Requirements for Frac-Packing long intervals in highly deviated wells are more and more frequent in many new projects. Although frac packing is a mature technology, its limits of applicability are not well known and are progressively extended by operational experience.
Today, it is a common practice to perform Frac-Pack in 65° deviated well over length of less than 100 ft and to achieve good completion efficiency (mechanical skin less than 5). This is possible with thorough engineering and QA/QC, and when accurate well data are available.
Over the last five years, Frac-Pack operating envelop has been pushed to 70 – 75° deviated wells and to lengths ranging from 100 to 322 ft. The success of such operations depends obviously on some specific precautions:
Enough information about reservoir conditions, geology and rock properties must be available to allow detailed fracture planning. In particular, time must be spent to obtain a representative mini frac and a correct interpretation; Requirements for hydraulic power and pressure rating must be properly assessed. Both the necessary pumping means and the proper down hole equipment (sand screens must be equipped with alternate path system) must be available.
The completion efficiency of such Frac-Pack is not always guaranteed. Global skin may be affected by induced (or not) partial penetration. The longer the interval, the higher the risk.