Table of Content

01 June 2017, Volume 39 Issue 3

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Control of Paleogene Reservoir by Tectonic Activity in North-western Margin of Bozhong Sag

PANG Xiaojun

2017, 39(3):  1-12.  DOI: 10.11885/j.issn.1674-5086.2016.01.12.01

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This study provides a quantitative analysis of features associated with tectonic activity in the north-western margin of the Bozhong Sag, with the aim of clarifying the relationship between reservoirs and tectonic activity. Using data from drilling, logging, three-dimensional seismic survey, and laboratory analysis, with related materials and the fault activity rate, the control of tectonic activity over the reservoir with respect to settlement rate, reservoir distribution, and physical characteristics is determined. The results show that, for the same period, fault activity varied in different locations. Es3 and Ed3 were characterized by strong fault activity, corresponding to a period of strong fault basin subsidence, and as the distance between settlement center and the boundary faults was short, they mainly developed into fan deltas with thick and coarse granularity. Es1 and Es2 had weak fault activity, corresponding to a weak rift basin, and as the distance between the boundary faults and subsidence center was relatively great, they mainly developed into braided river deltas with thick and coarse granularity. Ed2 had strong fault activity, corresponding to the transition stage, was less affected by the late boundary fault and more by distant provenance, and developed into braided river deltas with fine granularity, low thickness, and greater extension. Ed1 was characterized by very weak fault activity, and developed into braided river deltas with low thickness and long extension, mainly regulated by secondary fault activity. Border faulting controls the location of clastic sediment input to the basin, while secondary fault activity plays a regulatory role in the spread of clastic sediments. Regional tectonic uplift significantly improves the fan delta tight reservoir. This finding provides a reference for reservoir prediction in areas of low exploration with a similar tectonic setting.

Ore-forming Fluids Characteristics of Fluorite Deposits in Gudongkeng, Jinyun County, Zhejiang Province

FANG Yi, ZHONG Xiang, BAI Tiantian

2017, 39(3):  13-22.  DOI: 10.11885/j.issn.1674-5086.2016.12.05.01

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A large-scale fluorite deposit is located in Gudongkeng, Jinyun County, Zhejiang Province. Tectonically, it is located at the northeastern side of the Cathaysia Plate, adjacent to the Qinhang (Qinzhou Bay to Hangzhou Bay) bonding zone. The Gudongkeng fluorite deposit occurs in the contact zone of the Lower Cretaceous Guantou Group and Late Yanshan granite. The ore is strictly controlled by a NW-striking structure. Based on a systematical geological survey, studies were carried out on trace elements, rare earth elements, and fluid inclusions. The results show that the light rare earth in the Gudongkeng fluorite is a relatively weak enrichment and that the heavy rare earth is depleted relatively weakly. The fluorite has a strong Eu negative anomaly and a weak Ce negative anomaly. The distribution plots show a typical "V" shape feature. According to the La/HoY/Ho diagram, the fluorite samples in different positions show a tendency for recrystallization. The Tb/Ca-Tb/La diagram indicates that this fluorite is a hydrothermal genetic deposit. The temperature measurement results of fluid inclusions show a homogenizing temperature of ore-forming concentrates between 150 and 190℃. The salinity concentrates are between 0.3 and 1.5 NaCl equiv. The average density is 0.86 g/m³. The ore-forming fluids are characterized by medium-low temperature, low salinity, and a medium-low density NaCl H₂ Osystem. It can be inferred therefore that the fluorite deposit in Gudongkeng is a medium-low-temperature hydrothermal, fracture-filled deposit.

Main Controlling Factors of the Karst Dolomite Reservoir of Ma 5 Member in Daniudi Area

