23 February 2015, Volume 42 Issue 1

    

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油气勘探
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  The multi-staged “golden zones” of hydrocarbon exploration in superimposed petroliferous basins of onshore China and its significance

  Zhao Wenzhi; Hu Suyun; Liu Wei; Wang Tongshan and Jiang Hua

  . 2015, 42(1): 1-12.

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  The hydrocarbon generation model proposed by Tissot et al. points out the temperature and depth of “liquid HC window”, which has become a “golden zone” for hydrocarbon exploration. It has been proved by exploration that multi-staged “golden zones” for hydrocarbon exploration is commonly developed in the superimposed petroliferous basins of onshore China. There are three factors for the formation of multi-staged “golden zones” of HC exploration in the superimposed basins: (1) source kitchens developed with multi-periods and multi-centers which have been verified to lead multi-stages of HC generation with large scale, (2) multi-staged reservoirs develop with large scale, (3) hydrocarbon accumulations occur with the multi-periods and late effectiveness. The conventional source kitchens, dispersed liquid HC-cracking gas kitchens and effective reservoirs with large scale join together to control the distribution of “golden zones” in timing and space. Explorational “golden zones” have the characteristics of inherited stacking and lateral variation. Palaeo-highs, palaeo-slopes, palaeo-platform margins, and multi-period inherited fault zones control the distribution of hydrocarbons in the explorational “golden zones”. The concept of multi explorational “golden zones” helps to deepen the knowledge of new hydrocarbon distributional regularity which revealed recently in China. It shows that there exist economic resources in the deep section of the superimposed basins of onshore China. The hydrocarbon discovery history in the superimposed petroliferous basins has the feature of multi-peaks of proven reserve increase and lasting a quite long period, which indicates a huge potential for future exploration.
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  Formation, distribution, potential and prediction of global conventional and unconventional hydrocarbon resources

  Zou Caineng; Zhai Guangming; Zhang Guangya; Wang Hongjun; Zhang Guosheng; Li Jianzhong; Wang Zhaoming; Wen Zhixin; Ma Feng; Liang Yingbo; Yang Zhi; Li Xin and Liang Kun

  . 2015, 42(1): 13-25.

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  Since the Neoproterozoic, two important cycles of separation and junction of the Rodinia and Pangea supercontinents controlled the formation of the Tethys, Laurasia, Gondwana and Pacifica domains, as well as the sedimentary basin types including craton, passive margin, rift, foreland, fore-arc, and back-arc basins. Sixty-eight percent of the discovered reserves are from the Tethys domain, while 49% of the undiscovered possible reserves are in passive margin basins. Six major sets of source rocks, two types of reservoirs (carbonates and clastics), and two regional seals (shale and evaporite) formed in global evolution of basins. Ten patterns are summarized from the above factors controlling the distribution of global hydrocarbon resources. (1) Conventional-unconventional hydrocarbon is accumulated “orderly”. (2) Distribution of Tethys controls the accumulation of the global hydrocarbons. (3) Foreland thrusting zones control the distribution of structural oil/gas fields; (4) Intra-craton uplifts control the distribution of giant oil/gas fields; (5) Platform margins control the banded distribution of giant organic reef and bank type oil/gas fields. (6) Passive margins control the distribution of giant marine oil/gas fields. (7) Foreland deep slopes control the occurrence of large scale heavy oil and bitumen. (8) Basin deposition slopes control the accumulation of tight oil & gas and coalbed methane. (9) Organic rich deep basin sediments control the retention of shale oil and gas. (10) Low temperature and high pressure seafloor sediments control the distribution of hydrate. The conventional/unconventional resources ratio is 2:8. The conventional resources are mainly distributed in the Middle East, Russia, North America, and Latin America. The unconventional resources are mainly distributed in North America, Asia Pacific, Latin America, and Russia. According to the ten trends of global petroleum industry, hydrocarbon exploration is mainly focused on marine deep water, onshore deep layer, and unconventional oil & gas. The peak of oil production will probably come around 2040, and the life span of petroleum industry will last another 150 years. Renewable energy will replace fossil energy, not for the exhaustion of fossil energy, but because it is cheaper and cleaner.
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  Formation and evolution of Weiyuan-Anyue extension-erosion groove in Sinian system, Sichuan Basin

  Li Zhongquan; Liu Ji; Li Ying; Hang Wenyan; Hong Haitao; Ying Danlin; Chen Xiao; Liu Ran; Duan Xinguo and Peng Ji

  . 2015, 42(1): 26-33.

