石油实验地质

2015, 37(6): .

Abstract(500) PDF-CN(934)

Abstract:

Ultramicroscopic organic petrology characteristics and component classification of excellent marine source rocks

Qin Jianzhong, Tenger Borjin, Shen Baojian, Tao Guoliang, Lu Longfei, Yang Yunfeng

2015, 37(6): 671-680. doi: 10.11781/sysydz201506671

Abstract(1219) PDF-CN(1276)

Abstract:
Petrology and organic petrology analyses were completed for excellent marine source rocks collected from South China in order to study their ultramicroscopic structure. Scanning electron microscope (SEM) and energy dispersive spectrum (EDS) were applied to study mineral components and organic matter occurrence. Organic matter mainly occurs as siliceous biodetritus, calcareous biodetritus, clay-size particles and organic particles. Excellent marine source rocks were classified into six types, including shell detritus, biodetritus, bitumen, authigenic mineral, secondary mineral and terrigenous clay mineral, according to their biotype, biomolecule structure, hydrocarbon generation characteristics and diagenesis evolution.

Hydrocarbon phase in the deep Cambrian of the Tarim Basin

Ma Anlai, Jin Zhijun, Liu Jinzhong

2015, 37(6): 681-688. doi: 10.11781/sysydz201506681

Abstract(1247) PDF-CN(834)

Abstract:
The hydrocarbon phase of the deep Cambrian in the Tarim Basin is a scientific focus of geochemists and explorationists. Thermal simulations of heavy oil, normal oil and waxy-oil from the Tahe Oilfield in the Tarim Basin were carried out using a gold-tube confined system. For a frequency factor (A) of 1.78×10¹⁴s^-1, the activation energy range of C₁-C₅ gas yield of heavy oil is the widest, ranging from 56 to 66 kcal/mol, and the dominant potential is at 59 kcal/mol. In view of the ratio of oil conversion to gas, oil can be a separate phase at temperatures of 178-205℃. According to the paleo-temperatures of the Cambrian wells from the Tabei, Tazhong, Tadong and Machu uplifts, four dynamic models of the Cambrian reservoir cracking were established. The paleo-oil reservoir of well Tashen1 in the Tabei Uplift can be as a separate oil phase above Builtup Ⅰ in the Cambrian at present, whereas only condensate oil phase existsat the bottom of the UpliftⅠ. The models of the Cambrian paleo-oil reservoirs of typical wells from the Bachu Uplift, Tazhong Uplift and Tadong Uplift suggest that the hydrocarbon phase of the above areas may be dominated by gas and condensate phases.

Sedimentary model and development of the Cambrian source rocks in the Tarim Basin, NW China

Chen Qianglu, Chu Chenglin, Yang Xin, Hu Guang, Shi Zheng, Jiang Haijian, Shen Baojian, Liu Wenhui

2015, 37(6): 689-695. doi: 10.11781/sysydz201506689

Abstract(994) PDF-CN(947)

Abstract:
Outcrop, drilling and seismic data were utilized to analyze in detail the sedimentary characteristics of the Middle and Lower Cambrian in the Tarim Basin. A sedimentary model was established to provide a scientific basis for the prediction of source rock distribution. The studies suggested that both the sedimentary models of ramp and platform-shelf were involved in the Cambrian deposition in the Tarim Basin. As a whole, the trend of the Cambrian sedimentary evolution was characterized by the variation of a low angle to steep platform margin. It was assumed that the effective source rocks of Cambrian in the Tarim Basin were mainly formed in a deep water shelf environment combined with the Cambrian sedimentary pattern and the sedimentary structure, lithological assemblage, mineral composition and hydrocarbon generating organisms of the source rocks. Hydrocarbon generating organisms evolved together with the deep water shelf sedimentary environment. In the argillaceous and calcareous deep water shelf, the advantage of biofacies lay with benthic algae and planktonic algae, respectively. As a result of the migration of the deep water shelf through the Cambrian period, the distribution of source rocks was vertically stacked and laterally staggered. Since the black thin marlite in the lower Xiaoerbulake Formation developed in a deep water shelf, the sedimentary environment suggested that it was expected to be another source rock of the western Tarim Basin.