BAI Xiaoliang, ZHANG Shaonan, DING Xiaoqi, ZHAN Xiaohong, CHEN Quanjian

2017, 39(3):  23-33.  DOI: 10.11885/j.issn.1674-5086.2016.02.28.01

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We discuss the main controlling factors of the karst dolomite reservoir of the Ma 5 Member in the Daniudi area, with the aim of understanding its complexity and diversity. Through core and thin section observation, and analysis of porosity and permeability properties, we studied the petrology, reservoir space, and physical properties of the dolomite reservoir. Based on this analysis, we constructed a reservoir identification standard using well logging data, and inferred the main controlling factors of the dolomite reservoir through logging interpretation, the residual thickness of crust, and the profile of connected wells. We concluded that:(1) the hollows in the karst topography were intensively corroded, and had developed into collapse breccias which display weak reservoir properties, and the karst upland reservoir is generally superior; (2) lithologic differences determine the extent of dolomite reservoir dissolution, with gypsum dolomite being simultaneously corroded and collapsed and it is distributed in a comparatively wide area. However, serious collapse may occur vertically, which contributes to karst development. Solution pores and cracks, which are conducive to reservoir development, can easily develop in gypsum-bearing dolomite; (3) different dolomitization causes dolomite reservoir heterogeneity. Micrite dolomite in the penecontemporaneous period is tight and more pore spaces have developed powder-fine dolomite. Both types are interbedded, which makes the reservoir vary greatly laterally, but relatively continuous horizontally.

Multi-parameter Analysis of Identifying Micro Amplitude Structures by Moving Trend Surface Method

WU Yong, MA Teng, WANG Yu, ZHOU Lu, ZHOU Yadong

2017, 39(3):  34-46.  DOI: 10.11885/j.issn.1674-5086.2017.01.10.03

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The Qiketai Formation is located in the Pubei Region of the Turpan-Hami Basin. Within the formation, microamplitude structures (MAS) form a favorable tectonic zone for hydrocarbon accumulation. Presently, the resolution of seismic data limits seismic interpretation technologies, making them unable to satisfy the requirements for fine-grained identification of MAS. As an alternative, the moving trend surface method, was used in this study to repeatedly test and analyze MAS. The preferred selection methods for three critical parameters-number of fits, sampling interval, and radius of influence-were also comprehensively studied. After quadratic fitting was selected, the optimal combination of parameters for MAS identification using the moving trend surface method were found to be:(i) the sampling interval for the maximum degree of fit, and (ii) a radius of influence that was two times the sampling interval. These findings were useful for optimizing parameters for MAS identification in the Pubei Region. MAS were found to be mainly distributed along the axis of the nose-shaped tectonic setting and the northeastern slope. Their distributional characteristics were in agreement with the results found during drilling of the hydrocarbon areas.

Comprehensive Classification and Evaluation of Low Permeability Reservoirs Based on the Identification of Complex Lithological Characteristics

NIU Tao, WANG Hui, HU Xiaoqing, ZHANG Yukun, GAO Yufei

2017, 39(3):  47-56.  DOI: 10.11885/j.issn.1674-5086.2016.01.28.02

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The SHA1 and SHA2 reservoirs of the Q oil field have widely-developed mixed sedimentary rocks composed of terrestrial debris and lacustrine carbonates. The mixing of these sediments in varying degrees and forms has resulted in a variety of lithological combinations; as a whole, the SHA1 and SHA2 reservoirs are low-porosity/low-permeability reservoirs. In view of the complex lithology and low porosity/permeability of this oil field, the data obtained from rock cores, casting sheets, cathodoluminescence and elemental capture spectroscopy (ECS) logging were used to establish a comprehensive evaluation method for low permeability reservoirs based on the identification of complex lithological characteristics. This method uses 7 evaluative parameters including lithological characteristics, effective thickness, permeability, porosity, displacement pressure, median radius, and sorting coefficient, in which displacement pressure, median radius, and the sorting coefficient are the structural parameters of microscopic pore throats which are obtained via mercury porosimetry. An analytic hierarchy process was then used to obtain the weights of each parameter and the comprehensive evaluative parameters of the reservoir, under constraints applied by the reservoirs' geological conditions. Based on this method of evaluation, the reservoirs in this region were classified into three types; in particular, the lithology of Type I reservoirs is mainly composed of silkites and oolitic sandstones with well-developed dissolution pores, high levels of pore connectivity, and have excellent deliverability test results. Hence, this is the "sweet spot" of these low-permeability reservoirs.

