- 目录
### Application of the Fractal Theory to Seepage Mecha

#### SONG Rui, LIU Jianjun

##### Fractal theory, Fractal dimension, Seepage, Porous media

Better understanding of seepage mechanism is of great importance not only in the petroleum technology, but also in the biomechanics, material mechanics and environmental protection. However, it’s hard to describe the complex micro structures of the porous media by traditional geometry. Factual theory is regarded as a useful tool to solve this problem since it was born in 1960s. The development of factual theory and its core content are discussed in this paper. Based on this, the research status of the fractal character of the porous media is stated. Meanwhile, the research results of combing the fractal theory and seepage mechanism in porous media are briefly summarized. Moreover, the existing problems of the application of the fractal theory to seepage mechanism and the author’s opinions are presented, too.

### Predict the Effect of Fracturing Measures by Apply

#### LIU Yikun, WANG Fengjiao, WANG Yongping, HU Chaoya

##### Hydraulic fracturing, Prediction of fracturing effect, Expert System, Effect fracturing factors

Hydraulic fracturing is an important kind of stimulation. However, it is affected by various factors. This paper takes the influence of net thickness, permeability, flow pressure, water cut, injector—producer distance, cumulative injection-production ratio, sand input intensity, pad fluid volume, and sand ratio into account; applies the Expert System to establish the predictive knowledge basement; Divides various effect factors into four grades; and gives the different membership functions according to different grades. 75% prediction results established by the Expert System are the same as actual results, and 21.5% are close to the actual results. Study shows that the established Expert System has the guidance action on the layer selection of fracturing and the fracturing design.

### Flow Characteristic of Aqueous Dispersion System o

#### LIU Qipeng, JING Hong, YANG Baisong, LONG Yunqi

##### Nano/micron-sized polymer particles, Microporous membrane, Flow characteristic, Plugging, Deep profile control

To evaluate percolation ability of aqueous dispersion system of nano/micron-sized polymer particles in porous media, the flow characteristic and its influence factors were studied by laser particle size analyzer and filtration device of microporous membranes which were simulated to reservoir pore throat. The results show that at the same hydration time, plugging capacities of nano/micron-sized polymer particles gradually increase as their average particle sizes increase; at the different hydration time, plugging capacities of nano/micron-sized polymer particles show a trend of increasing first and then decreasing with increasing average particle sizes. With increasing pressure differentials, the plugging capacities of nano/micron-sized polymer particles gradually decrease and their deep profile control capacities gradually increase. When pore sizes of microporous membrane decrease, the plugging capacities of nano/micron-sized polymer particles rapidly increase and their deep profile control capacities quickly decrease. While the particle concentrations increase, the plugging capacities of nano/micron-sized polymer particles increase and their deep profile control capacities decrease.

### The Finite Element Analysis of Stress-Seepage-Temp

#### ZHOU Zhijun, WANG Da, YU Shaohua

##### Heavy oil reservoir, Seepage field, Stress field, Temperature field, Coupling, Theoretical model, Finite element analysis

In the oil and gas extraction process, especially in the high-pressure water or heavy oil thermal recovery processes, reservoir pressure and temperature are constantly changing, which results to the deformation of porous medium, and the reservoir deformation would affect the variations of reservoir pressure and temperature. The interaction between the fluid flow of reservoir pore, temperature changes and the rock deformation is called the seepage-stress-temperature three coupling problem. Putting the rock mechanics, heat transfer, fluid mechanics, petroleum engineering and reservoir physics together, establish the temperature, seepage and stress fields coupling theory mode. Taking thermal recovery wells for example with finite element analysis, studied the law of stress - strain variation with time and space and the law of dynamic variation of petrophysical parameters. The results showed that: the closer from the wellhole, the more significant changes in rock strain, porosity, permeability, compression factor of porosity and other physical parameters; The farther away from the wellhole, the change is less obvious. The change of physical parameters under the coupling condition is smaller than the uncoupled condition. The oil production under the coupling condition is less than the uncoupling condition, which is mainly due to the fluid-solid-thermal coupling effect. The seepage resistance is increasing when fluid flows through rocks, which makes oil production decreased. The establishment of this model gives the theoretical basis for analyses of numerical simulation of thermal recovery, the ground thermal recovery wellbore stability and subsidence caused by mining

