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01 January 2018, Volume 38 Issue zk(English) Previous Issue    Next Issue

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OIL AND GAS EXPLORATION

Fluorescence Characteristics of Oil Inclusions of Yingshan Formation in Ma'nan Structural Belt of Maigaiti Slope SI Shanghua, CHEN Honghan, XIONG Wanlin, LI Peijun, LU Ziye 2017, 38 (zk(English) ):  1-5.  Abstract ( 75 )   PDF (2626KB) ( 126 )   Save In order to understand the hydrocarbon accumulation of Yingshan Formation in Ma'nan structural belt of Maigaiti slope, the paper quantitatively describes the fluorescence spectrum of oil inclusions and identifies the oil inclusions with 4 fluorescent colors of orange, yellow-green, blue-green and blue-white by using peak wavelength (λmax), red-green quotient (Q) and QF535 parameters, which represents 4 different stages of oil and gas charging, respectively. The peak wavelength (λmax) and QF535 of oil inclusions are distributed in 4 different areas. The decrease of QF535 value reflects the gradual increase of the maturity of the oil trapped by inclusions. Hydrocarbon charging during stages Ⅰ, Ⅱ and Ⅲ made more contributions to the current oil and gas reservoirs of Yingshan Formation than that of stage Ⅳ. The stageⅠ is low-maturity oil charging at the early stage and the stages Ⅱ, Ⅲ and Ⅳ are high-maturity oil charging at the late stage. References | Related Articles | Metrics

Development of Large-Scale Shallow-Water Fan Delta: Sedimentary Laboratory Simulation and Experiments TANG Yong, YIN Taiju, QIN Jianhua, WANG Dongdong 2017, 38 (zk(English) ):  6-17.  Abstract ( 84 )   PDF (6054KB) ( 209 )   Save Hundreds of millions of OOIP discovered in the area around Mahu sag, Junggar Basin, reveals the giant oil and gas potential in the area. Exploration practice shows that the sedimentary system in the area around Mahu sag which is different from that of alluvial fan previously found is a set of shallow-water, gentle-slope fan delta system. To deeply understand the depositional characteristics and formation mechanism of this system, the flume simulation device designed by Yangtze University was adopted to simulate and analyze the formation process of the sedimentary system. In the experiment, 3 levels of slope-break and 3 periods of lake level change were set, which correspond to 3 depositional periods of T1b1, T1b2 and T1b3, respectively, and the gravity flow and tractive current were used to simulate the formation process of fan body. The results show that a kind of retrogradational sequence was formed due to the rise of lake level, resulting in obvious overlapping of sequences. The investigation on reservoir internal structures indicates that laminated interactive deposits of gravity flow and river are more commonly found in the fan-delta plain, and the deposits of tractive current and secondary gravity flow resulted from progradation occur in the fan delta front. The boundaries of fan bodies caused by gravity flow and progradation in different periods are not clear and it is difficult to distinguish them. Lake level, slope-break, sedimentary energy (elevation of ancient landform) and the compositions of deposits have significant influences on fan development during the deposition process. References | Related Articles | Metrics

Genesis and Identification of Sandstones with High Gamma Value in the Second Member of Kongdian Formation, Cangdong Sag JIAO Yuxi, YAN Jihua, CHEN Shiyue, PU Xiugang, DENG Yuan 2017, 38 (zk(English) ):  18-21.  Abstract ( 52 )   PDF (1624KB) ( 114 )   Save Regarding high natural gamma values in logging response of the sandstones in the second member of Kongdian formation in Cangdong sag, based on the core observation and thin section identification and combined with whole-rock X-ray diffraction analysis and well logging analysis, it is considered that the relatively high content of analcite and enrichment of thorium (Th) are commonly noted in the Ek22 tight sandstones of Cangdong sag, which leads to the high natural gamma value of the tight sandstone interval; relatively high content of muscovite and enrichment of uranium (U) in some local areas in the Ek42 tight sandstones result in the high natural gamma value of the sandstone interval locally. The integrated use of AC logging curves, AC-GR correlation and GR-RILD correlation allows effective identification of tight sandstones with high gamma value caused by high content of analcite. References | Related Articles | Metrics

