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2014 Vol. 36, No. 5

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2014, 36(5): .
Abstract(744) PDF-CN(1019)
Abstract:
Exploration targets in southern Yellow Sea through analysis of tectono-depositional evolution and hydrocarbon accumulation of marine basin in Yangtze area
Xu Xuhui, Zhou Xiaojin, Peng Jinning
2014, 36(5): 523-531. doi: 10.11781/sysydz201405523
Abstract(848) PDF-CN(928)
Abstract:
The Southern Yellow Sea Basin locates in the eastern extension region of the Yangtze area, where marine Mesozoic-Paleozoic strata with great thickness developed. In order to investigate the petroleum geologic conditions and exploration direction of these marine Mesozoic-Paleozoic strata, and based on the evolution of marine Mesozoic-Paleozoic basin prototype and the regional development characteristics of main source rocks, the paper indicates that four main source rocks developed in the marine Mesozoic-Paleozoic strata in the Southern Yellow Sea Basin, similar with four source rocks (∈1, O3-S1, P1, P2) in the Yangtze area. The later three main source rocks which were widely developed in the inner Yangtze area need to be paid more attention. Meanwhile, according to the analysis of the reformation characteristics of all previous Cenozoic-Mesozoic tectonic declensions to the marine Mesozoic-Paleozoic strata in Yangtze area as well as the main petroleum formation types in the Yangtze area and the structural features of the Southern Yellow Sea Basin, it is suggested that the middle uplift and the southern depression area are the favorable exploration areas of marine Mesozoic-Paleozoic primary petroleum reservoirs. The marine Mesozoic-Paleozoic source rocks are in great conditions in these areas, completely preserved, and shallowly buried, and most important is that the structure was relatively stable with weak reformation in the later period. There could be some residual marine Mesozoic-Paleozoic primary petroleum reservoirs similar as those in the Huangqiao area in the northern Jiangsu. The northern depression of this basin was closely adjoining to the Sulu orogenic belt, therefore, the marine Mesozoic-Paleozoic strata was undergoing great deformation and even deflection. Similar to the Jurong area in the southern Jiangsu, the deformation petroleum reservoir could be developed in the later fault depression area. The Wunansha uplift was in the Cenozoic-Mesozoic intense fold-uplift belt for a long time, and mainly destructive primary petroleum reservoirs were developed in the marine Mesozoic-Paleozoic strata.
Sealing capacity of carbonate cap rocks：A case study of Ordovician in northern slope of central Tarim Basin
Lü Xiuxiang, Qu Yiqian, Yu Hongfeng, Lan Xiaodong
2014, 36(5): 532-538. doi: 10.11781/sysydz201405532
Abstract(882) PDF-CN(936)
Abstract:
Based on well log and logging data, using experimental test method, the sealing condition and mechanism of three sets of Ordovician cap rocks in the northern slope of the central Tarim Basin were studied. Thick mudstones of the Upper Ordovician Sangtamu Formation cover the whole study area and provide good regional sealing for oil and gas. The difference of shale content of carbonate cap rocks in the Lower Ordovician Lianglitage 3rd-5th members is obvious, but the distribution of oil and gas is different, illustrating that shale content is an important factor affecting the sealing capacity of cap rocks in the Lianglitage 3rd-5th members. When GR value reaches 20 API, the Lianglitage 3rd-5th members work as effective cap rocks, sealing oil and gas in the underlying Yingshan Formation. Due to the influence of filling, cementation and selective corrosion of atmospheric precipitation, dense and high-resistivity layers were formed in the Yingshan Formation, blocking oil and gas mainly by the mechanism of displacement pressure difference. When the displacement pressure difference between high-resistance layer and underlying reservoir bed is above 1.5 MPa, the high-resistivity layer is considered as a local cap rock, providing certain sealing for oil and gas inside the Yingshan Formation.
