PERFORATION OPTIMIZATION DESIGN FOR OPERATION OF LIMITED ENTRY FRACTURING TECHNOLOGY

Limited entry fracturing technology is a chief method used to stimulate low permeability muti-layer reservoirs. The key point is how to optimize perforation process for different layers. Perforations are determined according to the formation thickness in conventional way. Then the fracturing fluid and sand volume is calculated proportionally based on the number of perforations. Therefore, the influence of characteristic nature of different layer on the operation scale and perforations is not considered. It is also not considered that the well bore; the perforations and the friction affect fluid entry volume in different layer during operation. A mathematic model to calculate limited entry volume changes with time, formation characteristic and perforations has been set up. Combining the model above and the model of fracture geometry can carry out the optimization design. The field test of 22 wells in Daqing Chang-huan shows a better production improvement.