石油实验地质

2014, 36(3): .

Abstract(386) PDF-CN(585)

Abstract:

Structural interpretation and petroleum exploration targets in northern slope of middle Tarim Basin

Huang Taizhu

2014, 36(3): 257-267. doi: 10.11781/sysydz201403257

Abstract(1006) PDF-CN(1047)

Abstract:
Based on the 3D seismic interpretation of the northern slope of the middle Tarim Basin, the evolution features, activity phases and their controlling on reservoirs of main faults were studied. There were 8 rows of NNE- or NEE-trending sinistral strike-slip faults in the study area, and the faults were active mainly during the middle Caledonian (the end of the Middle Ordovician) and the early Hercynian (the end of the Middle Devonian). The early Hercynian tense-shearing strike-slip faults developed based on the middle Caledonian compressive-torsional faults, and were controlled by previous basement weak zone and disproportion tectonic stress, hence belonged to typical passive strike-slip faults. Fractures and hydrothermal activities played important roles in the generation of fractured and vuggy reservoirs in Ordovician carbonate rocks. 3 main reservoir charging episodes were concluded including the late Caledonian, the late Hercynian and the Himalayan. Paleozoic tectonic frameworks and strike-slip fault activities controlled the longitudinal distribution and enrichment of hydrocarbon, featured by dry gas in the Middle and Lower Ordovician and oil in the Lower Silurian. The Ordovician carbonate rocks in northern slope of the middle Tarim Basin are actual domains for the industrial production of natural gas. The beaded seismic reflection anomalies near to strike-slip faults are most favorable exploration targets. The "desserts" in sands under mudstones in the middle Kepingtage Formation are also favorable targets.

Characteristics and deformation mechanism of staging differential fault activities in Bachu Uplift, Tarim Basin

Yang Yong, Tang Liangjie, Jiang Huashan, Chen Gang, Xie Daqing, Li Meng, Cao Zicheng

2014, 36(3): 275-284. doi: 10.11781/sysydz201403275

Abstract(2624) PDF-CN(10351)

Abstract:
Based on the interpretation and analysis of the typical seismic profiles, we determined the activity phases of the faults in the Bachu uplift by calculating the amounts and rates of shortening of regional geological sections, and discussed the characteristics and deformation mechanism of staging differential activity. Fault activities took place mainly during the middle Caledonian, early Hercynian, late Hercynian, early Himalayan, middle Himalayan and late Himalayan. They were controlled by regional tectonic setting, pre-existing basement faults, regional detachment layer and some other factors. Compressive stress which generated by the closure of oceanic basin and the collision of plates was the dynamic source of the fault activities. The pre-existing basement faults controlled the position and orientation of the later stage faults. The regional detachment layer controlled fault development and distribution horizons.

Hydrocarbon accumulation conditions of Chang7 section, Yanchang Formation, Ordos Basin

Shi Baohong, Zheng Fei, Zhang Yan, Huang Jing, Zhang Lei

2014, 36(3): 285-290. doi: 10.11781/sysydz201403285

Abstract(1027) PDF-CN(794)

Abstract:
The Ordos Lake in Chang7 phase was largest and deepest in Yanchang period, and deposited high-quality and widely-distributed source rocks with some sandstones of delta front facies and turbidites facies. The analyses of deposition environment, reservoir feature, diagenetic facies and the assemblage of source, reservoir and cap showed that the Chang7 section had favorable source conditions. The favorable reservoirs mainly included turbidites of underwater distributary channel at delta front and semi-deep/deep lake facies. The sandstones were mainly lithic arkose sandstones and feldspathic lithic sandstones with low compositional and textural maturities. The reservoirs had low porosity (8.45% in average) and low permeability (0.12×10^-3 μm² in average). Chang7 sandstones were divided into 5 diagenetic facies types, among which the most favorable type was the cemetation-micropore intergranular pore and dissolution-dissloved pore and micropore diagenetic facies, but the distribution area was limited. The diagenetic facies with worst reservoir physical properties was the compacted cement-microporous diagenetic facies, which had broader distribution area. The semi-deep/deep lake deposition environment led to poor plane connectivity in Chang7 section. Hydrocarbon mainly migrated vertically, or laterally for short distance, and accumulated when blocked by mudstones or tight sandstones.