Pore-throat characteristics of tight sandstones and its influence on reservoirs in Dibei area of the Kuqa Depression

Lin Tong, Ran Qigui, Wei Hongxing, Sun Xiongwei, Wang Rong

2015, 37(6): 696-703. doi: 10.11781/sysydz201506696

Abstract(890) PDF-CN(1158)

Abstract:
The pore-throat characteristics of tight sandstones from Dibei area of the Kuqa Depression were studied using cast thin section, scanning electron microscope, laser scanning confocal microscope and micro/nano CT analyses. A large amount of long, narrow and flat pore-throats were observed. Micro/nano throats and intercrystal pores in clay minerals are the most common in reservoirs. According to nitrogen adsorption, constant velocity mercury injection, and physical property analyses under overburden pressure, the throat radius ranges from 1 to 4μm, accounting for about 2/3 of the total reservoir space. The fluid flow in tight reservoirs is directly influenced by throat radius and pore/throat ratio. Clay minerals in pore-throats control fluid mobility.

Characteristics and genesis of marine hydrocarbons in the Halahatang Sag in the northern Tarim Basin

Sun Hao, Li Sumei, Zhang Baoshou

2015, 37(6): 704-712. doi: 10.11781/sysydz201506704

Abstract(1073) PDF-CN(1183)

Abstract:
The Halahatang Sag is an important oil and gas unit in the western part of the Northern Tarim Uplift. The Ordovician carbonate reservoir contains abundant petroleum resources with multiple phases, but the variable characteristics and genetic mechanism of the oil and gas are still unclear. Oil-oil and oil-rock correlations indicate that the crude oil has a close genetic relationship with the middle and upper Ordovician source rocks. The comparison of carbon isotopes for individual n-alkanes shows that the Cambrian source rocks might also contribute. Halahatang oils are rich in dibenzothiophenes, and also contain relatively abundant C₂₉-and C₃₀-hopane, which implies a contribution from carbonate source rocks. Based on the Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis, sulfides with low thermal stability have low concentrations, suggesting that TSR alteration is not significant. Source rock maturity is the major factor controlling the genesis of oils with high gas/oil ratios, while biodegradation is the major factor for heavy oil and H₂S formation in the relatively shallow reservoir.

Structural deformation and its controlling factors in the Yining Sag of Yili Basin

Lin Shuiqing, Wang Junhong, Zhang Gaoyuan, Ying Wenxi, Dong Xiaomei, Dong Yinlei, Wang Liang

2015, 37(6): 713-720. doi: 10.11781/sysydz201506713

Abstract(1198) PDF-CN(1039)

Abstract:
Balanced section recovery techniques were used to restore tectonic evolution in the Yining Sag of Yili Basin based on drilling, logging, outcrop and seismic data. The sag is faulted in the north and onlapping in the south. The intensity of tectonic deformation is stronger in the north. The study area entered the continental stage in the Permian, and has experienced four compression periods:end Permian, the end of Triassic to the early Jurassic, end Jurassic and end Neogene. Compressive deformation was the most severe from east to west at the end Permian, and then decreased and changed to north-south compression. The zonation structure from south to north in the sag formed at the end of the Neogene. Hedge and thrust structures developed in the sag and adjacent areas due to north-south compression, resulting in the present compressive tectonic style.

Diagenesis and favorable diagenetic facies of the eighth member of Yanchang Formation in Maling area, the Ordos Basin

Chen Dayou, Zhu Yushuang, Zhang Jiaosheng, Du Shouli, Sang Shizhe, Li Chao, Liu Ping

2015, 37(6): 721-728. doi: 10.11781/sysydz201506721

Abstract(1149) PDF-CN(752)

Abstract:
Conventional section, cast section, X-ray analysis, cathode luminescence and SEM samples were used to study the diagenesis of the eighth member of Yanchang Formation (Chang8) in Maling area of the Ordos Basin, analyze its effects on reservoirs, divide diagenetic facies, and to forecast favorable diagenetic facies. The Chang8 reservoir in the study area has experienced various diagenetic effects such as compaction, cementation, dissolution and metasomatism. Compaction and ferruginous carbonate cementation in the late diagenetic phase reduced the sandstone porosity and the permeability of the reservoir, while dissolution produced a lot of secondary dissolved pores and improved permeablility. According to diagenetic functions and pore types, the sandstone reservoirs in the study area were divided into five diagenetic facies including strongly-dissolved residual inter-granular pores+dissolution pores, weakly-cemented residual inter-granular pores, clay mineral cementation, carbonate cementation, and strong compaction, among which the first two facies are favorable for reservoir development.

