Qin Xuejie, Dai Tao, Song Dao, Wan Xiao Xizhen
Abstract analysis of the geology and development status of the Caogu 1 buried hill heavy oil reservoir; introduction of the establishment of a numerical model in numerical simulation research The technical methods adopted; the development rules and influencing factors of the reservoir were studied; the similarities and differences in the development rules of the reservoir and other domestic buried hill reservoirs were revealed.
Keywords Caogu 1 buried hill buried hill reservoir numerical simulation dual-pore model bottom water coning development law
1. Introduction
In the past 20 years, Reservoir numerical simulation technology has made great progress and been widely used in the development of fractured buried hill thin oil reservoirs. There have been many monographs and articles discussing its technological progress and application results. However, this technology has always been a problem in establishing geological models of fractured buried hill reservoirs in multi-porous media. Based on the development situation of the Caogu 1 buried hill fractured heavy oil reservoir, this paper conducted a more in-depth study on the numerical simulation method and development rules of the buried hill oil reservoir, and established a mathematical model that can represent the Caogu 1 buried hill oil reservoir. , and achieved certain research results.
The Caogu 1 oil reservoir is a massive fractured and cave-type carbonate rock with bottom water, which has a thin effective reservoir thickness, complex reservoir space development, and is controlled by structure and lithology. Bulk and super heavy oil reservoir
Lin Yi. Comprehensive geological study of Caozhan 1 buried hill reservoir in Le'an Oilfield, 2000. The development of this type of oil reservoir has not been reported at home or abroad. The development of Caogu 1 oil reservoir should be based on a step-by-step process of practice, understanding, development and adjustment, and strive to accumulate a set of successful development experience for the development of buried hill heavy oil reservoirs. From the analysis of the development status of the Caogu 1 oil reservoir, the main problem currently is that there is insufficient understanding of the oil well water production mechanism, water content change patterns, plane development conditions and production effects exposed by the mining performance of the Caogu 1 buried hill oil reservoir. know. The main purpose of this numerical simulation study is to use advanced reservoir numerical simulation technology to study the development rules of the Caogu 1 reservoir.
II. Geological overview and development profile
The Caogu 1 buried hill carbonate heavy oil reservoir is the northwest part of the Guangrao buried hill oil reservoir belt, and the main oil-bearing strata are Austrian The lithology of the Upper and Lower Majiagou Formations of the Pottery System and Lower Ordovician System is mainly limestone, leopard skin limestone and dolomite. The reservoir storage space is mainly composed of structural fractures, followed by dissolved pores and caves. Fractures have obvious organization and directionality, and high-angle fractures develop. Open fractures and the caves connected to them are good places for oil and gas enrichment. Effective reservoirs are mainly developed within 60m of the top of the buried hill. The types of reservoirs include fracture-cave composite type, pore and fracture type and micropore and micro-fracture type. The viscosity of ground degassed crude oil is 2.0×104~7.0×104mPa.s, which is a special and super heavy oil with high viscosity, high density and high colloid content. The Caogu 1 oil reservoir is a block-shaped edge and bottom water buried hill oil reservoir, with the original oil-water interface at about -950m. The geological reserves are 740.5×104t. Among them, the reserves in the 40m layer at the top of the buried hill account for about 3/4 of the total reserves in the Caogu 1 buried hill. The reserve abundance is 5.9×104t/(km2·m). It is a shallow, low-abundance heavy oil reservoir.
The Caogu 1 buried hill oil reservoir was put into full production in July 1997. It has only been 3 years since its comprehensive water content has reached 85.2%, and the recovery level is low, only 6.6%. Due to the complexity and particularity of the Caogu 1 buried hill fractured carbonate reservoir, there is currently insufficient understanding of the problems exposed by the mining performance of the Caogu 1 buried hill reservoir. In particular, there is a big difference in the development effect between the Caogu 1 buried hill oil reservoir and the buried hill thin oil reservoirs that have been developed in my country. For example, when the water content is 80%, the recovery rate of Renqiu Oilfield is about 28%, and the recovery rate of Yanling Oilfield is about 28%. The recovery degree of the oil field is 12%, while the Caogu 1 oil reservoir is only 6.2%; in terms of steam injection huff and puff production, the Caogu 1 oil reservoir also shows different characteristics from the sandy conglomerate heavy oil reservoir, and is basically not as thick as the sandy conglomerate heavy oil reservoir. Typical production change characteristics of thermal oil recovery in oil reservoirs. A new understanding is needed to address the above issues in the Caogu 1 oil reservoir.
