Description Of Metamorphic Basement Rock Reservoir Of Ma Bei Oil Field In Qaidam Basin

In the worldwide,with the continuous deepening of exploration and sdudy extent to the oil and gas,the complex and unconventional hydrocrabon reservoirs are being paid much more attention and researched increasingly high.Bedrock reservoir is one of them.A few bedrock reservoirs has been found and confirmed containing high-yileld industrial oil flow in Qaidam Basin.mainly the northern margin of the and the west,most of them are tiththe rractured metamorphic rocks asreservoir. Because of the strong heterogeneity of the fractured metamorphic rock reservoir as well as the difficulty of prediction,the exploration and development is blind and passive.A few Fractured hydrocarbon reservoirs have been found in domestic, however, at present one of the key Technologies that has not been solved and positively being researched and developed in petroleum industry is how to recognize the fractured reservoir and describe fractured spatial distribution and orient from well logging and seismic data.In this paper, we taken the basement rock reservoir of oil field in Qaidam Basin as example to characterize and peidict reservoir,after researched tectonic setting in this region and basin revolution. we chose to study the basement metamorphic rocks fractured reservoir which is quite challengely,a comprehensive analysis of research combined with core, conventional logging and imaging well logging data, and adopted to advanced three-dimensional pre-stack seismic data inversion techniques, explored the basement metamorphic fractured reservoir of the Qaidam Basin description and prediction methods,at first.The studies of fractured reservoir is difficult, especially the fractured reservoir of base rock in Ma Bei oil fields. Because the depth of bedrock is relatively shallow and the width of fracture is small and the fractures extend a short distance, it increases the difficulty of forecasting. It is still lack of methods and means to research and forecast the fractured reservoir of basement metamorphic rocks. It is necessary to carry out the research of fracture, and identify accurately and predict the spatial distribution and law of the development of the fracture, which plays a decisive role and has a great significance in the exploration and development of oil and gas of determining the net of well, projecting the points of wells, and choosing the distance of wells and the technical measure. This paper has carried out mainly in the following research work:(1)The reservoir rock of basement of Ma Bei oil field are the segment of metamorphic rocks of the fracture prolifically and the wall of the well which are seriously avalanche. The types of the reservoir space are mainly including cracks, holes and caverns dissolved. Cracks in the formation plays an important role and development of dissolution porosity has provided preconditions for improving the storage reservoir rock permeability conditions.The cracks mainly developed in the metamorphic section, who generally can be divided into low-angle joints, high-angle joints, and fine irregular mesh. Cracks tend to edge direction is NNE and SSW in both directions. The crack inclination angle of the main low, mostly in 30°-40.The caving of drilling bedrock wall of MaBei3 well is common, The avalanche edge of direction is NW-SE, reflecting the present maximum horizontal principal stress direction to the NE-SW.(2)The main base rock reservoir in Mabei Oilfield is metamorphic rock,with little deep buried depth,but need high requirements on three-dimensional seismic data processing. Analysing the azimuth and offset distribution of seismic data,which plays an important part in extracting the azimuth of seismic data volume, and is also the most important first step in fracture detection.Due to the different tuning frequencies caused by the differences of the reservoir acoustic wave characteristics and the thickness, we can use spectral imaging technology. Using the changes in space of amplitude and phase in different frequencies, we can identify reservoir, describe the discontinuous change of geological body, and establish a space geological model of reservoir. Combining with other attribute profiles, we establish the vertical reservoir geological model and understand the geological characteristics of the reservoir. Establishing correct geological model of reservoir is the base to study the reservoir characteristics of fracture distribution.We simulate the changes in amplitude of the oil, water fractured reservoir with azimuth changes, and establish the relationship between seismic reflection amplitude with azimuth elliptical and fracture orientation, though rock physics model of Mabei 3 well. The results show that the long axis of the amplitude ellipse represents the strike direction of fracture, and the short axis represents the normal direction of fracture in bedrock fracture segment. Fracture orientation is related to the distribution of reservoir fracture systems.(3)The developmental characteristics of the planar transverse crack:there are lot of fractures, the matrix storage capacitu is well.. The fractures are more appear at Mabei No3 well and the neighborhood slope of Mabei No3 well southern, the fractures are little at the neighborhood of Mabei 302 well. The anisotropic characteristics have great change in horizontal. Especially, the propped fractures are well in the tectonic slope and the trending tectonics.By the developmental degree of the propped fractures, the local structural position and lithologic character are main control factors in the matrix, Mabei oil field. The structural faults have little effect in the degree of fractures. The study of pre-stack detected fractures shows that the relation between the fracture-developed zone and the great fault should be reconsideration. In fact, The results show that fault strike and the direction of main fracture set are consistent. For example, north north-east.(4)The fracture reservoir characteristics is well reflected by seismic attribution preprocessing, for example, intrinsic attenuation, AVO/FVO, prestack elastic wave impedance inversion, and so on. The analsis results of its is consistent with the analsis results of azimuthal amplitude and bearing-frequency(5)there are two sets of fractures in basement metamorphic rock, Mabei oil field. One is north north-east and the other is west northwest. They are controlled by the Indo-china movement and the Himalayan movement. The stage of fracture formation is a important information to impove resevoirs physical property.The successful results of well testing in MaBei No.3 prove that, the 3D basement rock fracture bearing area is profitable for exploring fracture reservoir. Using preexisting data of geology logging seismic and various advanced technology this thesis, multidisciplinary analyze and study the basement rock fracture in this block, ascertain the distribution characteristics and variation in thickness of regularity of the basement rock reservoir in MaBei No.3, to provide technical evidence for the successor exploring and development.Owning to the exploration activity is becoming more and more difficult, unconventional hydrocarbon reservoirs have been given more and more significances all over the word. Because of the heterogeneous reservoir sands and the difficulty of predicting of fracture bearing, so it is becoming difficulty for the exploratory development of this style hydrocarbon reservoir. In this paper, we try to study the characteristics of basement metamorphic rock fracture reservoir and the reservoir description, to provide some references for the exploring the key factor—predicting reservoirs technology.