Microscopic pore structure of the fourth and fifth members of the Yanchang Formation in Zhenbei area of the Ordos Basin

Li Cheng, Zheng Qinghua, Zhang San, Liu Yiqun, Wang Lingli, Liang Xiaowei

2015, 37(6): 729-736. doi: 10.11781/sysydz201506729

Abstract(1042) PDF-CN(930)

Abstract:
The fourth and fifth members of the Yanchang Formation (Chang4+5) in Zhenbei area of the Ordos Basin are low-permeability reservoirs of diagenetic origin. Conventional methods such as thin section analysis, scanning electron microscopy and physical properties determination failed to analyze the microscopic pore structure of these reservoirs. We used conventional methods and applied constant rate mercury penetration to study the controlling factors to quantitatively determine microscopic pore structure. The microscopic pore structure of the Chang4+5 reservoirs was mainly impacted by diagenetic effects. When mechanical compaction and carbonate cementation were weaker and feldspar dissolution was more intense, intergranular pores and dissolution pores would be more developed, resulting in better connectivity and higher permeability. Microscopic pore structure and permeability were mainly controlled by throat radius. Generally, if average throat radius was >0.12μm, permeability would be higher, the smaller the pore/throat radius ratio, the better the microscopic pore structure, the greater the reservoir quality index (RQI), and the higher liquid oil yield, especially when the average throat radius was <1.26μm. Throats controlled the quality of the microscopic pore structure of low permeability reservoirs.

Sedimentary characteristics and petroleum geology of sublacustrine fan of the upper section of the first member of the Tenger Formation in the Aer Sag of the Erlian Basin

Yao Wei, Wu Chonglong

2015, 37(6): 737-741. doi: 10.11781/sysydz201506737

Abstract(1099) PDF-CN(1002)

Abstract:
The upper section of the first member of the Lower Cretaceous Tenger Formation in well Aer1 and neighboring area in the Aer Sag of the Erlian Basin is an oil-bearing formation sourced from a sublacustrine fan according to core, grain size, logging and seismic data. This fan is marked by abundant load structures, normally graded bedding, massive bedding, and incomplete Bouma sequences. Well logs show finger shapes on a background of low resistance and high GR values. Seismic profiles are characterized by lenticular shapes. A middle fan with obvious channels and a lower fan without significant channels have been recognized on seismic profiles. Source rocks surround massive sandstones or normally graded sandstones in a sublacustrine fan, with relatively high porosity (average 16.6%) and permeability (average 282×10^-3μm²) can be regarded as favorable petroleum reservoir.

Paleo-fluid characteristics and preservation of hydrocarbons in the Sangzhi-Shimen synclinorium and adjacent areas

Liu An, Wei Kai, Li Xubing, Wang Baozhong, Wang Qiang

2015, 37(6): 742-750. doi: 10.11781/sysydz201506742

Abstract(1144) PDF-CN(964)