Characteristics and Genesis of Paleo-Karst Collapses in Ordovician Carbonate Rocks, Tahe Oilfield WANG Jianfeng, DENG Guangxiao, LI Taola, MEN Hongkun, ZHANG Ziyi 2017, 38 (zk(English) ):  22-29.  Abstract ( 68 )   PDF (3701KB) ( 206 )   Save Fracture-caved reservoirs in Ordovician carbonate rocks are the main oil and gas reservoirs in Tahe oilfield and the collapse resulted from the subsidence of ancient cave systems is one of the important types of the late karst reformation. Using the data of core, conventional logging, imaging logging, seismic reflection configuration and production performance, the paper analyzes and studies the identification method and the genesis of the collapse in carbonate rocks, presents a set of identification methods applicable to the karst collapses of fracture-caved reservoirs and establishes the corresponding identification criteria for them. Based on the genetic analysis, the karst collapses in Tahe oilfield can be classified into 3 genetic types including fracture induced collapse, overlying stratum load collapse and late-stage hypergene karst collapse. The statistics of 122 collapses of the fracture-caved reservoirs in Tahe oilfield show that the late-stage hypergene karst collapse has the greatest potential for oil and gas development due to the developed fractures and caves within the reservoir. References | Related Articles | Metrics

Forming Mechanism and Prediction of Structural Fractures in the Second Member of Jialingjiang Formation in Puguang area ZU Kewei, ZENG Daqian, CHENG Xiushen, ZHUO Seqiang, LI Songfeng 2017, 38 (zk(English) ):  30-35.  Abstract ( 57 )   PDF (1786KB) ( 154 )   Save In order to accurately predict structural fracture development in carbonate reservoirs, taking the second member of Jialingjiang Formation in the Puguang area for example, the paper studies the characteristics of fracture development by using field outcrop, core and thin section data; analyzes the forming mechanism of the fractures in the study area by combining with the test results of acoustic emission and inclusion homogenization temperature in the fractures. Based on which, fractures of different periods are predicted through stress field numerical simulation. It is concluded that the structural fractures were mostly formed under the NW-SE trending compression during the late Yanshanian movement and the early Himalayan movement, and under the NE-SW trending compression during the late Himalayan movement. The development degree of shear fracture is higher than that of extensional fracture in the second member of Jialingjiang Formation in the Puguang area. The structural fractures are mainly developed in the areas near fault zones, in the middle-western areas of Qingxichang structure, in the main body of Puguang structure, in the northern parts of Dawan-Maoba and Fenshuiling structures and in the Tieshan structural belt. The fracture rate obtained from numerical simulation and the fracture development intensity have a good correlation with a relatively high correlation coefficient. References | Related Articles | Metrics

Lower Limits of Physical Properties of Glutenite Reservoir in Lower Section of the 4th Member of Shahejie Formation in Steep Slope Zone of Northern Dongying Sag GAO Yang 2017, 38 (zk(English) ):  36-44.  Abstract ( 65 )   PDF (2526KB) ( 116 )   Save Glutenite reservoir in the lower section of the 4th member of Shahejie Formation in the northern steep slop zone of Dongying sag is characterized by strong heterogeneity, complex lithology, large variation of reservoir burial depth and complicated oil and gas phases. In addition, due to the lack of drilling and single-ayer formation test data, it is difficult to determine the lower limits of physical properties of the effective reservoir. Base on methods of formation test, oil-bearing occurrence in cores, minimum flow pore throat radius and positive & negative cumulative method, the lower limits of porosity and permeability of the glutenite reservoir with different fluids and at different burial depth are determined. The research results show that the lower limits of porosity and permeability for reservoirs at the burial depth of 3000~4000 m are 6% and 1.0mD, respectively; those for condensate reservoirs at the burial depth of 4000~4500 m are 4% and 0.2mD; and those for gas reservoirs with the burial depth larger than 4500 m are 3% and 0.1mD. With the increase of burial depth, the properties of reservoir fluids change, and pore structures and reservoir space types change, too, which results in the gradual decline of the lower limits of reservoir physical properties. References | Related Articles | Metrics

