Fracture Characteristics Of Bedrock Reservoir In Kunbei Oilfield And Its Influence On Development

The bedrock reservoir in kunbei oilfield is rich in reserves,and the lithology is mainly granite and slate.In this paper,the development characteristics and control factors of natural fractures are analyzed by comprehensive application of core and slice data,and the distribution law of in-situ stress is revealed,which provides an important geological reference for fracturing and water injection to develop the reservoir.The natural fractures in bedrock reservoir of kunbei oilfield are mainly tectonic shear fractures,with the most developed in the near S-N direction and NNE-SSW direction.The dip Angle of fractures is widely distributed,mainly 30°?70° oblique fractures.In addition,there are a few high-angle fractures and near-horizontal fractures.The filling degree of fractures is relatively weak,most of them are effective fractures,and some of them are dissolved.The fracture development between different wells and different positions of the same well is obviously different and shows strong heterogeneity.The main underground crack openings are less than 100 ?m,mainly 60?m ?80?m,and most microcracks are less than 30?m.The degree of fracture development is mainly affected by lithology and tectonic position.Fractures develop in the parts with large structural curvature such as the core of the fold and the end of the transition.The direction of the maximum horizontal principal stress in the study area is NNE-SSW direction,the maximum horizontal principal stress is 43.23?49.23 Mpa,and the minimum horizontal principal stress is 31.2?36.33 Mpa.The stress field is used to simulate the threedimensional distribution of the stress,and it is revealed that the stress development has some heterogeneous characteristics.Affected by the present geostress,the subsurface opening of the natural fracture near S-N is large,which is the dominant direction of seepage of the fracture.Fractures provide important reservoir space and major seepage channels.Fractures have important effects on fracturing,water injection and well pattern layout of bedrock reservoir.Figure 59;Table 7;Reference 80...