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  Based on comprehensive analysis of deposition and structure, the horizontal and vertical characteristics of the Weiyuan-Anyue extension-erosion groove have been studied by outcrop, drilling, well logging and seismic data. According to the strata, lithology, structure and regional evolution, Sinian system before the erosion has been reconstructed to show the development and transformation of the erosion-extension groove in the Tongwan movement. The Weiyuan-Anyue extension-erosion groove is distributed along the Penglai-Anyue-Rongchang in NW direction, with the east area steeper than the west in groove. According to the study of the Weiyuan-Longnüsi seismic profile across the middle area of extension-erosion groove, the formation of the Weiyuan-Anyue extension-erosion groove is the synthetic result of different geological processes from differential uplift, differential erosion and dissolution in the Dengying Formation caused by the multiple-phase episode grabon or horst movement of the basement fault in Sinian. The formation of the Weiyuan-Anyue extension-erosion groove can be divided into three stages, and the erosion and dissolution can be calculated quantitatively by denudation recovery profile, its maximum can reach 600 m.
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  Lacustrine fine-grained sedimentary features and organic-rich shale distribution pattern: A case study of Chang 7 Member of Triassic Yanchang Formation in Ordos Basin, NW China

  Yuan Xuanjun; Lin Senhu; Liu Qun; Yao Jingli; Wang Lan; Guo Hao; Deng Xiuqin and Cheng Dawei

  . 2015, 42(1): 34-43.

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  The Chang 7 Member of Triassic Yanchang Formation in Ordos Basin is taken as an example to study the distribution rule and major controlling factors of the fine-grained sedimentary system by core description, thin section observation, X-ray diffraction, geochemical testing and TOC well logging quantitative calculation. The main sedimentary pattern of organic-rich shale in Chang 7 Member is transgression–water layering. The sedimentary facies, water depth, anoxic condition and lacustrine flow are the major controlling factors for the formation and distribution of organic-rich shale. During the deposition of the Chang 73 Member, lake water invaded rapidly, lake depth and scope sharply increased. Because of the temperature difference, the circulation between upper surface water and lower water in deep lake was restrained, then large-area anoxic environment was formed in deep lake, which was favorable for the development of organic-rich shale. In silent deep lake that is far away from the delta front, organic-rich shale was well developed, with high organic carbon content and mainly type I kerogen. In deep lake where sandy debris flows developed, organic-rich shale was inter-bedded with sandstone, which contains high organic carbon content, mainly with type I-II1 kerogen. In semi-deep lake close to the delta front, wavy-massive silty mudstone was developed, mainly with type II kerogen.
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  Distribution and formation of tight oil in Qijia area, Songliao Basin, NE China

  Shi Lizhi; Wang Zhuozhuo; Zhang Ge; Zhang Yongsheng and Xing Enyuan

  . 2015, 42(1): 44-50.

