc.; the third category is for the geological disasters caused by special soil, mainly refers to the deformation of humid loess, expansive soils, saline soils and permafrost disasters caused by the deformation.
1. Geological hazards caused by power geological action within the earth's crust
(1)Earthquake
Earthquake and active rupture is one of the major geological hazards that cause major accidents in pipelines, including the station, and countries around the world have made it the focus of the pipeline design. The possible hazards of earthquakes on the safety of long-distance pipelines mainly include two aspects (Dong Lusheng et al., 2002): First, the integrity and continuity of the soil body is damaged due to seismic effects, such as fault fault faults, cracks, landslides, liquefaction of sand and soil, etc.; Secondly, strong earthquakes occur in the area near the pipeline, and the propagation of seismic waves in the soil body will damage the pipeline and its auxiliary facilities, such as corroded or welded to the weak pipeline sections of poor quality, resulting in damage. The weak pipeline section of corrosion or poor welding quality damage; or trigger secondary disasters, such as oil and gas pipeline rupture, power supply interruption. The most direct damage caused by the earthquake is to make the pipe uneven sinking, arching and wrong break, caused by the pipe under the foundation subsidence or hollowing out, so that the foundation loss of support, resulting in pipeline overhang, the axial tensile force increases so that the pipe material failure, cracks, and even pull off. This situation often occurs in the rigid interface of the pipeline, or occurs in the vertical section connected with the horizontal pipe section, in addition to the welded joints is also a place where the fracture often occurs (Zheng Maosheng et al., 2004). All of these may lead to CO2 leakage in the pipeline, thus jeopardizing the safety of people and the environment.
A large number of facts have proved that damage to pipelines by earthquakes is mainly caused by large-scale fault displacement. Such as the Northwest region of the Ge (Golmud)-La (Lhasa) pipeline many sections of the pipeline through the active fault zone, in the high seismic intensity areas. 2001 November 14, the northern Tibetan Plateau Kunlun mountain range along a strong earthquake of magnitude 8.1, and then hundreds of aftershocks occurred. The earthquake formed a surface rupture zone with a length of 350-426km and a width of 30-50m in the NWW direction. The rupture zone intersected with the north-south oriented Gera refined oil pipeline, making the pipeline extruded into a flat shape under the action of complex alternating stresses such as squeezing pressure, bending force, shear force, etc., and a Z-shaped wrinkle fracture occurred at the port of the casing. The earthquake also damaged some facilities and equipments of 3#, 5#, 6# and 9# pumping stations to different degrees (Zeng Doli, 2004).
The damage to pipelines caused by earthquakes is catastrophic, so engineering measures to reduce seismic hazards should be focused on surface ruptures. In order to avoid or reduce the damage to pipelines due to rupture activities, it is particularly important to investigate and evaluate the activity of the major rupture blocks along the pipelines. Strengthen the monitoring of pipeline displacement or stress change in the active fault section and incorporate it into the pipeline management, so as to keep abreast of the fault activity and pipeline safety condition and ensure the safety of pipeline operation. When selecting the line, under the premise of obeying the general direction of the line, active faults (zones) and areas of high seismic intensity should be avoided as much as possible. If the pipeline crosses with the active fault or passes through the seismic high intensity area, it should choose the area with open terrain and thicker quaternary cover to pass through, and at the same time, it should take anti-seismic measures to improve the pipeline's ability to prevent and mitigate earthquakes.
(2)Tectonic ground cracks
Tectonic ground cracks are formed by internal stress (Wang Jingming, 2000). Tectonic ground cracks in the Tibetan Plateau are widely distributed, and there are three main types, namely, seismic rupture, fault creep-slip rupture and fault fracture zones, and inhomogeneous frostbite cracks. The Gera pipeline, which has already been constructed, passes through the tectonic fracture zone of the Tibetan Plateau. The Southwest Oil Products Pipeline (Maoming, Guangdong-Kunming Changpo) crosses the Sichuan-Yunnan fault zone. There are also geologic cracks in Jiangsu and Henan provinces, which are the eastern part of the West-East Natural Gas Pipeline Project (Li Ziyi et al., 2004). The ground cracks in Suzhou, Wuxi, and Changzhou in Jiangsu are a form of uneven ground subsidence, which is mainly caused by the bedrock uplift or escarpment underneath the Quaternary Loose Accumulation, resulting in sudden changes in the soil structure or the thickness of the pressurized water-bearing sand layer, and pumping of water induces the uneven ground subsidence, which leads to cracks on the surface of the ground. The cracks in Henan are located in the northern part of Xingyang and the areas of Taikang and Huaiyang. Tectonic ground cracks may cross the pipeline, which can have a destructive effect on the pipeline and can cause serious cracking damage.