3. Numerical simulation model
Establishing a numerical simulation model is the basic and critical step in numerical simulation research. The following focuses on the techniques and methods used to establish crack models and grid models.
1. Fracture model
For numerical simulation research on fractured buried hill reservoirs, the current method is to simplify the multi-porous media of the reservoir into dual-porous media. That includes fracture systems and rock block systems.
This modeling method will inevitably involve three key issues: ① Correctly divide the fracture system and rock system and determine their system parameters; ② Correctly determine the relationship between the two systems; ③ Establish an appropriate mathematical model to describe the reservoir fluid flow characteristics.
1) Lower limit of cracks
Usually, when studying a crack system, it is necessary to analyze the changes in crack width and determine the lower limit of the crack width of the crack system. From the perspective of seepage mechanics, the lower limit of the crack width of the fracture system should be studied and determined based on channel conditions, that is, conditions where capillary force can be ignored.
The research results of Davadant in France show that the lower limit of the crack width with channel conditions is 10μm.
Smekhov of the former Soviet Union pointed out that due to the action of molecular forces, a water film with a thickness of 0.16 μm adheres to the crack wall. When the crack width is greater than 10 μm, the capillary force effect is very small and can be ignored.
Iran A. Saidi believes that when the crack width is 20-30 μm, the capillary force effect becomes very small. When the crack width is 10 μm, the capillary force effect will be reduced to a negligible level.
According to my country’s research results on fracture system throats, the lower limit of fracture system throats in carbonate reservoirs in the Bohai Bay area is 10 to 20 μm.
From this, it can be preliminarily determined that the lower limit of the crack width of the crack system is 10 μm. The fracture system can be defined as: under reservoir conditions, the fracture pore network consists of fractures with a minimum width of 10 μm and connected caves.
Theoretically, determining the lower limit of the crack width of the fracture system is very necessary to correctly divide the fracture system and the rock block system. It can also be achieved through experiments and other means, but this is only a theoretical division. , which is far from enough for numerical simulation research. In numerical simulation research, it is not only necessary to correctly divide the boundaries between the fracture system and the rock block system, but more importantly, determine the parameters of the fracture system. However, this is difficult to achieve under current technical conditions. For example, under the current technical conditions, it is impossible to determine the porosity of the fracture system only through core analysis. The current method is to apply well logging, and the results are also inaccurate. In the numerical simulation study, the fracture system parameters must be used as Unsure of parameters to handle.
2) Fracture system and rock block system
The storage space of the Caogu 1 oil reservoir mainly includes three categories: fractures, holes, and pores. These three types of reservoirs The storage-seepage conditions in space vary greatly. Among them, fractures with different widths and connected caves are the effective storage-seepage space of this type of oil reservoir.
Based on the geological research results of Caogu 1 oil reservoir, the division of fracture system and rock block system and the relationship between the two can be discussed as follows.
The fracture system consists of large and medium fractures and connected caves. The characteristics of the system are low porosity, high oil saturation, strong pressure conduction and flow capabilities, good connectivity, negligible capillary force, high production at a small pressure difference, high oil displacement efficiency, and good fluid connection. The displacement process mainly relies on driving pressure difference, and gravity only plays a role when the reservoir fluid flow velocity is low.
The rock mass system is composed of small and micro-cracks and connected dissolved pores and matrix pores. Its system has high porosity, poor seepage capacity, and low oil drainage efficiency. The system mainly relies on capillary force to self-prime and discharge oil. Gravity can also play a role under certain conditions.
The fracture system and the rock block system are mutually restricted and interconnected. The fracture system is not only a channel for its own oil storage and flow, but also a channel for self-priming and oil discharge of the rock block system. The two form a unified reservoir-seepage combination, with the fracture system in a dominant position.
Based on the geological research results of the Caogu 1 reservoir and the fluid flow characteristics of the reservoir, it can be preliminarily determined that the Caogu 1 reservoir is a dual-pore and single-permeability flow system.
3) Reservoir numerical simulation model
(1) Dual-pore single-permeability model
The commonly used dual-pore single-permeability model (Figure 1). The fracture system is assumed to be the main channel for fluid flow. There is no direct connection between the rock masses and no exchange of fluids. Rock mass systems with low permeability and high storage capacity are considered sources or sinks of fracture systems. In this model, fractures and rock blocks in the same grid are considered to have the same depth, therefore, it is not possible to simulate the effect of gravity flooding within the grid.