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  By using geologic, geochemical, well test, well drilling and well logging data, the formation conditions and distribution pattern of tight oil in Gao 3 and Gao 4 oil layers of Gaotaizi layer, Upper Cretaceous Qingshankou Formation, Qijia area, Songliao Basin were examined systematically. There are four favorable conditions for the formation of tight oil: high quality source rocks and reservoirs, good source and reservoir combination, and formation pressure. There are three series of source rocks in this area, K2qn1, K2qn2+3 and K2n1, which provided material basis for the tight oil reservoirs; reservoirs including a variety of sands like distributaries channel,?mouth bar and?sheet sand are large in total thickness, wide in lateral distribution and good in continuity, providing accumulation space for tight oil; reservoir rocks of delta front in direct contact with the hydrocarbon source rock or pinching out in hydrocarbon source rock like fingers or interbedded with hydrocarbon source rock, constituted good source-reservoir combinations; abnormal overpressure in tight oil reservoirs with the pressure factor of 1.2-1.5, provided drive force for tight oil migration and charging. The study shows tight oil of Gao 3 and Gao 4 oil layers in Qijia area is mainly distributed in the center of, and slope and terrace around the sag.
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  Alkaline diagenesis and its effects on reservoir porosity: A case study of Upper Triassic Chang 7 tight sandstones in Ordos Basin, NW China

  Zhu Haihua; Zhong Dakang; Yao Jingli; Sun Haitao; Niu Xiaobing; Liang Xiaowei; You Yuan and Li Xin

  . 2015, 42(1): 51-59.

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  Petrologic features, diagenetic processes and origins of different pore types of Upper Triassic Chang 7 tight sandstones in Ordos Basin were analyzed based on cast thin sections, scanning electron microscope (SEM), and X-ray diffraction (XRD). The diagenetic processes caused by alkaline pore fluid and associated pores were studied in detail and the relationship between porosity evolution and hydrocarbon accumulation was analyzed. The Chang 7 tight sandstone commonly experienced alkaline environment and associated diagenesis, including quartz dissolution or replaced by mica, clay and carbonate minerals; carbonate cementation; abundant authigenic illite and chlorite with minor kaolinte and smectite; and albitization. Several types of associated pores were created in the alkaline environment, including quartz dissolution pore, intercrystal pore of clay minerals, interlamination pore of hydrated mica and pores associated with albitization. The alkaline diagenesis mainly occurred in two periods during the burial process: B stage of early diagenesis and A2 stage of mesogenetic diagenesis. The abundant intercrystal micropores of clay minerals, which mainly occurred during the B stage of early diagenesis, seriously reduced the permeability of sandstone. As a result, the acid dissolution in the later stage was not intense enough due to the low permeability, so it is inferred that the sandstone had already been compacted very tight before the major hydrocarbon accumulation period.
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  A new method for grading and assessing the potential of tight sand gas resources: A case study of the Lower Jurassic Shuixigou Group in the Turpan-Hami Basin

  Wang Weiming; Lu Shuangfang; Chen Xuan; Li Xingwei; Li Jijun and Tian Weichao

  . 2015, 42(1): 60-67.

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  A grading system from a pore structure perspective for assessing the quality of tight gas reservoirs in China is proposed based on an analysis of wettability, adsorption and pore throat size distribution and experiments such as X-ray diffraction, contact angle measurement and static nitrogen adsorption, upon tight sand samples from wells in Turpan-Hami Basin, western China. The hydrophilicity of tight sand has nothing to do with the overall clay content; instead, it is linked to the content of illite. Higher illite content means stronger hydrophilicity of the rocks. Indonesia’s formula is proven to be more suitable for the interpretation of gas saturation measurement in tight reservoirs with higher content of illite. The microscopic pore structure of tight reservoir is clearly related to the porosity. The tight sandstone reservoir with low porosity is characterized by high proportion of small pores and high drainage pressure, while the tight sandstone reservoir with high porosity is characterized by high proportion of large pores, low drainage pressure and large average pore size. In view of endowment and flowing of tight sand gas, a new reservoir potential assessment parameter is established by porosity, permeability and gas saturation. The parameter relates to the porosity in a clear manner of trichotomy. Given the porosity of 6% and 4% as threshold, the tight sand gas can be divided into three types: I (Good), II (Potential) and III (Challenging). The trichotomy corresponds to a consistent porosity limit with the pore size change.
油气田开发
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  Optimization of horizontal well injection-production parameters for ultra-low permeable–tight oil production: A case from Changqing Oilfield, Ordos Basin

  Zhao Jiyong; Fan Jianming; He Yonghong; Yang Ziqing; Gao Wei and Gao Wubin

  . 2015, 42(1): 68-75.