Classification and correlation of Cambrian in eastern Tarim Basin
Cai Xiyao, Dou Liwei, Jiang Huashan, Yu Tengxiao, Cao Zicheng
2014, 36(5): 539-545. doi: 10.11781/sysydz201405539
Abstract(935) PDF-CN(1255)
Abstract:
Through the observation and analysis of the Cambrian profile of Kuruktag area in the northeastern Ta-rim Basin, combined with the comprehensive study on the Cambrian in the well YL1, and adopting the international Cambrian division scheme, it was proposed in this paper a new standard which divided Cambrian into four series and four formations. Two marking beds, "reversal spoon shaped gamma segment" and "ultra-high gamma segment", were identified. Multi fossils were found in large quantity in the Xishan Braque and Moheershan Formations. A great geological event (ZHUCE) was identified in the Lower Cambrian with global comparing significance. By comparing stratigraphic division, the early Cambrian formations were found missing in the wells TD1 and TD2, which were regarded as the typical wells of trough facies in Cambrian, indicating that the southern edge of the famous "Manjiaer aulacogen" had not reached the line from well TD1 to well TD2 at the end of Sinian. Four second-order and six third-order sequences in Cambrian were concluded in the study area, providing a stratigraphic basement for the studies of sedimentary facies, tectonic movement and hydrocarbon accumulation.
Study of Maxi gas reservoir in northern margin of Qaidam Basin
Gan Guiyuan, Zhang Jianying, Song Bing, Xi Bin, Wang Mu, Yao Xihai, Zhang Zhiguo
2014, 36(5): 546-549. doi: 10.11781/sysydz201405546
Abstract(1104) PDF-CN(945)
Abstract:
The gas reservoir in the lower part of the Lower Ganchaigou Formation (E31) in Oligocene in the Maxi gas pool in the northern margin of the Qaidam Basin was formed in braided river delta sedimentary environment. The rock type of reservoir mainly includes fine sandstone, medium sandstone and siltstone. Lithic feldspar sandstones account for the largest proportion, while feldspar lithic sandstones the second. The separation of fragment grains is medium or good. Contact or pore cementations are common. Point contact is the leading contact type. Primary intergranular pores are dominant in sandstone reservoirs, featured by big pores and coarse throats. The average porosity and permeability of the reservoir are 25.21% and 963.52×10-3 μm2, respectively, indicating for a good reservoir with high porosity and permeability.
Time of hydrocarbon accumulation in eastern depression of North Yellow Sea Basin
Liu Zhenhu, Wang Feiyu, Liu Jinping, Hu Xiaoqiang
2014, 36(5): 550-554. doi: 10.11781/sysydz201405550
Abstract(1080) PDF-CN(966)
Abstract:
The eastern depression is the only depression in which petroleum was found with good potential in the North Yellow Sea Basin. The time of petroleum accumulation in this depression will decide the strategy of petroleum exploration. Based on the studies of petroleum generation and expulsion history as well as sandstone inclusions in oil layers, the accumulation time for reservoirs in the eastern depression was discussed. Hydrocarbon was formed and expulsed from the middle Jurassic source rocks in Oligocene, and the sandstone inclusions in the Lower Cretaceous and the Upper Jurassic reservoirs were filled by oil in the early Miocene. Combined with the tectonic evolution of the basin, it was inferred that petroleum accumulated from the Late Oligocene to the Early Miocene in the eastern depression of the North Yellow Sea Basin.
Formation conditions and development features of Neogene stratigraphic-lithologic traps in Pearl River Mouth Basin
Du Jiayuan, Chen Weitao, Zhang Changmin
2014, 36(5): 555-561. doi: 10.11781/sysydz201405555
Abstract(1151) PDF-CN(1088)
Abstract:
As exploration degree increases, stratigraphic-lithologic traps have become an important new field for oil and gas exploration in the Pearl River Mouth Basin. The formation conditions and development features of Neogene stratigraphic-lithologic traps were systematically investigated in this study. The basin has experienced several stages of sea level fluctuations ever since Neogene, resulting in the coexistence of multiple sedimentary systems. Two types of shelf edges and the corresponding low stand systems tracts as well as two significant tectonic movements provided favorable conditions for the development of stratigraphic-lithologic traps, which showed obviously different features in the continental shelf region and the shelf margin region. The intervals near to sequence boundary seem to have the most favorable potential. Oil and gas migration pathways play important roles in controlling final hydrocarbon accumulation.