Diagenetic facies identification and distribution study of ultra-low permeability reservoir in Su77 block of Sulige Gas Field

Gong Xue, Shen Wuxian, Li Wenhou, Wang Ruogu

2014, 36(3): 291-298. doi: 10.11781/sysydz201403291

Abstract(902) PDF-CN(704)

Abstract:
Braided channels developed well in the lower part of the 8th member of middle Permian Shihezi Formation in Su77 block of Sulige Gas Field. Lithic quartz sandstone and lithic sandstone are the main lithology of reservoir. After compaction, pressure solution, authigenic mineral cementation and later dissolution, most of re-servoirs that are low porosity and ultra-low permeability ones have entered middle diagenetic stage B. According to the main diagenetic minerals, fillings, diagenesis and pore combination, reservoirs of the lower part of the 8th member of middle Permian Shihezi Formation are divided into 4 diagenetic facies as followed: Ⅰ. quartz overgrowth and dissolved pore facies; Ⅱ. clay minerals filling and intergranular pore facies; Ⅲ. carbonate minerals cementation facies; Ⅳ. compaction and pressure dissolution dense facies. Facies Ⅰ are the best reservoirs and facies Ⅱ are second-best ones. Facies Ⅲ and Ⅳ are poor reservoirs. According to logging facies, diagenetic facies are combined as concentric pattern, lateral variation pattern and cross-layer pattern.

Structural deformation characteristics, mechanics and physical modeling of Kedong structure in piedmont of western Kunlun Mountain

Gong Yanping, Yin Hongwei, Wang Xin, Liang Han

2014, 36(3): 299-303. doi: 10.11781/sysydz201403299

Abstract(898) PDF-CN(1301)

Abstract:
The Kedong structure locates in the front of the western Kunlun orogenic belt and was impacted signi-ficantly by the uplift of the western Kunlun Mountain. Deformations took place mainly in Neogene and Quaternary. Seismic data showed that the deformations in deep series were featured by thrust and imbricate faults, while in the shallow series a set of Cenozoic monoclines inclined to the north developed. The structural deformation process and mechanism of the Kedong structure were analyzed with physical simulation. It was concluded that the Kedong structure was mainly controlled by compression from south to north, erosion and synkinematic sedimentation. Paleogene evaporate bed and Jurassic coal-series stratum worked as regional composite detachment and controlled the decoupling and differential evolution of the upper and lower structures.

Hydrocarbon accumulation pattern of Kayindike region in southern Junggar Basin

Lin Xiaoyun, Qin Jun, Nie Wan, Ni Qian

2014, 36(3): 304-309. doi: 10.11781/sysydz20140304

Abstract(885) PDF-CN(686)

Abstract:
Based on the static elements for reservoir formation, taking the dynamic evolution process of the elements as the main line, the comparison of biomarkers and the analyses of source rock thermal evolutions, fluid inclusions and typical reservoirs were made to study the hydrocarbon source and accumulation process in the Ka-yindike region in the southern Junggar Basin. A hydrocarbon accumulation model was established to guide hydrocarbon exploration. Crude oils in the Kayindike region were classified into 3 types, respectively, from the Jura-ssic coal series, the Paleogene lacustrine mudstones and the two mixed, and the Jurassic coal series were more contributive. There were 2 major charging periods, about 10-8 and 2 Ma, respectively, and the ancient reservoirs charged in the 1st period adjusted during the 2nd period. The permeable sand series in the Kayindike region were controlled by the northern source materials, and were poorly connected with the south. Hydrocarbon migrated mainly along regional unconformities, and faults played important roles in communicating deep source rocks and ancient reservoirs. Controlled by faults and anticlines, the reservoirs were mainly fault-controlled and squeeze anticline type. The main controlling factor for hydrocarbon accumulation was the faults communicating source rocks. The hydrocarbon accumulation model was featured by mixed sources, vertical migration and 2 accumulation periods, among which the 2nd period was the major one.

