This paper presents analyses of fracturing pressures measured, through a dead-string completion, in ten wells located in northern Mexico. Measured pressures are simulated with a novel pseudo-three-dimensional (P3D) model, matching the observed field data. Closure pressure is derived from a combination of a "step-rate" test, performed at the beginning of the treatment, and analysis of the pressure decline observed at the end of the treatment (closure on the proppant provides an upper bound to the closure pressure).
One well is discussed where bottomhole pressures were observed to be higher than the overburden, and indicated a fracture also propagating in the horizontal plane ("T" fracture). Two other wells showed a wellbore screenout as soon as proppant hit the perforated interval. Finally, a well where a tip-screenout was observed is considered.
Conclusions and recommendations are provided regarding the analyses of fracturing pressures and their importance for understanding and improving the fracturing process.