Distribution of ancient ditches in Leikoupo Formation and its control over gas accumulations in Yuanba Gas Field
Fan Zhiwei
2014, 36(5): 562-566. doi: 10.11781/sysydz201405562
Abstract(869) PDF-CN(833)
Abstract:
Based on the analyses of generation condition, identification method and distribution feature of the ancient ditches in the Leikoupo Formation in the Yuanba Gas Field, the influences of ancient ditches on reservoir, trap, flow and hydrocarbon enrichment were discussed, and several favorable exploration targets were pointed out. Erosion, early fracture and hot and humid climate controlled the generation of ancient ditches. The ditch area was featured by thin residue formation, thickening overlying formation and underflow development. "Concave" and "bidirectional onlap" were identified on seismic sections. There are four main ditch areas in the study area, usually 2-3 km wide for a single ditch, and the cutting depth is 30-60 m. Karst residual hills, which were well-preserved and favorable for reservoir, are potential targets for exploration.
Characteristics and its effect on reservoir physical property of quartz overgrowth at Daniudi Gas Field
Qu Xiyu, Qiu Longwei, Song Fan, Zhang Manli, Liu Bing
2014, 36(5): 567-573. doi: 10.11781/sysydz201405567
Abstract(835) PDF-CN(958)
Abstract:
The tight sandstone reservoirs from the Taiyuan, Shanxi and Xiashihezi Formations of the Daniudi Gas Field were studied. In view of the punctate type, zonary structure and multistage morphology of quartz overgrowth, and combined with the homogenization temperature fluid inclusions, the quartz overgrowth were divided into three stages, among which the stage Ⅱ was most developed and contained some organic inclusions. Quartz solution was found in the stages Ⅰ and Ⅲ. The corresponding reservoir physical property gradually became poor with the increasing stage of quartz overgrowth and the increasing width of enlargement margin; however, the porosity of the stage Ⅲ was obviously higher than that of the previous two stages. Pore filling was dominant when the content of siliceous cement was over 3% at the Daniudi Gas Field. After the quartz overgrowth in the stage Ⅲ, sandstone reservoirs were densified completely. Under the whole compact background, alkalinity dissolution resulted in pores of quartz solution type, which offered reservoir space for the Daniudi Gas Field, and was the main cause for secondary pores in the second member of the Taiyuan Formation.
Anatomy and application of facies-potential coupling on hydrocarbon accumulation in typical lithologic reservoirs in Jiyang Depression
Huo Zhipeng, Pang Xiongqi, Fan Kai, Chen Dongxia, Zhang Jun
2014, 36(5): 574-582. doi: 10.11781/sysydz201405574
Abstract(1057) PDF-CN(500)
Abstract:
Oil and gas exploration in the Jiyang Depression showed that lithologic reservoirs were mainly controlled by facies and interfacial potential. As to the facies-controlled effect, the favorable facies with high porosity and high permeability controlled hydrocarbon accumulation. And for the potential-controlled effect, low interfacial potential controlled hydrocarbon accumulation. Only in the coupling region of favorable facies and low interfacial potential, could lithologic reservoirs form. Through typical cases studies of the lithologic reservoirs of the Cheng913 in the Zhanhua Sag and the Niu35-Niu20-Wang70 in the Niuzhuang Sag, results showed that only when the facies-potential coupling index(FPI) was larger than 0.5, could hydrocarbons accumulate in lithologic traps. Besides, the critical condition for hydrocarbon accumulation displayed the characteristics of Two Lows or Two Highs, that was, low or high facies index (FI) and interfacial potential index (PIS). The larger the FPI was, the higher the oil saturation was, and the easier it was for hydrocarbons to accumulate. Based on the statistics of petroliferous property and the analysis of facies, the potential characteristics of 73 lithologic traps and 54 turbidite lens traps in the Jiyang Depression were concluded, and the quantitative models of the relationship between oil saturation and FPI for two categories of traps were established. Oil saturation of 13 lithologic traps in the Dongying Sag was predicted through this model, and it achieved the accuracy rate of 84.6% for the reservoirs with the deviation rate less than 20%. As a result, this model could be applicable in predicting the oil saturation of lithologic reservoirs.