In order to prevent the impact of tectonic cracks on pipeline safety, the following necessary measures can be taken (Li Danjie, 2002); ① bypassing, as far as possible, to avoid pipelines, stations, buildings, etc. arranged in the tectonic cracks; can not be bypassed as far as possible, to avoid the most dangerous section of the tectonic cracks (the age of the newer, the activity of the intensity of the greater) and the occurrence of large earthquakes in the ground surface of the fault; ② choose the appropriate angle of crossing the cracks, the appropriate angle of crossing the cracks, the appropriate angle of crossing the cracks, the appropriate angle of crossing the cracks, the appropriate angle of crossing the cracks, the appropriate angle of crossing the cracks. The appropriate angle through the cracks, the unfavorable state of force and strain into a more favorable way; ③ in the pipeline through the cracks in the earth to take practical anti-seismic measures, such as increasing the degree of freedom of pipeline deformation (laying pipe trench with slopes or the use of casing, etc.), to increase the strength of the pipeline or to take the flexible coupling, etc.; ④ Strengthening of the active tectonic cracks in the earth belt and the monitoring of geologic hazards and early warning work.
(3)Ground subsidence
The main reasons for ground subsidence are, firstly, the special geological structure, such as the karst topography in Guangxi and Yunnan; and secondly, it is caused by the human beings adopting the underground mining method of solid minerals (e.g., coal, iron ore, etc.).
China's karst distribution area of 365 × 104km2, accounting for more than 1/3 of the national territory, is one of the world's most developed karst countries. In recent years, with the rapid development of urbanization construction in karst areas, the development of land resources, water resources and mineral resources in karst areas has been continuously enhanced, and the resulting karst subsidence problem has become more and more prominent (Lei Mintang et al., 2004). Solid mineral extraction zones are distributed over large areas throughout the country. The existence of karst terrain and mineral extraction zones is likely to cause undesirable geological phenomena such as surface subsidence, collapse and deformation, and surface cracking. Ground subsidence in turn will cause underground pipelines to bend and deform, overhang or fracture, thus posing a hidden danger to pipeline safety. The collapse of air extraction zone will bring serious consequences to the oil and gas pipeline project, which should be highly concerned. Such as the middle section of the west-east gas pipeline project, the pipeline line below the air-mining zone already exists, especially the dense distribution of coal mines in Shaanxi Zichang coal mine Jiaojiagou - Wangjiawan section, Shanxi Puxian - Linfen coal mines and Fushan Houjiaogou coal mines densely distributed areas, and so on.
When selecting the line in the area where the ground surface has produced subsidence, cracks and collapse, it is appropriate to adopt the bypass method; if it is not possible to bypass, backfilling or pressure grouting can be used to deal with the method.
2. Extracrustal power geological action caused by geological disasters
(1) mudslides
China mudslide disasters occur in the inter-annual July-September, due to torrential rainfall stimulation, rapid, strong disaster. Especially in the Loess Plateau area, the soil structure is loose, collapse, landslide and gully development, for mudflow provides a rich source. In the torrential rainfall inspired by the formation of extremely high sand content of the torrent, from the dense hair ditch, branch ditch flow to the dry ditch and river, convergence and the formation of a strong mud flow, resulting in dam collapse, reservoir silting and other disasters. Most of the pipeline sections in the middle part of the West-East Gas Pipeline Project are located in the Loess Plateau, and the hazards of mudslide disasters on the pipeline are particularly serious. in May 1994, the Yuan (Cheng)-Yue (Le) pipeline in Changqing Oilfield suffered from a major flood that had not been encountered in the region for 70 years, and the ensuing mudslides upstream of the Zuoyuanchuan River destroyed the pipeline in as many as 26 places, which accounted for 35% of the entire pipeline, and the pipeline was pulled out in many places ( Zhu Sitong, 1998).
