الفهرس 
Chapter One -- IntroductionOnly 14 pages are availabe for public view
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Abstract
In hydraulic fracturing, various methods have been used to treat multiple zones with greater or lesser degree of effectiveness. Limited entry technique is one of them. Limited entry could be very effective and can result in considerable savings in well completion costs. The process is not difficult to apply. The technique of limited entry perforations is used to achieve large frictional pressure DROP across certain perforations to ensure fluid injection through each perforation in each interval. During the injection, the frictional pressure offsets the stress differences between the zones to enhance injection in all perforated zones. By limiting the number of perforations for multiple intervals, the number of intervals that can be penetrated by fracturing fluid will be increased As with every other technique, there are constraints associated with the limited entry technique. One such constraint is computing the optimum number of perforations that can fulfill a uniform distribution of fracturing fluid in all zones. Another constraint; the perforations may be eroded when the proppant is pumped through it which, in effect, reduces the perforation friction dramatically. Perforations erosion is often suspected as the major reason for inadequate treatment coverage. In this research; there will be an attempt to create the desired fracture geometry and fracture conductivity for each zone by limited entry technique as it could be if each zone stimulated separately. This will be achieved by trying to solve the problems associated with this technique utilizing hydraulic fracture simulator. The data of three different formations in the same well were simulated to be stimulated in one huge treatment throughout three different scenarios. In the first scenario, the treatment was simulated without using any diversion method. The result was not only the loss of stimulation of one zone but complete failure of the treatment. In the second scenario, a new procedure to calculate the optimum number of perforation for each zone was generated. By using this procedure with the same data in the last scenario, the treatment simulation was completed. By evaluating the results of this scenario, it was found that the perforation friction was lost nearby the end of the treatment. This problem was investigated from actual downhole memory gauges extracted from two dead strings used before in actual limited entry hydraulic fracturing treatments. The proppant effect on the perforations was found ruinous. The third scenario was created to overcome this problem. In this scenario, a certain percentage of the perforation profile used before in the second scenario was utilized to increase the amount of the perforation friction that will remain at the end of the treatment. This new perforation profile was run on the simulator again. The perforation friction remained at the end of the treatment was found meeting the minimum value necessary for diversion. Finally, the perforation friction that designed for the limited entry technique has to match the actual value determined from minifrac analysis before the main treatment. The industry solution for the higher perforation friction is the sand-slug. The effect of the sand slug was checked out from actual cases and was found destructive to the perforation friction and cannot be controlled. Another method was recommended by calculating the effective number of perforation from the flow through edge orifice equation and then are-perforation job has to be performed based on the effective number of perforations that obtained from step rate test.