Using a 3D Hydraulic Fracture Simulator to Assess the Impact of Perforation Design on High Near-Wellbore Pressure Loss in the Cooper Basin
EADES, Nicholas, PATTER, Mohit, SMOKAJ, Aldi
Engineering Honours 2015
Australian School of Petroleum
University of Adelaide
Fracture Stimulation in the Cooper Basin has long been challenged by high near-wellbore pressure loss (NWBPL) present in hydraulic fracture treatments. Though many strategies have been applied to either mitigate or prevent this, the industry is still in need of a broadly applicable, economic and practical solution. An approach that has significant potential, and targets NWBPL from its foundation is Perforation Design. Perforation Design has been shown in the past to have a significant effect on the initiation of a fracture and the success of its continued propagation.
A commercial 3D Hydraulic Fracture Simulator has been applied to data from a Cooper Basin Cowralli field well. This vertical well contains tight sand intervals located in the Patchawarra Formation. By introducing an artificial tectonic strain to the Gohfer model, we were more accurately able to create a high stress environment characteristic of high NWBPL conditions.
By running nearly a hundred simulations in Gohfer we were able to acquire enough data to perform a sensitivity analysis, focusing on parameters including perforation diameter, shot density, interval length, number of intervals and coefficient of discharge.
Interpretation of the results obtained through the sensitivity analysis yielded a number of conclusions pertaining to how perforation design within the industry should be adjusted or confirmed that some current practises were optimised. Key findings included stopping boundaries for shot density, interval length and number of intervals, beyond which no added benefit could be attained. Furthermore, the contrast between two different perforating strategies, extended interval and limited entry was characterised and compared. Through these analysis recommendations specific to some Cooper Basin wells were able to be made.
Though many previous authors have suggested that perforation design has limited impact on pressure loss, the analysis performed in this study indicates that there are methods inherent in perforation design that can impact greatly on high NWBPL amongst other pertinent factors. In particular this study has noted a potential for many cost saving strategies that could be applied to future completions.
This is an innovative study which examines the underlying links between perforation design and the resulting near-wellbore pressure loss. It focuses on problematic areas of the Cooper Basin in the hope that by examining these links, useful recommendations can be made to the industry.