To economically develop unconventional resource plays such as the Eagle Ford Shale in South Texas, multiple complex hydraulic fracturing stages must be executed in the horizontal section of the wellbore. Traditionally, a plug and perforate (P-n-P) process has been used. However, inherent difficulties in the process often limited completion cycle time and created barriers to economic delivery of the hydraulic fracturing treatment.
The Eagle Ford shale in Zavala County, Texas is similar to many high-carbonate-content oil-shale formations. As with other shale plays, the industry has preferred using cemented lateral sections as the primary means of fracture-stage isolation, coupled with the P -n-P horizontal completion technique. This paper explores an alternative completion method, cemented multi-stage sleeves (CMSS), that recently improved efficiency and reduced completion cycle time. This study discusses the process, procedures used, and lessons learned from applying this technology.
The subject well design was similar to most Eagle Ford shale wells. The completion included setting a deep surface casing string at 3030 feet, and then, drilling an 8.75-in. openhole section to MD. A 5.5-in. production casing was then set and cemented into place. The well was drilled to a measured depth of 11,965 feet with a lateral section of 5,913 feet. The well was completed using 15 stages of CMSS to fracture stimulate the entire lateral section. 3.80MM lbm of proppant with 2,901,000 gallons of fluid was used to fracture stimulate the wellbore, averaging 54 bbl/min. The 16 stage stimulation operation was completed in 24 hours with continuous pumping compared to an average of 3 days for P-n-P. The discussion also will show that production was comparable to that of offset wells, thus proving the technique viable for this type of oil-shale formation.