Combined Video and Ultrasonic Measurements for Fracture Diagnostics – Greater Than the Sum of the Parts

Abstract

Downhole imaging technology has been widely utilized in recent years to help diagnose proppant distribution during hydraulic fracturing operations. Abrasion leading to entry hole enlargement provides strong evidence of proppant placement into individual perforations, and treatment volume can be inferred by measuring the magnitude of this erosion. Results from individual perforations are easily aggregated to cluster and stage level to provide information on overall treatment distribution. Two different technologies have been deployed for this purpose – an array of downhole video cameras able to capture a full 360 view of the borehole and, more recently, multi-transducer ultrasonic instruments. These services have been considered competitors, and arguments for and against both technologies have included their relative measurement resolutions and how this impacts result accuracy, along with sensitivity to ‘stick and slip’ effects on toolstring motion. Both technologies are also affected to differing degrees by the well fluid and the presence of diverters and proppant in perforations. The recent introduction of a toolstring able to simultaneously acquire images from both sensor types affords the opportunity to objectively compare results acquired under identical conditions and establish their merits and limitations. The paper considers the underlying physical principles of each of the measurements and reviews in detail the real world results from North American wells that have been logged using both technologies. The aim of the paper is to provide a more complete understanding of the technologies involved, and how they can be viewed as complementary rather than competitive when they are run simultaneously, allowing potential users to make fully informed decisions on when, why and how to deploy them. We will also demonstrate how the information derived from simultaneous application is of greater value than that derived from the individual technologies in isolation, and how this can be applied to further enhance completion design and frac execution for unconventional wells.