This paper presents a skin analysis of Frac and Pack (F&P) completions and summarizes our F&P design methodology, field execution procedures, and productivity responses for ten F&P jobs done in a wide range of field conditions in the Gulf of Mexico (GOM). The purpose of the paper is to identify design and job execution requirements to better optimize F&P treatments.
The skin analysis revealed that near-wellbore skins, from perforation tunnels (casing and cement sheath) and a choked fracture, can dominate the final F&P completion skin. Near-wellbore skins are particularly damaging when F&P treatments have low dimensionless fracture conductivity ratios (FCD) and when perforation tunnels are not filled with permeable proppant. Therefore, F&P designs should aim for high fracture conductivities with FCD greater than one and fill perforation tunnels with proppant permeability greater than 200 times the formation permeability. For most applications in GOM, such requirements require larger proppant sizes that may not satisfy gravel packing requirements,
Besides maximizing the FCD, the perforating completion and the execution of F&P should include steps to minimize near-wellbore damage. These include perforating with high shot density and big hole charges, initiating or breaking down the fracture with high pump rate, packing the fracture (near the wellbore) with high concentration loading of sand, implementing fluid quality control, and providing sufficient breakers for the fracturing fluid.
Author(s): G.K. Wong, Shell Development Co.; R.R. Fors, J.S. Casassa, and R.H. Hite, Shell Offshore Inc.; and Jacob Shlyapobersky, Shell Development Co.
Paper Number: SPE 26563