In addition, gully erosion is one of the most serious erosion modes harmful to pipeline projects. The loess area of northern Shaanxi and western Jinxi is very developed, the backward erosion of gully, gully bed undercutting, gully bank widening and expansion, making the gully wall slope soil instability, easy to produce collapse or landslide, resulting in the pipeline hollowing out the lower part of the pipeline, overhanging exposed, endangering the safety of the pipeline. Such as Ma Huining pipeline along the line due to the soil permeability coefficient is small (1.54 × 10-5 ~ 6.61 × 10-5), convergence of fast, very easy to quickly form a gully, and in the gully at the formation of a catchment, washed out the maintenance of the road, resulting in the pipeline is exposed overhanging. 1994 in the distance from the Sun Jiatan about 5km, a flood formed a depth of 2.5m, width 8m, length as long as the pipe, the pipe is exposed. m deep, 8m wide and 50m long washout ditch, posing a serious threat to pipeline safety (Mei Yunxin, 2003).
For large and medium-sized mudslides with serious hazards, the selection of the line is in principle to take avoidance, avoiding direct passage; if it is impossible to avoid, it can be taken across; for small mudslides, it can be selected in the downstream of the mudslides (the accumulation area of the flooding fan) to pass through, and at the same time in the upper reaches of the channel to supplement the measures of interception and retention. Pipeline safety threat to the gully, should be reinforced, specific treatment methods are: increase the depth of the pipeline, at least up to the stabilization layer below, the upper fill should be compacted in layers; take the interception and drainage, cut off the source of water, to stop the gully continue to develop; backfill rammed reinforced site; the use of woven bags filled with soil piled up the slope to enhance the gully's anti-erosion capacity.
(2) landslides
This type of disaster has a sudden onset, and is extremely hazardous to engineering construction. Traditional engineering geology and geotechnical engineering slope geohazard research usually slope gravity geohazard is divided into two categories of landslides and landslides. Loess Plateau landslides are mostly loess landslides, loess is deep and rich in calcium carbonate, loose and porous, vertical joints are developed, and it is underneath Mesozoic sandy mudstone or Neoproterozoic laterite, the rainwater seeping down the loess joints during flood season to the underneath water-isolating rock layer is blocked and forms contact surface runoff zone, triggering landslides, which are generally larger in scale; in addition, when the rainwater seeps down the slope of loess to the vertical joints, it will trigger shallow landslides because of the submerged erosion effect. triggered shallow landslides are also more.
The loess slope (slope) landslide effect in the generation mechanism and damage mode between the collapse and landslide, loess landslide disaster refers to the natural factors or human engineering activities under the influence of loess slope zone occurs both landslide and collapse characteristics of the geologic disaster. Its occurrence is controlled by its unique material composition and engineering properties, and has the characteristics of regional distribution, usually need to have the following conditions (Qu Yongxin et al., 2001): ① the height of more than 10m, or even more than 100m, by the thick layer of Malan loess slope zone, the slope is usually in 55 ° or more; ② rainy season than the frequency of occurrence of the dry season; ③ in the natural conditions in the river valley plains and the large gully Both sides due to lateral erosion of river water or flood scouring of loess slope foot and occur; ④ in the river valley plain area or large gullies, due to the construction of reservoirs caused by the elevation of the water level, reservoir water infiltration of loess slope foot, etc., can also be induced to produce; ⑤ in the source of loess side and other loess slope area, due to the slope height, the slope ratio of the excessively high, when the artificial excavation is induced to produce.
Because of the high cost of treatment and remediation of this type of geological hazards, and therefore in the selection of pipeline routes, should be taken as far as possible to avoid the program. For the treatment of general easy to landslide section, you can take appropriate measures to stabilize the slope, such as taking cut slopes, berms or fish scale pits planting trees and water storage measures, soil and water conservation and engineering treatment; or in the back edge of the body of the landslide to build interception, drainage, water conduit system, in order to prevent the surface water into the body of the landslide, the front edge of the body of the landslide using slurry masonry schist berms, to prevent lateral erosion of the water flow caused by the decrease in the resistance to the slide force, so as to stabilize the slope, to ensure that the Pipeline safety. For the slope landslide that may be generated by the construction and excavation of pipe trench on loess slopes, comprehensive management countermeasures such as diversion of water, support and blocking, and slope reduction can be taken; at the same time, measures can be taken to improve the impact resistance of the pipeline foundation and backfill to ensure the safety of pipeline construction and operation (Liang Wei et al., 2005).