Petroleum accumulation conditions and exploration direction of Rio Muni Basin, West Africa
Ni Chunhua, Zhou Xiaojin, Bao Jianping, Duan Tiejun, Cheng Jian, Pei Wei
2014, 36(5): 583-588. doi: 10.11781/sysydz201405583
Abstract(1183) PDF-CN(790)
Abstract:
Based on the background of regional structural evolution, the tectono-sedimentary evolution of Rio Muni Basin, West Africa can be divided into three phases: intracontinental rift, intercontinental rift and passive continental margin. It has been proved by exploration and research that there are multilayer source rocks, reservoirs and caps in the basin. With the Aptian Salt developed in the intracontinental rift phase as the interface, there are pre-salt and post-salt petroleum systems. It is showed that salt structures and favorable reservoirs control the effective hydrocarbon accumulation of the post-salt system, while high-quality source rocks and caps are the key reservoir forming factors of the pre-salt system. It is recognized by comprehensive analysis that the petroleum exploration focus should be the Cretaceous on the salt and the complex hydrocarbon reservoirs with structure stratigraphy with the development of salt structure and turbidite sand body. It is suggested that the near-source favorable structures are priority exploration targets to the pre-salt strata in the area located in the hydrocarbon generation center of rift sag.
Controlling factors of hydrocarbon accumulation and play fairway in North Sakhalin Basin
Chen Wenxue, Lü Xueyan, Zhou Shengyou, Li Changzheng
2014, 36(5): 589-596. doi: 10.11781/sysydz201405589
Abstract(1174) PDF-CN(837)
Abstract:
Locating in the circum-Pacific fold belts of far-east in Russia, the North Sakhalin Basin is a back-arc basin developed from Mesozoic to Cenozoic. There are three sets of source rocks including shale in the Okobykay Formation of the Upper Miocene, shale in the lower Nutovo Formation of the Upper Miocene, and coal-bearing strata in the Weining Formation of the Lower Miocene and the Dagi Formation of the Lower Miocene. Its main oil production derived from the sandstones in the Dagi Formation of the Middle and Lower Miocene and the lower Nutovo Formation of the Upper Miocene. The major trap types are anticlines, complex faulted anticlines and fault blocks. Oil and gas mainly accumulated in the Sakhalin sub-basin in the northeast, with larger reserves offshore than onshore. Vertically, they were mainly found in the Dagi Formation of the Middle Miocene and the Nutovo Formation of the Upper Miocene. The comprehensive evaluation of reservoir conditions showed that the distribution of oil and gas were mainly controlled by structure and reservoir development. The structural traps formed during the late Pliocene provided spaces for hydrocarbon accumulation, and the folding event which took place from the late Pliocene to Holocene functioned as adjustment and even destruction to traps. The distribution of sandstones in the Dagi Formation of the Middle and Lower Miocene and the Nutovo Formation of the Upper Miocene controlled the plane and vertical distributions of hydrocarbon. Compared to the highly explored onshore area, the offshore area has a great potential, and the exploration targets should be focused on the structural-stratigraphic and stratigraphic traps in the Nutovo and Dagi Formations.