Petroleum geologic characteristics and profitable exploration zone selection of Changtu Sag

Sun Yibu, Chen Xia, Xu Shilin, Zhao Hongwei

2014, 36(3): 310-315. doi: 10.11781/sysydz201403310

Abstract(758) PDF-CN(633)

Abstract:
The studies of petroleum geologic characteristics, structural unit division and profitable exploration zone selection of the Changtu Sag showed that Cretaceous was well developed in the study area, and the Lower Cretaceous was a main exploration target. The dark mudstones of the Jiufotang Formation, with high organic carbon abundance, type Ⅱ₂ kerogen and in mature stage, served as the main source rocks and mainly developed in the north of the sag. There were 3 sets of reservoirs including the Jiufotang, Shahai and Fuxin Formations. The Jiu-fotang reservoirs developed in the north and the south, and belonged to type Ⅱ. 2 kinds of petroleum systems were concluded. As to the 1st kind, hydrocarbon generated and self-stored in the Jiufotang and Shahai Formations. While for the 2nd kind, hydrocarbon generated from the mudstones in the Jiufotang Formation, stored in the sandstones in the Shahai Formation, and capped by the mudstones in the lower part of the Fuxin Formation. The Central Structural Zone, which was adjacent to hydrocarbon generation sag and had many traps, was the target for hydrocarbon migration for a long time, hence was a favorable petroleum exploration zone.

Sedimentary features and evolution of deep series in Lishu Fault Depression, Songliao Basin

Wang Li, Wang Guoshou, Qiu Qi, Wang Dongyan, Yang Hao

2014, 36(3): 316-324. doi: 10.11781/sysydz201403316

Abstract(806) PDF-CN(694)

Abstract:
According to the drilling cores, well logging and seismic facies data of the Lishu Fault Depression, the analyses of sedimentary features and evolution showed that the basement was cut by syngenetic fractures and seve-ral small fault depressions developed during the early stage. As lake plane rose during the early Shahezi period, a half-graben fault depression controlled by the Sangshutai Fault developed gradually. A structural pattern featured by fault in the west and overlap in the east and north controlled wide basin deposition in an unified water system. The sedimentary assemblage was characterized by deep/semi-deep lake, shallow lake, fan delta, delta, submerged fan and turbidite fan. The fault depression developed from shallow lake basin-swamp, to semi-deep/deep lake, and to semi-deep/shallow lake, and finally to shallow lake-river-delta. The exploration and sedimentary facies analyses of the Lishu Fault Depression showed that favorable reservoirs generated in every formation during fault depression evolution, mainly as fan delta front and delta front underwater distributary channel, mouth bar microfacies and gravity channel sand body. The Yangdachengzi area in the north and the Shuanglong-Dayushu-Xiaochengzi area in the east were favorable for exploration.

Reservoir-forming analysis of tight gas in Weibei Sag, Bohai Bay Basin

Sun Yaoting

2014, 36(3): 325-331. doi: 10.11781/sysydz201403325

Abstract(832) PDF-CN(681)

Abstract:
There were good geological conditions for tight gas reservoirs in the northern subsag of the Weibei Sag, forming the combination of self-generation, self-storage and self-cover in the 2nd member of the Kongdian Formation. Tight gas reservoirs generated in the area deeper than 3 500 m. The natural gas migration patterns under different porosity conditions were analyzed, and the influencing factors for gas saturation were studied with experiments. The relationship between permeability and final gas saturation was defined, and the coefficient was 0.904. Experimental results showed that gas charged early and abnormal high pressure existed during gas accumulation stage. The homogenization temperature of fluid inclusions showed that tight gas reservoirs experienced 2 charging periods. The 1st period was the early Shahejie period (52-50.5 Ma) and the 2nd one was before the Shahejie structural movement (43.5-36 Ma), among which the 2nd period played a more important role. The Shahejie structural movement caused pressure reducing and tight gas reservoirs were destroyed. The deposition of Neogene made reservoirs further compact, which was favorable for tight gas reservoir preservation in the Kongdian Formation. The tight gas reservoirs of the Kongdian Formation in the Weibei Sag were residual gas reservoirs, and still had good exploration prospects.

