Abstract
Appraisal drilling of a recently discovered Cambrian-aged gas field in Oman is indicating that the field may have significant amounts of gas locked in a challenging deep, hot, and highly pressured reservoir environment. The low porosity and permeability values of the Amin reservoir allow the classification of the reservoir as a tight gas sand. The variability of reservoir properties, both spatially and vertically, makes it difficult to standardize perforation and fracture stimulation design which, in turn, complicates delineation of a development plan for the project. One of the difficulties relates to uncertainty in vertical propagation of hydraulic fractures. Fracture height based on evaluation of radioactive tracer logs indicates that vertical barriers to fracture propagation may relate to specific geologic zones in the reservoir. The mapping of the reservoir zones into undeveloped areas of the field would allow selection of primary and secondary production targets based on the specific physical properties of the individual zones. To assume that no barrier to fracture propagation exists between separate production units may lead to attempts to stimulate them synchronously, which would be disadvantageous for several reasons, such as premature screenouts and incomplete coverage of gas-bearing layers. Reserves booking and allocation can also be jeopardized should the fractures propagate into undesired zones.