### Study of Lateral Pressure Calculation Under Multi-

#### DAI Kui

##### Multi-field coupling, Seepage, Lateral pressure, Water-earth pressure, Foundation, Pore water pressure

The under earth pressure field and water pressure field action, the lateral pressures are provided by multi-field coupling. Neglect of the groundwater seepage field is one of the main reasons why measured values of water-earth pressure on supporting structures are generally very different from those calculated values. Under the action of seepage, seepage force changes soil effective stress and affects soil shear strength. We set up legitimate equations through calculating the interaction of the hindering force and seepage force under a multi-field coupling. KEYWORDS: Multi-field coupling, Seepage, Lateral pressure, Water

### Study on the Change Rules of Reservoir Parameters

#### LI Jishan

##### Porosity, Permeability, Time-variant, Water flooding development

During the conventional flow theory analysis, the porosity and permeability are usually considered as the constant. However, the production practice in water flooding oil fields has proved that, reservoir parameters will change due to the influence of long time water flooding. The present study on time-variant characteristic of reservoir parameters is limited in the qualitative analysis of time-variant mechanisms and statistical description of reservoir parameters change, only several authors introduce the time-variant characteristic into numerical simulation. In this paper, with deep analysis on time-variant mechanism of water flooding, reservoir parameters and the continuum damage mechanics, the mathematical modeling of porosity and permeability with time-variant mechanism is built, and the quantitative relationships among porosity, permeability and time-variant parameters are described. Then, mechanical model is proposed to describe the basic reason and mechanic basis of time-variant parameters for the first time, mathematical derivation is processed in detail and the final results are verified by experiments results. Results show that, the reservoir permeability increases with flooding times increasing, the permeability change times have a linear relationship with 3/4 power of flooding times.

### Minimizing Subsurface Geological Uncertainties Usi

#### SUN Pengxiao, Dwandari Ralanarko, Julius Sunarta

##### Production optimization, Water flooding, 4D seismic time lapse

Widuri field, one of the major mature fields in South East Sumatra (SES) block, has a cumulative oil production up to 357 MMBO. There are several productive reservoirs, mainly in Talang Akar Formation (TAF). These reservoirs are generally classified into two types of drive mechanism, i.e. water drive and depletion drive. Current recovery factor in depletion drive reservoir is not optimum, and needs to be increased by IOR. Water flooding is one of the effective methods to overcome pressure depletion by injecting water to the reservoir. Water flooding, a very common method of secondary recovery, will improve oil reservoir sweep efficiency and eventually increase reservoir recovery factor. One of challenge in water flooding is establishing reservoir uniformity, connectivity and fluid content. This obstacle can be solved using time lapse 4D seismic. Time lapse 4D seismic has been applied to be effective for monitoring pressure decrease and subsequent water flooding sweep patterns. Practically, this method is used to map differences in seismic response over time attributable to production related processes, especially amplitude response which directly interpreted as replacement of oil by dissolved gas, and also indicating re-pressuring at the reservoir. Comprehensive analysis of time lapse 4D seismic has been well implemented for increasing infill and injector success ratio, as well as predominating pressure degradation in Widuri field.

### Screening and Evaluation of New Surfactants Used t

#### LI Xin, CAO Guangsheng1, CHEN Xin, WANG Yang, W

##### Steam flooding, Control H2S, Surfactant, Heavy oil reservoir

A high-temperature resistant surfactant is usually mixed into steam to reduce oil-water interfacial tension and enhance oil displacement efficiency in the process of heavy oil development. At present, S is produced in steam flooding wells under any of the following three circumstances. The higher temperature of oil recovery is and the longer production time is the higher content of H2S becomes. Thus, the genetic mechanism of H2S relates to the thermo-chemical decomposition sulfur- containing compounds and the thermo-chemical reduction of sulphate in crude oil. Also, the additives such as sulfonate and sulphite, has the same genetic mechanism of producing H2S. Now, a high-temperature resistant surfactant is mixed into steam to reduce oil-water interfacial tension and enhance oil displacement efficiency greatly in Jinzhou oil production plant. For the sake of providing a basis for the development of heavy oil reservoir with steam mixed with an appropriate surfactant, we screened and evaluated three types of non-sulfur surfactant through experimental study in laboratory.