Quantitative Evaluation of Hydrocarbon Lateral Passage in the Southen Part of Bodong Low Uplift

ZHANG Hongguo, GUAN Dayong, LIU Pengbo, MA Xugang, SU Kai

2017, 39(3):  57-65.  DOI: 10.11885/j.issn.1674-5086.2016.03.20.01

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Uncertainty about the lateral passage and migration capability of hydrocarbon in the southern part of the Bodong Low Uplift influences the establishment of a reservoir-forming model, as well as Neogene exploration. Based on the well drilling and logging data, together with the extraction of seismic attributes and the observation of the rock core, hydrocarbon migration was analyzed in the study area. This study concludes that the lateral passage of a sand body in the Guantao Group was subject to the degree of development of a long-lived fault embedded in the hydrocarbon source rock, and its sand-carrying capacity. The passage layer and cover layer at the surface of the unconformity at the top of a buried hill of volcanic rock have a good configuration relationship. The semi-weathered rock has developed primary and secondary pores and fractures, and the buried hill extends to a deep depressional area at the end of the ramp, which is the main lateral passage for hydrocarbon. Based on the establishment of a reservoir-forming model, the lateral migration capability is affected by the contact length between the migration ridge of the carrier ridge of the buried hill and the source rock, the dip angle of the ridge, and the trap area on the ridge. A migration index of semi-weathered rock was established to reflect quantitatively the lateral accumulation capacity, which facilitates practical Neogene exploration.

Sedimentary Evolution and Exploration Prospects of Axial Channel in Ying-Qiong Basin

HE Xiaohu, ZHANG Yingchao, ZHANG Daojun, CHEN Yang, HUANG Can

2017, 39(3):  66-76.  DOI: 10.11885/j.issn.1674-5086.2015.12.31.01

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Channel sandstone is the most important oil and gas reservoir type in deep-water sedimentary systems. A large-scale axial channel deposition system is present in the Yinggehai and Huangliu Formations in the Ying-Qiong Basin. Axial channels are considered an important area for oil and gas exploration in the Ying-Qiong basin, and are valued by domestic and international companies. However, due to a lack of systematic understanding of the formation mechanism and distribution of sandstones in such axial channels, exploration thus far has been unable to yield a commercial breakthrough. This study aimed to resolve issues of provenance and reservoir distribution, which have restricted the exploration of axial channel depositional systems. The central valley, which is the most representative axial channel in the Qiongdongnan Basin, was taken as an example. Combined geological and seismic analysis, multi-attribute integration technology, seismic sedimentology, and other new technologies suited to canyon channel systems were applied in this study. We then carried out targeted research on the provenance system, sedimentary evolution, and reservoir distribution, thereby clarifying the provenance, sedimentary evolution and quality reservoir distribution patterns of the central valley channel. We have also established a sedimentation model and channel sandstone superimposition method for the central valley, which could be used to predict the structure of the reservoir. Our results revealed the existence of four potential large lithologic traps, such as in the Ledong 10-1 Valley channel. These areas are favorable for the next step of exploration of axial channels, thus greatly enhancing their exploration potential.

Sand Control Model and Exploration Practice for East Wushi Sag Strike Slope

XU Xuefeng, HU Lin, MAN Yong, XUE Hongtao, LI Anqi

2017, 39(3):  77-84.  DOI: 10.11885/j.issn.1674-5086.2016.03.21.02

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Considering the key problems of complex sediment provenance, rapid facies variation and difficulties in locating and predicting high-quality reservoirs in the Wushi Sag continental rift basin, we have carried out a detailed analysis on the fault evolution stage, plane activity variability along the fault cross-section, and sedimentation system. Using key techniques, such as fine identification and description of marine continental complex fault block/fault, micro landform restoration, and faciescontrolled reservoir prediction, we arrived to the conclusion that the dominant sand-body distribution could be determined from the strike slope formed by differential activity of three NE-direction sedimentary faults. We have also proposed a source-sink time-space coupling model for sand control, and predicted the development of a high-quality reservoir on the downthrown side of the F₂ fault. Guided by these results, a new drilling was initiated, which led to the discovery of a major oil reservoir. This has greatly promoted the exploration and development of the Wushi Oilfield.