Hydrocarbon differential accumulation of foreland basins in western South America and its controlling factors
Ma Zhongzhen, Xie Yinfu, Li Jia, Liu Yaming, Zhou Yubing, Wang D
2014, 36(5): 597-604. doi: 10.11781/sysydz201405597
Abstract(1095) PDF-CN(948)
Abstract:
In order to study the hydrocarbon differential accumulation of the foreland basins in the western South America and its controlling factors, we collected over 4 400 data of 14 foreland basins within IHS2009 database. Several conclusions were made as followed. (1) The foreland basins have distinct segmental accumulation characters. Hydrocarbon mainly accumulated in the north, accounting for 85% of total recoverable reserve, while in the center and south, only 6.9% and 8.1%, respectively. Vertically, hydrocarbon mainly distributes in the Upper Cretaceous and Tertiary reservoirs in the north, below Jurassic in the center, and in Jurassic and Cretaceous in the south. (2) The segmental features of petroleum geology controlled the differential accumulation of hydrocarbon. The segmental development of source rocks determined the plane enrichment of oil and gas. The segmental development of reservoirs and cap rocks controlled the vertical distribution of hydrocarbon.
Molecular biological analysis of methanotrophic bacterial community above typical oil and gas reservoirs
Tang Yuping, Gao Junyang, Zhao Kebin, Ren Chun, Xu Kewei
2014, 36(5): 605-611. doi: 10.11781/sysydz201405605
Abstract(1012) PDF-CN(915)
Abstract:
In this study, the community structure of aerobic methanotrophic communities were investigated at light hydrocarbon microseeps above a known oil band gas field in the Shengli Oilfield. Clone library analysis of the pmoA gene revealed major differences in the methanotrophic community composition between oil and gas fields and the surrounding soils. The relative abundance of methanotrophic Methylocystis and Methylosinus (type Ⅱ) in surrounding soils is obviously lower in oil and gas field soils than surrounding soils, ut the relative abundance of methanotrophic Methy-lococcus and Methylocaldum (type I) presents a reverse tread. Terminal restriction fragment length polymorphism (T-RFLP) analysis confirmed that one distinct Methylococcus and Methylobacter-related group may dominate the community at hydrocarbon microseeps. The pmoA gene copy numbers determined by real time PCR also indicated that methane oxidizing microbial community anomalies above typical oil and gas reservoirs exist objectively.
Identification and distribution of C1-and C2-alkylated dibenzothiophenes in petroleum and sedimentary organic matter
Shi Shengbao, Li Meijun, Zhu Lei
2014, 36(5): 612-617. doi: 10.11781/sysydz201405612
Abstract(762) PDF-CN(869)
Abstract:
Based on internal standards co-elution, retention indices comparison and molecular structure and chemical properties, a series of C1-and C2-alkylated dibenzothiophene isomers in oils and related sedimentary organic matters were firmly identified in this paper. The corresponding retention indices were also determined. This study corrected several compound peaks on mass chromatograms which were wrongly identified in previous publications. The elution order of all C1 and C2-dibenzothiophene isomers on GC column (HP-5MS) was systematically determined, and the distribution patterns of C1-and C2-alkylated dibenzothiophenes in petroleum and sedimentary organic matters were preliminarily discussed.
Comparative research on hydrocarbon generation conditions of Meso-Neoproterozoic between east and west of North China Platform
Lin Yuxiang, Li Xiaofeng, Yan Xiaoxia, Guo Fengxia, Liu Hu, Li Xiuqin
2014, 36(5): 618-625. doi: 10.11781/sysydz201405618
Abstract(1144) PDF-CN(1098)
Abstract:
Based on the analysis of the abundance, type, thermal evolution degree of organic matter and the hydrocarbon generation history in Meso-Neoproterozoic in the North China Platform, the western part of the platform represented by the Mengshan Aulacogen was compared with the eastern part represented by the Jiliao Aulacogen in hydrocarbon generation condition. The hydrocarbon source rocks of Meso-Neoproterozoic in the eastern part of the North China Platform are premium source rocks for high abundance and good type of organic matter while the western hydrocarbon source rocks with low abundance of organic matter are only medium to bias, even though their type is also good. Although the thermal evolution of the eastern part is similar to the western part, their thermal evolutions are quite different from the Late Paleozoic: the eastern part uplifted in succession and the overlying strata denuded; while the western part continued to subside and achieved the highest thermal evolution degree in Mesozoic. Generally speaking, the Jiliao Aulacogen is the most favorable hydrocarbon generation area in the North China platform, then the Mengshan Aulacogen and the Yushan Aulacogen.
