Method of completing welbores to control fracturing screenout caused by multiple near-welbore fractures

摘要

In the preferred embodiment of the present invention, completion operations are performed which include a perforation operation followed by a fracturing operation. During the perforation operation perforatons (or other means for creating flow paths) are shot at a low perforation density, in order to create a flowpath between the wellbore and the hydrocarbon bearing formaton as well as an unknown number of relatively wide fractures and relatively few, but unknown number of fracture initiation sites in the hydrocarbon bearing formation. During the fracturing operations, relatively small, high-concentration proppant slugs with clean spacer stages are pumped early in the treatment, in order to screenout the narrower fractures, but these slugs are not sufficient to screenout the wider fractures. Next, conventional fracturing operations are employed to create and/or enlarge and widen the remaining wider fractures, without the risk of loss of relatively- expensive carrier fluids and proppant material (such as sand) to the now- screened-out smaller fractures. Experimentation has revealed that this technique can be employed to (1) likely create longer and wider fractures, and (2) increase the overall sand-to-fluid ratios.