Permeability and Electrical Response Characteristics of Rocks Under Effective Stress

WANG Minpei, CHEN Meng, LI Min, TANG Yanbing, LI Linfang

2017, 39(3):  85-96.  DOI: 10.11885/j.issn.1674-5086.2016.05.26.03

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This study focused on the influence of the effective stress change on the permeability and the formation factor of sandstone reservoirs. By analyzing the deformation rules of differently shaped pore throats under effective stress, we inferred the influence of the change in effective stress on five structural parameters:coordination number (z), pore throat distribution variation coefficient (V_r), hydraulic radius (r_H), pore throat length (l), and pore throat cross-section aspect ratio (ε). In combination with BLM model analysis, we inferred that three types of corresponding relationships exist between the formation factor, permeability, and effective stress:exponential, linear, and log-linear. Moreover, we selected experimental data on the effective stress response of sandstone from different areas, which were verified using different physical properties and varying formation factors and permeability. The results show that the change in the formation factors and permeability of highly porous and highly permeable sandstone under effective stress is mostly caused by changes in the hydraulic radius (r_H) and is manifested through pore throat deformation. The change in the formation factor and permeability of low-porosity low-permeability sandstone samples under effective stress is mostly caused by the coordination number (z) and hydraulic radius (r_H) and is manifested through changes in both pore throat shape and connectivity.

Quantitative Study on Abnormal High Pressure by Extrusion Effect

ZHOU Penggao, LI Yashuang, LIU Yan

2017, 39(3):  97-102.  DOI: 10.11885/j.issn.1674-5086.2015.08.14.02

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Pore volume in closed formation reduces when it is squeezed, and the compressed fluid that cannot be discharged in the pores causes the pressure to rise. A number of previous studies have argued that the tectonic compression effect is one of the main factors that lead to abnormal pressure. However, instead of a quantitative analysis, current studies have paid attention solely to qualitative analysis. In this study, stratum elastic compression caused by extrusion effect was investigated by close reasoning based on the double effective stress theory and the poroelasticity theory, by which the theoretical calculation formula of pore pressure coefficient increment was calculated. Quantitative calculation suggest that, under certain geological conditions, squeezed closed formation leads to a small increase in pore pressure and a slight pressure abnormality, with a limited increment of pore pressure coefficient. It was possible to cause abnormal high pressure by the extrusion effect only when the following occurred simultaneously:stratigraphic burial was sufficiently deep, the strength was sufficiently high, the sealing property of the surrounding rocks was excellent, extrusion occurred in the direction of minimum horizontal stress, and the external extrusion was sufficiently high. The extrusion effect could not generate abnormal high pressure, nor did it serve as the main cause.

Investigation of Unstable Production Decline in Fractured Low-Permeability Gas Reservoir Horizontal Wells

CAO Lina, LI Xiaoping, LUO Cheng, ZHANG Jiqiang, TAN Xiaohua

2017, 39(3):  103-110.  DOI: 10.11885/j.issn.1674-5086.2016.03.21.03

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With respect to the problem of starting pressure gradients during the low-speed flow of a gas from low-permeability gas reservoirs, a flow model was constructed, solved, and qualitatively analyzed. Using a low-speed non-Darcy flow mechanism, a model of the unstable flow in fractured low-permeability gas reservoir horizontal wells was constructed with the starting pressure gradient taken into account. The mathematical model was solved and a typical curve of production decline in the horizontal wells was plotted. The last solution of this flow model, that is, the unstable production of low-permeability gas wells under constant pressure production conditions was used to provide the theoretical basis for the use of graph fitting methods to assess the reservoir parameters. Analysis of the effects of the starting pressure gradients and other related parameters on the production- decline curve showed that as the starting pressure gradient increased, the storage properties became poorer, the flow became more difficult, the horizontal well production decreased, and the production decline curve shifted downward. With the decrease in the elastic storage ratio, the matrix channeling occurred earlier, the concave down portion of the production derivative curve increased in duration, and the degree of the downward concavity increased. When the channeling coefficient decreased, the concave down portion of the production-derivative curve shifted later and the channeling occurred less easily.