(3) Mobile sand dunes (ridges) and wind erosion sand burial
Mobile sand dunes (ridges) are extremely mobile, and the direction of movement is perpendicular to the pipeline. If the pipeline overburden is blown away by the wind, it will cause the pipeline to be exposed and suspended, and if it exceeds the flexural strength of the pipeline, the pipeline will break.
Wind erosion and sand burial is also the most prominent category of geological hazards. Such as the Taklamakan, Batang Jilin, Tengger and Mao Wusu and other dunes (Monopoly) side of the mobile dunes ranging from 3 to 15m high, the rate of movement of 4 to 6m/a; some of the wind-eroded depressions of the maximum depth of wind erosion up to 30m, the pipeline buried and the station is more hazardous.
The flow of sand dunes (ridges) control measures can be taken to increase the depth of the pipeline, set up steel (or this) piles to fix the pipeline and vertical sand barriers and so on. In the Tengger Desert, the southern edge of the Tengger Desert and the southern edge of the Mao Wusu Desert dunes, due to the size and activity is relatively small, the line can be selected in the lowlands between the mounds through; or dunes pushed flat and then dug the pipe trench, properly buried, and in the construction of the construction at the same time, planting grass and trees, sand barriers and other sand and solidification projects, sand and sand hazards to prevent and control, and to improve the ecological environment.
3. Geological hazards caused by special soil
(1)Wet subsidence loess
Luteous soil properties determine the loess layer is prone to water wetting, the formation of loess trap, loess cavity, loess fissure, loess columns and other landforms to the construction of the pipeline, especially through the loess gully section caused difficulties, while the threat of damage and destruction of the pipeline's normal use. Wet subsidence loess is characterized by vertical joint development and loss of strength in case of water immersion, which is prone to adverse geological phenomena such as landslides, collapses and cavities in the rainy season, which in turn form steep gullies, and at the same time, due to the infiltration of water along the vertical joints of loess, submerged erosion and scouring erosion are formed, leading to the development of new gullies (Sun Guoxiang et al., 1996).
These factors will cause uneven settlement deformation of the pipeline, while the negative frictional resistance generated by excessive wet subsidence deformation may lead to bending and deformation of the pipeline, exposure, overhanging, and even fracture; in addition, there is the possibility of uneven subsidence of the strata and cracks, etc., or induced collapses and landslides, which will pose a hazard to the pipeline.
Wet subsidence loess leads to geological disasters on the other hand is the loess submerged, its distribution and wet subsidence loess is basically the same, mostly in the upper Pleistocene and Holocene loess, in the role of groundwater to form traps, caves, Born Bridge and other "loess karst" phenomenon. Because of its role in the process is more hidden, often with the distribution of dark trench, once the sudden fall, will bring serious consequences to the pipeline safety.
If non-self-weight wet subsidence loess, because the weight of the pipeline unit length is less than the weight of digging out the same volume of loess, paving the pipe will not increase the additional pressure and wetting, generally do not need to deal with; if it belongs to the self-weight wet subsidence loess, the treatment measures are mainly used in the way of soil improvement and the adoption of interception and drainage measures.
(2) expansion (rock) soil
Expansion (rock) soil geohazard has become a global engineering geology and geotechnical engineering problems. Expansion (rock) soil is mostly distributed in the low hills and desert areas of the ancient near-Neoproterozoic mudstone development area, with a weak - medium degree of latent expansion, when water will disintegrate.
Expansion (rock) soil to China's pipeline safety has caused extremely serious hazards, such as 1989 put into operation in Inner Mongolia Arshan - Saikhan Tara pipeline project, the following year, No. 4 and No. 6 heating station of the building floor and wall cracking occurred to varying degrees of damage; Lan - Chengdu - Chongqing pipeline near Sumugou. -Yu pipeline near the Sumugou cretaceous purple-red expansion rock of the collapsed bank disaster, as well as the west-east gas pipeline project in Anhui's Fuyang to Jiangsu's Jiangpu between the distribution of a large area of expansion of the soil, also produced foundation deformation and collapse problems.
(3)Salt-stained Soil
Salt-stained soil is caused by the gathering of salts in the soil on the surface due to the shallow depth of groundwater, stagnant transportation and strong evaporation in an arid climate environment. Highly mineralized saline soil has strong corrosive properties on concrete and steel pipe, and the dissolved salt crystallization produces body expansion, and will produce additional pressure on the pipe and station foundation. Therefore, the salty soil solubility and salt expansion of the pipeline foundation of the soil destructive force is very strong, easy to cause the pipeline "dark overhang" phenomenon.