On the other hand, when the divided rock blocks are relatively large, it will lead to erroneous calculation results. Especially in the early stages of reservoir development, erroneous simulation results will be produced due to delayed effects of the rock blocks. Using this model to simulate the development process of the Caogu 1 reservoir is correct in describing the fluid flow relationship between the fracture system and the rock mass system, but it will produce erroneous results because it ignores the role of gravity flooding. Therefore, the dual-pore and single-permeability model of the Caogu 1 reservoir was improved.
Fig. 1 Dual porosity and single permeability model diagram
The dual porosity and single permeability model (Fig. 2) of the Caogu 1 reservoir fully considers the influence of gravity and the gravity flooding mechanism. In this model, the rock block is subdivided into several parts in the vertical direction, fluid exchange can occur between sub-rock blocks in the vertical direction, and fluid exchange between sub-rock blocks and fractures occurs in the non-vertical direction. In this model, the sub-rocks and fractures have different depths, and the role of gravity can be reflected. When fluid exchange occurs between fractures and rock blocks, gradient changes in parameters such as pressure and saturation are formed inside the rock blocks. This model fully considers the early effects of the rock mass system and is suitable for bottom water massive oil reservoirs with developed vertical fractures (similar to the Caogu 1 oil reservoir). However, applying this model to simulate reservoirs with horizontal fractures will produce large errors. Therefore, when establishing a numerical model of fractured reservoirs, it is necessary to grasp the main characteristics of the reservoir.
(2) Reservoir numerical simulation model
Figure 3 is a simplified diagram of the Caogu 1 reservoir numerical simulation model. The dotted line is the grid boundary, and cracks are distributed within the grid to form a crack network. In the cracks, the water displacement process is close to piston drive. The relative permeability curve of the oil and water phases used in the numerical model has a diagonal straight line relationship, which is better. The flow characteristics of oil and water in fractures are simulated. The rock block system is cut by cracks and is composed of independent units composed of small cracks and connected dissolution holes. There is no fluid flow between the rock blocks. There is fluid exchange between the fractures and the rock mass. The rock mass system mainly relies on capillary force to self-prime and expel oil. The capillary force curve is used in the numerical model to simulate the oil expulsion process of the rock mass.
Figure 2: Dual-pore and single-permeability model of Caogu 1 reservoir
Figure 3: Simplified digital model of Caogu 1 reservoir
2. Grid Model
Establishing a grid model in numerical simulation actually divides the reservoir into numerous basic calculation units. Each grid appears as a homogeneous body, and the changes in reservoir parameters between grids are used to calculate the model. Describe reservoir heterogeneity. When the heterogeneity of fractured reservoirs is abnormally severe, large grid step sizes will produce large errors. Theoretically, the finer the grid is divided, the more realistic the description of the reservoir will be, and the more accurate the simulation calculation results will be. At the same time, the calculation time will be correspondingly prolonged. Therefore, what grid step size should be used and what should be used when establishing the grid model? The type grid system is very important. On the other hand, for fractured reservoirs, when establishing a grid model, in order to reduce calculation errors, the grid axis direction should be consistent with the direction of fracture development. The Caogu 1 reservoir grid model uses corner grid technology to establish a grid system with a grid step size of about 30m. The X-axis direction of the grid model is consistent with the direction of the main fractures, which reduces the impact of the grid shape on the calculation results. the resulting error.
From the perspective of historical matching, the established numerical simulation model of the Caogu 1 reservoir basically reflects the actual characteristics of the reservoir, and the established dual-pore and single-permeability model captures the main contradiction of the reservoir .