Simulation Study on the Effects of Wettability on Depressurization Based on Lattice Boltzmann Model

ZHANG Chunhua, LIU Weidong, GOU Feifei

2017, 39(3):  111-120.  DOI: 10.11885/j.issn.1674-5086.2015.12.29.02

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Changing the wettability of a reservoir and decreasing the oil-water interfacial tension is an effective method for solving the high pressure water injection problem in low and ultra-low permeability oil fields. However, during in-lab displacement experiments, the surfactant concentration not only affects the interfacial tension between oil and water, but also the wettability of the rock surface. As such, the effect of the surfactant wetting ability on depressurization cannot be accurately evaluated. Lattice Boltzmann models can control the interfacial tension independently through the interaction parameters between fluid and solid, and simulate any change in contact angle. Based on a lattice Boltzmann two-dimensional plane model, considering surface roughness and creating a micro-ladder structure, this study investigated the effects of changing wettability on depressurization rate under the dimensionless parameters of capillary number, Bond number, and viscosity ratio. The results show that with decreasing capillary number, the Bond number and viscosity ratio increase, and with decreasing contact angle, the depressurization rate and depressurization effect improve. There is an optimum range for the contact angle. Continued decrease in the contact angle outside this range produces no obvious depressurization. The changing wettability has a more pronounced effect on the depressurization rate for a porous medium than for a single channel.

Discrete Fracture Network Modeling and Numerical Simulation of Fractured Reservoirs

ZHANG Liehui, JIA Ming, ZHANG Ruihan, GUO Jingjing

2017, 39(3):  121-127.  DOI: 10.11885/j.issn.1674-5086.2016.03.31.03

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Discrete fracture network models have become the focus of much research owing to their ability to better characterize the non-homogeneity of fractured reservoirs. The FILTERSIM multi-point geostatistical method was introduced into the discrete fracture network model to overcome the deficiencies of the Monte Carlo method and to provide a fracture network model for the subsequent numerical simulation of the flow. Based on the oil-water two-phase flow model, the finite-element numerical solution of the degree of oil-water two-phase saturation was derived. Taken together with the constructed fracture network model, the dynamic process of the oil displacement by water and pattern of moisture content increase during single-well injections were studied. The study showed that compared with the homogeneous model, injection of water through the channels of the fracture network in the discrete fracture network model led to the premature emergence of water from oil wells. After the emergence of water from the oil well, the two models exhibited consistent patterns of water cut increase.

Study on the Connection Type of Fracture-cavity Unit in H Block and Water Flooding Development Strategy

XUE Jianglong, ZHOU Zhijun, LIU Yingfei

2017, 39(3):  128-134.  DOI: 10.11885/j.issn.1674-5086.2015.12.08.03

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There is a significant difference in the development effect of water flooding displacement of well groups in fracturecavity reservoir units of H blocks. This study conducted research into the connection type of fracture-cavity units and water flooding development strategy. A geophysical method was used to describe micro-fracture, large-scale fracture, effective matrix, and pores, based on which three connection types of fracture-cavity unit were proposed:underground river karst conduit, largescale fracture, and dispersed fracture with large-scale fracture. Moreover, numerical simulation of and field test research on different fracture-cavity connection units were conducted; a rational water flooding development strategy was developed. The underground river system featured an injection-production relationship of low-injection high-production and cavity-injection underground river displacement production. For different units, there are differences in the matching of dispersed fracture with large-scale fracture and fracture-cavity connection units. As a result, it is advisable to take rational control over the injectionproduction ratio with follow-up dynamic adjustment to improve the recovery ratio of water flooding development and the water flooding displacement effect of connecting units in the block. This study is of reference and guiding significance for the same or similar water flooding development of connected units of fracture-cavity karst reservoirs.

On Misunderstandings of the Rock Lateral Pressure Coefficient

LI Chuanliang, ZHU Suyang

2017, 39(3):  135-140.  DOI: 10.11885/j.issn.1674-5086.2015.10.26.01

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To address the issue of the prediction of rock lateral pressure coefficient in oil and gas engineering, we studied the formation mechanisms of horizontal stress in a medium, and methods for calculating lateral pressure coefficients. We analyzed differences in the horizontal stresses of three different media (water, soil, and rocks) and the engineering significance of the lateral pressure coefficient. Further, we investigated methods for predicting lateral pressure coefficients of rocks. We found that the mechanisms of horizontal stress formation in rocks are completely different from those in water and soil, due to differences in the structure and fluidity of these media. Horizontal stresses in soil and water are produced by their intrinsic weights, whereas horizontal stresses in rocks are primarily generated by tectonic actions. As these tectonic actions vary greatly in strength, the horizontal stresses of rocks also vary over a large range, and the rock lateral pressure coefficient varies between -∞ and +∞. Therefore, methods for calculating the lateral pressure coefficient in soil media cannot be used to calculate the lateral pressure coefficient of rocks. In addition, since methods for predicting the lateral pressure coefficient are based on measurements of crustal stress, the predictions yielded from these methods are meaningless in practice.