Comprehensive Dissection of Meandering-River Sedimentary System in Qinhuangdao 32-6 Oilfield, Bohai Bay Basin MA Pinghua, HUO Mengying, HE Jun, SHAO Xianjie, HUO Chunliang, WU Ning 2017, 38 (zk(English) ):  45-52.  Abstract ( 65 )   PDF (2308KB) ( 155 )   Save Because the lateral oscillation amplitude of a meandering river is large, channel deposits are in stagger arrangement and there are no isochronous surface and stable marker bed in the sedimentary system, which leads to difficulties for sand body tracing. The use of well logging-seismic joint inversion technology can improve the resolution of sand body in point bars. Based on the establishment of lithofacies, logging facies and seismic facies and making full use of the characteristics of cores, high vertical resolution of logging curves and good lateral continuity of seismic signals, the accuracies of vertical classification and lateral correlation for channel units of different periods are improved. Abandoned river channel, point bar, flood plain and crevasse splay are identified accurately by overlapping sand body thickness contours, logging facies and seismic wave impedance slices. Based on the statistics of modern meandering river and outcrop data at home and abroad, the paper establishes relationships among geometrical parameters of point bars, puts forward methods to identify lateral accretion body, accretion surface and accretion bed of point bars and a method for internal architecture study, which provides reliable constraint conditions for accurate geological model establishment. References | Related Articles | Metrics

Conditions of Oil and Gas Accumulation in Qingshuihe Formation of Shinan Area, Junggar Basin QU Jianhua, WU Tao, FEI Liying, ZENG Delong, ZHOU Liping, LIU Zhenyu 2017, 38 (zk(English) ):  53-59.  Abstract ( 68 )   PDF (7781KB) ( 29 )   Save In order to expand the prospecting achievements in Cretaceous strata of Shinan area in Junggar Basin, stratigraphic classification and hydrocarbon accumulation condition analysis are re-performed for the Qingshuihe Formation by the comprehensive use of seismic forward modeling, seismic inversion and seismic attribute etc. Both sedimentary cycle and well logging curves are used to determine the marker bed, based on which a unified framework of the whole area is established through the integration of well data and seismic data, and the ancient landform during the deposition of the first member of the Qingshuihe Formation is characterized. Gullies developed in Shinan area control the distribution of sedimentary facies and high-quality reservoirs are found in the down-incised scour channels. Reservoir prediction and hydrocarbon detection can prove that high-quality reservoir with a floor is the first condition for oil and gas accumulation and oil-bearing sand body is the favorable target for drilling. Multiple favorable targets are determined by using density inversion and seismic attribute fusion methods, which reveals the good oil and gas exploration prospects in the area. References | Related Articles | Metrics

Recognition of the Reservoir in Well Shinan-21 of the Hinterland of Junggar Basin ZHU Feng, QU Jianhua, YU Baoli, DENG Yong, LIU Yahui, SONG Mingxing 2017, 38 (zk(English) ):  60-65.  Abstract ( 63 )   PDF (3955KB) ( 113 )   Save There is no significant follow-up breakthrough of exploration after the large scaled discovery has been gained in the Middle Jurassic Toutunhe formation of Well Shinan-21 in the hinterland of Junggar Basin. Through the re-analysis on the reservoir of Toutunhe formation in Well Shinan-21, it is considered that transporting fault and lithology are 2 key factors constraining oil and gas exploration. Based on the detailed interpretation of newly-deployed high-precision 3D seismic data, the paper performs fine study of transporting fault and lithological targets and basically determines the distribution of 2 groups of transporting faults of 2 periods. Multiple periods of slope-break belts are discovered along the two flanks of Jidong swell and mudstone barrier is present in the up-dipping direction of the slope-break belts. Reservoirs formed in and separated by the underwater distributary channels. Controlled by the slope-break belts of 3 periods, multi-period overlapped sand bodies are developed in the eastern flank and match well with faults, resulting in large scale exploration in the future. The detailed characterization of lithological targets is carried out to provide basis for next drilling target determination. References | Related Articles | Metrics