IV. Research on the development rules of Caogu 1 oil reservoir
Caogu 1 oil reservoir is a buried hill heavy oil reservoir and there is currently no experience that can be used for reference. For buried hill thin oil reservoirs, China has a 30-year development history and has accumulated rich development experience, which should serve as a reference for the development of the Caogu 1 reservoir. The Renqiu Oilfield, which has been developed successfully, and the Yanling Oilfield, which has a similar reservoir type to the Caogu 1 oil reservoir, were selected for comparative analysis. The biggest difference in reservoir types between Caogu 1 and Renqiu and Yanling oil fields is the nature of the crude oil. Judging from the comparison of development effects, the development effects of the three oil fields are quite different. When the water content is 80%, the recovery degree of the Renqiu Oilfield is 28%, the Yanling Oilfield is 12%, and the Caogu 1 oil reservoir is only 6.2%; when the water content of the three buried hill oil fields is from 40% to 80%, the recovery degree is 4% to 5%, there is basically no difference; it can be seen that the main reason for the poor recovery effect of the Caogu 1 oil reservoir is that the recovery degree of the reservoir in the low water content stage is too low. When the water content is 40%, the recovery degree is only 1.02%, while the Renqiu Oilfield It is 24% in Yanling Oilfield and 8% in Yanling Oilfield.
1. Water content change rules
From the reservoir development water content curve, the Caogu 1 oil reservoir has the following characteristics: ① After the oil well is put into production, it is a low water content stage, with basically no Waterless oil production period; ② Water content rises quickly, and low water content oil production period is short.
There is no water-free production period after the oil well is put into production, which is rare in other oil fields. Judging from the simulation results, this situation should be an inherent characteristic of the Caogu 1 oil reservoir. The reason for water production is that the Caogu 1 oil reservoir is a special and super heavy oil, and the initial development stage is a short-term elastic production stage. The oil layer pressure drops rapidly, and the original reservoir balance condition is broken, causing pore shrinkage and bound water expansion. , causing water to change from a non-flowing state to a flowable state. At the same time, the high oil-water viscosity ratio leads to an increase in the flow ability of water, which is reflected in the water cut of the oil well. It is a low water cut stage in the early stage of production. In the same geological model, this situation rarely occurs in thin oil reservoirs. . Using the same geological model, the thickened oil is crude oil of 30 mPa.s, and the simulation result is that the water content is 0 after the oil well is put into production.
Another reason that affects the water content of oil wells is the rapid breakthrough of bottom water (low water content results in a short oil production period). For example, 1 year after Well Cao 100-Ping 1 was put into production, the water cone height reached 150m and bottom water was reached. Reflected on the water cut of the oil well, the production well showed low water cut, short oil production period, and rapid increase in water content. From the analysis of the physical process of water cone formation in bottom water massive oil reservoirs, it can be seen that the mining effect of the oil reservoir is closely related to the properties of the crude oil. The difference in oil and water gravity plays a role in stabilizing the water cone during the coning process of bottom water. The gravity of crude oil in the Caogu 1 reservoir is similar to that of water, so the difference in oil and water gravity plays a much smaller role in controlling the height of the water cone. This is also an important reason for the rapid rise in water content in the Caogu 1 reservoir.
2. Oil-water movement rules
The mining of Caogu 1 oil reservoir is mainly driven by bottom water, and the oil-water movement reflects the characteristics of two oil-water interfaces and three oil-water distribution zones. As the oil reservoir is exploited, bottom water rushes toward the bottom of the well along the fractures in the near-well area, forming a water cone at the bottom of the well. The height of the water cone and its changes are the main factors affecting changes in water content in oil wells. The water cone height is mainly affected by reservoir conditions, well layout, liquid production rate, and crude oil properties. In the far-well zone, the rising bottom water forms an oil-water interface in the fracture system and an oil-water interface in the rock block system in the reservoir. The three-dimensional display of numerical simulation shows that the oil-water interface of the Caogu 1 reservoir is a dynamically changing irregular surface, and its shape is affected by reservoir conditions and production conditions. The oil-water interface of the fracture system is the commonly measured oil-water interface. Its height and change are mainly affected by the liquid production speed. If the liquid production speed is reasonable, the oil-water interface of the fracture system rises slowly, and the self-priming and oil-drainage process of the rock block system is sufficient, it can Achieve higher oil discharge efficiency and achieve good development results.
With the development of the reservoir, the fluid in the Caogu 1 reservoir has obvious zoning characteristics in the longitudinal direction. From top to bottom, it is the oil-bearing zone, the oil-water transition zone and the water-flooded zone. In the oil-bearing zone, oil production is the main one; in the oil-water transition zone, oil and water come out at the same time, and water production is the main one; the water-flooded zone has lost its oil production capacity. The size of the water-flooded zone mainly depends on the reservoir conditions and the size of the production volume, while the size of the transition zone mainly depends on the oil production rate.