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  There are two kinds of displacement mechanisms and three different seepage stages during horizontal well development process with water injection energy. A reasonable injection-production working system of the basic principles and parameters are determined according to the evaluation results of horizontal well development test on the basis of understanding fundamental rules. (1) Advanced water injection energy supplement mode is proposed with the combination of injection wells and large volume water fracturing of horizontal wells. (2) Theoretical calculation chart of directional well advanced water injection and water injection intensity is established for various reservoirs. (3) The timing of advanced water injection should follow the completion of the horizontal wells. (4) Reasonable initial production of horizontal well is determined by the relationship of remaining fluid volume with row spacing, advanced injection water volume and flood front advancing velocity. (5) Reasonable production flowing pressure is slightly greater than saturation pressure before water injection does not work, when it works, the reasonable production flow pressure maintains no less than two-thirds of saturation pressure, and adjust it timely combining with dynamic production. Based on the research results, the HQ oilfield put 80 horizontal wells into production during 2013, the proportion of water-breakthrough wells reduces from 8.8% to 3.0%, the annual decrease of the average production of single horizontal well is controlled within 15%.
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  3D geological modeling for tight sand gas reservoir of braided river facies

  Guo Zhi; Sun Longde; Jia Ailin and Lu Tao

  . 2015, 42(1): 76-83.

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  Considering the poor applicability of conventional geological modeling to tight sand gas reservoir in braided river facies, a modeling method of “multi-stage constraint, hierarchical facies and multi-step models” was put forward taking Sulige gas field in Ordos Basin as the study object. The method obtains the GR field by seismic inversion constrained by logging data, and GR modeling is built under the control of the prior geological knowledge; the relation regression is realized between the GR model and the sandstone probability, sandstone probability modeling is built, and rock facies modeling is obtained by multi-point geostatistics theory; sedimentary microfacies modeling controlled by rock facies and braided-river-system is made; and eventually build effective sand body modeling by integrating sedimentary microfacies, effective sand body scale and reservoir properties distribution. The research method discussed in this paper has put geological constraints into the model as far as possible, enhanced the inter-well sand body predictability and improved the precision rate, thus it can provide a more reliable geological basis for gas reservoir development.
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  Gas-water relative permeability measurement of high temperature and high pressure tight gas reservoirs

  Fang Jianlong; Guo Ping; Xiao Xiangjiao; Du Jianfen; Dong Chao; Xiong Yuming and Long Fang

  . 2015, 42(1): 84-87.

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  Generally, gas-water relative permeability curves of tight gas reservoirs are obtained from unsteady experiment under room temperature and normal pressure, which greatly differs from the curves under high temperature and high pressure. In this research, the relative permeability curves of three cores were firstly measured using conventional standard method by displacing formation water with nitrogen under room temperature and normal pressure. Then the relative permeability curves of the same cores were measured by displacing formation water with natural gas on one self-developed full-diameter seepage flow equipment (200 ℃, 200 MPa) under reservoir conditions (160 ℃, 116 MPa) after several processing of the cores. Difference between the relative permeability curves obtained by the two methods shows that, under high temperature and high pressure, there exists a larger two-phase seepage zone and lower irreducible water saturation. At the same gas saturation, gas relative permeability under high temperature and high pressure is higher than that under room temperature and normal pressure, which means, under reservoir situation, the two-phase flow ability of gas and water is stronger and the irreducible water saturation is lower in tight gas reservoirs. The gas-water viscosity ratio, gas-water density ratio and interfacial tension are lower under this situation, which leads to higher sweep efficiency.
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  Dissolving capacity and volume expansion of carbon dioxide in chain n-alkanes

  Han Haishui; Yuan Shiyi; Li Shi; Liu Xiaolei and Chen Xinglong

  . 2015, 42(1): 88-93.