RESERVOIR ENGINEERING

Quantitative Characterization of Architecture Units for Braided River Reservoir in Su36-11 EOR Test Area ZHAO Zhongjun, LI Jinbu, MA Zhixin, WU Xiaoning, FU Bin, WANG Wensheng 2017, 38 (zk(English) ):  66-73.  Abstract ( 60 )   PDF (3601KB) ( 165 )   Save Braided channel bar and braided channel are important oil and gas accumulation sandbodies, which are characterized by rapid lateral variation, poor continuity and connectivity, strong reservoir heterogeneity and significantly difference of sandbody scale from area to area and from type to type. These features seriously constrain the development of the braided river reservoir. Based on the reservoir architecture theory, this paper quantitatively characterizes the architecture units of the braided river reservoir of the lower He-8 Member (i.e. H8x) in Su36-11 EOR test area of Sulige Gas Field and analyzes the effective sandbody distribution. The results show that the width of a single braided channel ranges from 100 to 550 m, and the length and width of braided bars are 1,350~4,300 m and 480~1,950 m, respectively. Finally, based on the development scale and distribution of sedimentary microfacies units, together with the production performance data, effective sandbodies are comprehensively evaluated. According to the evaluation results, channel bars and braided channels are distributed continuously in H8x1-3 and H8x2-3 and they are both effective sandbodies, with high drilling ratio, suggesting H8x1-3 and H8x2-3 as the most favorable target horizons. The channel bars in H8x1-2 and H8x2-2 have high drilling ratio and island-like channel bars are favorable reservoir sandbodies. Gas may be discovered in only a few channel bars in H8x1-2 and H8x2-2, so that the risks to develop the 2 horizons will be the highest. References | Related Articles | Metrics

Variations of Rock Resistivity in Water-Flooded Zones of Waterflooding Oilfield ZHANG Hengrong, TAN Wei, WANG Lijuan, DING Lei 2017, 38 (zk(English) ):  73-78.  Abstract ( 66 )   PDF (1074KB) ( 122 )   Save The changes of electrical properties of water flooded reservoirs are complex, which brings great difficulty to the identification of water flooded zone and the evaluation of remaining oil saturation. In this paper, simulated waterflooding experiments under reservoir conditions are carried out by using sealed coring samples, the variations of rock resistivity are analyzed for the situations when the water of different salinities is injected to displace oil and the influences of changes of pore structures, and formation water salinity on rock electrical parameters are discussed. The experimental results show that when high salinity water or formation water is injected to displace oil, the rock resistivity always monotonously decreases and exhibits a“L”shape, and the better the physical properties are, the larger the decrease amplitude of rock resistivity will be; when low-salinity water is injected to displace oil, the rock resistivity generally displays a“U”or“S”shape and the better the physical properties are, the resistivity will change to monotonous increase from monotonous decrease, and the higher the water saturation at the first inflection point will be. The changes of pore structure resulted from the changes of injected water volume have no significant impact on rock electrical parameter. With the increase of formation water salinity, cementation index and saturation index will gradually increase. The influence of the difference of formation water salinity at different waterflooded stage on rock electrical parameters should be considered when calculating residual oil saturation. References | Related Articles | Metrics