By analyzing the oil and water movement process of the Caogu 1 oil reservoir, it can be seen that the Caogu 1 oil reservoir and other bottom water massive buried hill oil reservoirs have great similarities in the bottom water rising pattern. . The degree of fracture development and water cone height in the near-well zone determine the bottom water breakthrough time of the oil well. In order to delay the bottom water breakthrough time and control the rise in water content, the oil production rate of a single well should be controlled; the oil-water interface of the fracture system and the oil-water interface of the rock block system in the far-well zone The rising speed mainly affects the oil displacement efficiency and development effect.
3. Stages in the development process
The development process of fractured buried hill reservoirs has obvious stages. In different development stages, various factors that affect development effects play different roles. According to the dynamic characteristics and main contradictions of different development stages, corresponding comprehensive adjustment measures can be taken to improve development effects. According to the development practice of fractured buried hill reservoirs in my country, it is more reasonable to use a method that comprehensively considers changes in oil production and water content to divide the development stages, because the oil production and water content of this type of reservoir affect the development process and development effect. Two important factors that restrict each other. Taking into account the changes in oil production and water content, the development process of the Caogu 1 buried hill reservoir can be divided into three stages: production increase (production stage), production decrease, and low-speed and slow decline.
There is basically no high-production and stable-production stage in the development process of this reservoir, which is similar to the production process of some small and medium-sized buried hill oil fields (such as Yanling, Wangzhuang, and Yihezhuang oil fields) under high-speed mining conditions.
Numerical simulation results show that the oil production in the first development stage of the Caogu 1 reservoir accounts for 37% of the recoverable oil, the second stage is 50%, and the third stage is 13%. Compared with the oil production in the development stages of some small and medium-sized buried hill oil fields (the oil production in the first development stage accounts for 14.5% of the recoverable oil, the second stage is 55.7%, and the third stage is 29.8%), the Caogu 1 oil reservoir is in The oil production volume in the third stage is less. At present, the Caogu 1 oil reservoir is in the late stage of the second development stage and is about to enter the low-speed and low-efficiency development stage. At this stage, the main characteristics are high water flooding, small amount of oil produced per unit time, large amount of water produced, and economical The efficiency is low and the development difficulty is further increased.
4. Factors affecting the development effect
The two main contradictions in the development of fractured oil reservoirs are how to maintain formation pressure and how to control the rise in water content. For the Caogu 1 oil reservoir, the bottom water energy is sufficient and the formation pressure is stable. The following mainly analyzes how to control the increase in water content.
From the perspective of well layout, horizontal wells have greater advantages than vertical wells in controlling water content. The low water cut oil production period of horizontal wells is longer than that of vertical wells, the oil production is increased, and the development effect is significantly better than that of vertical wells. The reason is that horizontal wells can encounter more fractures, have large plane control reserves, and have small production pressure differences, which have a significant inhibitory effect on bottom water coning.
The degree of drilling also has a relatively large impact on the water content and development effect (the degree of drilling is the ratio of the thickness of the intrusion to the oil-bearing section). When the drilling degree of the Caogu 1 oil reservoir is 10% to 20%, it has little impact on the mining effect. When the drilling degree is greater than 20%, the mining effect becomes significantly worse. Therefore, the drilling effect of the Caogu 1 oil reservoir The opening degree should not be greater than 20% of the oil-bearing section.
In the development of fractured reservoirs, the impact of oil production rate on the development effect is very obvious. For the Caogu 1 oil reservoir, when the liquid production volume in a single well is 10m3/d, the recovery rate in the low water cut period is 6%; when the liquid volume in a single well is increased to 30m3/d, the recovery rate in the low water cut period is 1.7%.
5. Effect of huff and puff mining
In the history of Caogu 1 oil reservoir mining, there are two main oil well working systems, steam huff and puff and cold production, among which steam injection huff and puff mining is the main one. Judging from the effect of steam injection huff and puff mining, no obvious benefits have been achieved. After steam injection to open the well, there is no obvious peak temperature and peak liquid volume. The Caogu 1 reservoir did not meet the screening standards for steam injection reservoirs in terms of effective thickness, net-to-gross ratio, porosity, and reserve abundance. On the other hand, steam injection reservoirs specifically require that there be no strong edge and bottom water and no water in the oil layer. There are obvious fractures, and these two points are exactly the basic characteristics of the Caogu 1 oil reservoir. From the perspective of reservoir characteristics, the Caogu 1 reservoir has obvious disadvantages to the thermal oil recovery method.
