Lithologic Reservoirs

In order to reveal the characteristics of nonmarine organic-rich formations and the productivity of different types of stratigraphic structure sections, taking the Da’anzhai member of Jurassic Ziliujing Formation and the fifth member of Triassic Xujiahe Formation in Sichuan Basin as examples, this paper divided the statigraphic structure section by making the ratio of shale to gross and thickness of single sand （limestone） as standards based on the field observed profiles, drilling data and sedimentary settings, and compared with the structure sections of Bakken Formation in North America. The nonmarine organic-rich stratigraphic structure sections were divided into five types: tight sandstone （limestone）, sandstone-rich （limestone-rich） with shale, sandstone （limestone） and shale interbed, shale-rich with sandstone （limestone） and shale. The tight sandstone （limestone） oil and gas coexist with shale oil and gas in nonmarine organic-rich formations, and the shale oil and gas are mainly produced in the last three types of structure sections. There are multiple productive targets in nonmarine organic-rich formations, so, it is proposed that the formation of organic-rich shale interbedded with limestone or sandstone should be considered to explore as a whole.

Research method of time effectiveness of hydrocarbon transporting by oil-source fault and its application

Fu Guang， Chen Xueqing， Deng Wei，Hu Xinlei

2016, Vol.28(6): 9–15 Abstract ( 376 ) PDF (592 KB) ( 350 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.002

depositional stage of Huoshiling Formation and Yingcheng Formation, and the late depositional stage of Palaeogene,and there is no gas migration and accumulation. These results are in accord with the currently gas accumulation stagerevealed by the homogenization temperature of fluid inclusions in K1 yc volcanic rock of Xujiaweizi Rift, so it is provedthat this method is feasible to study the time effectiveness of hydrocarbon transporting by oil-source fault.

Typical cases analysis of effective source rocks existence in ancient carbonate rock of the middle basins of China

Xie Yunxin， Zhou Wen， Guo Min，Chen Yicai， Qiumei Zhou

2016, Vol.28(6): 16–22 Abstract ( 368 ) PDF (691 KB) ( 230 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.003

The question if ancient carbonate rocks can be effective source rocks was discussed through typical pyrolysis experiments results and examples in Ordos basin and Sichuan basin in middle of China. The results indicate that rocks such as marlstone and micrite with relatively high organic matter content have high quantity of hydrocarbon generation during pyrolysis experiments, and oil expulsion is probably difficult during primary migration, and gas expulsion is the main form which is mainly expulsed through microfracture and diffusion. It is suggested that marlstone and micrite with relatively high organic matter content are effective gas source rocks. This understanding provides theoretical basis for source rock evaluation of ancient carbonates.

Ramp facies limestone reservoir characteristics and controlling factorof Callovian-Oxflordian in Bieshikent Depression

Wang Hao， Fei Huaiyi， Chen Xubin， Li Hongxi

2016, Vol.28(6): 23–29 Abstract ( 372 ) PDF (845 KB) ( 294 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.004

The Bieshikent Depression at the right bank of Amu Darya in Turkmenistan is characterized by low degree of exploration and lack of geologic knowledge. Based on core and thin section observation, combined with the analysis of physical properties and logging interpretation, the methods such as crossplot and electrofacies analysis were applied to study the lithologies, physical properties, reservoir spaces, reservoir types and main controlling factors of reservoir development of limestone reservoir of Callovian-Oxfordian. The results show that the reservoir rocks of Callovian-Oxfordian are mainly composed of micrite limestones and micrite granular limestones, and micro sparite granular limestones come second. The reservoir physical properties are poor, with low porosity and low-medium permeability. The main reservoir spaces are secondary dissolved pores, with some micro fractures and a small amount of biological cavity hole, so it mainly belongs to porous-fracture reservoir. The reservoir development is mainly controlled by sedimentary facies. The favorable reservoirs are mainly developed in microfacies such as bioclastic beach, bioclastic mound and grannular mound, with a little in lime mound. Dissolution and tectonic fracturing improve the reservoir properties. This study results can provide a reference for further exploration and development of Callovian-Oxfordian reservoir.

