A Study Of Metamorphic Buried Hill Reservoir Characteristics In Shulu Sagure

Shulu sag is located in the south of Jizhong depression. Since2000when oil reservoir in Xi caogu buried hill was found, none massive reserves in this area were found in last decade, which led to an unsure main attack direction and zone of the exploration. This dissertation is a monographic study of metamorphic rock buried hill in Shulu sag, which combined theories and methods about the oil reservoir exploration of metamorphic rock buried hill in last years to recognize and summarize the oil and gas reservoir characteristics and regularity of forming reservoir in an unique perspective.This paper attempted to study the reservoir geological characteristics of metamorphic rock buried hill through making full use of materials about well logging, earthquake and well drilling as well as test analysis by focusing lithology identification of metamorphic rock buried hill, classification of reservoirs, fracture development characteristics, distribution of reservoirs and influencing factors, and obtains some outcomes.With the fundamental theories of structural geology, reservoir geology, oil and gas reservoir geology and combining the materials about earthquake and well logging, this paper firstly presented a detailed research on the geological background, buried hill structural characteristics and buried hill reservoir characteristics. The geographic comprehensive research methods were utilized to examine the forming of buried hill stratum and to explore the structural evolution and the forming of entrapment of Shulu sag metamorphic rock buried hill, through which this paper found that the buried hill stratum mainly spread along the construction line orientation (NNE). The stratum exposure of Xinhe heave zone was also from west to east, and the stratum was gradually younging. The archaeozoic stratum was distributed in the frature region of Leijiazhuang which located in the south side of the sag and the west side of Xinhe heave with a shallow buried hill and a good exposure. The metamorphic rock buried hill was mainly distributed in Xinhe heave and Leijiazhuang heave zone. The depth of the lower paleozoic buried hill of Shulu sag increased with the growing of its overlying strata; the buried hill in archaeozoic and proterozoic was greatly influenced by the structure, for which the long-term denudation led to a thin overlying strata. According to the classification of the structure, the metamorphic rock buried hill in the sag mainly included double-fault buried hill, single-fault buried hill and monadnock as well as inner buried hill.Secondly, through petrologic research method to explore the lithology, degree of metamorphism, distribution pattern of geologic body of bed rock and macroscopic method to observe the core as well as rock chemical analysis, microelement analysis, thin section analysis to conduct a micro analysis on the core, this paper found that various types of metamorphic rock with the complicated metamorphism existed in Shulu area, in which the main type was regional metamorphic rock including gneiss, migmatite, marble, white mica quartz schist and slate, etc. Through the chemical analysis on the major elements of the core and element analysis of the palosome by using the A-C-FM, this paper found the main palosome of this area is parametamorphic rock.Thirdly, with a comprehensive application of rock characteristics, cause of formation of fracture and law of development, and a comprehensive consideration of the influence of structure, burial depth, lithology of metamorphic rock, supergene weathering, degree of metamorphism and corrosion on reservoir space, this paper explored and evaluated the regularity of distribution of reservoir from vertical and horizontal aspects, and found that dissolved pores of metamorphic rock in the superface of the buried hill greatly developed as the long-term dissolution made the soluble minerals dissolved and migrated. However, the dissolved pores were not be found in the inner rocks of the buried hill but only existed in the superface of the buried hill. With the growing of burial depth, the development degree of rock fracture gradually reduced, and the reservoir space achieved the turn from binary medium including pores and fratures to the single reservoir only with fractures. The superior reservoir mainly distributed in superficial part of the metamorphic rock of Leijiazhuang fault zone which is located in south of the sag, and Xinhe fracture heave zone.Finally, through analyzing the structure environment, reservoir-cap groups’ condition, oil sources and dredging condition, this paper made a comprehensive evolution of the buried hill oil and gas reservoir forming condition and proposed the exploration orientation of "superficial digging" and "depth exploring":to explore the weathtering crust oil and gas reservoir in the shallow part of Xinhe heave zone; to explore the fault block and inner buried hill oil and gas reservoir in the well area of Jingu in Leijiazhuang.