Steam injection into the oil layer mainly plays four roles: increasing temperature and reducing viscosity, increasing oil phase permeability, increasing formation pressure to increase oil displacement energy, removing well wall contamination and reducing bottom well seepage resistance. According to the numerical simulation, after steam is injected into the reservoir, the steam propagates far along the fractures, has a large heating radius (100-150m), a small temperature rise (10-40°C), and serious heat loss. The biggest role of steam is to remove pollution from the well wall and reduce the seepage resistance at the bottom of the well. From the above analysis, it can be seen that the reservoir characteristics of the Caogu 1 reservoir should be the main reason for the poor thermal recovery results.
6. Research on the distribution law of remaining oil
After several years of development, the oil and water distribution of Caogu 1 reservoir has undergone great changes. At present, the cumulative oil production in the digital model area is 4×104t, and the recovery degree is 8.3%. Oil is mainly produced from well sections with developed fractures. For example, the oil produced from the top 5m of a buried hill accounts for 48% of the entire oil production. Due to the effect of bottom water coning, the bottom layer has a high degree of recovery and has basically lost its ability to produce oil. The remaining oil is mainly concentrated on the top of the buried hill.
The contribution of the fracture system and the rock block system in the mining process is different. The reserve of the rock block system is 30×104t, and the system recovery degree is 1.77%; the fracture system reserve is 18×104t, and the system recovery degree is 19%. Oil production accounts for 87% of the total oil production. Judging from the system contribution value changing curve with time, the contribution value of the fracture system is more than 90% in the early stage of production, and the contribution value in the end stage of production is no less than 60%. It can be seen that the fracture system is the main object of oil production, and its reserves represent The main body of recoverable reserves.
The small contribution value of the rock mass system is due to its low oil drainage efficiency. The oil drainage efficiency of the Caogu 1 oil reservoir rock mass system is 8%, while that of buried hills in North China is 16% to 26%. Mountains can reach 30% to 40%.
There are four main factors that affect the self-priming oil discharge efficiency of rock blocks: ①Heterogeneity; ②Rock wettability; ③Oil-water viscosity ratio; ④Reservoir production speed. The Caogu 1 oil reservoir is very heterogeneous. The rock wettability is weakly hydrophilic, the oil-to-water viscosity ratio is high, and the production speed is too high, resulting in low oil drainage efficiency of the rock block system and large remaining reserves, but it is difficult to Mining.
In the fracture system, the water displacement process is close to piston drive, the oil saturation changes greatly, and the oil drainage efficiency of the fracture system is high. The current remaining oil is mainly distributed at the top of the buried hill, but due to the increase in the oil-water interface, the oil-bearing section has been reduced from the initial 130 to 220m to the current 30 to 80m, making extraction more and more difficult. At present, the oil-water interface in the Caogu 1 reservoir has risen to or close to the bottom of the production well. The driving method is mainly vertical driving by bottom water. It is difficult for oil and water to flow on a flat surface, and a continuous distribution of dead oil is formed at the top of the reservoir. district. Due to the open-hole completion method, the drilling degree is about 30%, and the remaining oil is still considerable. At the same time, it is very difficult to use this remaining oil.
5. Conclusion
The development of buried hill heavy oil reservoirs is a new research category. Through numerical simulation research on the Caogu 1 buried hill heavy oil reservoir, some important insights have been obtained. In terms of establishing a numerical simulation model, it is necessary to correctly divide the fracture system and rock block system and determine their system parameters; correctly determine the flow type of the reservoir; and establish a correct mathematical model according to the reservoir type. In terms of reservoir development rules, the Caogu 1 oil reservoir has many similar characteristics with other domestic buried hill oil reservoirs in terms of oil and water movement rules, and also has similar influencing factors; on the other hand, the Caogu 1 oil reservoir has high oil and water viscosity The ratio creates particularities in the development process.
Main references
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[2] Huo Guangrong, Li Xianmin, Zhang Guangqing. Thermal recovery technology of heavy oil reservoirs in Shengli Oilfield. Beijing: Petroleum Industry Press, 1999.
[3] Chen Yueming. Steam injection thermal oil recovery. Dongying: Petroleum University Press, 1996.
[4] Zhang Jianguo. Oil and gas layer seepage mechanics. Dongying: Petroleum University Press, 1994.