Since no other single expenditure has a greater impact on a tight reservoir's profitability than a hydraulic fracture profitability than a hydraulic fracture treatment, optimal job size selection is imperative. However, the actual reservoir deliverability improvement is usually quite different from the forecasted results. Poor fracturing results are primarily attributed to poor reservoir characterization and reduction of the in-situ fracture conductivity Over the laboratory estimates. To estimate in-situ fracture conductivity, and subsequently enhance the fracturing job design, a historical correlation between job size and wellbore improvement was established. This correlation was based on the post-fracture evaluation of 70 wells in the post-fracture evaluation of 70 wells in the Arkoma basin.
Matching our data with McGuire and Sikora's solution, the retained fracture conductivity ranged from 20% to 50% of laboratory estimates depending on the aggressiveness of proppant placement. The influence of a different thickness in propped height and net pay height was factored into the optimal job sizing process. When modified for this process. When modified for this difference, the PKN modeled FCD was consistent with our field observation for low FCD treatments. A field estimate of the optimal job size was also developed from the historical correlation using a marginal benefit and marginal cost model. Ease of application and historical accuracy are the two major strengths of this approach.
Greater cost effectiveness was achieved when these design considerations were incorporated into the field practice in the Arkoma basin. Since this study surveyed the diverse reservoirs and depositional environments within the Pennsylvanian age, we feel the approach Pennsylvanian age, we feel the approach will be applicable in similar areas.
The Arkoma basin, located in eastern Oklahoma and western Arkansas Fig.1), is one of the most prolific gas producing areas in the United States. producing areas in the United States. The basin extends for approximately 260 miles (418 km) in an east-west direction, and is 20 to 50 miles (32 to 81 km) wide from north to south. This long, arcuate trough is bounded on the south by the Ouachita overthrust belt, and on the north by the Ozark uplift. The stress associated with the Ouachita orogeny and the uplift of the Ozark dome resulted in extreme folding and faulting, which created a series of long, narrow, east-west trending anticlines and synclines.
Most of gas production from the basin is associated with anticlinal or fault-trap structures where sufficient effective porosity was developed. Currently more porosity was developed. Currently more than 30 gas producing horizons have been discovered which range in age from early Pennsylvanian to the Cambrian-Ordovician. Pennsylvanian to the Cambrian-Ordovician. Since the Pre-Pennsylvanian formations (Boone, Penters, Hunton, and Arbuckle) are typically treated with acid fracturing, our emphasis was placed on the hydraulic fracturing treatments of the Atokan and Morrowan sandstone series of the Pennsylvanian age.