Characterization of the Relative Permeability Relationship Based on a Weibull Model

LIU Xilei

2017, 39(3):  141-146.  DOI: 10.11885/j.issn.1674-5086.2015.10.29.01

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This study aims to solve the large inaccuracy in characterizing the relative permeability relationship at ultra low and ultra high water saturations in gas reservoirs. We conducted a thorough analysis of measured experimental data for relative permeabilities of rock core samples. We found a good linear relationship between the natural log of water and oil relative permeability ratio, ln(K_rw/K_ro), and double natural log of normalized water saturation, ln(ln 1/SS_wn). These two parameters fit a Weibull function. On this basis, a new equation for the relationship between relative permeability is proposed based on a Weibull model; this improves the fitting calculation for the relative permeability fractional flow equation. Compared to traditional methods used in reservoir physics, this method and the relative permeability fractional flow equation derived from it, can significantly improve the fitting accuracy for water production rate in the ultra low to medium water cutting period.

Full-Field Modeling and Analysis of Surface Deformations Induced by Gas Injections into Reservoirs

LI Hong, ZHENG Lina, LIU Jianjun

2017, 39(3):  147-157.  DOI: 10.11885/j.issn.1674-5086.2015.03.06.02

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The simulation analysis of ground surface deformation caused by gas injection into reservoir can predict working hazards in the reservoir, provide design guidance of tiltmeter arrays for monitoring rock strata deformations, and calibrate current geological models.It is thus the basis for monitoring ground surface deformations in an effective manner, implementing history matching for practical processes, and inversions and predictions of deep-lying reservoirs.To provide an effective simulation analysis, we have developed a user-controllable large-scale gridding discretization method that automatically converts Eclipse reservoir models and extends them into FLAC^3D full-field geological models, and transforms Eclipse reservoir flow analyses into usable data for FLAC^3D rock mechanics analyses. Thus realizes one-way coupled reservoir simulation-geomechanical modelling. On this basis, we have simulated surface deformation in a large-scale saline aquifer CO₂ storage project that occur after gas injection. Highly accurate numerical computations are required for these studies as the rock mass deformations induced by permeation processes during reservoir injection are very minute. Here, we have demonstrated the causes and have provided solutions for special problems that are encountered during conventional simulation processes, such as limitations in their capacity for approximation. In addition, we have investigated the effect of the underlying stratum thickness of reservoirs in geological models on simulation accuracies.

Numerical Simulation Study on the Stability of K-type Derrick for Deep-water Drilling Rigs

ZHAO Guanghui, LIU Dandan, WANG Weixu, LIU Jing, ZHAO Bo

2017, 39(3):  158-164.  DOI: 10.11885/j.issn.1674-5086.2015.10.31.30

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To address the overall weak protection of a K-type derrick and its potential instability in a severe marine environment, taking the motion responses of a deep-water semi-submersible drilling platform under operation regimes in South China Sea as the research setting, a study was thus carried out on the stability of a K-type derrick that is associated with floating drilling platforms. The dynamic load induced by the dynamic boundary of the platform is exerted on the derrick, which can be equivalent to the inertia force that is applied to the derrick. The transverse component of the gravity imposed on the derrick that is attributed to oceanic wind loads and the tilting of the platform as well as additional dynamic loads induced by heaving motions of the platform was considered. This was essential for computing the force-bearing states and overall stability of the derrick using a finite element. The local stability of various member bars under axial forces and biaxial bending moments was investigated. Further, the front legs of the derrick are equivalent to elastic support beams, and buckling analyses were conducted under the influence of axial compressive forces. Further, the stability properties of this drilling derrick used for land rigs were compared. Results demonstrated that ocean environmental loads decrease the stability of K-type derrick considerably; however, the stability requirement for the above-mentioned operation regimes is still satisfied.