### A Practical Solution for Water Invasion Calculatio

#### ZHANG Jicheng, LI Qi, HE Xiaoru

##### Edge water, Bottom water, Water invasion, Material balance, Solution method

When calculating reserves or predicting performance of reservoirs with edge water or bottom water energy, we must consider the impact that natural waters had on reservoir development dynamic, make the evaluation of reservoir capacity of natural energy accurately. In view of the steady state water invasion, quasi-steady state water invasion, modified steady state water invasion and non-steady state water invasion of four types of water influx, this paper gives a practical solution method which based on the principle of material balance. It has certain significance for the calculation of the water influx energy of edge and bottom water reservoir and the prediction of development index.

### A New Efficient Calculation Procedure for Equivale

#### ZHANG Shiming, WU Xiaodong, YAN Xia, HUANG Z

##### Oversample technology, Fractured reservoir, Equivalent permeability, Discrete fracture modeling, Finite element method

The existing calculation procedure for equivalent permeability of fractured reservoir is inaccurate when handling large fractures. In this work, we have developed a new efficient procedure to obtain the equivalent permeability of fractured reservoir based on oversample technology, which means using the peripheral region in the object gridlock. Firstly, the oversample technology is implemented on all gridlocks. Then, an efficient discrete fracture numerical simulation is implemented in each oversample grid with constant pressure-no flow boundary by using Galerkin finite element method. After that, the equivalent permeability can be obtained based on the volume average method and Darcy’s law. At last, several numerical examples have been shown to verify the validity and accuracy of our procedure.

### Research on the Fatigue Life of the Wellbore of th

#### XIA Rui, DONG Shier, YANG Dezhi, LYU Hengfu

##### CNG, Underground gas well, Fatigue life, Pit defect, Numerical analysis

This paper establishes an appropriate finite element model according to the structure and operating characteristics of gas wells, and then conducts fatigue analysis to wellbore casing containing pit defects. The results show that the fatigue life of the outer surface is slightly longer than which of the inner surface when the pit depth Z is less than 5mm, but both are the same when Z is greater than 5mm. Furthermore, for pits with equal sharpness (the ratio of long axis to depth 2X/Z is equivalent), degree of fatigue failure will be greater if the ratio of depth to wall-thickness ratio (Z/B) is larger. It gives the suggestion that defining shrill pit of which 2X/Z is greater than 1.5, Z/B is greater than 0.6 as dangerous pit and taking it as judgment standard of critical defects in wellbore detection projects, which provides the basis for the next amendment of specification (SY/T6535-2002).

### Experimental Study on the Law for Permeability of

#### LIU Jie, ZHANG Yongli, SU Chang, ZHANG Yao, CUI Ho

##### Permeability, Heat, Stress, Coupling effect

The law for permeability of coal body containing methane considering coupling effect of heat and stress has been experimentally researched in this article. Permeability measurement experiment has been done under different axial compression, confining pressure, pore pressure, and temperature by using the Triaxial Permeameter. Through analysis of the experimental results, the permeability of coal presents an increasing trend with the increase of pore pressure, and the increasing trend is more significant with the increase of temperature. The permeability of coal presents a decreasing tendency with the increase of effective stress, and the decreasing tendency is more significant with the increase of the temperature.

### Coupled Analysis of Thermo-Hydro-Mechanical Field

#### LIU Naifei, LI Ning, WANG Liping, XU Shua

##### Coupled model, Thermo-hydro-mechanical, Roadbed, Numerical result, Measured data

Multi-field coupling is one of the important forward subjects in geotechnical engineering and the coupled analysis of Thermo-Hydro-Mechanical field is one of the most important parts of the multi-field coupling. Based on the Thermo-Hydro-Mechanical coupling model for frozen soil and the 3G2012 software developed by the coupling theory, the temperature field, deformation field and stress field are investigated in this paper and the numerical results has been compared with the measured data which are well agreed with each other. The results indicated that the deformation of roadbed can be divided into two parts: frost heaving and thaw-settlement. Frost heaving period is from middle of November to next April and thaw-settlement period is from the beginning of May to the next beginning of November. This research result has directive significance to the similar project.