Abstract:
The paleo-fluid characteristics and hydrocarbon preservation in the Sangzhi-Shimen synclinorium and adjacent areas are discussed using comparisons of C, O, and Sr isotopes between the calcite veins and surrounding rocks in the Sinian and Triassic formations and combined with the tests of fluid inclusions in calcite veins. The ⁸⁷Sr/⁸⁶Sr values of surrounding rocks in the Lower Paleozoic are higher than those of contemporary seawater and calcite veins, which suggests that the surrounding rocks had been reformed by fluid with high ⁸⁷Sr/⁸⁶Sr values before fracturing. The calcite veins close to thermal springs in the north of Sangzhi-Shimen synclinorium have high ⁸⁷Sr/⁸⁶Sr values, low δ¹³C and low δ¹⁸O values, which can be explained by the mixing of meteoric water during calcite vein deposition and suggests that reverse faults might have been open when they were formed. The salinity and homogenization temperature of fluid inclusions shows that the residual cap formations above the Upper Cambrian Loushanguan Formation are less than 3 km thick with poor sealing capacity. The high salinity of calcite inclusions in the Middle Cambrian Kongwangxi Formation showed that gypsum salt cap layers are distributed widely in the study area, and the gypsum salt layers buried over 2 km deep have excellent sealing capacity. The preservation conditions of the Tianerya, Xiangjiaya, Chefang anticline traps, and the Qiaotou, Zhongping buried structural traps are favorable. The dolomites in the Sinian Dengying Formation and Cambrian Qingxudong Formation are exploration targets except for those in the Tianerya anticline.

Sedimentary filling characteristics and the main controlling factors during the Early-Middle Miocene in the deep-water area of Shuangfengnan Slope in the northern South China Sea

Qian Xing, Zhang Li, Yi Hai, Wei Zhenquan, Shuai Qingwei

2015, 37(6): 751-757. doi: 10.11781/sysydz201506751

Abstract(1012) PDF-CN(905)

Abstract:
Deep-water deposition on the slope has become one of the major issues in China's offshore oil and gas exploration in recent years.We studied the seismic facies of the Shuangfengnan Slope in the northern South China Sea during the Early-Middle Miocene by combining external form and inner structure based on 2D multi-channel seismic and drilling data.Four typical seismic facies were recognized, including "S" type progradational seismic facies, mound type progradational seismic facies, parallel chaotic seismic facies, and parallel seismic facies. The paleogeographic evolution of the study area and the tectonic-sedimentary evolution of its adjacent area during the same period showed that three typical sedimentary systems (shelf-margin delta, slope fans, and slump deposits) were developed under the control of relative sea level change, provenance and the tectonic movement. The delta system with sources from South China and the Pearl River is the most important factor affecting the development of slope depositional system, and is the material basis of the depositional system. Tectonic movement and relative sea level change provided accommodation for the slope sedimentary system development.

Hydrocarbon accumulation and favorable objectives in the Amu Darya Basin, central Asia

Yu Yixin, Yin Jinyin, Zheng Junzhang, Li Feng, Wang Zhen, Xu Xiaolong, Wu Hang

2015, 37(6): 758-763. doi: 10.11781/sysydz201506758

Abstract(1051) PDF-CN(1121)

Abstract:
This paper summarizes the rules of hydrocarbon accumulation and their controlling factors, and predicts some favorable exploration targets based on the integrated analysis of the basic geological features and distribution of discovered oil and gas fields in the Amu Darya Basin.In map view, the distribution of oil and gas fields is controlled mainly by source rocks, structures and lithology.The phenomenon of differential accumulation of oil and gas is also obvious.There are sub-salt and supra-salt petroleum-bearing layers, separated by the Kimmeridgian-Tithonian evaporites.Sub-salt hydrocarbon accumulation is present in favorable reservoir belts and local structures. In addition, thinning of evaporite seals and activity of strike-slip faults are beneficial to supra-salt fields.According to the analysis of reservoirs, seals and source rocks, it is proposed that the sub-salt carbonate reservoirs of the Upper Jurassic Callovian-Oxfordian formations in the Murgab Depression, especially the reefs with structural background, are favorable exploration objectives.

Geochemical characteristics and types of natural gas from well Hugu 2 in the Dongpu Sag of Bohai Bay Basin

Ni Chunhua, Bao Jianping, Zhou Xiaojin, Xu Shutang, Xu Liangfa, Xu Tianwu, Su Songchen

2015, 37(6): 764-769. doi: 10.11781/sysydz201506764

Abstract(955) PDF-CN(1288)

Abstract:
The Dongpu Sag is a typical oil and gas producing unit in the Bohai Bay Basin in east China. A series of oil and gas fields have been discovered in recent years. In 2013, well Hugu 2 was drilled in the Huzhuangji area, finding industrial gas flows in the upper Shihezi and Shiqianfeng formations in the Permian. The geochemical characteristics and types of natural gas from well Hugu 2 were studied. The natural gas has a high methane content and low heavy hydrocarbon content. The dryness coefficient ranges from 0.977 to 0.985. The carbon isotopic values of methane, ethane and propane range from -28.7‰ to -28.4‰, -16.0‰ to -14.5‰, and -19.0‰ to -15.7‰, respectively. The carbon isotopic values of ethane and propane display reversal due to the mixing gases from the same source rocks at different stages. The gases from the Permian in well Hugu 2 are derived from the Carboniferous and Permian coal measures. A large proportion of the gases was cracked from kerogens during the Himalayan period.