Turbodrill Blade Profile Design Based on the Singularity Distribution Method

GONG Yan, ZHANG Xiaodong, ZHANG Ye, LI Yilan, ZHANG Jin

2017, 39(3):  165-172.  DOI: 10.11885/j.issn.1674-5086.2015.06.14.02

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In terms of blade profile design, using conventional methods for high-speed and small-diameter turbodrills may be challenging in obtaining a satisfactory blade profile. However, the blade profile design for turbodrills using the singularity distribution method is worth pursuing. According to the design process, the number of turbodrill cascade blades, circulation around the airfoil, and velocity of the uniform inflow at infinity should first be calculated. The distribution pattern of the circulation density is then identified. Subsequently, the blade camber line of the turbodrill is designed and smoothened using a sextic polynomial. Moreover, the approach to thicken the blade profile along the blade camber line is investigated in accordance with the airfoil representation methods in the airfoil base, thereby obtaining a thickened blade profile. In addition, the method to calculate the tangent points between the thickened circle and the profile lines of the blade suction and pressure surfaces is determined to provide the coordinates required for blade manufacturing. Finally, the blade profile for a certain type of turbodrill is designed based on engineering data, and the computational fluid dynamics software is employed to simulate its flow field. The simulation results demonstrate the excellent performance of the designed blade profile, which proves the feasibility and effectiveness of the singularity distribution method in the blade profile design for turbodrills, particularly with respect to highspeed turbodrills.

Desulfurization Selectivity and Regeneration Studies of Sterically Hindered Amines

LI Yuntao, LI Lulu, LI Hui, ZHANG Zhi, XU Jilei

2017, 39(3):  173-179.  DOI: 10.11885/j.issn.1674-5086.2016.03.23.03

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A set of devices was designed and constructed for the desulfurization selectivity studies of sterically hindered amines. In the presence of CO₂, the changing patterns of the desulfurization selectivity and regeneration over time of three aqueous sterically hindered amines-TBE (tert-butylaminoethanol), TBDEE (tert-butylaminodiethoxyethanol), and AMP (2-amino-2-methyl-1-propanol)-were investigated. The results showed that the absorption rate of H₂S for all three sterically hindered amines was higher than that of CO₂ and the H₂S absorption rate and desulfurization selectivity initially increased but decreased over prolonged time periods. TBE showed the highest desulfurization selectivity, and its selectivity reached a maximal value of 34 at 22 min. Finally, the desorption regeneration of these amine solutions was carried out via heating reflux, and the effects of desorption duration on the regeneration capacity of amine solutions were studied. The results showed that the desulfurization selectivity of regenerated amine solutions was lower than that of fresh amine. AMP showed the highest regeneration capacity, for which 85% of the absorption rate for H₂S was retained even after 1 h of regeneration.

Influence of Amphiphilic Polymer Functional Monomer on Aggregation and Interface Behavior

YANG Guang, ZHANG Fengying, ZHAO Juan, ZHU Yuejun, CUI Yingxian

2017, 39(3):  180-188.  DOI: 10.11885/j.issn.1674-5086.2015.12.15.01

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The functional monomers, including ethylene oxide and propylene oxide copolymer (m=the number of ethylene oxide, n=the number of propylene oxide, m and n values correspond to m=16 and n=18, m=16 and n=6, m=16 and n=2), phenyl-4-pentene (1-phenyl, 1, 1-diphenyland 1, 1, 1-triphenyl), and 1, 3-bis (dimethyl methylbutyl bromide) 2-acryloyloxy propane (the number of carbon chain is 8, 12 and 16, respectively.) were synthesized as a series of amphiphilic polymer samples. Through steady-state fluorescence experiments, dynamic light scattering, electron microscopy scanning, and transmission electron microscopy, we made a study on m/n values, and on how phenyl and carbon atoms influence the aggregate behavior of amphiphilic polymers and interfacial properties of water and oil. It was found that a spatial network structure formed after adsorption of amphiphilic polymer solutions by a solid surface. In the bulk solution phase, with an increase in the m/n value, phenyl group, carbon number, and the aggregate size, the morphology was denser. In terms of oil-water interfacial properties and emulsion for crude oil capacity, with an increase in m/n values, phenyl and carbon atoms, the lesser the oil-water interfacial tension and the smaller the contact angle, the smaller was the emulsion droplet size.