### Study on the Productivity of Multi-fractured Horiz

#### YANG Chuncheng, XU Ziyi, YIN Chao, ZHONG Huiyin

##### Multi-fractured horizontal wells, Ultra-low permeability, Threshold pressure gradient, Productivity

Based on the equivalent radius model, a productivity model for ultra-low permeability reservoirs was developed, which considered the influence of the threshold pressure gradient and the variable mass flow in fractures, and the effect of threshold pressure gradient, fracture number, fracture half-length, fracture angel, and fracture distribution on the productivity were analyzed. The results show that the greater the threshold pressure gradient, the greater the effect of it on multi-fractured horizontal well productivity, so the threshold pressure gradient must be accounted to evaluate the productivity in ultra-low permeability reservoirs; with the increase of fracture number, fracture half-length and fracture angel, the productivity increases; in order to obtain higher productivity, the angle between the fracture and horizontal well should be between 75 to 90 degree; When the total half-length of the fracture is certain, reducing the fracture interference, the length of the outer fractures should be bigger than that among the inner fractures. The research results provide a scientific basis for the design of multi- fractured horizontal wells in ultra-low permeability reservoirs.

### Research on Coupling Law of Stress Field-Seepage F

#### WU Junxian

##### Gaoqianbei oil field, Seepage field, Stress field, Fluid-solid coupling, Mathematical model, Numerical simulation

On the basic theory of rock mechanics, permeation fluid mechanics, geomechanics and computational mechanics, the mathematical model of stress field-seepage field coupling between oil and water phase in the porous media is established. The coupling law of stress field-seepage field between oil and water phase in Gaoqianbei oil field is researched with ANSYS. The result shows that the strain of reservoir rock affects the production performance in two aspects. Firstly, the rock contraction affected by the descend of fluid pressure in pores increases the energy of elastic-driving, which is benefit for enhancing oil recovery; Secondly, the rock contraction destroys the pore structure of rock, reduce the ability of seeping and oil accumulating, being harm for production performance. The most important is that the influence affected by rock contraction is serious than elastic energy. The descend of permeability and pore because of coupling make the production a decrease in various degree, comparing with non-coupling model. So we must analyze the adverse effect on the production because of coupling effect and draft corresponding production measures, in order to decrease the changing velocity of drawdown pressure and ensure the extent of the damage of the ability of seeping and oil accumulating is the minimum. This paper is the finite element analysis of coupling law of stress field / seepage field in permeable stratum medium.

### Numerical Simulation of the Nonlinear Flow in Tigh

#### SU Haibo, DONG Yajuan, SONG Fuquan

##### Tight sandstone reservoirs, Non-Darcy flow, Boundary layer, Pressure-sensitive effect, Numerical simulation

According to the pore-throat structural feature of cores of tight sandstone reservoirs and boundary layer theory, generalized nonlinear model of tight sandstone reservoirs is established. On this basis, non-linear flow mathematical model of tight sandstone reservoirs is found, and corresponding software is developed. Applying this software, the numerical simulation researches are conducted to the F154 Block, which is a tight sandstone reservoir in Shengli Oilfield. The researches show that, in F154 Block, the expansion rate of drainage radius is fast during initial stage. Effective drainage radius is about 70m and ultimate drainage radius is about 100m.

### Numerical Simulation of Water Coning in a Naturall

#### SHEN Weijun, LI Xizhe, LIU Xiaohua, LU Jialia

##### Numerical simulation, Water coning, Fractured gas reservoir, Water gas ratio, Recovery

Water coning is the tendency of the water to drive gas downward in an inverse cone due to the downward movement of water into the perforations of a producing well thereby reducing gas production and the overall recovery efficiency of the gas reservoir. This work addresses water coning issues in a naturally fractured sandstone gas reservoir via a numerical simulation approach on a single-well radial cross-section using the ECLIPSE 100 reservoir simulator. A parametric study is conducted to investigate and analyze the effect of the most relevant parameters on water coning phenomenon in a naturally sandstone fractured reservoir, such as gas production rate, matrix and fracture permeability, vertical and horizontal permeability ratio, etc. Results show that reservoir parameters that affect water coning include gas production rate, matrix and fracture permeability, vertical and horizontal permeability ratio, well penetration and aquifer size. And fracture permeability, vertical and horizontal permeability ratio, and aquifer size have considerable significant effect on water coning.

### Chromatographic Separation and Its Effect on the E

#### YAO Tongyu, LI Jishan

##### ASP flooding, Chromatographic separation, Multiple adsorption factors, Efficient length

Because of the different adsorption and different mass transfer rule of each chemical, chromatography separation is very serious, resulting in high interfacial tension and low recovery of ASP flooding, so laboratory experiments were conducted to study the chromatography separation. Results show that the concentration changes (c/c0) of different chemicals are different: the c/co of polymer decreases most slowly, while that of surfactant decreases fastest. The slug of the ASP is longer, the chromatography separation is weaker, and the interfacial tension is lower. According to interfacial tension, the efficient length of ASP slug is discussed, and the longer slug has larger efficient length.

