Multi-Frac Stage Selection Criteria for Vertical Wells in Thick, Condensate-Rich, Stacked Tight Gas Sandstones
The Barik Formation is a tight to low-end conventional gas reservoir in the Sultanate of Oman. It is a series of stacked sandstones which require massive hydraulic fracturing to produce at economic rates. Recent vertical wells have penetrated a thicker section and correlatable shale/silt barriers between which can act as baffles and barriers to vertical stimulation growth. Potentially resources are under-developed and project value is being eroded. The Formation is modelled in one-dimensional Mechanical Earth Models and the hydraulic fracture treatment simulated to model fracture growth and propagation. Radioactive tracer logs are run in key wells to calibrate the stimulation simulation and Mechanical Earth Models to accurately predict the fracture height growth. Through integration of a multi-disciplinary subsurface and stimulation team a strategy to identify where multiple stages may be required is developed using several inputs: the calibrated stimulation models to determine where fracture height growth may be inadequate to stimulate all in place resource; maps of the gas in place for intervals throughout the section to ensure recoverable resource is in place; rock quality (permeability thickness) from petrophysical rock typing; and fluid variation. To maximise value as well as resource recovery, reservoir simulation using the same inputs determines the optimum timing for any subsequent stages over the course of the well’s producing life. Consideration of reservoir quality to support production as well as variations in condensate gas ratio are incorporated into the model to determine the point of optimal value for the Operator and the Sultanate.
AAPG Datapages/Search and Discovery Article #90328 © 2018 AAPG Middle East Region GTW, Maximizing Asset Value: Integrating Geoscience with Reservoir Management & Facilities Optimization, Muscat, Oman, April 30 – May 1, 2018