Fracture Displacement

Structural Traps. The attitude of the rocks, whether they are folded, fractured, displaced, or otherwise disturbed, is called their geologic structure. Traps that are due to geologic structure tire known as structural traps. 

Kopylov P, Aspenbeeg P, Yuan X and Ryd L (2001) Radiostereometric analysis of distal radial fracture displacement during treatment a randomized study comparing Norian SRS and external fixation in 23 patients. Acta Orthop Scand 72 57-61. 

Osteonecrosis is the commonest complication of hip fractures in children and the occurrence is increased if there is significant fracture displacement and compromise of blood supply at the time of fracture. Immediate reduction, internal fixation and removal of intra-articular haematoma may reduce the risk of osteonecrosis but this has not been confirmed. 

Fig. 18.18. a,b AP and lateral radiographs of radial neck fracture displaced by reduction of the dislocated elbow. Radial head lies adjacent to the capitellum. c Intraoperative radiographs showing intramedullary nancy nail and percutaneous wire used to manipulate the femoral head, d Post reduction film... 

As can be seen from the vector diagram of principal stress (Figure 9), the principal stress orientation is NE and is nearly perpendicular to the weak zone the principal stress orientation shows NW-trending at the edge of the south-western, and is nearly parallel to the strike of the weak zone, but it turns in the northwestern end and the southeastern end, turns clockwise in the northwestern end and turns counter-clockwise in the southeastern end. This distribution law of stress vector is different from surface fracture displacement that is observed after earthquake. 

Whereas faults displace formerly connected lithologic units, fractures do not show appreciable displacement. They also represent planes of brittle failure and affect hard... 

Field analogues should be based on reservoir rock type (e.g. tight sandstone, fractured carbonate), fluid type, and environment of deposition. This technique should not be overlooked, especially where little information is available, such as at the exploration stage. Summary charts such as the one shown in Figure 8.19 may be used in conjunction with estimates of macroscopic sweep efficiency (which will depend upon well density and positioning, reservoir homogeneity, offtake rate and fluid type) and microscopic displacement efficiency (which may be estimated if core measurements of residual oil saturation are available). 

Example 2.19 During tensile tests on 4 mm thick acrylic sheets of the type shown in Fig. 2.63(a), the force-displacement characteristics shown in Fig. 2.64(a) were recorded when the crack lengths were as indicated. If the sheet containing a 12 mm long crack fractured at a force of 330 N, determine the fracture toughness of the acrylic and calculate the applied force necessary to O acture the sheets containing the other crack sizes. 

Radioactive events occur in the measured depth interval (8,100-8,200 ft) with no displacement of the low/high side gamma ray logs. The radioactive events must be perpendicular to the gamma detector and could be indications of vertical natural fractures in the formation. 

One way of looking at the fracture characteristics of a ductile material is by measuring the amount of plasticity at a crack tip prior to crack propagation (Fig. 8.84). One test which measures this is the crack-tip opening displacement (CTOD), 5. Wells has found that 6 can be related to the strain energy release rate, G, by the formula ... 

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