Optimization of Volcanic Gas Reservoir Development Program Based on the Improved AHP-Entropy Weight Method and TOPSIS MA Xu, YANG Shuangchun, LI Bingfan, PAN Yi, MA Peimin 2017, 38 (zk(English) ):  79-84.  Abstract ( 68 )   PDF (463KB) ( 111 )   Save How to choose the optimal program for volcanic gas reservoir development economically is an urgent problem to be solved. According to the construction principle of the indexes of volcanic gas reservoir development program optimization, 7 optimum indexes of development program are determined. By using the improved analytical hierarchy process (AHP) and combined with entropy weight method and the technique for order preference by similarity to ideal solution（TOPSIS), an improved AHP-entropy weight & TOPSIS-based model for volcanic gas reservoir development program optimization is established and its validity has been verified by a case study of optimization for 8 volcanic gas reservoir development programs in a block of Songliao basin. The results show that the approximation degrees of each program are 0.2947, 0.5041, 0.6798, 0.7675, 0.3165, 0.6407, 0.6213 and 0.2546, respectively. Based on the optimal selection principle, it is considered that the optimal solution is the program No.8. The optimization result could provide references for decision making in oilfields, which has some practical and theoretical significance. References | Related Articles | Metrics

Microscopic Damage Mechanism of Asphaltene Deposition on Cores during CO2 Flooding WANG Chen, LI Tiantai, GAO Hui, ZHAO Jinsheng, GAO Yuan, DOU Liangbin 2017, 38 (zk(English) ):  85-89.  Abstract ( 62 )   PDF (1230KB) ( 131 )   Save In order to study microscopic damage mechanism of asphaltene deposition on reservoirs with different permeabilities during CO2 flooding, cores with high, medium and low permeabilities are selected for indoor CO2 flooding experiments and plugging degree of pore throat in cores are analyzed quantitatively by using NMR technology. The experimental results show that the deposition rate of asphaltene during miscible flooding stage is obviously higher than that during immiscible flooding stage, and the deposition rates are basically same in the cores with different permeabilities; permeability damage rate is positively correlated with the asphaltene deposition rate and the larger the core permeability, the smaller the permeability damage rate; the pore throats in low permeability cores are blocked seriously with the plugging rate of relatively smaller pore throats (0.01~1 ms) reaching 38.19%, the plugging rate of relatively smaller pore throats tin high permeability cores is only 9.59%, which is significantly lower than the previous one. References | Related Articles | Metrics

Water Cut Rising Law of Horizontal Wells in Low-Amplitude Heavy Oil Reservoirs with Bottom Water OUYANG Yuwei, HU Yong, ZHANG Yunlai, ZHANG Wei, XU Ya'nan 2017, 38 (zk(English) ):  90-93.  Abstract ( 67 )   PDF (821KB) ( 127 )   Save To determine water cut rising law of horizontal wells low-amplitude heavy oil reservoirs with bottom water, the paper considers dynamic and static parameters, uses a comprehensive method combining numerical simulation, waterflooding type curves with production performance analysis, and summarizes the order of influences of different parameter on water cut variations in reservoirs with bottom water in horizontal wells. Linear regression equations related to each parameter are obtained and a chart showing water cut rising in horizontal wells is established. Based on the comparison of production performance data in horizontal wells with that of Q oilfield in the middle of Bohai Sea, it is considered that the method has relatively high prediction accuracy, which could provide basis for production system adjustment in horizontal wells, meanwhile provide theoretical basis for horizontal well production allocation at the early stage. References | Related Articles | Metrics

