Between 1997 and 2001, HS Resources refractured 750 Codell wells, generating a project ROR of 100%. Although well spacing is 40 acres, it appears wells drain 15 to 30 acres. Refracturing is a preferable choice to infill drilling to recover reserves. Added 20 MMBOE reserves (26.6 MBOE/well) by refracturing. Daily production increased 10 bopd and 148 mcfd on average.
Restimulation of wells completed in the Codell formation, a tight gas sand, has proven to be successful in the Wattenberg Field in Colorado. Beginning in 1997, Codell refracturing evolved into a massive program involving hundreds of wells per year. To date, HS Resources has restimulated over 750 Codell wells, increasing reserves and resulting in a project ROR of 100% with finding costs below $4.23 per barrel oil equivalent. This is a case study of the program conducted by HS Resources.
This paper summarizes the refrac program, and its evolution, since its inception. The candidate selection process is examined, as well as geological and operational considerations when restimulating old wells. The evolution of stimulation treatments and fluids are also investigated. The use of 3D fracture simulations, run in real-time during the refracture treatments, and their results are discussed. Finally, both economic and production results are presented.
Author(s): BJ Services, R.N. Sencenbaugh, D.M. Lytle, T.J. Birmingham, J.C. Simmons, HS Resources, Inc.; M.T. Shaefer
Paper Number: SPE 71045