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  Five kinds of n-alkanes, which have high proportions in crude oil from China, were mixed with CO2 of different molar fractions forming oil-gas systems. The dissolution of CO2 in the five n-alkanes and the system volume swelling were studied through the constant component expansion (CCE) experiments in different temperatures. The pressure-volume curves of the n-alkanes–CO2 systems are not strictly two-part straight lines. The bending degree is affected by the parameters of temperature, pressure, CO2 molar fraction and n-alkanes. Saturation pressure and the temperature of the oil-CO2 system is a linear relationship. Besides, as the CO2 fraction increases, the saturation pressure goes up largely. There is a fact that the CO2 solubility in different kinds of alkanes is nearly the same in low pressure condition, while the solubility is inversely proportional to the carbon number in high pressure. The dissolution of CO2 may swell the system, and temperature and pressure are not the main reasons. However, the swelling factor increases quickly as the CO2 molar fraction goes up, and lowers with the carbon number increase. The oil swelling has a great significance for oilfield development and well production.
石油工程
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  Mechanical properties of oil well cement stone reinforced with hybrid fiber of calcium carbonate whisker and carbon fiber

  Li Ming; Liu Meng; Yang Yuanyi; Li Zaoyuan and Guo Xiaoyang

  . 2015, 42(1): 94-100.

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  To decrease the brittleness of oil well cement stone, the effects of carbon fiber, calcium carbonate whisker and hybrid fiber of them on mechanical prosperities of the cement stone were studied by experiments. The microstructures and micromechanical behaviors of the cement stone were investigated using scanning electron microscopy. The strengthening and toughening mechanisms of hybrid fiber were discussed. The experimental results show that: the compressive, flexural, split tensile strengths of the cement stone can be improved effectively with each of carbon fiber, calcium carbonate whisker and hybrid fiber; compared with adding a single fiber, the hybrid fiber can strengthen the cement stone better; the mechanical deformation capacity of the cement stone added the hybrid fiber is significantly improved, and the cement stone shows obvious toughness. Observing the microstructures and micromechanical behaviors of the cement stone and analyzing the reinforcement mechanism of hybrid fiber reveal that, the calcium carbonate whisker and carbon fiber have different sizes, morphologies and performances, which can work in different structure levels and loading stages, controlling generation and development of microcracks and fractures and improving the strength and toughness of the cement stone.
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  Vortex-induced vibration mechanism of drilling riser under shear flow

  Mao Liangjie; Liu Qingyou; Zhou Shouwei; Jiang Wei; Liu Zhengli and Peng Tao

  . 2015, 42(1): 101-106.

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  Vortex-induced vibration of the drilling riser under shear flow was studied by experimental method, and the characteristic parameters of vortex-induced vibration under the shear flow were obtained. The vortex-induced vibration response in both in-line and cross-flow directions were captured by measuring technique based on the fiber Bragg. The influence of the pre-tension during the experiment was eliminated and the experimental data was analyzed by modal analysis method. Results show that, under the shear flow, the dominant frequencies of the drilling riser at different locations are the same, however the shedding frequencies at different locations are different; when the vortex shedding frequency is close to the maximum order of the natural frequency, the lock-in phenomenon occurs, and the dominant frequency equals to this natural frequency; the vortex-induced vibration caused by shear flow is in the form of multi-modal for the influence of modal competition; the in-line direction response frequency is twice the cross-flow direction one; a single vibration period of the riser’s displacement trajectory appears as an inclined “8” shape, and the multiple vibration period of the riser’s overlapped displacement trajectory appears as a crescent shape.
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  Calculation method of riser top tension in deep water drilling

  Yang Jin; Meng Wei; Yao Mengbiao; Gao Deli; Zhou Bo and Xu Yunjin

  . 2015, 42(1): 107-110.