Pore characteristics and adsorption capacity of Chang 7 shale of Yanchang Formation in the southeastern Ordos Basin

Xu Yong， Hu Shijun， Chen Guojun， Lü Chengfu， Xue Lianhua

2016, Vol.28(6): 30–35 Abstract ( 407 ) PDF (533 KB) ( 393 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.005

In order to investigate the pore characteristics and methane adsorption capacity of Chang 7 shale of Yanchang Formation in the southeastern Ordos Basin, eight core samples were selected to carry out experiments, such as Arion milling field emission scanning electron microscope, low-temperature nitrogen adsorption and isothermal adsorption. The results show that five types of microcosmic pores are mainly developed,including intergranular pores, intragranular pores, intergranular pores in pyrite, organic pores and microfractures. The specific surface area ranges from 1.166 m2/g to 6.964 m2/g by BET equation, pore volume ranges from 0.004 8 m3/g to 0.024 2 m3/g by BJH equation, and the average pore diameter ranges from 8.812 nm to 17.882 nm. The methane adsorption capacity of Chang 7 shale under actual reservoir condition was simulated, and the maximum adsorption capacity is 2.0-4.0 mg/g. Mesopores are the main pores in Chang 7 shale, macropore and micropores come second, and nano scale pores are also developed, which indicates that the shale reservoir have good adsorption capacity. This study can provide theoretical basis for the further shale gas resource evaluation.

Reservoir characteristics and controlling factors of Middle Triassic T₂l₄³ in Longgang area

Long Yi， Liu Shugen， Song Jinmin,Sun Wei， Lin Tong， Yu Yongqiang

2016, Vol.28(6): 36–44 Abstract ( 377 ) PDF (1232 KB) ( 450 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.006

of gypsum rock in evaporative carbonate platform and sedimentation of gypsum, granular carbonate rocks controlled by paleo geomorphology in the carbonate platform, epigenic karstification and infilling after Indosinian tectonic uplift.The reservoir physical property is generally poor. Regionally, the reservoir characteristics in neighboring Yuanba area is similar to that in Longgang area, but it is different from that in the middle and southern West Sichuan Depression with the epigenic karstification decreases. As a result of eustatic movement, the reservoirs are controlled respectively by microbial reefs （beaches） and granular beaches in the middle and southern West Sichuan Depression

Organic geochemical characteristics of shale of Xujiahe Formation in the southern Longmen Mountain foreland basin

Zhou Qiwei， Li Yong， Wang Zhengjiang， Yu Qian， Wang Jincheng， Wang Weiming

2016, Vol.28(6): 45–51 Abstract ( 399 ) PDF (873 KB) ( 267 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.007

With the possibility of shale gas accumulation, the shale of the Upper Triassic Xujiahe Formation is well developed in the southern Longmen Mountain for-land basin, but the degree of prospecting is low. Based on the field profile mea-surement and fixed-point sampling, rock pyrolysis experiment, TOC determination, the test of vitrinite reflectance （Ro） and core data, the organic geochemical characteristics of shale was analyzed. The results show that the TOC content of shale ranges from 1% to 2%, reaching fair-good according to gas generation standards. Kerogen is mainly Ⅲ type, secondly Ⅱ2 type. Being from 0.8% to 1.7% generally, some above 2.0%, the maturity of organic matter is at the mature to high mature stage of evolution. Through the analysis of the organic geochemical characteristics and geologic parameters （porosity, burial depth and effetive thickness） of the shale of Xujiahe Formation, it is considered that the fifth member and third member of Xujiahe Formation are favorable for shale gas exploration in the southern Longmen Mountain foreland basin.

Adsorption characteristics，types and influencing factors of Chang 7 shale of Triassic Yanchang Formation in Ordos Basin

Kou Yu, Zhou Wen, Zhao Yinan, Chen Wenling, Li Na, Xu Hao

2016, Vol.28(6): 52–57 Abstract ( 333 ) PDF (443 KB) ( 283 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.008

The theoretical absorption gas amount in shale is an important index to judge whether shale has economic exploitation value. It is significant for shale gas-bearing property evaluation to study isothermal adsorption features of shale and calculate shale adsorption capacity. In order to find the isothermal adsorption features of Chang 7 shale in Ordos Basin, eight shale samples of Chang 7 were selected to carry out high temperature and high pressure methane isothermal adsorption experiments, then the adsorption gas content and adsorption heat were calculated according to the isothermal adsorption characteristic curves, and its influencing factors were analyzed. The results show that the isothermal adsorption of the eight samples from Chang 7 shale is in accord with Langmuir adsorption theory. The theoretical adsorption gas content of the eight shale samples is 0.57-4.35 m3/t, with an average value of 1.98 m3/t. The adsorption heat of Chang 7 shale samples is 10.67-37.67 kJ/mol, the average value is 21.73 kJ/mol, therefore, its adsorption type is physical adsorption. The shale adsorption gas content is mainly affected by specific surface area, TOC content and clay mineral content, among which the specific surface area is the most direct influencing factor. Key words： nonmarine shale； adsorption features； influencing factors； Chang 7 oil reservoir set； Ordos Basin