Evaluation of Single-Well Gas Production Capacity of Shuang-6 Gas Storage in Liaohe Oilfield CHEN Xianxue, WEN Haibo 2017, 38 (zk(English) ):  94-97.  Abstract ( 74 )   PDF (641KB) ( 110 )   Save Shuang-6 Gas Storage in Liaohe oilfield is the largest gas cap and oil ring gas storage with edge and bottom water in China and there is no mature experience. Gas production capacity of injection-production wells is the key to peak shaving of the gas storage. Taking Well X as an example, a method suitable for Shuang-6 Gas Storage is established to evaluate gas production capacity of injection-production wells. The critical differential pressure of reservoir sand production was determined through indoor sand production experiment of cores. A binomial productivity equation for injection-production wells was established through systematic well testing. The critical differential pressure of reservoir sand production was substituted into the binomial productivity equation for injection-production wells to obtain the gas production capacity that reservoirs can support. The gas production capacity was constrained according to the erosion flow rate in injection-production strings of different sizes. The comprehensive evaluation results show that in Well X the upper limit of gas production rate that the reservoir can support reaches 282×104 m3/d, but constrained by erosion flow rate, the upper limit of gas production rate is determined as 122×104 m3/d. References | Related Articles | Metrics

Influences of Interlayer on Reservoir Thickness for Horizontal Well Deployment in Heavy Oil Reservoirs with Bottom Water: A Case from Qinhuangdao 32-6 oilfield ZHANG Yunlai, ZHANG Jilei, XU Ya'nan, MIAO Feifei, ZHANG Chi 2017, 38 (zk(English) ):  98-103.  Abstract ( 46 )   PDF (5877KB) ( 136 )   Save Qinhuangdao 32-6 oilfield is a typical offshore low-amplitude bottom-water heavy oil field. Oil reservoirs with the thickness of less than 10 m account for 22% in respect of reserves due to the low amplitude. To produce the reserves in these reservoirs efficiently, based on the interlayer logging identification and core analysis, this paper carries out a study on the influences of interlayer on development and the limits for horizontal well deployment by using numerical simulation method. According to the study results, interlayer can effectively block the rapid coning of bottom water when the interlayer permeability to matrix permeability ratio is 0.01. Bottom water can be diverted to flow around and the producing degree of reserves can be maximized when the interlayer area is 2~3 times the oil drainage area in horizontal wells. The coning of bottom water can be effectively slowed down and the swept volume of waterflooding be expanded when the interlayer is located at the position with the distance of 3/4 reservoir thickness to the reservoir top. Taking the cumulative oil production of 5×104 m3 as the lower economic limit for horizontal well deployment, the lower limit of reservoir thickness for horizontal well deployment in offshore low-amplitude heavy oil reservoirs with bottom water should be 5 m. These conclusions have been proved by pilot tests, and they provide technical support for horizontal well deployment in low-amplitude heavy oil reservoirs with bottom water. References | Related Articles | Metrics

APPLICATION OF TECHNOLOGY

Establishment and Application of Integrated Near-Surface and Subsurface Q Model in Desert Area JIANG Li, WANG Xiaotao, TAN Jia, XIAO Yanling, CHEN Yong, ZHANG Jin 2017, 38 (zk(English) ):  104-108.  Abstract ( 75 )   PDF (4351KB) ( 129 )   Save The hinterland of Junggar Basin is covered by desert. The majority of middle-high frequency energy in seismic reflection waves is absorbed by near-surface sand dunes. To improve seismic data resolution, the paper proposes a method to build an integrated near-surface and subsurface, pre-stack Q model. Firstly, the method calculates the relative near-surface Q field at shot and receiver points with simplified spectral ratio based on amplitude and main frequency of seismic data and seismic travel time on the surface; then uses formation quality factors at near-surface shot-receiver points to modify average sub-surface Q model and establishes a pre-stack average Q model containing near-surface variations, which could further compensate seismic data of one-step pre-stack Q model. The seismic data resolution obtained from the model in the desert area is better than that obtained from conventional subsurface Q compensation method and deconvolution method. The results of synthetic seismogram calibration and pre-stack inversion are better than those of conventional methods as well. Therefore, the model has good prospects for application. References | Related Articles | Metrics

