STUDY ON HYDRAULIC FRACTURING FLUID SELECTION TO MAXIMIZE EFFECTIVE HYDRAULIC FRACTURE LENGTH

Effective fracture length is often observed to be only a fraction of created fracture length. The poor fracture performance is consequence of poor recovery of fracturing fluid during flowback. This usually happens when water-based fracturing fluid is used in low permeability reservoir. Unrecovered fracturing fluid stays in formation and creates obstruction for hydrocarbon flow. The residue fluid which has become immobile reduces effective fracture length and thus decreases hydrocarbon production. The problem becomes more severe by the water-wet nature of most tight gas reservoirs.
This study is conducted to evaluate performance of liquefied petroleum gas (LPG) as hydraulic fracturing fluid in order to maximize effective fracture length. The term LPG and propane are used interchangeably in this report, however they are all subject to propane. LPG has demonstrated quick and complete fracture fluid recovery, significant production improvements and longer effective fracture length. This is proven by the application of propane based hydraulic fracturing in McCully Gas Field, New Brunswick, Canada. Once well is drawn down during flow back, a large portion of injected LPG may be produced back as gas. The remaining LPG that remains in created fracture dissolved in formation hydrocarbon during production. For fields that has limited storage and handling facilities, return of LPG fracturing fluids can easily be flared during flowback.