Fracture height is typically used by fracturing engineers to calibrate propagation models. Having an accurate height measurement reduces the uncertainty and non uniqueness of fracture pressure matching, better determining placed frac length and width, stress profile across the target zone and its boundaries, and fracture containment. This is particularly important when there is concern with vertical penetration into an unwanted zone, or determining adequate zonal coverage and development of reserves.
In most cases, fracture height is measured by the industry through the use of radioactive tracers which are blended into the proppant at the wellsite. Clearly this can present both a safety and environmental hazard. Furthermore, in some regions of the world operators are prohibited from using these hazardous materials altogether.
This paper presents an innovative, environmentally responsible proppant detection technology and the associated logging techniques for propped height measurement and/or proppant placement. Its non-radioactive nature eliminates the risks and difficulties inherent to other tracing methods. Furthermore, being inert the proppant has no half-life time limitation and is permanently detectable. In this manner it provides the flexibility of conducting multiple post-frac logging at any time after fracturing for initial assessment or to identify intervals for re-stimulation further down the life in the well. The tracing capability doesn’t interfere with the proppant physical properties, crucially its strength and conductivity, assuring adequate performance.
The theory and physical principles of the technology are discussed in detail and supported by case histories of its application in various environments around the world.