Sedimentary facies and gentle slope model of the Middle Permian Qixia Formation in the northwestern Sichuan Basin

Liang Ning， Zheng Rongcai， Deng Jigang， Jiang Huan， Guo Chunli， Gao Zhiyong

2016, Vol.28(6): 58–67 Abstract ( 428 ) PDF (1310 KB) ( 521 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.009

There are many research results about the Middle Permian Qixia Formation in the northwestern Sichuan Basin, however, the great differences in the cognition of the sedimentary facies characteristics and models have seriously restricted its exploration. In order to deepen the understanding of the characteristics of sedimentary facies of Qixia Formation and improve the efficiency of hydrocarbon exploration, based on the data of core description,field profile measurement, logging and seismic data, the characteristics of sedimentary facies were studied. The maps of sedimentary facies of the early and late Qixia Formation were compiled. It is considered that Qixia Formation mainly developed three types of sedimentary facies including open platform, platform edge, foreland gentle slope,as well as six types of subfacies and 11 types of microfacies. According to the relative sea level changes, the distribution characteristics of the sedimentary microfacies, subfacies and facies and their sedimentary evolution rule, the evolution model of gentle slope platform of Qixia Formation was established, which coordinates the relationship of carbonate platform model with carbonate slop model.

High-precision sequence division and sedimentary model of Yingshan Formation in Tahe area

Wei Duan， Gao Zhiqian， Meng Miaomiao,Yang Xiaoqun， Wang Jingbin,Wang Shanshan

2016, Vol.28(6): 68–77 Abstract ( 367 ) PDF (1562 KB) ( 353 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.010

The Yingshan Formation is of great scientific interest for being the significant replacing productive for-mation in Tahe Oilfield. However, the researches on high-precision sequence division and the sedimentary model are inadequate. Based on the thin sections, well logging and seismic data, the Yingshan Formation in Tahe area was divided into two third-order sequences （SQ1 and SQ2）, and it was further divided into four fourth-order sequencesthrough the identification of unconformity and stratigraphic stacking patterns. Seven microfacies （Mf1-Mf7） wererecognized and three microfacies assemblagses（MA1-MA3） were summarized, including platform interior interme-diate-high energy bank（MA1）, platform interior low energy bank and intrabank sea（MA2） and platform interior tidal flat （MA3）. Based on the microfacies analysis and correlated with wells, the sedimentary model of the Ying- shan Formation was analyzed. During the SQ1 period, it was restricted platform environment, and the MA1 and the MA3 developed. During the SQ2 period, it transferred to open platform gradually, the MA2 was the dominant microfacies assemblage. The closer to the platform margin, the more platform interior intermediate-high energy bank（MA1） developed.

Characteristics and evolution of the Ordovician sedimentary facies in Dongpu area, Bohai Bay Basin

Xiao Jing， Ji Hancheng， Hua Nan， Fang Chao， Li Haiquan， Ma Pengpeng

2016, Vol.28(6): 78–87 Abstract ( 297 ) PDF (1303 KB) ( 412 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.011

The understanding of the Ordovician sedimentary facies distribution in Dongpu area is unclear, which restricts the hydrocarbon exploration and development. Based on the data of outcrops, cores, thin sections and logging,combined with stratigraphy, petrology, paleontology, sedimentary texture and structure, the Ordovician sedimentary facies in Dongpu area was divided into three types of subfacies （open platform, restricted platform and evaporate platform）and eleven types of microfacies. According to “single factor analysis and multi factor comprehensive mapping method”,the map of the Ordovician sedimentary microfacies was compiled. The sedimentary evolution rule was analyzed according to the sea level change and sedimentary microfacies characteristics. The open platform developed three types of sedimentary microfacies: grain banks, interbank sea and dolomitic lime flat. The restricted platform developed ten kinds of sedimentary microfacies, such as tidal flat and lagoon. The evaporate platform developed three kinds of sedimentary microfacies: dolomitic flat, lime dolomitic flat and gypseous dolomite flat. The Ordovician have experienced three and a half transgression-regression cycle from Yeli to Fengfeng period in Dongpu area. During regression period, Eli Formation and Liangjiashan Formation, the upper Majiagou Formation, the lower Fengfeng Formation and the top of upper Fengfeng Formation are composed of tidal flat and lagoon subfacies in the restricted platform and evaporation platform. During transgression period, the lower Majiagou Formation, the top of upper Majiagou Formation and the top of Fengfeng Formation are composed of the interbank sea and the small scale grain bank subfacies in open platform and the local restricted platform environment.