### Effect Study of Cr3+ on Polymer Molecular Aggregat

#### LU Xiangguo, WANG Rongjian, CHEN Xin, LIU Yigan

##### Polymer, Organic chromium, Aggregate, Permeability characteristics, Mechanism analysis

Bohai oilfield is characterized by thick layers, high average permeability, serious heterogeneity, high viscosity crude oil and injection water salinity, which resulted in poor water-flooding recovery. So there is an urgent need to take new technologies to improve the water-flooding efficiency. Based on the theories of reservoir engineering, physical chemistry and polymer materials, by means of chemical analysis, instrumental detection and physical modeling, set evaluating indicators of polymer molecular aggregate, viscosity, resistant coefficient and residual resistance factor, set the LD10-1 oilfield reservoir conditions as the study object, conduct performance evaluation and mechanism analysis of the “salt-resistant” polymer solution and the “high molar mass” Cr3+ polymer gel. The results showed that at the early time of adding cross-linking agents to the polymer solution, Cr3+ mainly leads to the cross-linking reaction of different branches (carboxyl) on the same polymer molecular chain. Polymer molecular chains in the polymer gel are mainly “local reticular” aggregate. At that time, polymer molecular clew dimension increase is not big, and the viscosity hardly increases. As time went on, Cr3+ begins to actuate the cross-linking reaction among branched chains (carboxyl) on different polymer molecules, and polymer molecule chains in the polymer gel are mainly “local reticular” aggregate, the viscosity increases prominently, and its compatibility with the oil reservoir becomes poor. Compared with the molecular chain in the salt-resistant polymer solution presenting “linear and branched” aggregate, flexibility of the “local reticular” aggregate in the Cr3+ polymer gel becomes weak, and its rigidity increases, which showed excellent fluid steering capability. What’s more, when Cr3+ polymer gel was diluted by injected water, its molecular clew dimension would increase, and its blocking effect to rock pore was enhanced, which made the residual resistance factor higher than the resistance factor, and showed peculiar permeability characteristics from common polymer solution.

### Study on the Relationship Between the Submerged De

#### LI Dezhong, ZHANG Zhenhua, SUN Qiancheng, DU

##### Gravel soil bank slope, Moment equilibrium, Depth of submergence, Factor of safety

Due to the large pores and high permeability of the gravel soil in bank slopes, when the reservoir water level changes, the structure, strength and the stress distribution of the gravel soil in bank slope will change, which will bring effects on the stability of gravel soil slope exposed to reservoir water level fluctuation. In order to further study the effect of the submerged depth on the stability of bank slope composed of gravel soil, this paper chose standard examination question used for slope stability analysis in ACADS as study object, and derived the formulation between submerged depth and factor of safety of the bank slope based on the principal of moment equilibrium. The study results show that the factor of safety first increases with the increase of the reservoir water submerged depth, and then decreases with the increase in water submerged depth. These results can give references to stability evaluations for gravel soil bank slope when exposed to the reservoir water fluctuation.

### Research of Composite Oil Displacement Effect of M

#### LIU Yikun, YANG Ming, FAN Meng, WANG Xueming, WANG

##### Interfacial tension, Viscoelasticity, Surfactant/polymer system, Displacement characteristics

This paper selected the Daqing Refining & Chemical polymer whose relative molecular mass is 1,900×104, the concentration of the polymer solution is 1,500mg/L, the SS (petroleum sulfonate) alkali free binary system, and the sodium carbonate ternary system are concentration components to achieve ultra-low interfacial tension, and on this basis the viscoelastic properties, viscosity and oil displacement experiments were simulated. Research shows that the concentration of the surfactant in ASP system is 0.3%, the alkali concentration is 1.2%, and the interfacial tension can reach 10-3mN/m; surfactant concentration of the binary system is 0.3%, which can reach 10-3mN/m. Because of the absence of alkali, the viscoelastic properties of the monomer are higher than that of the composite system. In the composite systems, elastic properties of the binary system are better than the ternary system. Artificial heterogeneous oil displacement experiment results show that recovery rate of the alkali free binary system reached 30.1%, which is 6.7 percentage points higher than the single polymer, and 2.7 percentage points higher than the ASP composite system.