Characteristics of Cambrian source rocks in well XH1, Shaya Uplift, Tarim Basin
Zhu Chuanling, Yan Hua, Yun Lu, Han Qiang, Ma Huiming
2014, 36(5): 626-632. doi: 10.11781/sysydz201405626
Abstract(1033) PDF-CN(703)
Abstract:
In the northwestern Shaya Uplift of the Tarim Basin, gray and black carbonaceous mudstones were collected from the Cambrian Yuertusi Formation in the well XH1, and were tested for organic geochemistry. The analyses included the determinations of organic carbon (TOC), chloroform bitumen "A", hydrocarbon generation potential, pyrolysis peak temperature, marine vitrinite, soluble extraction of source rock, gas chromatography and so on. The organic matter abundance, maturity and type of source rocks were studied. The Cambrian source rocks in the well XH1 were compared with other Cambrian source rocks in previous reports. Oil-source correlation of the studied source rocks was made compared to those from the Tahe oilfield. The studied source rocks have high organic matter abundance, and have entered the high-mature stage for thermal evolution, which is similar with the source rocks in the Lower Cambrian Yuertusi Formation on the Xiaoerbulak profile in the Keping area. There are some similar geochemical characteristics between the Lower Cambrian black carbonaceous shale and the crude oil from the Tahe oilfield.
Uncertainty evaluation of petroleum risk assessment
Sheng Xiujie, Jin Zhijun, Xu Zhongmei, Jiang Han
2014, 36(5): 633-641. doi: 10.11781/sysydz201405633
Abstract(987) PDF-CN(844)
Abstract:
The margin and condition probability analysis is broadly applied to the geological risk evaluation for an immature play with joining the "success" probabilities subjectively specified for those independently involved geological factors. Considering that it is difficult to specify a reasonable scoring distribution curve for each geological factor, this method contributes a "point" estimation about whether there exists petroleum resource. Obviously, subjected to lack efficient ways to encode the information about geological multi-scene of subsurface and possibi-lities for each geological factor, the above crisp estimation conclusion would be generally either higher or lower. In order to enhance the capability of uncertainty expression of geological risk evaluation, this paper presents three heuristic mathematic models to deeply quantify the understanding of a geological expert and objectively delineate the possibilities of subsurface occasion, etc. Meanwhile, the uncertainty assessment methods discussed also de-monstrate a reasonable uncertainty evaluation process from subjective guess to objective prediction in order to shrink the uncertainty of evaluation as more as possible. Firstly, the double linear conversion between subjective inference for each factor and quantized confidence shares an efficient alternative to describe subjective uncertainty. Next, the specification of multi-value model and setup of corresponding fuzzy rules for each geological factor may accurately and honestly reflect the worldly uncertainty of subsurface multi-scene while matching the domain expert’s understanding as more as possible. At last, Montecarlo method randomly joins the objective uncertainty distribution curve of each factor and shares experts with quantiles evaluation which would benefit incoming reasonable exploration solution. As a conclusion, this paper not only investigates how to make full scale uncertainty evaluation for geological evaluation, but also expands a new horizon about geological risk uncertainty research.
ESR dating of Helan Mountain Fault Zone
Yang Fan, Fang Chengmin, Huang Zeguang, Zhou Xiaojin, Xu Liangfa
2014, 36(5): 642-644. doi: 10.11781/sysydz201405642
Abstract(1081) PDF-CN(827)
Abstract:
It is very difficult to form new metamorphic minerals in the movement of brittle faults under shallow and low-temperature situation. Therefore it is impossible to determine the active ages of faults exactly through traditional methods. In the activation of shallow faults, homochromous quartz veins often develop. As a result, we can use thermal activated ESR dating to obtain the ages of quartz veins, and then to determine the active ages of faults. If there are several stages of quartz veins in fault belts, the corresponding active ages of faults can also be determined. The western Ordos thrust-fold belt has a complicated structure, and its development mechanism is still controversial. A case study was made in the Helan Mountain area. According to the ESR dating of quartz veins, the SN-trending fault which thrusted from east to west in the study area was formed after the Late Jurassic, and experienced several active stages.