Quantification of chromatographic fingerprints of mixed crude oils and its exploration significance: A case study of the southern fault zone in Gaoyou Sag

Ye Shaodong, Qian Shiyou, Li Xingli

2015, 37(6): 770-775. doi: 10.11781/sysydz201506770

Abstract(959) PDF-CN(676)

Abstract:
The discovered crude oils in the southern fault zone of Gaoyou Sag are binary mixtures mainly derived from the second and fourth members of the Funing Formation. An artificial mixing experiment of two typical end-member oils in the laboratory indicates that the chromatographic fingerprint of artificially mixed oil samples changes linearly with mixing proportions, so it is an effective method to quantify mixture proportions.An important key is to screen the fingerprint peaks. The application of a quantitative identification model created using an artificial oil mixing experiment can quantify the contribution of different oil sources and its migration path way. The model shows that the contribution rate of source rocks from the fourth member of Funing Formation is 80% in well X33, 30% in well X5-5, 40% in well F4-9, and 10% in well F5. Results indicate that the model has broad exploration applications for mixed crude oils in the southern fault zone of Gaoyou Sag. Source rocks from the second member of Funing Formation contribute more oil in the higher locations of the sag. Reservoirs are found in the first member of Funing Formation and the first member of Taizhou Formation.

Hydrocarbon and crude oil adsorption abilities of minerals and kerogens in lacustrine shales

Zhang Linye, Bao Youshu, Li Juyuan, Li Zheng, Zhu Rifang, Zhang Lei, Wang Yurong

2015, 37(6): 776-780. doi: 10.11781/sysydz201506776

Abstract(1023) PDF-CN(742)

Abstract:
The hydrocarbon and oil adsorption ability of minerals in continental shales and methanol-acetone-benzene (MAB) extracted shale residues were studied experimentally under formation temperatures. Hydrocarbon and oil adsorption ability decreases from illites to montmorillonites and to carbonates and oil adsorption amount in minerals is greater than hydrocarbon adsorption amount. MAB extracted shale residues, which mainly include minerals and kerogens, show better hydrocarbon and oil adsorption ability than mixed minerals. Minerals can adsorb hydrocarbon and oil at 0.20-3.13 mg/g, while kerogens can adsorb hydrocarbon or oil at 55-150 mg/g.

Quantitative classification of diagenetic facies in tight sandstone gas reservoirs based on multi-parameter evaluation: A case study of the first member of Shanxi Formation in the Shenmu Gas Field,Ordos Basin

Gao Hui, Fan Zhiqiang, Wen Kaifeng, Li Tiantai, Yang Ling

2015, 37(6): 781-788. doi: 10.11781/sysydz201506781

Abstract(1105) PDF-CN(706)

Abstract:
Diagenesis types, intensity and facies were evaluated using a variety of laboratoryresults and logging data in order to explore the quantitative classification method of diagenetic facies in tight sandstone gas reservoirs. Diagenetic facies classification standardswere established based on diagenesis and logging parameters. The basic characteristics of different diagenetic facies were elaborated taking the first member of Shanxi Formation in the Shenmu Gas Field in the Ordos Basin as an example.Dissolved pores, intercrystalline pores and small amounts of intergranular pores developed in the first member of Shanxi Formation in the study area. The formation is characterizedby medium compaction (locally weak or strong compaction), medium cementation (locally weak or strong cementation), and medium to strong dissolution. Five diagenetic facies weredefinedaccording to diagenesis intensity, cementation and pore types.Furthermore, diagenetic facies could be effectively recognized based on natural gamma ray logging, deep lateral resistivity logging, density logging and acoustic logging.The distribution of favorable diagenetic facies was controlled by advantageous sedimentary microfacies. Obvious differences appear among different diagenetic facies. Moderate compaction illite, dissolution pore+intergranular pore facies with eitherchloriteor kaolinite cementation, distributed in distributary channel microfacies of delta plains are favorable diagenetic facies in the study area.