Molecular simulation of shale gas adsorption in graphite slit-pores

He Yingjie， Yang Yang， Zhang Tingshan， Wu Kunyu

2016, Vol.28(6): 88–94 Abstract ( 417 ) PDF (632 KB) ( 571 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.012

In order to understand the methane adsorption mechanism in organic matter pores in shale, graphite slit-pores were established to characterize the organic matter pores by using molecular simulation software, the grand canonical Monte Carlo method, molecular mechanics and molecular dynamics were used to simulate methane adsorption in graphite slit-pores at the common shale burial depth of 2-4 km in Yangtze Plate. The results show that the adsorption was physical. With the increasing of temperature and pressure, the adsorption capacity in graphite slit-pores increased dramatically first, then increased slowly, and decreased at last, and the maximum adsorption capacity appeared at the buried depth of 2-4 km （4 km is the best buried depth for shale gas）. The relative density of methane along the normal direction of the graphite slit-pore wall shows a trend of symmetric distribution, which reflects apparent adsorption stratification, and it reduced with the increase of buried depth. The self-diffusion coefficient of methane increased with the increase of buried depth, which is consistent with the changes of adsorption heat and adsorption capacity.

Design of large-scale multi-channel seismic physical modeling system and its implementation

Wang Guoqing, Wei Jianxin, Liu Weifang,Di Bangrang, Yong Xueshan, Gao Jianhu

2016, Vol.28(6): 95–102 Abstract ( 366 ) PDF (876 KB) ( 386 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.013

As an actual physical stimulation technique, seismic physical modeling technology is of great significance to actual seismic exploration. Aimed at the complicated targets of seismic exploration, the existing seismic physical simulation equipments are difficult to meet the demand of deep and wide azimuth seismic simulation. A new type of seismic physical modeling system was designed from three aspects of physical model positioning, ultrasonic signal acquisition and physical modeling. The system can achieve high precision positioning of large-scale physical model,ultrasonic signal acquisition with multi-channel, high efficiency, high signal to noise ratio and high resolution, as well as high precision model form scanning and other functions. Combined with the specific physical model experiment, the indicators and function of the modeling system could meet the design requirements. This modeling system could provide an effective experimental platform for guiding the practical production and the study of seismic exploration theory.

Washing oil methods of cores from tight reservoirs in Junggar Basin： a case study of Lucaogou Formation in Jimsar Sag

Jin Jun，Wang Ziqiang，Li Zhen，Deng Yong

2016, Vol.28(6): 103–108 Abstract ( 357 ) PDF (526 KB) ( 530 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.014

In order to resolve the existing problems of long cycle and poor quality of washing oil for cores from tight reservoirs, a variety of pumping solvents, washing oil solvents and different methods to remove oil from tight cores were studied experimentally. The results show that dimethylbenzene is an excellent water extraction solvent due to its high boiling point, while the mixture of alcohol, benzene and chloroform with the ratio of 1∶2∶2 performed outstandingly good in the extraction of oil from tight cores because of high oil percentage of its leach liquor （14%）. The fluorescence level is less than three and the quality, porosity and permeability are steady after 7-8 circles （16 days） with pressurized saturated solvent method and CO2 pressure method. The effect met the standard of SY/T 5336－2006. This method isproved to be suitable for washing oil from tight cores in Junggar Basin.

Application of seismic sedimentology to prediction of beach and bar sand bodies in lacustrine basin: a case study of Jianquanzi member in Y block, Jiuxi Basin

Zhang Wenting， Pan Shuxin， Liu Zhenhua，Zhang Liping， Li Wei， Wang Wei

2016, Vol.28(6): 109–116 Abstract ( 378 ) PDF (809 KB) ( 520 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.015

The beach bar sand bodies have become an important exploration target in lacustrine basins of China. The prediction of beach bar sand bodies is difficult due to its thin bed characters. Under the guidance of seismic sedimentary theory, the techniques of 90° phase shift and stratal slicing were used to identify and characterize the distribution of beach bar sand bodies of Jianquanzi member in Y block of Jiuxi Basin. Based on the comprehensive analysis of core, lithology and logging data, stratal slices were interpreted. The identification signs of beach bar sand bodies were summed up from the aspects of origin, lithology, sedimentary thickness and geophysical response characteristics, and the distribution rule and controlling factors of beach bar sand bodies were discussed. The beach bar sand bodies were developed in lake-bays between braided deltas, and vertically in L3 reservoir group of descending half cycle of fifth-order cycle, and were characterized by thin and multi-row distribution parallel to the shore line. The frequent change of lake level, gentle sedimentary palaeotopography and sufficient supply of source rocks are the main controlling factors for the large area distribution of beach bar sand bodies. The research results show that seismic sedimentology technology is an effective means to predict thin reservoirs and could advantageously guide the fine lithologic reservoir exploration and development. This research could provide reference for the reservoir prediction in other similar areas.

