Well stimulation by pinpoint multi-stage hydraulic fracturing.
Mohd Azreen Zhafran Omar, Mohamad Khairol Affendy Abdul Razak
Engineering Honours Degree 2009
University of Adelaide
Hydraulic fracturing has been one of the stimulation techniques which are widely used in the oil and gas industry to increase well productivity over the past several decades. However, in recent years, new technologies and techniques for hydraulic fracturing have been advanced which lead to pinpoint multi-stage hydraulic fracturing. Today, this technique has become technically sound and economical method to stimulate large pay intervals. Multi-stage hydraulic fracturing is very similar to conventional hydraulic fracturing except that in this technique, the selected reservoir intervals are divided and fractured stimulated in sequential stages.
Modelling and designing the fracture treatment is very challenging. This report describes the pinpoint multi-stage hydraulic fracturing on two hypothetical sandstone reservoirs based on two-dimensional PKN-C and KGD-C models for a non-Newtonian fracturing fluid. To account for this fluid behaviour, the models have been combined with Carter II solution of the material balance. Integration of these with material balance equations and conductivity models provide great insight and understanding of the fracture treatments conducted in this study. In this report, the fracture treatments are designed based on unified fracture design concept.
Sensitivity analysis has also been conducted to provide greater understanding of how different design parameters such as injection rate, pumping time, power law parameters and fracture half length might impact the dimensionless conductivity. The dimensionless fracture conductivity is one of the indicators to value how successful the fractures treatments are.
Following the sensitivity analysis, a forward production model for both vertical PKN-C and radial horizontal KGD-C fracture models is constructed using Microsoft Excel. The production model considers only for transient flow regime and the aim of this model is to value the fractures over a period of production time rather than the more widely used productivity ratio. Further analysis against single-stage and unstimulated cases are also conducted to assess the merits of the multi-stage fracturing treatments.