Because of salinization and groundwater have a direct relationship, in the season of abundant water, the rise of the water table, will have a negative impact on the construction of pipelines; in the salinization of the phenomenon of the lot, the general depth of the groundwater is shallow, in the good corrosion should be at the same time should have measures to reduce the water, the construction of as far as possible in the dry season. Preventive measures for saline soil, you can lay a compacted layer of gray soil at the top of the pipe, in order to isolate the surface water infiltration; non-saline soil type of coarse-grained soil backfill pipe trench, isolate the rise of harmful capillary water; at the same time, the corrosion protection design should focus on the consideration of saline and alkali corrosion-resistant corrosion-resistant materials and corrosion-resistant layer of mechanical strength.
(4) permafrost
The threat of permafrost on the pipeline is mainly the soil freezing and expansion of the soil, the main mechanism is the water phase in the soil into ice, resulting in expansion of the soil, so that the ground rises. After the soil freezes and expands the pipes buried in the permafrost will also rise with the soil; and when the soil freezes and ablates, due to the foundation of the pipe or the pipe under the small void has been partially filled with soil, so the pipe can not fall back, year after year, many times the freezing-ablation-filling-re-freezing process, resulting in the pipeline is elevated . Gera pipeline has been arched out of the ground in many places and deformation of the pipeline, arched out of the ground height of about 0.7m, 3.6m long, and fracture under the action of bending stress, posing a threat to the safe operation of the pipeline.
Through the permafrost zone of the pipeline, in order not to damage the permafrost layer, the following measures should be taken: ① the pipeline will be buried in the freezing force is relatively small, "weak freezing zone", to avoid the pipeline contact permafrost layer; ② in order to avoid the pipe trench excavation is too deep or excavation exposure to the atmosphere for too long to make the permafrost layer damage in the control of the depth of the At the same time, try to do while excavating, while laying pipe, while backfilling, to maintain the stability of the permafrost layer; ③ pipe depth should be determined according to the different sections of the soil moisture content and seasonal thawing layer thickness segments; ④ pipe trench bottom shall be paved with a certain thickness of fine soil, and the maximum digging depth should not exceed the upper limit of the permafrost layer of 0.5m; ⑤ pipe total depth of burial of less than 0.8m, in order to keep the pipe in the stability of the thermal stress effect, it is appropriate to cultivate the soil on the surface and to ensure a certain width. And ensure a certain width.
(II) Geological hazard investigation of CO2 long-distance pipeline
1. Attaching importance to remote sensing interpretation of geological hazards of CO2 transmission pipeline
Through remote sensing interpretation of geological hazards of CO2 transmission pipeline, the key areas along the pipeline that may cause geological hazards (e.g., seismic-prone areas, fracture zones, etc.) will be calibrated by using geographic information system (GIS); by outlining the salty soil, desert, loess, expansive soil, and so forth; by drawing the geologic conditions of the pipeline. and desert, loess, expansive soil and other special soil distribution areas, comprehensively decipher the development of geologic hazards along the pipeline project, and then apply remote sensing technology to predict geologic hazards (Fang J. et al., 1997; 2000).
2.Carrying out special investigation of geological hazards along CO2 pipelines
Carrying out special investigation of geological hazards along CO2 pipelines according to the relevant industrial norms, and making in-depth analysis of geological hazards that play a major or decisive role. For example, according to the requirements of the current Code for Seismic Design of Submerged Steel Pipelines for Oil (Gas) Transmission, the direction of geologic fractures, the location of intersections with pipelines, and the possibility of horizontal and vertical dislocations will be identified, and the maximum magnitude of earthquakes that may occur in the next hundred years will be evaluated, as well as the amount of possible sudden dislocations.
3. Gradually establish a nationwide prediction and forecasting system for geological disasters of carbon dioxide pipelines
One is to establish a research on geological disaster forecasting with monitoring as the main means: monitoring the ground temperature and stress through geophysical methods, studying earthquakes through monitoring of underground ruptures and underground deflation; and carrying out real-time monitoring of, for example, sanding and salinization of the land. Secondly, it focuses on the research on the prediction and forecasting of the causes and mechanisms of geologic disasters. Third, the establishment of prediction models applicable to pipeline engineering.