Permeability calculation of tight sandstone reservoir by conductivity parameters

Yin Shuai, Ding Wenlong, Shan Yuming, Zhou Wen, Fang Kedong, Zhao Xin, Zhang Huinan

2016, Vol.28(6): 117–124 Abstract ( 339 ) PDF (620 KB) ( 300 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.016

The tight sandstone reservoirs have strong heterogeneity, and it is difficult to realize effective prediction of permeability by conventional methods. In order to solve this problem, this paper established a permeability model for tight sandstone reservoirs considering rock conductivity （Cs）, grain conductivity （Cg）, formation water conductivity （Cw）and cementation index （m）, then discussed their effects on permeability, and established the relevant interpretation chart in the reasonable value selection range. The results show that: （1） With the increase of Cs, the permeability of tight sand-stone increases. When the Cs of rock is lower, its effect on permeability is less; otherwise, the effect is greater. （2） With the increase of Cg, the permeability of tight sandstone decreases, but the effect of Cg on permeability of tight sandstone is not great. Comparing with Cg, the effect of Cs on permeability of tight sandstone is greater. （3）With the increase of m,the permeability of tight sandstone increases. When the m is lower, its effect on permeability is less; otherwise, the effect is greater. This method was applied to predict the permeability of the Triassic tight sandstone reservoirs in western Sichuan Basin, and a good application effect has been achieved. This research could provide important reference for tight sandstone reservoir evaluation and logging interpretation.

Geological unit division and development model optimization of coalbed methane: a case study from Zhengzhuang block in Qinshui Basin

Wu Yaqin， Shao Guoliang， Xu Yaohui，Wang Qiao， Liu Zhenxing， Shuai Zhe

2016, Vol.28(6): 125–133 Abstract ( 332 ) PDF (671 KB) ( 523 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.017

In order to plan the optimal development model for different coal reservoirs, combined with production data and static geological data, the numerical simulation technology was applied to analyze the main controlling factors of single well productivity, and to divide geological unit of Zhengzhuang block and optimize the development model.The result shows that the difference of productivity of vertical well is mainly caused by the mismatch of hydraulic fracturing technique with geological characteristics of regional coal reservoir. The single well productivity is controlled by coal body structure, desorption pressure and ground stress. Zhengzhuang block was divided into four types of development geological unit. According to the numerical simulation, the reservoirs in type Ⅰ and Ⅱ development geological units are suitable for vertical well hydraulic fracture, and the reservoirs in the type Ⅲ and Ⅳ development geological units are suitable for multi-branched horizontal well. The optimized well spacing is 280 m in the type Ⅰdevelopment geological unit, the single well productivity can reach 2 000 m3/d or above, and the yield rate is 10.8%.The optimized well spacing is 240 m in the type Ⅱ development geological unit, the single well productivity can reach 800-2 000 m3/d, and the yield rate is 10.2%. The optimized well spacing is 80 m in the type Ⅲ development geological unit, the single well productivity is 3 000 m3/d, and the yield rate is 7.2%. The optimized well spacing is 60 m in the type Ⅳ development geological unit, the single well productivity is 3 200 m3/d, and the yield rate is only 3.1%, so it is risk to put into production under current economic technology.

Pore-throat ratio can not be determined by constant-speed mercury injection method

Li Chuanliang， Zhu Suyang， Nie Kuang，Deng Peng， Liu Donghua

2016, Vol.28(6): 134–139 Abstract ( 440 ) PDF (485 KB) ( 710 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2016.06.018

Mercury injection method is very important in research of pore structure of rocks. Conventional mercury injection method can be used to determine rock’s pore size and its distribution. Constant-speed mercury injection method expanded the functions of conventional mercury injection method, and can determine pore’s and throat’s parameters of rocks. However, according to the study of this paper, the function expanded by the constant-speed mercury injection method is the misuse of the “noise” of pressure data. Pores of rocks build an interconnected 3D pore net. There are no concepts of pore body and pore throat. Every pore is connected with surrounding big pores and small pores. Mercury would not enter throats before entering pore bodies, which choose the bigger pores first and then the smaller pores to enter. The sawtooth-like curve of mercury injection is not the reflection of pore-throat structures of rocks, which is the pressure fluctuation caused by the mechanical process of mercury injection apparatus. The pressure fluctuation of oil wells in production process is also not caused by pore-throat structures of reservoir rocks.