Using Well Production Performance to Identify Fracture-Vug Complexes in Fractured-Vuggy Carbonate eservoirs: A Case Study of Ha-6 Well Block in alahatang Oilfield WANG Ping, PAN Wenqing, LI Shiyin, LIU Zhiliang, HE Jun, MA Hui 2017, 38 (zk(English) ):  109-115.  Abstract ( 80 )   PDF (1676KB) ( 107 )   Save Taking Ha-6 well block as an example, based on the study of reservoir distribution and spatial relationship of oil and water in the study area, this paper analyzes the development features of producing wells, establishes 3 patterns of oil and water distribution in fracture-vug complexes which can be identified from single wells—separate oil and bottom/edge water connection pattern, separate water and bottom/edge water connection pattern and composite fracture connection pattern, and demonstrates the causes of the 3 patterns and the production characteristics. The paper also presents 3 performance analysis methods to identify fracture-vug complexes, i.e. production test data analysis method, waterflooding type curve analysis method and elastic productivity analysis method, and demonstrates the correspongding identification methods applicable for each fracture-vug complex. Combined with the principle of planar distribution area determination for fracture-vug complexes, 3 types of fracture-vug complexes are identified in the study area. References | Related Articles | Metrics

Application of Diffracted Wave Separation & Imaging Technology in Fracture Identification LI Xiaofeng, KONG Xue, LIN Juan 2017, 38 (zk(English) ):  116-121.  Abstract ( 71 )   PDF (3934KB) ( 126 )   Save Fractures as the important oil-gas accumulation spaces and migration pathways control the formation and distribution of oil and gas reservoirs. Accurate understanding of the distribution of underground fracture systems is critical for petroleum exploration and further oil and gas field development. Diffracted waves are the seismic responses of small-sized geologic discontinuities such as faults and fractures etc. According to the differences of event shapes between the diffracted wave and reflected wave on the plane wave record, and using diffracted wave separation & imaging technology based on plane wave prediction, the diffracted wave field is extracted from the seismic record and imaged separately. Thus the identification accuracy of small-sized structures is improved. The numerical model and actual application result show that the diffracted wave separation & imaging technology can characterize breakpoints more clearly, which could be guidance for fracture interpretation. References | Related Articles | Metrics

Application of NMR Logging in Low-Resistivity Reservoir Evaluation: A Case Study of Toutunhe Formation on the Eastern Fukang Slope, Junggar Basin LUO Xingping, SU Dongxu, WANG Zhenlin, WANG Gang 2017, 38 (zk(English) ):  122-128.  Abstract ( 57 )   PDF (3290KB) ( 146 )   Save Conventional logging methods can't be used to effectively identify low-resistivity pays. In this paper, the NMR logging was used to classify and evaluate low-resistivity pays in the Toutunhe Formation on the Eastern Fukang slope of Junggar Basin. Based on the data of NMR, cation exchange capacity, thin section and grain size analysis, the genesis of low-resistivity pays was discussed. Then, the NMR T2 spectrum was used to qualitatively identify oil/water zones and to calculate porosity, permeability and water saturation. Although the Toutunhe Formation reservoir contains a small amount of mud and clay minerals, its special clay minerals can generate relatively high additional electrical conductivity and high irreducible water content, allowing for the low-resistivity pay (with resistivity lower than 6 Ω·m). According to the shape of NMR T2 spectrum and the potential existence of spectral peak at 200 ms, oil zone, water-bearing oil zone, oil-bearing water zone and water zone could be effectively classified. Taking 3 ms as the cutoff of T2 and combined with the porosity-permeability correlation obtained from core experiments, the porosity and permeability of the low-resistivity pays could be calculated. Finally, the cation exchange capacity calculated from NMR logging was substituted into a W-S model to determine the water saturation of the low-resistivity pay. The qualitative identification and quantitative evaluation results of the proposed method for low-resistivity pays well match with the experimental results, showing a good applicability in oil production. References | Related Articles | Metrics