Discussion on origin of dolomite reservoirs in Feixianguan Formation, Puguang Gas Field, Sichuan Basin

Jiang Xiaoqiong, Guan Honglin, Zheng Herong, Wang Shuyi, Fan Ming, Bao Yunjie, Li Fengli, Han Yu

2014, 36(3): 332-336. doi: 10.11781/sysydz201403332

Abstract(1159) PDF-CN(738)

Abstract:
As an important natural gas reservoir in the Puguang Gas Field, the Feixianguan Formation in the Lower Triassic is featured by big thickness and good physical property. The formation mechanism of high-quality reservoirs is directly related to carbonate diagenesis, and the dolomitization of carbonate rocks is one of the key controlling factors. Based on rock structure analysis and combined with the order degree of dolomites, the geochemical characters of carbon and oxygen isotopes and sedimentary environments, it has been analyzed in this paper the dolomite genesis of the Feixianguan reservoirs in the Puguang Gas Field. It has been concluded that the dolomites in the Feixianguan Formation generated from seepage reflux during penecontemporaneous stage with the following evidences: 1) The structural characteristics of the original rock minerals remain obviously in the dolomites in the Feixianguan Formation, indicating for rapid dolomitization. 2) The sparry oolitic dolomites composed by micritic oolites have the same low order degree with the contemporaneous micro-micritic dolomites. 3) The carbon and oxygen isotopes composition and the paleosalinity of dolomites show that the dolomitizing fluids have high salinity, which is obviously different from the mixing water dolomitization. 4) The platform edge oolite beach facies of the Feixianguan Formation is adjacent to restricted platform, so it is easy to obtain quantities of saline water with high Mg/Ca ratios. What's more, this environment is beneficial to the development of dolomites and the formation of quantities of early dolomites. Thereby, the dolomites in the Feixianguan Formation mainly came from seepage reflux during penecontemporaneous stage. The reef-bank facies adjacent to the high-salinity environments such as restricted platform or evaporate platform facies are favorable for the generation of high-quality reservoirs.

Development of PVTx calculation software for CH₄-H₂O-NaCl system in fluid inclusions based on Microsoft Foundation Class (MFC) program frame

Zhang Jun, Zhang Jiali, Xi Binbin, Shi Weijun, Jiang Hong

2014, 36(3): 385-390. doi: 10.11781/sysydz201403385

Abstract(796) PDF-CN(875)

Abstract:
Fluid inclusions including CH₄-H₂O-NaCl system are widespread in reservoirs, and their parameters of P-V-T-x are very important for determining hydrocarbon accumulation stage and process. Since the calculation of above parameters is complicated, the automatic calculation of parameters using computer program is often used by geologists. By means of the PVTx calculation software for CH₄-H₂O-NaCl system in fluid inclusions based on Microsoft Foundation Class (MFC) program frame, the homogenization pressure in CH₄-H₂O-NaCl system in fluid inclusions are automatically calculated according to indoor temperature, homogenization temperature, ice temperature and Raman shift of fluid inclusion. The calculation results are directly showed in the P-T phase diagram and the gas-liquid saturation curve is obtained in the situation. The software in calculating is quick and perfect, and affords important consult in choosing tool and language for developing processing software of homogenization temperature of fluid inclusion.

2014, 36(3): 999-999.

Abstract(370) PDF-CN(362)

Abstract:

2014 Vol. 36, No. 3

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