Application of mercury injection and rate-controlled mercury penetration in quantitative characterization of microscopic pore structure of tight reservoirs: A case study of the Chang7 reservoir in Huachi-Heshui area, the Ordos Basin

Yu Jian, Ma Jie, Lu Jungang, Cao Yan, Feng Shengbin, Li Weicheng

2015, 37(6): 789-795. doi: 10.11781/sysydz201506789

Abstract(1163) PDF-CN(1035)

Abstract:
Huachi-Heshui area in the Ordos Basin is a typical enrichment region for tight reservoirs. It has poor physical properties and complicated characteristics of microscopic pore throat structure, which has a great effect on oil and gas accumulation and exploitation.Mercury injection and rate-controlled mercury penetration were used to quantitatively characterize nanometer pore throats and to study fluid mobility characteristics in tight sandstone reservoirs in the seventh member of the Yanchang Formation (Chang7). The reservoir in the study area has high displacement pressure, low average throat radius, large pore/throat volume ratio, big pore throat and poor permeability. The distribution range of pore radius of rock samples with different properties is consistent, while the distribution of throat geometry among them is obviously different. Mercury injection saturation increases with the increase of pore numbers. The curve of S_Hg-ΔS_Hg/ΔP_ccan preferably reflect mercury injection velocity and pore throat structure. Nanometer throat pore sare well developed in tight reservoirs, which make a great contribution to reservoir capacity and permeability. In the course of injection, fluid first enters the main controlling area of the pore, then the common control area of pore and throat, and finally the main control area of the throat.Rate-controlled mercury penetration is useful for the reservoirs with good physical properties, but it can not reflect the characteristics of nanometer pore throats in studying the pore throat structure of tight reservoirs.

A novel method for the determination of diamondoids in crude oils

Zhang Wanfeng, Tong Ting, Li Donghao, Dai Wei, Guo Pengfei, He Sheng, Zhu Shukui

2015, 37(6): 796-801. doi: 10.11781/sysydz201506796

Abstract(947) PDF-CN(695)

Abstract:
A novel device, termed as gas purge microsyringe extraction (GP-MSE), has been developed and applied to the preparation of different kinds of oil samples, including condensates, light and normal oils for the first time.Oils from the Pearl River Mouth Basin were firstly extracted by GP-MSE and then qualitatively and quantitatively analyzed by comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometry (GC×GC-TOFMS).The proposed method has many advantages over traditional column chromatography, such as simple and fast steps, satisfactory recoveries, and lower consumption of solvents and samples.The relative standard deviations (RSD%) of adamantane and diamantane are 1.57% and 2.63%, respectively.Crude oil samples are purified and enriched effectively. The relative deviation is less than 9%, and the correlation coefficient is over 0.997.

Change types of coal permeability to gas and its identification pattern

Li Junqian, Lu Shuangfang, Xue Haitao, Wang Weiming, Zhang Pengfei

2015, 37(6): 802-808. doi: 10.11781/sysydz201506802

Abstract(1144) PDF-CN(729)

Abstract:
Coal shows a variety of permeabilities to gas flow. Coal samples of different ranks were collected from 32 mines in China, and were prepared into 54 cylindrical cores to investigate coal permeability to gas (CO₂) flow. The results were classified based on rebound pressure and permeability damage rate. Furthermore, apattern of change types was established. These included "declining type", "rebounding type" and "increasing type", which could be further sub-divided into 8 types. The permeability change types can be identified from cross-plots of "maximum vitrinite reflectance-initial permeability", "ratio of inertinite content to vitrinite content-initial permeability", "ratio of fixed carbon content to ash yield-initial permeability" and "ratio of inertinite content to vitrinite content-ratio of fixed carbon content to ash yield".

2015 Vol. 37, No. 6

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