Physical simulation of exploiting fractured-vuggy carbonate gas condensate reservoirs by water injection
Peng Song, Guo Ping
2014, 36(5): 645-649. doi: 10.11781/sysydz201405645
Abstract(940) PDF-CN(407)
Abstract:
Due to the development of fissures and cavities with different sizes and shapes, fractured-vuggy carbonate gas condensate reservoirs are distinct from the general sand gas condensate reservoirs, hence are characterized by strong heterogeneity and complicated flow regularity. To these reservoirs, it is a question of concern that which developing strategy is benefit to maximize the recoveries of oil and gas. As a mature technology, water injection possesses advantages such as lower cost, better gas-water mobility ratio, and higher sweep efficiency. Taking well TZ86 as a target, we accomplished a physical simulation research under initial reservoir conditions (140.6 ℃,58 MPa) by using an artificial fractured-vuggy full-diameter core which was made from an outcrop of carbonate rock. The experimental results show that the effectiveness of exploiting fractured-vuggy carbonate gas condensate reservoirs by water injection is significant. The factors such as the connectivity pattern between fissure and cavern, the pressure maintenance level of water injection, and cavern whether or not filling have effects on the recovery of condensate oil.
Simulation experiment for ankerite dissolution in clastic reservoir of saline lacustrine basin
Huang Chenggang, Yuan Jianying, Cao Zhenglin, Zhang Shiming, Wang Ying, She Min, Mi Haijie
2014, 36(5): 650-655. doi: 10.11781/sysydz201405650
Abstract(1037) PDF-CN(836)
Abstract:
It is generally believed that carbonate minerals can easily dissolve. This process will lead to the formation of secondary pores, thereby enlarging the reservoir space and improving the permeability of reservoir rocks. In the Qaidam Basin, clastic reservoirs of the Lower Eocene Gancaigou Formation are deposits of saline lacustrine basin, with plaster and ankerite well developed in rock flacks as revealed by polarized light microscopy and scanning electron microscope. Experimental results of fluid-rock dynamic stimulation show that the ankerite dissolution can generate secondary pores, and gypsum catalyzes the dissolution. The iron and magnesium ions generated are reactants in the transformation from koalinite to chlorite. The foliated chlorite easily blocks thin throat, leading to the decrease of permeability, while the dissolution of easily soluble minerals like ankerite increases porosity.
Experimental study on methane adsorption of coal bed from Sihe Mine in Qinshui Basin
Zhang Zhenbing, Qiu Xiaolong, Yuan Yueqin, Li Xiangfeng, Hao Qi, Wang Jun
2014, 36(5): 656-658. doi: 10.11781/sysydz201405656
Abstract(874) PDF-CN(799)
Abstract:
Due to abundant racks and pores, coal bed has a huge specific surface area which provides the necessary conditions for the adsorption of methane in coal. A case study was made in the Sihe Mine in the Qinshui Basin. Using the self-developed CBM adsorption experiment instrument, the absorption rules (including rate and amount) within 12 h of methane in coal of different sizes were studied. The absorption amount during the prior 10 minutes accounts for 40%-60% of total absorption amount. Moreover, the smaller the coal particle is, the bigger proportion the small particle accounts for, the faster the methane is absorbed. The adsorption capacities for different coal sizes range from 15.1 to 33.6 mL/g. The smaller the coal particle is, the more methane is absorbed in coal per unit. The study of the adsorption law of coal bed provides technological supports for the exploration and development of the Qinshui Basin.
2014, 36(5): 659-659.
Abstract(504) PDF-CN(764)
Abstract:

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