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  Through mechanical analysis, a calculation method which meets the requirements of both the riser stability and the bottom overpull margin was deduced. It was verified by an example of ultra deepwater well in South China Sea, and compared with two other common methods. Based on the related theories of pipe string mechanics, the effects of true axial force and effective axial force on the riser mechanical behavior were analyzed. The results show that, the bottom tensile force to Lower Marine Riser Package is determined by true axial force, and the riser’s stability depends on effective axial force. Through the force analysis of riser which simultaneously bears the internal and external pressures, the correspondent mechanical model was established, and a new calculation method of top tension was derived, which remedies the deficiencies of algorithms proposed by American Petroleum Institute and Institute of French Petroleum. Field application shows that, the value of top tension calculated by this method is basically the same as the value set by field operation, and moreover, it is more accurate than the value obtained by the algorithms of American Petroleum Institute and Institute of French Petroleum. This method can be used to guide the design and operation of conductor.
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  Test approach of downhole pump diagram for beam bumping wells

  Jia Deli; Liu He; Pei Xiaohan; Wang Guoqing; Yang Qinghai and Wang Yao

  . 2015, 42(1): 111-116.

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  A direct test approach of downhole pump diagram for beam bumping wells was presented using acceleration transducer to measure the pump stroke, and it was verified through laboratory experiments and field tests. The feature of the low-frequency and weak signal exported from the acceleration transducer with impact interference was analyzed. The periodic signal and its drift were modeled to work out the accumulative error of long-term integration and its influence on measurement results. Based on elimination principles, the DC-blocking and denoising filter was designed and its mathematical model was established. Through the filter, the drift component can be separated from the acquired signal. The laboratory experiments and field tests indicate that, the displacement signal without drift can be obtained from the initial acceleration data through filtering and quadratic integral, thus the downhole pump diagram can be obtained; the data measurement error is within ±2.0%, which will be further reduced with the increase of stroke times; the test approach of downhole pump diagram can realize the calculation of pump effectiveness and the direct measurement of stroke loss, thereby providing criteria for the process analysis of beam bumping well.
综合研究
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  New brittleness indexes and their application in shale/clay gas reservoir prediction

  Liu Zhishui and Sun Zandong

  . 2015, 42(1): 117-124.

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  Aiming at the disadvantages of the brittleness index commonly used in oil/gas exploration, this article proposed two new brittleness indexes (elastic brittleness and mineral brittleness) in order to predict brittle shale distribution accurately: the former index, based on elastic parameters (Young’s modulus and Poisson’s ratio), characterizes the original physical properties of reservoirs, the other takes the volume content of minerals in the shale and brittle factor of each kind of mineral into consideration. The two proposed brittleness indexes have theoretical advantages and can explain the brittleness of reservoir rocks from logging and prestack seismic inversion reasonably. According to the rock physics model of organic-enriched shale, a rock physics template for mineral-elastic parameter-brittle factor was established to find out the elastic parameter features of high quality brittle shale from logging data. The spatial distribution of high-quality gas-bearing brittle shale was predicted utilizing pre-stacked seismic inversion results, and the predicted results match well with the well-logging data.
学术讨论
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  Characteristics of ethoxylated fatty amine emulsion: Effects on the wettability and permeability of silicate formation under various pH conditions

  Ren Yanjun; Jiang Guancheng; Zheng Dujian; Sun Shilin; An Yuxiu and Wang Chunlei

  . 2015, 42(1): 125-128.

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  The effects of ethoxylated fatty amine emulsion on the wettability and permeability of silicate rock under various pH conditions, as well as the adsorption behavior of ethoxylated fatty amine on the silicate rock surface, were investigated using core displacement test, contact angle test and infrared spectroscopy. A new knowledge about the characteristic and mechanism of formation damage from reversible invert emulsion drilling fluids and a new method for the completion and cementing of a well drilled by reversible invert emulsion drilling fluids were proposed. Under pH of 4 to 8, exthoxylated fatty amine can adsorb on the rock surface to various degrees, resulting in the strong oil-wet condition of rock which does a serious harm to the permeability of the formation. Under pH of 10, no exthoxylated fatty amine adsorbs in the rock, resulting in the water-wet condition of the rock surface which is benefit to mitigating the damage of mud to the permeability of the formation. It is suggested removing the reversible invert emulsion drilling fluid using acidic fluids followed by basic fluids or using acidic fluids combined with wettability alteration agents.